WIP

Pass task network at registration time
WIP
2025-11-22 20:56:04 +00:00 · 2025-11-18 17:56:01 +01:00 · 2025-11-18 10:37:54 +01:00 · 2025-11-17 15:48:43 +01:00 · 2025-11-15 10:03:15 +00:00 · 2025-11-13 17:54:01 +00:00
62 changed files with 3705 additions and 858 deletions
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -310,6 +310,7 @@ dependencies = [
 "const-random",
 "getrandom 0.3.3",
 "once_cell",
+ "serde",
 "version_check",
 "zerocopy",
 ]
@@ -344,12 +345,6 @@ version = "0.2.21"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "683d7910e743518b0e34f1186f92494becacb047c7b6bf616c96772180fef923"

-[[package]]
-name = "allocator-api2"
-version = "0.3.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c583acf993cf4245c4acb0a2cc2ab1f9cc097de73411bb6d3647ff6af2b1013d"
-
 [[package]]
 name = "anes"
 version = "0.1.6"
@@ -492,7 +487,7 @@ dependencies = [
 "backoff",
 "base64 0.22.1",
 "bytes",
- "derive_builder 0.20.2",
+ "derive_builder",
 "eventsource-stream",
 "futures",
 "rand 0.8.5",
@@ -589,7 +584,7 @@ source = "git+https://github.com/meilisearch/bbqueue#cbb87cc707b5af415ef203bdaf2

 [[package]]
 name = "benchmarks"
-version = "1.24.0"
+version = "1.26.0"
 dependencies = [
 "anyhow",
 "bumpalo",
@@ -799,7 +794,7 @@ dependencies = [

 [[package]]
 name = "build-info"
-version = "1.24.0"
+version = "1.26.0"
 dependencies = [
 "anyhow",
 "time",
@@ -812,7 +807,7 @@ version = "3.19.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "46c5e41b57b8bba42a04676d81cb89e9ee8e859a1a66f80a5a72e1cb76b34d43"
 dependencies = [
- "allocator-api2 0.2.21",
+ "allocator-api2",
 "serde",
 ]

@@ -822,7 +817,7 @@ version = "0.1.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "4ce682bdc86c2e25ef5cd95881d9d6a1902214eddf74cf9ffea88fe1464377e8"
 dependencies = [
- "allocator-api2 0.2.21",
+ "allocator-api2",
 "bitpacking",
 "bumpalo",
 "hashbrown 0.15.5",
@@ -945,7 +940,7 @@ dependencies = [
 "rand 0.9.2",
 "rand_distr",
 "rayon",
- "safetensors",
+ "safetensors 0.4.5",
 "thiserror 1.0.69",
 "ug",
 "ug-cuda",
@@ -972,7 +967,7 @@ dependencies = [
 "half",
 "num-traits",
 "rayon",
- "safetensors",
+ "safetensors 0.4.5",
 "serde",
 "thiserror 1.0.69",
 ]
@@ -1052,6 +1047,15 @@ version = "0.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "37b2a672a2cb129a2e41c10b1224bb368f9f37a2b16b612598138befd7b37eb5"

+[[package]]
+name = "castaway"
+version = "0.2.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "dec551ab6e7578819132c713a93c022a05d60159dc86e7a7050223577484c55a"
+dependencies = [
+ "rustversion",
+]
+
 [[package]]
 name = "cc"
 version = "1.2.37"
@@ -1214,7 +1218,7 @@ dependencies = [
 "anstream",
 "anstyle",
 "clap_lex",
- "strsim 0.11.1",
+ "strsim",
 ]

 [[package]]
@@ -1253,6 +1257,21 @@ version = "1.0.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b05b61dc5112cbb17e4b6cd61790d9845d13888356391624cbe7e41efeac1e75"

+[[package]]
+name = "compact_str"
+version = "0.9.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3fdb1325a1cece981e8a296ab8f0f9b63ae357bd0784a9faaf548cc7b480707a"
+dependencies = [
+ "castaway",
+ "cfg-if",
+ "itoa",
+ "rustversion",
+ "ryu",
+ "serde",
+ "static_assertions",
+]
+
 [[package]]
 name = "concat-arrays"
 version = "0.1.2"
@@ -1511,38 +1530,14 @@ dependencies = [
 "libloading",
 ]

-[[package]]
-name = "darling"
-version = "0.14.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7b750cb3417fd1b327431a470f388520309479ab0bf5e323505daf0290cd3850"
-dependencies = [
- "darling_core 0.14.4",
- "darling_macro 0.14.4",
-]
-
 [[package]]
 name = "darling"
 version = "0.20.11"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "fc7f46116c46ff9ab3eb1597a45688b6715c6e628b5c133e288e709a29bcb4ee"
 dependencies = [
- "darling_core 0.20.11",
- "darling_macro 0.20.11",
-]
-
-[[package]]
-name = "darling_core"
-version = "0.14.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "109c1ca6e6b7f82cc233a97004ea8ed7ca123a9af07a8230878fcfda9b158bf0"
-dependencies = [
- "fnv",
- "ident_case",
- "proc-macro2",
- "quote",
- "strsim 0.10.0",
- "syn 1.0.109",
+ "darling_core",
+ "darling_macro",
 ]

 [[package]]
@@ -1555,28 +1550,17 @@ dependencies = [
 "ident_case",
 "proc-macro2",
 "quote",
- "strsim 0.11.1",
+ "strsim",
 "syn 2.0.106",
 ]

-[[package]]
-name = "darling_macro"
-version = "0.14.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a4aab4dbc9f7611d8b55048a3a16d2d010c2c8334e46304b40ac1cc14bf3b48e"
-dependencies = [
- "darling_core 0.14.4",
- "quote",
- "syn 1.0.109",
-]
-
 [[package]]
 name = "darling_macro"
 version = "0.20.11"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "fc34b93ccb385b40dc71c6fceac4b2ad23662c7eeb248cf10d529b7e055b6ead"
 dependencies = [
- "darling_core 0.20.11",
+ "darling_core",
 "quote",
 "syn 2.0.106",
 ]
@@ -1586,6 +1570,9 @@ name = "dary_heap"
 version = "0.3.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "04d2cd9c18b9f454ed67da600630b021a8a80bf33f8c95896ab33aaf1c26b728"
+dependencies = [
+ "serde",
+]

 [[package]]
 name = "deadpool"
@@ -1641,34 +1628,13 @@ dependencies = [
 "syn 2.0.106",
 ]

-[[package]]
-name = "derive_builder"
-version = "0.12.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8d67778784b508018359cbc8696edb3db78160bab2c2a28ba7f56ef6932997f8"
-dependencies = [
- "derive_builder_macro 0.12.0",
-]
-
 [[package]]
 name = "derive_builder"
 version = "0.20.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "507dfb09ea8b7fa618fcf76e953f4f5e192547945816d5358edffe39f6f94947"
 dependencies = [
- "derive_builder_macro 0.20.2",
-]
-
-[[package]]
-name = "derive_builder_core"
-version = "0.12.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c11bdc11a0c47bc7d37d582b5285da6849c96681023680b906673c5707af7b0f"
-dependencies = [
- "darling 0.14.4",
- "proc-macro2",
- "quote",
- "syn 1.0.109",
+ "derive_builder_macro",
 ]

 [[package]]
@@ -1677,29 +1643,19 @@ version = "0.20.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "2d5bcf7b024d6835cfb3d473887cd966994907effbe9227e8c8219824d06c4e8"
 dependencies = [
- "darling 0.20.11",
+ "darling",
 "proc-macro2",
 "quote",
 "syn 2.0.106",
 ]

-[[package]]
-name = "derive_builder_macro"
-version = "0.12.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ebcda35c7a396850a55ffeac740804b40ffec779b98fffbb1738f4033f0ee79e"
-dependencies = [
- "derive_builder_core 0.12.0",
- "syn 1.0.109",
-]
-
 [[package]]
 name = "derive_builder_macro"
 version = "0.20.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "ab63b0e2bf4d5928aff72e83a7dace85d7bba5fe12dcc3c5a572d78caffd3f3c"
 dependencies = [
- "derive_builder_core 0.20.2",
+ "derive_builder_core",
 "syn 2.0.106",
 ]

@@ -1738,7 +1694,7 @@ dependencies = [
 "serde-cs",
 "serde_json",
 "serde_urlencoded",
- "strsim 0.11.1",
+ "strsim",
 ]

 [[package]]
@@ -1828,7 +1784,7 @@ dependencies = [

 [[package]]
 name = "dump"
-version = "1.24.0"
+version = "1.26.0"
 dependencies = [
 "anyhow",
 "big_s",
@@ -2071,7 +2027,7 @@ checksum = "37909eebbb50d72f9059c3b6d82c0463f2ff062c9e95845c43a6c9c0355411be"

 [[package]]
 name = "file-store"
-version = "1.24.0"
+version = "1.26.0"
 dependencies = [
 "tempfile",
 "thiserror 2.0.16",
@@ -2093,7 +2049,7 @@ dependencies = [

 [[package]]
 name = "filter-parser"
-version = "1.24.0"
+version = "1.26.0"
 dependencies = [
 "insta",
 "levenshtein_automata",
@@ -2121,7 +2077,7 @@ dependencies = [

 [[package]]
 name = "flatten-serde-json"
-version = "1.24.0"
+version = "1.26.0"
 dependencies = [
 "criterion",
 "serde_json",
@@ -2278,7 +2234,7 @@ dependencies = [

 [[package]]
 name = "fuzzers"
-version = "1.24.0"
+version = "1.26.0"
 dependencies = [
 "arbitrary",
 "bumpalo",
@@ -2804,7 +2760,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e5274423e17b7c9fc20b6e7e208532f9b19825d82dfd615708b70edd83df41f1"
 dependencies = [
 "ahash 0.8.12",
- "allocator-api2 0.2.21",
+ "allocator-api2",
 ]

 [[package]]
@@ -2813,7 +2769,7 @@ version = "0.15.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9229cfe53dfd69f0609a49f65461bd93001ea1ef889cd5529dd176593f5338a1"
 dependencies = [
- "allocator-api2 0.2.21",
+ "allocator-api2",
 "equivalent",
 "foldhash",
 "serde",
@@ -3232,7 +3188,7 @@ dependencies = [

 [[package]]
 name = "index-scheduler"
-version = "1.24.0"
+version = "1.26.0"
 dependencies = [
 "anyhow",
 "backoff",
@@ -3245,7 +3201,7 @@ dependencies = [
 "convert_case 0.8.0",
 "crossbeam-channel",
 "csv",
- "derive_builder 0.20.2",
+ "derive_builder",
 "dump",
 "enum-iterator",
 "file-store",
@@ -3412,15 +3368,6 @@ dependencies = [
 "either",
 ]

-[[package]]
-name = "itertools"
-version = "0.12.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ba291022dbbd398a455acf126c1e341954079855bc60dfdda641363bd6922569"
-dependencies = [
- "either",
-]
-
 [[package]]
 name = "itertools"
 version = "0.13.0"
@@ -3514,7 +3461,7 @@ dependencies = [

 [[package]]
 name = "json-depth-checker"
-version = "1.24.0"
+version = "1.26.0"
 dependencies = [
 "criterion",
 "serde_json",
@@ -3765,7 +3712,7 @@ dependencies = [
 "bincode 2.0.1",
 "byteorder",
 "csv",
- "derive_builder 0.20.2",
+ "derive_builder",
 "encoding",
 "encoding_rs",
 "encoding_rs_io",
@@ -4033,7 +3980,7 @@ checksum = "490cc448043f947bae3cbee9c203358d62dbee0db12107a74be5c30ccfd09771"

 [[package]]
 name = "meili-snap"
-version = "1.24.0"
+version = "1.26.0"
 dependencies = [
 "insta",
 "md5",
@@ -4044,7 +3991,7 @@ dependencies = [

 [[package]]
 name = "meilisearch"
-version = "1.24.0"
+version = "1.26.0"
 dependencies = [
 "actix-cors",
 "actix-http",
@@ -4141,7 +4088,7 @@ dependencies = [

 [[package]]
 name = "meilisearch-auth"
-version = "1.24.0"
+version = "1.26.0"
 dependencies = [
 "base64 0.22.1",
 "enum-iterator",
@@ -4160,7 +4107,7 @@ dependencies = [

 [[package]]
 name = "meilisearch-types"
-version = "1.24.0"
+version = "1.26.0"
 dependencies = [
 "actix-web",
 "anyhow",
@@ -4195,7 +4142,7 @@ dependencies = [

 [[package]]
 name = "meilitool"
-version = "1.24.0"
+version = "1.26.0"
 dependencies = [
 "anyhow",
 "clap",
@@ -4229,9 +4176,8 @@ dependencies = [

 [[package]]
 name = "milli"
-version = "1.24.0"
+version = "1.26.0"
 dependencies = [
- "allocator-api2 0.3.1",
 "arroy",
 "bbqueue",
 "big_s",
@@ -4289,6 +4235,7 @@ dependencies = [
 "roaring 0.10.12",
 "rstar",
 "rustc-hash 2.1.1",
+ "safetensors 0.6.2",
 "serde",
 "serde_json",
 "slice-group-by",
@@ -4810,7 +4757,7 @@ checksum = "9b4f627cb1b25917193a259e49bdad08f671f8d9708acfd5fe0a8c1455d87220"

 [[package]]
 name = "permissive-json-pointer"
-version = "1.24.0"
+version = "1.26.0"
 dependencies = [
 "big_s",
 "serde_json",
@@ -5399,12 +5346,12 @@ dependencies = [

 [[package]]
 name = "rayon-cond"
-version = "0.3.0"
+version = "0.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "059f538b55efd2309c9794130bc149c6a553db90e9d99c2030785c82f0bd7df9"
+checksum = "2964d0cf57a3e7a06e8183d14a8b527195c706b7983549cd5462d5aa3747438f"
 dependencies = [
 "either",
- "itertools 0.11.0",
+ "itertools 0.14.0",
 "rayon",
 ]

@@ -5825,6 +5772,16 @@ dependencies = [
 "serde_json",
 ]

+[[package]]
+name = "safetensors"
+version = "0.6.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "172dd94c5a87b5c79f945c863da53b2ebc7ccef4eca24ac63cca66a41aab2178"
+dependencies = [
+ "serde",
+ "serde_json",
+]
+
 [[package]]
 name = "same-file"
 version = "1.0.6"
@@ -6306,12 +6263,6 @@ dependencies = [
 "indexmap",
 ]

-[[package]]
-name = "strsim"
-version = "0.10.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "73473c0e59e6d5812c5dfe2a064a6444949f089e20eec9a2e5506596494e4623"
-
 [[package]]
 name = "strsim"
 version = "0.11.1"
@@ -6637,21 +6588,24 @@ checksum = "1f3ccbac311fea05f86f61904b462b55fb3df8837a366dfc601a0161d0532f20"

 [[package]]
 name = "tokenizers"
-version = "0.15.2"
-source = "git+https://github.com/huggingface/tokenizers.git?tag=v0.15.2#701a73b869602b5639589d197e805349cdba3223"
+version = "0.22.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6475a27088c98ea96d00b39a9ddfb63780d1ad4cceb6f48374349a96ab2b7842"
 dependencies = [
+ "ahash 0.8.12",
 "aho-corasick",
- "derive_builder 0.12.0",
+ "compact_str",
+ "dary_heap",
+ "derive_builder",
 "esaxx-rs",
- "getrandom 0.2.16",
- "itertools 0.12.1",
- "lazy_static",
+ "getrandom 0.3.3",
+ "itertools 0.14.0",
 "log",
 "macro_rules_attribute",
 "monostate",
 "onig",
 "paste",
- "rand 0.8.5",
+ "rand 0.9.2",
 "rayon",
 "rayon-cond",
 "regex",
@@ -6659,7 +6613,7 @@ dependencies = [
 "serde",
 "serde_json",
 "spm_precompiled",
- "thiserror 1.0.69",
+ "thiserror 2.0.16",
 "unicode-normalization-alignments",
 "unicode-segmentation",
 "unicode_categories",
@@ -7021,7 +6975,7 @@ dependencies = [
 "num-traits",
 "num_cpus",
 "rayon",
- "safetensors",
+ "safetensors 0.4.5",
 "serde",
 "thiserror 1.0.69",
 "tracing",
@@ -7251,7 +7205,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "6b2bf58be11fc9414104c6d3a2e464163db5ef74b12296bda593cac37b6e4777"
 dependencies = [
 "anyhow",
- "derive_builder 0.20.2",
+ "derive_builder",
 "rustversion",
 "vergen-lib",
 ]
@@ -7263,7 +7217,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "4f6ee511ec45098eabade8a0750e76eec671e7fb2d9360c563911336bea9cac1"
 dependencies = [
 "anyhow",
- "derive_builder 0.20.2",
+ "derive_builder",
 "git2",
 "rustversion",
 "time",
@@ -7278,7 +7232,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9b07e6010c0f3e59fcb164e0163834597da68d1f864e2b8ca49f74de01e9c166"
 dependencies = [
 "anyhow",
- "derive_builder 0.20.2",
+ "derive_builder",
 "rustversion",
 ]

@@ -7925,7 +7879,7 @@ dependencies = [

 [[package]]
 name = "xtask"
-version = "1.24.0"
+version = "1.26.0"
 dependencies = [
 "anyhow",
 "build-info",
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -23,7 +23,7 @@ members = [
 ]

 [workspace.package]
-version = "1.24.0"
+version = "1.26.0"
 authors = [
    "Quentin de Quelen <quentin@dequelen.me>",
    "Clément Renault <clement@meilisearch.com>",
--- a/crates/dump/src/lib.rs
+++ b/crates/dump/src/lib.rs
@@ -9,8 +9,9 @@ use meilisearch_types::error::ResponseError;
 use meilisearch_types::keys::Key;
 use meilisearch_types::milli::update::IndexDocumentsMethod;
 use meilisearch_types::settings::Unchecked;
+use meilisearch_types::tasks::enterprise_edition::network::{NetworkTopologyChange, DbTaskNetwork};
 use meilisearch_types::tasks::{
-    Details, ExportIndexSettings, IndexSwap, KindWithContent, Status, Task, TaskId, TaskNetwork,
+    Details, ExportIndexSettings, IndexSwap, KindWithContent, Status, Task, TaskId,
 };
 use meilisearch_types::InstanceUid;
 use roaring::RoaringBitmap;
@@ -95,7 +96,9 @@ pub struct TaskDump {
    )]
    pub finished_at: Option<OffsetDateTime>,
    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub network: Option<TaskNetwork>,
+    pub network: Option<DbTaskNetwork>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub custom_metadata: Option<String>,
 }

 // A `Kind` specific version made for the dump. If modified you may break the dump.
@@ -161,6 +164,7 @@ pub enum KindDump {
    IndexCompaction {
        index_uid: String,
    },
+    NetworkTopologyChange(NetworkTopologyChange),
 }

 impl From<Task> for TaskDump {
@@ -178,6 +182,7 @@ impl From<Task> for TaskDump {
            started_at: task.started_at,
            finished_at: task.finished_at,
            network: task.network,
+            custom_metadata: task.custom_metadata,
        }
    }
 }
@@ -246,6 +251,9 @@ impl From<KindWithContent> for KindDump {
            KindWithContent::IndexCompaction { index_uid } => {
                KindDump::IndexCompaction { index_uid }
            }
+            KindWithContent::NetworkTopologyChange(network_topology_change) => {
+                KindDump::NetworkTopologyChange(network_topology_change)
+            }
        }
    }
 }
@@ -396,6 +404,7 @@ pub(crate) mod test {
                    started_at: Some(datetime!(2022-11-20 0:00 UTC)),
                    finished_at: Some(datetime!(2022-11-21 0:00 UTC)),
                    network: None,
+                    custom_metadata: None,
                },
                None,
            ),
@@ -421,6 +430,7 @@ pub(crate) mod test {
                    started_at: None,
                    finished_at: None,
                    network: None,
+                    custom_metadata: None,
                },
                Some(vec![
                    json!({ "id": 4, "race": "leonberg" }).as_object().unwrap().clone(),
@@ -441,6 +451,7 @@ pub(crate) mod test {
                    started_at: None,
                    finished_at: None,
                    network: None,
+                    custom_metadata: None,
                },
                None,
            ),
@@ -554,7 +565,8 @@ pub(crate) mod test {
        Network {
            local: Some("myself".to_string()),
            remotes: maplit::btreemap! {"other".to_string() => Remote { url: "http://test".to_string(), search_api_key: Some("apiKey".to_string()), write_api_key: Some("docApiKey".to_string()) }},
-            sharding: false,
+            leader: None,
+            version: Default::default(),
        }
    }

--- a/crates/dump/src/reader/compat/v5_to_v6.rs
+++ b/crates/dump/src/reader/compat/v5_to_v6.rs
@@ -164,6 +164,7 @@ impl CompatV5ToV6 {
                    started_at: task_view.started_at,
                    finished_at: task_view.finished_at,
                    network: None,
+                    custom_metadata: None,
                };

                (task, content_file)
--- a/crates/index-scheduler/src/dump.rs
+++ b/crates/index-scheduler/src/dump.rs
@@ -150,6 +150,7 @@ impl<'a> Dump<'a> {
            details: task.details,
            status: task.status,
            network: task.network,
+            custom_metadata: task.custom_metadata,
            kind: match task.kind {
                KindDump::DocumentImport {
                    primary_key,
@@ -237,6 +238,9 @@ impl<'a> Dump<'a> {
                KindDump::IndexCompaction { index_uid } => {
                    KindWithContent::IndexCompaction { index_uid }
                }
+                KindDump::NetworkTopologyChange(network_topology_change) => {
+                    KindWithContent::NetworkTopologyChange(network_topology_change)
+                }
            },
        };

--- a/crates/index-scheduler/src/error.rs
+++ b/crates/index-scheduler/src/error.rs
@@ -3,10 +3,13 @@ use std::fmt::Display;
 use meilisearch_types::batches::BatchId;
 use meilisearch_types::error::{Code, ErrorCode};
 use meilisearch_types::milli::index::RollbackOutcome;
+use meilisearch_types::milli::DocumentId;
+use meilisearch_types::tasks::enterprise_edition::network::ReceiveTaskError;
 use meilisearch_types::tasks::{Kind, Status};
 use meilisearch_types::{heed, milli};
 use reqwest::StatusCode;
 use thiserror::Error;
+use uuid::Uuid;

 use crate::TaskId;

@@ -191,6 +194,15 @@ pub enum Error {
    #[error(transparent)]
    HeedTransaction(heed::Error),

+    #[error("No network topology change task is currently enqueued or processing")]
+    ImportTaskWithoutNetworkTask,
+    #[error("The network task version (`{network_task}`) does not match the import task version (`{import_task}`)")]
+    NetworkVersionMismatch { network_task: Uuid, import_task: Uuid },
+    #[error("The import task emanates from an unknown remote `{0}`")]
+    ImportTaskUnknownRemote(String),
+    #[error("The import task with key `{0}` was already received")]
+    ImportTaskAlreadyReceived(DocumentId),
+
    #[cfg(test)]
    #[error("Planned failure for tests.")]
    PlannedFailure,
@@ -248,6 +260,10 @@ impl Error {
            | Error::Persist(_)
            | Error::FeatureNotEnabled(_)
            | Error::Export(_)
+            | Error::ImportTaskWithoutNetworkTask
+            | Error::NetworkVersionMismatch { .. }
+            | Error::ImportTaskAlreadyReceived(_)
+            | Error::ImportTaskUnknownRemote(_)
            | Error::Anyhow(_) => true,
            Error::CreateBatch(_)
            | Error::CorruptedTaskQueue
@@ -307,6 +323,10 @@ impl ErrorCode for Error {
            Error::TaskDeletionWithEmptyQuery => Code::MissingTaskFilters,
            Error::TaskCancelationWithEmptyQuery => Code::MissingTaskFilters,
            Error::NoSpaceLeftInTaskQueue => Code::NoSpaceLeftOnDevice,
+            Error::ImportTaskWithoutNetworkTask => Code::ImportTaskWithoutNetworkTask,
+            Error::NetworkVersionMismatch { .. } => Code::NetworkVersionMismatch,
+            Error::ImportTaskAlreadyReceived(_) => Code::ImportTaskAlreadyReceived,
+            Error::ImportTaskUnknownRemote(_) => Code::ImportTaskUnknownRemote,
            Error::S3Error { status, .. } if status.is_client_error() => {
                Code::InvalidS3SnapshotRequest
            }
@@ -345,3 +365,12 @@ impl ErrorCode for Error {
        }
    }
 }
+
+impl From<ReceiveTaskError> for Error {
+    fn from(value: ReceiveTaskError) -> Self {
+        match value {
+            ReceiveTaskError::UnknownRemote(unknown) => Error::ImportTaskUnknownRemote(unknown),
+            ReceiveTaskError::DuplicateTask(dup) => Error::ImportTaskAlreadyReceived(dup),
+        }
+    }
+}
--- a/crates/index-scheduler/src/index_mapper/mod.rs
+++ b/crates/index-scheduler/src/index_mapper/mod.rs
@@ -361,6 +361,11 @@ impl IndexMapper {
        Ok(())
    }

+    /// The number of indexes in the database
+    pub fn index_count(&self, rtxn: &RoTxn) -> Result<u64> {
+        Ok(self.index_mapping.len(rtxn)?)
+    }
+
    /// Return an index, may open it if it wasn't already opened.
    pub fn index(&self, rtxn: &RoTxn, name: &str) -> Result<Index> {
        if let Some((current_name, current_index)) =
--- a/crates/index-scheduler/src/insta_snapshot.rs
+++ b/crates/index-scheduler/src/insta_snapshot.rs
@@ -21,7 +21,7 @@ pub fn snapshot_index_scheduler(scheduler: &IndexScheduler) -> String {
    let IndexScheduler {
        cleanup_enabled: _,
        experimental_no_edition_2024_for_dumps: _,
-        processing_tasks,
+        runtime_tasks,
        env,
        version,
        queue,
@@ -50,7 +50,7 @@ pub fn snapshot_index_scheduler(scheduler: &IndexScheduler) -> String {
        snap.push_str(&format!("index scheduler running on version {indx_sched_version:?}\n"));
    }

-    let processing = processing_tasks.read().unwrap().clone();
+    let processing = runtime_tasks.read().unwrap().processing.clone();
    snap.push_str(&format!("### Autobatching Enabled = {}\n", scheduler.autobatching_enabled));
    snap.push_str(&format!(
        "### Processing batch {:?}:\n",
@@ -232,6 +232,7 @@ pub fn snapshot_task(task: &Task) -> String {
        status,
        kind,
        network,
+        custom_metadata,
    } = task;
    snap.push('{');
    snap.push_str(&format!("uid: {uid}, "));
@@ -252,6 +253,9 @@ pub fn snapshot_task(task: &Task) -> String {
    if let Some(network) = network {
        snap.push_str(&format!("network: {network:?}, "))
    }
+    if let Some(custom_metadata) = custom_metadata {
+        snap.push_str(&format!("custom_metadata: {custom_metadata:?}"))
+    }

    snap.push('}');
    snap
@@ -321,6 +325,9 @@ fn snapshot_details(d: &Details) -> String {
        Details::IndexCompaction { index_uid, pre_compaction_size, post_compaction_size } => {
            format!("{{ index_uid: {index_uid:?}, pre_compaction_size: {pre_compaction_size:?}, post_compaction_size: {post_compaction_size:?} }}")
        }
+        Details::NetworkTopologyChange { moved_documents, received_documents, message } => {
+            format!("{{ moved_documents: {moved_documents:?}, received_documents: {received_documents:?}, message: {message:?}")
+        }
    }
 }

--- a/crates/index-scheduler/src/lib.rs
+++ b/crates/index-scheduler/src/lib.rs
@@ -68,10 +68,10 @@ use meilisearch_types::milli::vector::{
 };
 use meilisearch_types::milli::{self, Index};
 use meilisearch_types::task_view::TaskView;
-use meilisearch_types::tasks::{KindWithContent, Task, TaskNetwork};
+use meilisearch_types::tasks::enterprise_edition::network::{DbTaskNetwork, TaskNetwork};
+use meilisearch_types::tasks::{KindWithContent, Task};
 use meilisearch_types::webhooks::{Webhook, WebhooksDumpView, WebhooksView};
 use milli::vector::db::IndexEmbeddingConfig;
-use processing::ProcessingTasks;
 pub use queue::Query;
 use queue::Queue;
 use roaring::RoaringBitmap;
@@ -82,6 +82,7 @@ use uuid::Uuid;
 use versioning::Versioning;

 use crate::index_mapper::IndexMapper;
+use crate::processing::RuntimeTasks;
 use crate::utils::clamp_to_page_size;

 pub(crate) type BEI128 = I128<BE>;
@@ -163,7 +164,7 @@ pub struct IndexScheduler {
    pub(crate) env: Env<WithoutTls>,

    /// The list of tasks currently processing
-    pub(crate) processing_tasks: Arc<RwLock<ProcessingTasks>>,
+    pub(crate) runtime_tasks: Arc<RwLock<RuntimeTasks>>,

    /// A database containing only the version of the index-scheduler
    pub version: versioning::Versioning,
@@ -225,7 +226,7 @@ impl IndexScheduler {
    fn private_clone(&self) -> IndexScheduler {
        IndexScheduler {
            env: self.env.clone(),
-            processing_tasks: self.processing_tasks.clone(),
+            runtime_tasks: self.runtime_tasks.clone(),
            version: self.version.clone(),
            queue: self.queue.private_clone(),
            scheduler: self.scheduler.private_clone(),
@@ -331,7 +332,7 @@ impl IndexScheduler {
        wtxn.commit()?;

        Ok(Self {
-            processing_tasks: Arc::new(RwLock::new(ProcessingTasks::new())),
+            runtime_tasks: Arc::new(RwLock::new(RuntimeTasks::new())),
            version,
            queue,
            scheduler: Scheduler::new(&options, auth_env),
@@ -639,19 +640,19 @@ impl IndexScheduler {
    /// 3. The number of times the properties appeared.
    pub fn get_stats(&self) -> Result<BTreeMap<String, BTreeMap<String, u64>>> {
        let rtxn = self.read_txn()?;
-        self.queue.get_stats(&rtxn, &self.processing_tasks.read().unwrap())
+        self.queue.get_stats(&rtxn, &self.runtime_tasks.read().unwrap().processing)
    }

    // Return true if there is at least one task that is processing.
    pub fn is_task_processing(&self) -> Result<bool> {
-        Ok(!self.processing_tasks.read().unwrap().processing.is_empty())
+        Ok(!self.runtime_tasks.read().unwrap().processing.processing.is_empty())
    }

    /// Return true iff there is at least one task associated with this index
    /// that is processing.
    pub fn is_index_processing(&self, index: &str) -> Result<bool> {
        let rtxn = self.env.read_txn()?;
-        let processing_tasks = self.processing_tasks.read().unwrap().processing.clone();
+        let processing_tasks = self.runtime_tasks.read().unwrap().processing.processing.clone();
        let index_tasks = self.queue.tasks.index_tasks(&rtxn, index)?;
        let nbr_index_processing_tasks = processing_tasks.intersection_len(&index_tasks);
        Ok(nbr_index_processing_tasks > 0)
@@ -677,8 +678,8 @@ impl IndexScheduler {
        filters: &meilisearch_auth::AuthFilter,
    ) -> Result<(Vec<Task>, u64)> {
        let rtxn = self.read_txn()?;
-        let processing = self.processing_tasks.read().unwrap();
-        self.queue.get_tasks_from_authorized_indexes(&rtxn, query, filters, &processing)
+        let processing = &self.runtime_tasks.read().unwrap().processing;
+        self.queue.get_tasks_from_authorized_indexes(&rtxn, query, filters, processing)
    }

    /// Return the task ids matching the query along with the total number of tasks
@@ -696,18 +697,18 @@ impl IndexScheduler {
        filters: &meilisearch_auth::AuthFilter,
    ) -> Result<(RoaringBitmap, u64)> {
        let rtxn = self.read_txn()?;
-        let processing = self.processing_tasks.read().unwrap();
-        self.queue.get_task_ids_from_authorized_indexes(&rtxn, query, filters, &processing)
+        let processing = &self.runtime_tasks.read().unwrap().processing;
+        self.queue.get_task_ids_from_authorized_indexes(&rtxn, query, filters, processing)
    }

-    pub fn set_task_network(&self, task_id: TaskId, network: TaskNetwork) -> Result<()> {
+    pub fn set_task_network(&self, task_id: TaskId, network: DbTaskNetwork) -> Result<Task> {
        let mut wtxn = self.env.write_txn()?;
        let mut task =
            self.queue.tasks.get_task(&wtxn, task_id)?.ok_or(Error::TaskNotFound(task_id))?;
        task.network = Some(network);
        self.queue.tasks.all_tasks.put(&mut wtxn, &task_id, &task)?;
        wtxn.commit()?;
-        Ok(())
+        Ok(task)
    }

    /// Return the batches matching the query from the user's point of view along
@@ -725,8 +726,8 @@ impl IndexScheduler {
        filters: &meilisearch_auth::AuthFilter,
    ) -> Result<(Vec<Batch>, u64)> {
        let rtxn = self.read_txn()?;
-        let processing = self.processing_tasks.read().unwrap();
-        self.queue.get_batches_from_authorized_indexes(&rtxn, query, filters, &processing)
+        let processing = &self.runtime_tasks.read().unwrap().processing;
+        self.queue.get_batches_from_authorized_indexes(&rtxn, query, filters, processing)
    }

    /// Return the batch ids matching the query along with the total number of batches
@@ -744,8 +745,8 @@ impl IndexScheduler {
        filters: &meilisearch_auth::AuthFilter,
    ) -> Result<(RoaringBitmap, u64)> {
        let rtxn = self.read_txn()?;
-        let processing = self.processing_tasks.read().unwrap();
-        self.queue.get_batch_ids_from_authorized_indexes(&rtxn, query, filters, &processing)
+        let processing = &self.runtime_tasks.read().unwrap().processing;
+        self.queue.get_batch_ids_from_authorized_indexes(&rtxn, query, filters, processing)
    }

    /// Register a new task in the scheduler.
@@ -756,6 +757,31 @@ impl IndexScheduler {
        kind: KindWithContent,
        task_id: Option<TaskId>,
        dry_run: bool,
+    ) -> Result<Task> {
+        self.register_with_custom_metadata(kind, task_id, None, dry_run, None)
+    }
+
+    /// Register a new task in the scheduler, with metadata.
+    ///
+    /// If it fails and data was associated with the task, it tries to delete the associated data.
+    ///
+    /// # Parameters
+    ///
+    /// - task_network: network of the task to check.
+    ///
+    /// If the task is an import task, only accept it if:
+    ///
+    /// 1. There is an ongoing network topology change task
+    /// 2. The task to register matches the network version of the network topology change task
+    ///
+    /// Always accept the task if it is not an import task.
+    pub fn register_with_custom_metadata(
+        &self,
+        kind: KindWithContent,
+        task_id: Option<TaskId>,
+        custom_metadata: Option<String>,
+        dry_run: bool,
+        task_network: Option<TaskNetwork>,
    ) -> Result<Task> {
        // if the task doesn't delete or cancel anything and 40% of the task queue is full, we must refuse to enqueue the incoming task
        if !matches!(&kind, KindWithContent::TaskDeletion { tasks, .. } | KindWithContent::TaskCancelation { tasks, .. } if !tasks.is_empty())
@@ -766,13 +792,86 @@ impl IndexScheduler {
        }

        let mut wtxn = self.env.write_txn()?;
-        let task = self.queue.register(&mut wtxn, &kind, task_id, dry_run)?;
+
+        if let Some(TaskNetwork::Import { import_from, network_change, metadata }) = &task_network {
+            let mut network_tasks = self
+                .queue
+                .tasks
+                .get_kind(&wtxn, meilisearch_types::tasks::Kind::NetworkTopologyChange)?;
+            if network_tasks.is_empty() {
+                return Err(Error::ImportTaskWithoutNetworkTask);
+            }
+
+            let network_task = {
+                let processing = self.runtime_tasks.read().unwrap().processing.processing.clone();
+                if processing.is_disjoint(&network_tasks) {
+                    let enqueued = self
+                        .queue
+                        .tasks
+                        .get_status(&wtxn, meilisearch_types::tasks::Status::Enqueued)?;
+
+                    network_tasks &= enqueued;
+                    if let Some(network_task) = network_tasks.into_iter().next() {
+                        network_task
+                    } else {
+                        return Err(Error::ImportTaskWithoutNetworkTask);
+                    }
+                } else {
+                    network_tasks &= &*processing;
+                    network_tasks.into_iter().next().unwrap()
+                }
+            };
+
+            let mut network_task = self.queue.tasks.get_task(&wtxn, network_task)?.unwrap();
+            let network_task_version = network_task
+                .network
+                .as_ref()
+                .map(|network| network.network_version())
+                .unwrap_or_default();
+            if network_task_version != network_change.network_version {
+                return Err(Error::NetworkVersionMismatch {
+                    network_task: network_task_version,
+                    import_task: network_change.network_version,
+                });
+            }
+
+            let KindWithContent::NetworkTopologyChange(network_topology_change) =
+                &mut network_task.kind
+            else {
+                return Err(Error::CorruptedTaskQueue);
+            };
+
+            network_topology_change.receive_remote_task(
+                &import_from.remote_name,
+                &import_from.index_name,
+                metadata.task_key,
+                import_from.document_count,
+                metadata.index_count,
+                metadata.total_index_documents,
+            )?;
+
+            self.queue.tasks.update_task(&mut wtxn, &mut network_task)?;
+        }
+
+        let task = self.queue.register(
+            &mut wtxn,
+            &kind,
+            task_id,
+            custom_metadata,
+            dry_run,
+            task_network.map(DbTaskNetwork::from),
+        )?;

        // If the registered task is a task cancelation
        // we inform the processing tasks to stop (if necessary).
        if let KindWithContent::TaskCancelation { tasks, .. } = kind {
            let tasks_to_cancel = RoaringBitmap::from_iter(tasks);
-            if self.processing_tasks.read().unwrap().must_cancel_processing_tasks(&tasks_to_cancel)
+            if self
+                .runtime_tasks
+                .read()
+                .unwrap()
+                .processing
+                .must_cancel_processing_tasks(&tasks_to_cancel)
            {
                self.scheduler.must_stop_processing.must_stop();
            }
--- a/crates/index-scheduler/src/processing.rs
+++ b/crates/index-scheduler/src/processing.rs
@@ -6,6 +6,28 @@ use roaring::RoaringBitmap;

 use crate::utils::ProcessingBatch;

+pub struct RuntimeTasks {
+    pub processing: ProcessingTasks,
+    pub enqueued_network: EnqueuedNetworkTasks,
+}
+impl RuntimeTasks {
+    pub(crate) fn new() -> Self {
+        Self { processing: ProcessingTasks::new(), enqueued_network: Default::default() }
+    }
+}
+
+#[derive(Default)]
+pub struct EnqueuedNetworkTasks {
+    tasks: RoaringBitmap,
+}
+
+impl EnqueuedNetworkTasks {
+    pub fn swap(&mut self, mut new: RoaringBitmap) -> RoaringBitmap {
+        std::mem::swap(&mut self.tasks, &mut new);
+        new
+    }
+}
+
 #[derive(Clone, Default)]
 pub struct ProcessingTasks {
    pub batch: Option<Arc<ProcessingBatch>>,
--- a/crates/index-scheduler/src/queue/batches_test.rs
+++ b/crates/index-scheduler/src/queue/batches_test.rs
@@ -26,7 +26,7 @@ fn query_batches_from_and_limit() {
    handle.advance_n_successful_batches(3);
    snapshot!(snapshot_index_scheduler(&index_scheduler), name: "processed_all_tasks");

-    let proc = index_scheduler.processing_tasks.read().unwrap().clone();
+    let proc = index_scheduler.runtime_tasks.read().unwrap().processing.clone();
    let rtxn = index_scheduler.env.read_txn().unwrap();
    let query = Query { limit: Some(0), ..Default::default() };
    let (batches, _) = index_scheduler
@@ -359,7 +359,7 @@ fn query_batches_special_rules() {
    handle.advance_till([Start, BatchCreated]);

    let rtxn = index_scheduler.env.read_txn().unwrap();
-    let proc = index_scheduler.processing_tasks.read().unwrap().clone();
+    let proc = index_scheduler.runtime_tasks.read().unwrap().processing.clone();

    let query = Query { index_uids: Some(vec!["catto".to_owned()]), ..Default::default() };
    let (batches, _) = index_scheduler
--- a/crates/index-scheduler/src/queue/mod.rs
+++ b/crates/index-scheduler/src/queue/mod.rs
@@ -15,6 +15,7 @@ use file_store::FileStore;
 use meilisearch_types::batches::BatchId;
 use meilisearch_types::heed::{Database, Env, RoTxn, RwTxn, WithoutTls};
 use meilisearch_types::milli::{CboRoaringBitmapCodec, BEU32};
+use meilisearch_types::tasks::enterprise_edition::network::DbTaskNetwork;
 use meilisearch_types::tasks::{Kind, KindWithContent, Status, Task};
 use roaring::RoaringBitmap;
 use time::format_description::well_known::Rfc3339;
@@ -257,7 +258,9 @@ impl Queue {
        wtxn: &mut RwTxn,
        kind: &KindWithContent,
        task_id: Option<TaskId>,
+        custom_metadata: Option<String>,
        dry_run: bool,
+        network: Option<DbTaskNetwork>,
    ) -> Result<Task> {
        let next_task_id = self.tasks.next_task_id(wtxn)?;

@@ -279,7 +282,8 @@ impl Queue {
            details: kind.default_details(),
            status: Status::Enqueued,
            kind: kind.clone(),
-            network: None,
+            network,
+            custom_metadata,
        };
        // For deletion and cancelation tasks, we want to make extra sure that they
        // don't attempt to delete/cancel tasks that are newer than themselves.
@@ -344,7 +348,9 @@ impl Queue {
                tasks: to_delete,
            },
            None,
+            None,
            false,
+            None,
        )?;

        Ok(())
--- a/crates/index-scheduler/src/queue/tasks_test.rs
+++ b/crates/index-scheduler/src/queue/tasks_test.rs
@@ -27,7 +27,7 @@ fn query_tasks_from_and_limit() {
    snapshot!(snapshot_index_scheduler(&index_scheduler), name: "processed_all_tasks");

    let rtxn = index_scheduler.env.read_txn().unwrap();
-    let processing = index_scheduler.processing_tasks.read().unwrap();
+    let processing = &index_scheduler.runtime_tasks.read().unwrap().processing;
    let query = Query { limit: Some(0), ..Default::default() };
    let (tasks, _) = index_scheduler
        .queue
@@ -317,7 +317,7 @@ fn query_tasks_special_rules() {
    handle.advance_till([Start, BatchCreated]);

    let rtxn = index_scheduler.env.read_txn().unwrap();
-    let proc = index_scheduler.processing_tasks.read().unwrap();
+    let proc = &index_scheduler.runtime_tasks.read().unwrap().processing;

    let query = Query { index_uids: Some(vec!["catto".to_owned()]), ..Default::default() };
    let (tasks, _) = index_scheduler
@@ -414,7 +414,7 @@ fn query_tasks_canceled_by() {
    snapshot!(snapshot_index_scheduler(&index_scheduler), name: "start");

    let rtxn = index_scheduler.read_txn().unwrap();
-    let proc = index_scheduler.processing_tasks.read().unwrap();
+    let proc = &index_scheduler.runtime_tasks.read().unwrap().processing;
    let query = Query { canceled_by: Some(vec![task_cancelation.uid]), ..Query::default() };
    let (tasks, _) = index_scheduler
        .queue
--- a/crates/index-scheduler/src/queue/test.rs
+++ b/crates/index-scheduler/src/queue/test.rs
@@ -203,26 +203,30 @@ fn test_disable_auto_deletion_of_tasks() {
        )
        .unwrap();

-    let rtxn = index_scheduler.env.read_txn().unwrap();
-    let proc = index_scheduler.processing_tasks.read().unwrap();
-    let tasks =
-        index_scheduler.queue.get_task_ids(&rtxn, &Query { ..Default::default() }, &proc).unwrap();
-    let tasks = index_scheduler.queue.tasks.get_existing_tasks(&rtxn, tasks).unwrap();
-    snapshot!(json_string!(tasks, { "[].enqueuedAt" => "[date]", "[].startedAt" => "[date]", "[].finishedAt" => "[date]" }), name: "task_queue_is_full");
-    drop(rtxn);
-    drop(proc);
+    {
+        let rtxn = index_scheduler.env.read_txn().unwrap();
+        let proc = &index_scheduler.runtime_tasks.read().unwrap().processing;
+        let tasks = index_scheduler
+            .queue
+            .get_task_ids(&rtxn, &Query { ..Default::default() }, &proc)
+            .unwrap();
+        let tasks = index_scheduler.queue.tasks.get_existing_tasks(&rtxn, tasks).unwrap();
+        snapshot!(json_string!(tasks, { "[].enqueuedAt" => "[date]", "[].startedAt" => "[date]", "[].finishedAt" => "[date]" }), name: "task_queue_is_full");
+    }

    // now we're above the max number of tasks
    // and if we try to advance in the tick function no new task deletion should be enqueued
    handle.advance_till([Start, BatchCreated]);
-    let rtxn = index_scheduler.env.read_txn().unwrap();
-    let proc = index_scheduler.processing_tasks.read().unwrap();
-    let tasks =
-        index_scheduler.queue.get_task_ids(&rtxn, &Query { ..Default::default() }, &proc).unwrap();
-    let tasks = index_scheduler.queue.tasks.get_existing_tasks(&rtxn, tasks).unwrap();
-    snapshot!(json_string!(tasks, { "[].enqueuedAt" => "[date]", "[].startedAt" => "[date]", "[].finishedAt" => "[date]", ".**.original_filter" => "[filter]", ".**.query" => "[query]" }), name: "task_deletion_have_not_been_enqueued");
-    drop(rtxn);
-    drop(proc);
+    {
+        let rtxn = index_scheduler.env.read_txn().unwrap();
+        let proc = &index_scheduler.runtime_tasks.read().unwrap().processing;
+        let tasks = index_scheduler
+            .queue
+            .get_task_ids(&rtxn, &Query { ..Default::default() }, &proc)
+            .unwrap();
+        let tasks = index_scheduler.queue.tasks.get_existing_tasks(&rtxn, tasks).unwrap();
+        snapshot!(json_string!(tasks, { "[].enqueuedAt" => "[date]", "[].startedAt" => "[date]", "[].finishedAt" => "[date]", ".**.original_filter" => "[filter]", ".**.query" => "[query]" }), name: "task_deletion_have_not_been_enqueued");
+    }
 }

 #[test]
@@ -267,59 +271,69 @@ fn test_auto_deletion_of_tasks() {
        )
        .unwrap();

-    let rtxn = index_scheduler.env.read_txn().unwrap();
-    let proc = index_scheduler.processing_tasks.read().unwrap();
-    let tasks =
-        index_scheduler.queue.get_task_ids(&rtxn, &Query { ..Default::default() }, &proc).unwrap();
-    let tasks = index_scheduler.queue.tasks.get_existing_tasks(&rtxn, tasks).unwrap();
-    snapshot!(json_string!(tasks, { "[].enqueuedAt" => "[date]", "[].startedAt" => "[date]", "[].finishedAt" => "[date]" }), name: "task_queue_is_full");
-    drop(rtxn);
-    drop(proc);
+    {
+        let rtxn = index_scheduler.env.read_txn().unwrap();
+        let proc = &index_scheduler.runtime_tasks.read().unwrap().processing;
+        let tasks = index_scheduler
+            .queue
+            .get_task_ids(&rtxn, &Query { ..Default::default() }, &proc)
+            .unwrap();
+        let tasks = index_scheduler.queue.tasks.get_existing_tasks(&rtxn, tasks).unwrap();
+        snapshot!(json_string!(tasks, { "[].enqueuedAt" => "[date]", "[].startedAt" => "[date]", "[].finishedAt" => "[date]" }), name: "task_queue_is_full");
+    }

-    // now we're above the max number of tasks
-    // and if we try to advance in the tick function a new task deletion should be enqueued
-    handle.advance_till([Start, BatchCreated]);
-    let rtxn = index_scheduler.env.read_txn().unwrap();
-    let proc = index_scheduler.processing_tasks.read().unwrap();
-    let tasks =
-        index_scheduler.queue.get_task_ids(&rtxn, &Query { ..Default::default() }, &proc).unwrap();
-    let tasks = index_scheduler.queue.tasks.get_existing_tasks(&rtxn, tasks).unwrap();
-    snapshot!(json_string!(tasks, { "[].enqueuedAt" => "[date]", "[].startedAt" => "[date]", "[].finishedAt" => "[date]", ".**.original_filter" => "[filter]", ".**.query" => "[query]" }), name: "task_deletion_have_been_enqueued");
-    drop(rtxn);
-    drop(proc);
+    {
+        // now we're above the max number of tasks
+        // and if we try to advance in the tick function a new task deletion should be enqueued
+        handle.advance_till([Start, BatchCreated]);
+        let rtxn = index_scheduler.env.read_txn().unwrap();
+        let proc = &index_scheduler.runtime_tasks.read().unwrap().processing;
+        let tasks = index_scheduler
+            .queue
+            .get_task_ids(&rtxn, &Query { ..Default::default() }, &proc)
+            .unwrap();
+        let tasks = index_scheduler.queue.tasks.get_existing_tasks(&rtxn, tasks).unwrap();
+        snapshot!(json_string!(tasks, { "[].enqueuedAt" => "[date]", "[].startedAt" => "[date]", "[].finishedAt" => "[date]", ".**.original_filter" => "[filter]", ".**.query" => "[query]" }), name: "task_deletion_have_been_enqueued");
+    }

-    handle.advance_till([InsideProcessBatch, ProcessBatchSucceeded, AfterProcessing]);
-    let rtxn = index_scheduler.env.read_txn().unwrap();
-    let proc = index_scheduler.processing_tasks.read().unwrap();
-    let tasks =
-        index_scheduler.queue.get_task_ids(&rtxn, &Query { ..Default::default() }, &proc).unwrap();
-    let tasks = index_scheduler.queue.tasks.get_existing_tasks(&rtxn, tasks).unwrap();
-    snapshot!(json_string!(tasks, { "[].enqueuedAt" => "[date]", "[].startedAt" => "[date]", "[].finishedAt" => "[date]", ".**.original_filter" => "[filter]", ".**.query" => "[query]" }), name: "task_deletion_have_been_processed");
-    drop(rtxn);
-    drop(proc);
+    {
+        handle.advance_till([InsideProcessBatch, ProcessBatchSucceeded, AfterProcessing]);
+        let rtxn = index_scheduler.env.read_txn().unwrap();
+        let proc = &index_scheduler.runtime_tasks.read().unwrap().processing;
+        let tasks = index_scheduler
+            .queue
+            .get_task_ids(&rtxn, &Query { ..Default::default() }, &proc)
+            .unwrap();
+        let tasks = index_scheduler.queue.tasks.get_existing_tasks(&rtxn, tasks).unwrap();
+        snapshot!(json_string!(tasks, { "[].enqueuedAt" => "[date]", "[].startedAt" => "[date]", "[].finishedAt" => "[date]", ".**.original_filter" => "[filter]", ".**.query" => "[query]" }), name: "task_deletion_have_been_processed");
+    }

    handle.advance_one_failed_batch();
    // a new task deletion has been enqueued
    handle.advance_one_successful_batch();
-    let rtxn = index_scheduler.env.read_txn().unwrap();
-    let proc = index_scheduler.processing_tasks.read().unwrap();
-    let tasks =
-        index_scheduler.queue.get_task_ids(&rtxn, &Query { ..Default::default() }, &proc).unwrap();
-    let tasks = index_scheduler.queue.tasks.get_existing_tasks(&rtxn, tasks).unwrap();
-    snapshot!(json_string!(tasks, { "[].enqueuedAt" => "[date]", "[].startedAt" => "[date]", "[].finishedAt" => "[date]", ".**.original_filter" => "[filter]", ".**.query" => "[query]" }), name: "after_the_second_task_deletion");
-    drop(rtxn);
-    drop(proc);
+    {
+        let rtxn = index_scheduler.env.read_txn().unwrap();
+        let proc = &index_scheduler.runtime_tasks.read().unwrap().processing;
+        let tasks = index_scheduler
+            .queue
+            .get_task_ids(&rtxn, &Query { ..Default::default() }, &proc)
+            .unwrap();
+        let tasks = index_scheduler.queue.tasks.get_existing_tasks(&rtxn, tasks).unwrap();
+        snapshot!(json_string!(tasks, { "[].enqueuedAt" => "[date]", "[].startedAt" => "[date]", "[].finishedAt" => "[date]", ".**.original_filter" => "[filter]", ".**.query" => "[query]" }), name: "after_the_second_task_deletion");
+    }

    handle.advance_one_failed_batch();
    handle.advance_one_successful_batch();
-    let rtxn = index_scheduler.env.read_txn().unwrap();
-    let proc = index_scheduler.processing_tasks.read().unwrap();
-    let tasks =
-        index_scheduler.queue.get_task_ids(&rtxn, &Query { ..Default::default() }, &proc).unwrap();
-    let tasks = index_scheduler.queue.tasks.get_existing_tasks(&rtxn, tasks).unwrap();
-    snapshot!(json_string!(tasks, { "[].enqueuedAt" => "[date]", "[].startedAt" => "[date]", "[].finishedAt" => "[date]", ".**.original_filter" => "[filter]", ".**.query" => "[query]" }), name: "everything_has_been_processed");
-    drop(rtxn);
-    drop(proc);
+    {
+        let rtxn = index_scheduler.env.read_txn().unwrap();
+        let proc = &index_scheduler.runtime_tasks.read().unwrap().processing;
+        let tasks = index_scheduler
+            .queue
+            .get_task_ids(&rtxn, &Query { ..Default::default() }, &proc)
+            .unwrap();
+        let tasks = index_scheduler.queue.tasks.get_existing_tasks(&rtxn, tasks).unwrap();
+        snapshot!(json_string!(tasks, { "[].enqueuedAt" => "[date]", "[].startedAt" => "[date]", "[].finishedAt" => "[date]", ".**.original_filter" => "[filter]", ".**.query" => "[query]" }), name: "everything_has_been_processed");
+    }
 }

 #[test]
--- a/crates/index-scheduler/src/scheduler/autobatcher.rs
+++ b/crates/index-scheduler/src/scheduler/autobatcher.rs
@@ -74,6 +74,7 @@ impl From<KindWithContent> for AutobatchKind {
            | KindWithContent::DumpCreation { .. }
            | KindWithContent::Export { .. }
            | KindWithContent::UpgradeDatabase { .. }
+            | KindWithContent::NetworkTopologyChange(_)
            | KindWithContent::SnapshotCreation => {
                panic!("The autobatcher should never be called with tasks with special priority or that don't apply to an index.")
            }
--- a/crates/index-scheduler/src/scheduler/create_batch.rs
+++ b/crates/index-scheduler/src/scheduler/create_batch.rs
@@ -4,6 +4,7 @@ use std::io::ErrorKind;
 use meilisearch_types::heed::RoTxn;
 use meilisearch_types::milli::update::IndexDocumentsMethod;
 use meilisearch_types::settings::{Settings, Unchecked};
+use meilisearch_types::tasks::enterprise_edition::network::NetworkTopologyState;
 use meilisearch_types::tasks::{BatchStopReason, Kind, KindWithContent, Status, Task};
 use roaring::RoaringBitmap;
 use uuid::Uuid;
@@ -59,6 +60,13 @@ pub(crate) enum Batch {
        index_uid: String,
        task: Task,
    },
+    NetworkIndexBatch {
+        network_task: Task,
+        inner_batch: Box<Batch>,
+    },
+    NetworkWait {
+        task: Task,
+    },
 }

 #[derive(Debug)]
@@ -140,9 +148,14 @@ impl Batch {
                    ..
                } => RoaringBitmap::from_iter(tasks.iter().chain(other).map(|task| task.uid)),
            },
-            Batch::IndexSwap { task } => {
+            Batch::IndexSwap { task } | Batch::NetworkWait { task } => {
                RoaringBitmap::from_sorted_iter(std::iter::once(task.uid)).unwrap()
            }
+            Batch::NetworkIndexBatch { network_task, inner_batch } => {
+                let mut tasks = inner_batch.ids();
+                tasks.insert(network_task.uid);
+                tasks
+            }
        }
    }

@@ -156,12 +169,14 @@ impl Batch {
            | Dump(_)
            | Export { .. }
            | UpgradeDatabase { .. }
+            | NetworkWait { .. }
            | IndexSwap { .. } => None,
            IndexOperation { op, .. } => Some(op.index_uid()),
            IndexCreation { index_uid, .. }
            | IndexUpdate { index_uid, .. }
            | IndexDeletion { index_uid, .. }
            | IndexCompaction { index_uid, .. } => Some(index_uid),
+            NetworkIndexBatch { network_task: _, inner_batch } => inner_batch.index_uid(),
        }
    }
 }
@@ -184,6 +199,8 @@ impl fmt::Display for Batch {
            Batch::IndexCompaction { .. } => f.write_str("IndexCompaction")?,
            Batch::Export { .. } => f.write_str("Export")?,
            Batch::UpgradeDatabase { .. } => f.write_str("UpgradeDatabase")?,
+            Batch::NetworkIndexBatch { .. } => f.write_str("NetworkTopologyChange")?,
+            Batch::NetworkWait { .. } => f.write_str("NetworkTopologyChange")?,
        };
        match index_uid {
            Some(name) => f.write_fmt(format_args!(" on {name:?} from tasks: {tasks:?}")),
@@ -460,7 +477,6 @@ impl IndexScheduler {
        let mut current_batch = ProcessingBatch::new(batch_id);

        let enqueued = &self.queue.tasks.get_status(rtxn, Status::Enqueued)?;
-        let count_total_enqueued = enqueued.len();
        let failed = &self.queue.tasks.get_status(rtxn, Status::Failed)?;

        // 0. we get the last task to cancel.
@@ -519,7 +535,15 @@ impl IndexScheduler {
            return Ok(Some((Batch::TaskDeletions(tasks), current_batch)));
        }

-        // 3. we get the next task to compact
+        // 3. Check for enqueued network topology changes
+        let network_changes =
+            self.queue.tasks.get_kind(rtxn, Kind::NetworkTopologyChange)? & enqueued;
+        if let Some(task_id) = network_changes.iter().next() {
+            let task = self.queue.tasks.get_task(rtxn, task_id)?.unwrap();
+            return self.start_processing_network(rtxn, task, enqueued, current_batch);
+        }
+
+        // 4. we get the next task to compact
        let to_compact = self.queue.tasks.get_kind(rtxn, Kind::IndexCompaction)? & enqueued;
        if let Some(task_id) = to_compact.min() {
            let mut task =
@@ -534,7 +558,7 @@ impl IndexScheduler {
            return Ok(Some((Batch::IndexCompaction { index_uid, task }, current_batch)));
        }

-        // 4. we batch the export.
+        // 5. we batch the export.
        let to_export = self.queue.tasks.get_kind(rtxn, Kind::Export)? & enqueued;
        if !to_export.is_empty() {
            let task_id = to_export.iter().next().expect("There must be at least one export task");
@@ -545,7 +569,7 @@ impl IndexScheduler {
            return Ok(Some((Batch::Export { task }, current_batch)));
        }

-        // 5. we batch the snapshot.
+        // 6. we batch the snapshot.
        let to_snapshot = self.queue.tasks.get_kind(rtxn, Kind::SnapshotCreation)? & enqueued;
        if !to_snapshot.is_empty() {
            let mut tasks = self.queue.tasks.get_existing_tasks(rtxn, to_snapshot)?;
@@ -555,7 +579,7 @@ impl IndexScheduler {
            return Ok(Some((Batch::SnapshotCreation(tasks), current_batch)));
        }

-        // 6. we batch the dumps.
+        // 7. we batch the dumps.
        let to_dump = self.queue.tasks.get_kind(rtxn, Kind::DumpCreation)? & enqueued;
        if let Some(to_dump) = to_dump.min() {
            let mut task =
@@ -568,8 +592,25 @@ impl IndexScheduler {
            return Ok(Some((Batch::Dump(task), current_batch)));
        }

-        // 7. We make a batch from the unprioritised tasks. Start by taking the next enqueued task.
-        let task_id = if let Some(task_id) = enqueued.min() { task_id } else { return Ok(None) };
+        // 8. We make a batch from the unprioritised tasks. Start by taking the next enqueued task.
+        let (batch, current_batch) =
+            self.create_next_batch_unprioritized(rtxn, &enqueued, current_batch)?;
+        Ok(batch.map(|batch| (batch, current_batch)))
+    }
+
+    fn create_next_batch_unprioritized(
+        &self,
+        rtxn: &RoTxn,
+        enqueued: &RoaringBitmap,
+        mut current_batch: ProcessingBatch,
+    ) -> Result<(Option<Batch>, ProcessingBatch)> {
+        let count_total_enqueued = enqueued.len();
+
+        let task_id = if let Some(task_id) = enqueued.min() {
+            task_id
+        } else {
+            return Ok((None, current_batch));
+        };
        let mut task =
            self.queue.tasks.get_task(rtxn, task_id)?.ok_or(Error::CorruptedTaskQueue)?;

@@ -586,7 +627,7 @@ impl IndexScheduler {
                kind: Kind::IndexSwap,
                id: task.uid,
            });
-            return Ok(Some((Batch::IndexSwap { task }, current_batch)));
+            return Ok((Some(Batch::IndexSwap { task }), current_batch));
        };

        let index_already_exists = self.index_mapper.exists(rtxn, index_name)?;
@@ -651,7 +692,7 @@ impl IndexScheduler {
            autobatcher::autobatch(enqueued, index_already_exists, primary_key.as_deref())
        {
            current_batch.reason(autobatch_stop_reason.unwrap_or(stop_reason));
-            return Ok(self
+            let batch = self
                .create_next_batch_index(
                    rtxn,
                    index_name.to_string(),
@@ -659,11 +700,127 @@ impl IndexScheduler {
                    &mut current_batch,
                    create_index,
                )?
-                .map(|batch| (batch, current_batch)));
+                .map(|batch| batch);
+            return Ok((batch, current_batch));
        }

        // If we found no tasks then we were notified for something that got autobatched
        // somehow and there is nothing to do.
-        Ok(None)
+        Ok((None, current_batch))
+    }
+
+    fn start_processing_network(
+        &self,
+        rtxn: &RoTxn,
+        mut task: Task,
+        enqueued: &RoaringBitmap,
+        current_batch: ProcessingBatch,
+    ) -> Result<Option<(Batch, ProcessingBatch)>> {
+        let change_version =
+            task.network.as_ref().map(|network| network.network_version()).unwrap_or_default();
+        let KindWithContent::NetworkTopologyChange(network_topology_change) = &task.kind else {
+            panic!("inconsistent kind with content")
+        };
+        match network_topology_change.state() {
+            NetworkTopologyState::WaitingForOlderTasks => {
+                let mut old_tasks = RoaringBitmap::new();
+                for task_id in enqueued {
+                    let task = self
+                        .queue
+                        .tasks
+                        .get_task(rtxn, task_id)?
+                        .ok_or(Error::CorruptedTaskQueue)?;
+
+                    let has_index = task.index_uid().is_some();
+
+                    if !has_index {
+                        continue;
+                    }
+
+                    let has_older_network_version = task
+                        .network
+                        .map(|network| network.network_version() <= change_version)
+                        // if there is no version, we never retain the task
+                        .unwrap_or_default();
+
+                    if has_older_network_version {
+                        old_tasks.push(task_id);
+                    }
+                }
+
+                let res = self.create_next_batch_unprioritized(rtxn, &old_tasks, current_batch);
+                self.runtime_tasks.write().unwrap().enqueued_network.swap(old_tasks);
+
+                let (batch, mut current_batch) = res?;
+
+                current_batch.processing(Some(&mut task));
+
+                let batch = match batch {
+                    Some(batch) => {
+                        let inner_batch = Box::new(batch);
+
+                        Batch::NetworkIndexBatch { network_task: task, inner_batch }
+                    }
+                    None => Batch::NetworkWait { task },
+                };
+
+                Ok(Some((batch, current_batch)))
+            }
+            NetworkTopologyState::ImportingDocuments => {
+                let mut import_tasks = RoaringBitmap::new();
+                for task_id in enqueued {
+                    let task = self
+                        .queue
+                        .tasks
+                        .get_task(rtxn, task_id)?
+                        .ok_or(Error::CorruptedTaskQueue)?;
+
+                    let has_index = task.index_uid().is_some();
+
+                    if !has_index {
+                        continue;
+                    }
+
+                    let is_import_task = task
+                        .network
+                        .map(|network| {
+                            network.network_version() == change_version
+                                && network.import_data().is_some()
+                        })
+                        // if there is no version, we never retain the task
+                        .unwrap_or_default();
+
+                    if is_import_task {
+                        import_tasks.push(task_id);
+                    }
+                }
+
+                let res = self.create_next_batch_unprioritized(rtxn, &import_tasks, current_batch);
+                self.runtime_tasks.write().unwrap().enqueued_network.swap(import_tasks);
+
+                let (batch, mut current_batch) = res?;
+
+                current_batch.processing(Some(&mut task));
+
+                let batch = match batch {
+                    Some(batch) => {
+                        let inner_batch = Box::new(batch);
+
+                        Batch::NetworkIndexBatch { network_task: task, inner_batch }
+                    }
+                    None => Batch::NetworkWait { task },
+                };
+
+                Ok(Some((batch, current_batch)))
+            }
+            NetworkTopologyState::ExportingDocuments | NetworkTopologyState::Finished => {
+                Ok(Some((Batch::NetworkWait { task }, current_batch)))
+            }
+        }
    }
 }
+
+pub enum BatchOutcome {
+    NoTaskToProcess,
+    Batch { batch: Batch, processing: ProcessingBatch },
+}
--- a/crates/index-scheduler/src/scheduler/mod.rs
+++ b/crates/index-scheduler/src/scheduler/mod.rs
@@ -200,9 +200,10 @@ impl IndexScheduler {
        // We reset the must_stop flag to be sure that we don't stop processing tasks
        self.scheduler.must_stop_processing.reset();
        let progress = self
-            .processing_tasks
+            .runtime_tasks
            .write()
            .unwrap()
+            .processing
            // We can clone the processing batch here because we don't want its modification to affect the view of the processing batches
            .start_processing(processing_batch.clone(), ids.clone());

@@ -453,7 +454,7 @@ impl IndexScheduler {

        // We should stop processing AFTER everything is processed and written to disk otherwise, a batch (which only lives in RAM) may appear in the processing task
        // and then become « not found » for some time until the commit everything is written and the final commit is made.
-        self.processing_tasks.write().unwrap().stop_processing();
+        self.runtime_tasks.write().unwrap().processing.stop_processing();

        // Once the tasks are committed, we should delete all the update files associated ASAP to avoid leaking files in case of a restart
        tracing::debug!("Deleting the update files");
--- a/crates/index-scheduler/src/scheduler/process_batch.rs
+++ b/crates/index-scheduler/src/scheduler/process_batch.rs
@@ -1,15 +1,22 @@
-use std::collections::{BTreeSet, HashMap, HashSet};
+use std::collections::{BTreeMap, BTreeSet, HashMap, HashSet};
 use std::fs::{remove_file, File};
 use std::io::{ErrorKind, Seek, SeekFrom};
 use std::panic::{catch_unwind, AssertUnwindSafe};
 use std::sync::atomic::Ordering;
+use std::time::Duration;

+use bumpalo::Bump;
 use byte_unit::Byte;
 use meilisearch_types::batches::{BatchEnqueuedAt, BatchId};
+use meilisearch_types::enterprise_edition::network::Remote;
 use meilisearch_types::heed::{RoTxn, RwTxn};
+use meilisearch_types::milli::documents::PrimaryKey;
 use meilisearch_types::milli::heed::CompactionOption;
-use meilisearch_types::milli::progress::{Progress, VariableNameStep};
+use meilisearch_types::milli::progress::{EmbedderStats, Progress, VariableNameStep};
+use meilisearch_types::milli::update::new::indexer;
+use meilisearch_types::milli::update::new::indexer::enterprise_edition::sharding::Shards;
 use meilisearch_types::milli::{self, ChannelCongestion};
+use meilisearch_types::tasks::enterprise_edition::network::{NetworkTopologyState, Origin};
 use meilisearch_types::tasks::{Details, IndexSwap, Kind, KindWithContent, Status, Task};
 use meilisearch_types::versioning::{VERSION_MAJOR, VERSION_MINOR, VERSION_PATCH};
 use milli::update::Settings as MilliSettings;
@@ -23,6 +30,7 @@ use crate::processing::{
    IndexCompaction, InnerSwappingTwoIndexes, SwappingTheIndexes, TaskCancelationProgress,
    TaskDeletionProgress, UpdateIndexProgress,
 };
+use crate::scheduler::process_export::{ExportContext, ExportOptions, TargetInstance};
 use crate::utils::{
    self, remove_n_tasks_datetime_earlier_than, remove_task_datetime, swap_index_uid_in_task,
    ProcessingBatch,
@@ -539,9 +547,209 @@ impl IndexScheduler {

                Ok((tasks, ProcessBatchInfo::default()))
            }
+            Batch::NetworkIndexBatch { mut network_task, inner_batch } => {
+                let (mut tasks, info) =
+                    self.process_batch(*inner_batch, current_batch, progress)?;
+                let KindWithContent::NetworkTopologyChange(network_topology_change) =
+                    &mut network_task.kind
+                else {
+                    return Err(Error::CorruptedTaskQueue);
+                };
+                for task in &tasks {
+                    let Some(network) = task.network.as_ref() else {
+                        continue;
+                    };
+                    let Some(import) = network.import_data() else {
+                        continue;
+                    };
+                    network_topology_change.process_remote_tasks(
+                        &import.remote_name,
+                        &import.index_name,
+                        import.document_count,
+                    );
+                }
+                tasks.push(network_task);
+                Ok((tasks, info))
+            }
+            Batch::NetworkWait { mut task } => {
+                let KindWithContent::NetworkTopologyChange(network_topology_change) =
+                    &mut task.kind
+                else {
+                    tracing::error!("network topology change task has the wrong kind with content");
+                    return Err(Error::CorruptedTaskQueue);
+                };
+
+                let Some(task_network) = &task.network else {
+                    tracing::error!("network topology change task has no network");
+                    return Err(Error::CorruptedTaskQueue);
+                };
+
+                let origin;
+                let origin = match task_network.origin() {
+                    Some(origin) => origin,
+                    None => {
+                        let myself =
+                            network_topology_change.in_name().expect("origin is not the leader");
+                        origin = Origin {
+                            remote_name: myself.to_string(),
+                            task_uid: task.uid,
+                            network_version: task_network.network_version(),
+                        };
+                        &origin
+                    }
+                };
+
+                if let Some((remotes, out_name)) = network_topology_change.export_to_process() {
+                    self.balance_documents(
+                        remotes,
+                        out_name,
+                        network_topology_change.in_name(),
+                        origin,
+                        &progress,
+                        &self.scheduler.must_stop_processing,
+                    )?;
+                }
+                network_topology_change.update_state();
+                if network_topology_change.state() == NetworkTopologyState::Finished {
+                    task.status = Status::Succeeded;
+                }
+                Ok((vec![task], Default::default()))
+            }
        }
    }

+    fn balance_documents(
+        &self,
+        remotes: &BTreeMap<String, Remote>,
+        out_name: &str,
+        in_name: Option<&str>,
+        network_change_origin: &Origin,
+        progress: &Progress,
+        must_stop_processing: &crate::scheduler::MustStopProcessing,
+    ) -> crate::Result<()> {
+        let new_shards = Shards::from_remotes_local(remotes.keys().map(String::as_str), in_name);
+
+        // TECHDEBT: this spawns a `ureq` agent additionally to `reqwest`. We probably want to harmonize all of this.
+        let agent = ureq::AgentBuilder::new().timeout(Duration::from_secs(5)).build();
+
+        let mut indexer_alloc = Bump::new();
+
+        let scheduler_rtxn = self.env.read_txn()?;
+
+        let index_count = self.index_mapper.index_count(&scheduler_rtxn)?;
+
+        // process by batches of 20MiB. Allow for compression? Don't forget about embeddings
+        let _: Vec<()> = self.index_mapper.try_for_each_index(
+            &scheduler_rtxn,
+            |index_uid, index| -> crate::Result<()> {
+                indexer_alloc.reset();
+                let err = |err| Error::from_milli(err, Some(index_uid.to_string()));
+                let index_rtxn = index.read_txn()?;
+                let all_docids = index.external_documents_ids();
+                let mut documents_to_move_to: HashMap<String, RoaringBitmap> = HashMap::new();
+                let mut documents_to_delete = RoaringBitmap::new();
+
+                for res in all_docids.iter(&index_rtxn)? {
+                    let (external_docid, docid) = res?;
+                    match new_shards.processing_shard(external_docid) {
+                        Some(shard) if shard.is_own => continue,
+                        Some(shard) => {
+                            documents_to_move_to
+                                .entry(shard.name.clone())
+                                .or_default()
+                                .insert(docid);
+                        }
+                        None => {
+                            documents_to_delete.insert(docid);
+                        }
+                    }
+                }
+
+                let fields_ids_map = index.fields_ids_map(&index_rtxn)?;
+
+                for (remote, documents_to_move) in documents_to_move_to {
+                    /// TODO: justify the unwrap
+                    let remote = remotes.get(&remote).unwrap();
+
+                    let target = TargetInstance {
+                        base_url: &remote.url,
+                        api_key: remote.write_api_key.as_deref(),
+                    };
+                    let options = ExportOptions {
+                        index_uid,
+                        payload_size: None,
+                        override_settings: false,
+                        export_mode: super::process_export::ExportMode::NetworkBalancing {
+                            index_count,
+                            export_old_remote_name: out_name,
+                            network_change_origin,
+                        },
+                    };
+                    let ctx = ExportContext {
+                        index,
+                        index_rtxn: &index_rtxn,
+                        universe: &documents_to_move,
+                        progress,
+                        agent: &agent,
+                        must_stop_processing,
+                    };
+
+                    self.export_one_index(target, options, ctx)?;
+
+                    documents_to_delete |= documents_to_move;
+                }
+
+                if documents_to_delete.is_empty() {
+                    return Ok(());
+                }
+
+                let mut new_fields_ids_map = fields_ids_map.clone();
+
+                // candidates not empty => index not empty => a primary key is set
+                let primary_key = index.primary_key(&index_rtxn)?.unwrap();
+
+                let primary_key = PrimaryKey::new_or_insert(primary_key, &mut new_fields_ids_map)
+                    .map_err(milli::Error::from)
+                    .map_err(err)?;
+
+                let mut index_wtxn = index.write_txn()?;
+
+                let mut indexer = indexer::DocumentDeletion::new();
+                indexer.delete_documents_by_docids(documents_to_delete);
+                let document_changes = indexer.into_changes(&indexer_alloc, primary_key);
+                let embedders = index
+                    .embedding_configs()
+                    .embedding_configs(&index_wtxn)
+                    .map_err(milli::Error::from)
+                    .map_err(err)?;
+                let embedders = self.embedders(index_uid.to_string(), embedders)?;
+                let indexer_config = self.index_mapper.indexer_config();
+                let pool = &indexer_config.thread_pool;
+
+                indexer::index(
+                    &mut index_wtxn,
+                    index,
+                    pool,
+                    indexer_config.grenad_parameters(),
+                    &fields_ids_map,
+                    new_fields_ids_map,
+                    None, // document deletion never changes primary key
+                    &document_changes,
+                    embedders,
+                    &|| must_stop_processing.get(),
+                    &progress,
+                    &EmbedderStats::default(),
+                )
+                .map_err(err)?;
+
+                index_wtxn.commit()?;
+
+                Ok(())
+            },
+        )?;
+        Ok(())
+    }
+
    fn apply_compaction(
        &self,
        rtxn: &RoTxn,
@@ -711,7 +919,7 @@ impl IndexScheduler {

        // 1. Remove from this list the tasks that we are not allowed to delete
        let enqueued_tasks = self.queue.tasks.get_status(wtxn, Status::Enqueued)?;
-        let processing_tasks = &self.processing_tasks.read().unwrap().processing.clone();
+        let processing_tasks = &self.runtime_tasks.read().unwrap().processing.processing.clone();

        let all_task_ids = self.queue.tasks.all_task_ids(wtxn)?;
        let mut to_delete_tasks = all_task_ids & matched_tasks;
--- a/crates/index-scheduler/src/scheduler/process_export.rs
+++ b/crates/index-scheduler/src/scheduler/process_export.rs
@@ -7,6 +7,7 @@ use backoff::ExponentialBackoff;
 use byte_unit::Byte;
 use flate2::write::GzEncoder;
 use flate2::Compression;
+use meilisearch_types::error::Code;
 use meilisearch_types::index_uid_pattern::IndexUidPattern;
 use meilisearch_types::milli::constants::RESERVED_VECTORS_FIELD_NAME;
 use meilisearch_types::milli::index::EmbeddingsWithMetadata;
@@ -15,7 +16,11 @@ use meilisearch_types::milli::update::{request_threads, Setting};
 use meilisearch_types::milli::vector::parsed_vectors::{ExplicitVectors, VectorOrArrayOfVectors};
 use meilisearch_types::milli::{self, obkv_to_json, Filter, InternalError};
 use meilisearch_types::settings::{self, SecretPolicy};
+use meilisearch_types::tasks::enterprise_edition::network::{
+    headers, ImportData, ImportMetadata, Origin,
+};
 use meilisearch_types::tasks::{DetailsExportIndexSettings, ExportIndexSettings};
+use roaring::RoaringBitmap;
 use serde::Deserialize;
 use ureq::{json, Response};

@@ -50,6 +55,7 @@ impl IndexScheduler {
        let agent = ureq::AgentBuilder::new().timeout(Duration::from_secs(5)).build();
        let must_stop_processing = self.scheduler.must_stop_processing.clone();
        for (i, (_pattern, uid, export_settings)) in indexes.iter().enumerate() {
+            let err = |err| Error::from_milli(err, Some(uid.to_string()));
            if must_stop_processing.get() {
                return Err(Error::AbortedTask);
            }
@@ -61,104 +67,31 @@ impl IndexScheduler {
            ));

            let ExportIndexSettings { filter, override_settings } = export_settings;
+
            let index = self.index(uid)?;
            let index_rtxn = index.read_txn()?;
-            let bearer = api_key.map(|api_key| format!("Bearer {api_key}"));
-
-            // First, check if the index already exists
-            let url = format!("{base_url}/indexes/{uid}");
-            let response = retry(&must_stop_processing, || {
-                let mut request = agent.get(&url);
-                if let Some(bearer) = &bearer {
-                    request = request.set("Authorization", bearer);
-                }
-
-                request.send_bytes(Default::default()).map_err(into_backoff_error)
-            });
-            let index_exists = match response {
-                Ok(response) => response.status() == 200,
-                Err(Error::FromRemoteWhenExporting { code, .. }) if code == "index_not_found" => {
-                    false
-                }
-                Err(e) => return Err(e),
-            };
-
-            let primary_key = index
-                .primary_key(&index_rtxn)
-                .map_err(|e| Error::from_milli(e.into(), Some(uid.to_string())))?;
-
-            // Create the index
-            if !index_exists {
-                let url = format!("{base_url}/indexes");
-                retry(&must_stop_processing, || {
-                    let mut request = agent.post(&url);
-                    if let Some(bearer) = &bearer {
-                        request = request.set("Authorization", bearer);
-                    }
-                    let index_param = json!({ "uid": uid, "primaryKey": primary_key });
-                    request.send_json(&index_param).map_err(into_backoff_error)
-                })?;
-            }
-
-            // Patch the index primary key
-            if index_exists && *override_settings {
-                let url = format!("{base_url}/indexes/{uid}");
-                retry(&must_stop_processing, || {
-                    let mut request = agent.patch(&url);
-                    if let Some(bearer) = &bearer {
-                        request = request.set("Authorization", bearer);
-                    }
-                    let index_param = json!({ "primaryKey": primary_key });
-                    request.send_json(&index_param).map_err(into_backoff_error)
-                })?;
-            }
-
-            // Send the index settings
-            if !index_exists || *override_settings {
-                let mut settings =
-                    settings::settings(&index, &index_rtxn, SecretPolicy::RevealSecrets)
-                        .map_err(|e| Error::from_milli(e, Some(uid.to_string())))?;
-                // Remove the experimental chat setting if not enabled
-                if self.features().check_chat_completions("exporting chat settings").is_err() {
-                    settings.chat = Setting::NotSet;
-                }
-                // Retry logic for sending settings
-                let url = format!("{base_url}/indexes/{uid}/settings");
-                retry(&must_stop_processing, || {
-                    let mut request = agent.patch(&url);
-                    if let Some(bearer) = bearer.as_ref() {
-                        request = request.set("Authorization", bearer);
-                    }
-                    request.send_json(settings.clone()).map_err(into_backoff_error)
-                })?;
-            }
-
-            let filter = filter
-                .as_ref()
-                .map(Filter::from_json)
-                .transpose()
-                .map_err(|e| Error::from_milli(e, Some(uid.to_string())))?
-                .flatten();
-
-            let filter_universe = filter
-                .map(|f| f.evaluate(&index_rtxn, &index))
-                .transpose()
-                .map_err(|e| Error::from_milli(e, Some(uid.to_string())))?;
-            let whole_universe = index
-                .documents_ids(&index_rtxn)
-                .map_err(|e| Error::from_milli(e.into(), Some(uid.to_string())))?;
+            let filter = filter.as_ref().map(Filter::from_json).transpose().map_err(err)?.flatten();
+            let filter_universe =
+                filter.map(|f| f.evaluate(&index_rtxn, &index)).transpose().map_err(err)?;
+            let whole_universe =
+                index.documents_ids(&index_rtxn).map_err(milli::Error::from).map_err(err)?;
            let universe = filter_universe.unwrap_or(whole_universe);
-
-            let fields_ids_map = index.fields_ids_map(&index_rtxn)?;
-            let all_fields: Vec<_> = fields_ids_map.iter().map(|(id, _)| id).collect();
-
-            // We don't need to keep this one alive as we will
-            // spawn many threads to process the documents
-            drop(index_rtxn);
-
-            let total_documents = universe.len() as u32;
-            let (step, progress_step) = AtomicDocumentStep::new(total_documents);
-            progress.update_progress(progress_step);
+            let target = TargetInstance { base_url, api_key };
+            let ctx = ExportContext {
+                index: &index,
+                index_rtxn: &index_rtxn,
+                universe: &universe,
+                progress: &progress,
+                agent: &agent,
+                must_stop_processing: &must_stop_processing,
+            };
+            let options = ExportOptions {
+                index_uid: uid,
+                payload_size,
+                override_settings: *override_settings,
+                export_mode: ExportMode::ExportRoute,
+            };
+            let total_documents = self.export_one_index(target, options, ctx)?;

            output.insert(
                IndexUidPattern::new_unchecked(uid.clone()),
@@ -167,155 +100,307 @@ impl IndexScheduler {
                    matched_documents: Some(total_documents as u64),
                },
            );
-
-            let limit = payload_size.map(|ps| ps.as_u64() as usize).unwrap_or(20 * 1024 * 1024); // defaults to 20 MiB
-            let documents_url = format!("{base_url}/indexes/{uid}/documents");
-
-            let results = request_threads()
-                .broadcast(|ctx| {
-                    let index_rtxn = index
-                        .read_txn()
-                        .map_err(|e| Error::from_milli(e.into(), Some(uid.to_string())))?;
-
-                    let mut buffer = Vec::new();
-                    let mut tmp_buffer = Vec::new();
-                    let mut compressed_buffer = Vec::new();
-                    for (i, docid) in universe.iter().enumerate() {
-                        if i % ctx.num_threads() != ctx.index() {
-                            continue;
-                        }
-
-                        let document = index
-                            .document(&index_rtxn, docid)
-                            .map_err(|e| Error::from_milli(e, Some(uid.to_string())))?;
-
-                        let mut document = obkv_to_json(&all_fields, &fields_ids_map, document)
-                            .map_err(|e| Error::from_milli(e, Some(uid.to_string())))?;
-
-                        // TODO definitely factorize this code
-                        'inject_vectors: {
-                            let embeddings = index
-                                .embeddings(&index_rtxn, docid)
-                                .map_err(|e| Error::from_milli(e, Some(uid.to_string())))?;
-
-                            if embeddings.is_empty() {
-                                break 'inject_vectors;
-                            }
-
-                            let vectors = document
-                                .entry(RESERVED_VECTORS_FIELD_NAME)
-                                .or_insert(serde_json::Value::Object(Default::default()));
-
-                            let serde_json::Value::Object(vectors) = vectors else {
-                                return Err(Error::from_milli(
-                                    milli::Error::UserError(
-                                        milli::UserError::InvalidVectorsMapType {
-                                            document_id: {
-                                                if let Ok(Some(Ok(index))) = index
-                                                    .external_id_of(
-                                                        &index_rtxn,
-                                                        std::iter::once(docid),
-                                                    )
-                                                    .map(|it| it.into_iter().next())
-                                                {
-                                                    index
-                                                } else {
-                                                    format!("internal docid={docid}")
-                                                }
-                                            },
-                                            value: vectors.clone(),
-                                        },
-                                    ),
-                                    Some(uid.to_string()),
-                                ));
-                            };
-
-                            for (
-                                embedder_name,
-                                EmbeddingsWithMetadata { embeddings, regenerate, has_fragments },
-                            ) in embeddings
-                            {
-                                let embeddings = ExplicitVectors {
-                                    embeddings: Some(
-                                        VectorOrArrayOfVectors::from_array_of_vectors(embeddings),
-                                    ),
-                                    regenerate: regenerate &&
-                                    // Meilisearch does not handle well dumps with fragments, because as the fragments
-                                    // are marked as user-provided,
-                                    // all embeddings would be regenerated on any settings change or document update.
-                                    // To prevent this, we mark embeddings has non regenerate in this case.
-                                    !has_fragments,
-                                };
-                                vectors.insert(
-                                    embedder_name,
-                                    serde_json::to_value(embeddings).unwrap(),
-                                );
-                            }
-                        }
-
-                        tmp_buffer.clear();
-                        serde_json::to_writer(&mut tmp_buffer, &document)
-                            .map_err(milli::InternalError::from)
-                            .map_err(|e| Error::from_milli(e.into(), Some(uid.to_string())))?;
-
-                        // Make sure we put at least one document in the buffer even
-                        // though we might go above the buffer limit before sending
-                        if !buffer.is_empty() && buffer.len() + tmp_buffer.len() > limit {
-                            // We compress the documents before sending them
-                            let mut encoder =
-                                GzEncoder::new(&mut compressed_buffer, Compression::default());
-                            encoder
-                                .write_all(&buffer)
-                                .map_err(|e| Error::from_milli(e.into(), Some(uid.clone())))?;
-                            encoder
-                                .finish()
-                                .map_err(|e| Error::from_milli(e.into(), Some(uid.clone())))?;
-
-                            retry(&must_stop_processing, || {
-                                let mut request = agent.post(&documents_url);
-                                request = request.set("Content-Type", "application/x-ndjson");
-                                request = request.set("Content-Encoding", "gzip");
-                                if let Some(bearer) = &bearer {
-                                    request = request.set("Authorization", bearer);
-                                }
-                                request.send_bytes(&compressed_buffer).map_err(into_backoff_error)
-                            })?;
-                            buffer.clear();
-                            compressed_buffer.clear();
-                        }
-                        buffer.extend_from_slice(&tmp_buffer);
-
-                        if i > 0 && i % 100 == 0 {
-                            step.fetch_add(100, atomic::Ordering::Relaxed);
-                        }
-                    }
-
-                    retry(&must_stop_processing, || {
-                        let mut request = agent.post(&documents_url);
-                        request = request.set("Content-Type", "application/x-ndjson");
-                        if let Some(bearer) = &bearer {
-                            request = request.set("Authorization", bearer);
-                        }
-                        request.send_bytes(&buffer).map_err(into_backoff_error)
-                    })?;
-
-                    Ok(())
-                })
-                .map_err(|e| {
-                    Error::from_milli(
-                        milli::Error::InternalError(InternalError::PanicInThreadPool(e)),
-                        Some(uid.to_string()),
-                    )
-                })?;
-            for result in results {
-                result?;
-            }
-
-            step.store(total_documents, atomic::Ordering::Relaxed);
        }

        Ok(output)
    }
+
+    pub(super) fn export_one_index(
+        &self,
+        target: TargetInstance<'_>,
+        options: ExportOptions<'_>,
+        ctx: ExportContext<'_>,
+    ) -> Result<u64, Error> {
+        let err = |err| Error::from_milli(err, Some(options.index_uid.to_string()));
+
+        let bearer = target.api_key.map(|api_key| format!("Bearer {api_key}"));
+        let url = format!(
+            "{base_url}/indexes/{index_uid}",
+            base_url = target.base_url,
+            index_uid = options.index_uid
+        );
+        let response = retry(ctx.must_stop_processing, || {
+            let mut request = ctx.agent.get(&url);
+            if let Some(bearer) = &bearer {
+                request = request.set("Authorization", bearer);
+            }
+
+            request.send_bytes(Default::default()).map_err(into_backoff_error)
+        });
+        let index_exists = match response {
+            Ok(response) => response.status() == 200,
+            Err(Error::FromRemoteWhenExporting { code, .. })
+                if code == Code::IndexNotFound.name() =>
+            {
+                false
+            }
+            Err(e) => return Err(e),
+        };
+        let primary_key =
+            ctx.index.primary_key(&ctx.index_rtxn).map_err(milli::Error::from).map_err(err)?;
+        if !index_exists {
+            let url = format!("{base_url}/indexes", base_url = target.base_url);
+            retry(ctx.must_stop_processing, || {
+                let mut request = ctx.agent.post(&url);
+                if let Some(bearer) = &bearer {
+                    request = request.set("Authorization", bearer);
+                }
+                let index_param = json!({ "uid": options.index_uid, "primaryKey": primary_key });
+                request.send_json(&index_param).map_err(into_backoff_error)
+            })?;
+        }
+        if index_exists && options.override_settings {
+            retry(ctx.must_stop_processing, || {
+                let mut request = ctx.agent.patch(&url);
+                if let Some(bearer) = &bearer {
+                    request = request.set("Authorization", bearer);
+                }
+                let index_param = json!({ "primaryKey": primary_key });
+                request.send_json(&index_param).map_err(into_backoff_error)
+            })?;
+        }
+        if !index_exists || options.override_settings {
+            let mut settings =
+                settings::settings(&ctx.index, &ctx.index_rtxn, SecretPolicy::RevealSecrets)
+                    .map_err(err)?;
+            // Remove the experimental chat setting if not enabled
+            if self.features().check_chat_completions("exporting chat settings").is_err() {
+                settings.chat = Setting::NotSet;
+            }
+            // Retry logic for sending settings
+            let url = format!(
+                "{base_url}/indexes/{index_uid}/settings",
+                base_url = target.base_url,
+                index_uid = options.index_uid
+            );
+            retry(ctx.must_stop_processing, || {
+                let mut request = ctx.agent.patch(&url);
+                if let Some(bearer) = bearer.as_ref() {
+                    request = request.set("Authorization", bearer);
+                }
+                request.send_json(settings.clone()).map_err(into_backoff_error)
+            })?;
+        }
+
+        let fields_ids_map = ctx.index.fields_ids_map(&ctx.index_rtxn)?;
+        let all_fields: Vec<_> = fields_ids_map.iter().map(|(id, _)| id).collect();
+        let total_documents = ctx.universe.len() as u32;
+        let (step, progress_step) = AtomicDocumentStep::new(total_documents);
+        ctx.progress.update_progress(progress_step);
+
+        let limit = options.payload_size.map(|ps| ps.as_u64() as usize).unwrap_or(20 * 1024 * 1024);
+        let documents_url = format!(
+            "{base_url}/indexes/{index_uid}/documents",
+            base_url = target.base_url,
+            index_uid = options.index_uid
+        );
+        let results = request_threads()
+            .broadcast(|broadcast| {
+                let mut task_network = if let ExportMode::NetworkBalancing {
+                    index_count,
+                    export_old_remote_name,
+                    network_change_origin,
+                } = options.export_mode
+                {
+                    Some((
+                        ImportData {
+                            remote_name: export_old_remote_name.to_string(),
+                            index_name: options.index_uid.to_string(),
+                            document_count: 0,
+                        },
+                        network_change_origin.clone(),
+                        ImportMetadata {
+                            index_count,
+                            task_key: 0,
+                            total_index_documents: ctx.universe.len(),
+                        },
+                    ))
+                } else {
+                    None
+                };
+
+                let index_rtxn = ctx.index.read_txn().map_err(milli::Error::from).map_err(err)?;
+
+                let mut buffer = Vec::new();
+                let mut tmp_buffer = Vec::new();
+                let mut compressed_buffer = Vec::new();
+                for (i, docid) in ctx.universe.iter().enumerate() {
+                    if i % broadcast.num_threads() != broadcast.index() {
+                        continue;
+                    }
+                    if let Some((import_data, _, metadata)) = &mut task_network {
+                        import_data.document_count += 1;
+                        metadata.task_key = docid;
+                    }
+
+                    let document = ctx.index.document(&index_rtxn, docid).map_err(err)?;
+
+                    let mut document =
+                        obkv_to_json(&all_fields, &fields_ids_map, document).map_err(err)?;
+
+                    // TODO definitely factorize this code
+                    'inject_vectors: {
+                        let embeddings = ctx.index.embeddings(&index_rtxn, docid).map_err(err)?;
+
+                        if embeddings.is_empty() {
+                            break 'inject_vectors;
+                        }
+
+                        let vectors = document
+                            .entry(RESERVED_VECTORS_FIELD_NAME)
+                            .or_insert(serde_json::Value::Object(Default::default()));
+
+                        let serde_json::Value::Object(vectors) = vectors else {
+                            return Err(err(milli::Error::UserError(
+                                milli::UserError::InvalidVectorsMapType {
+                                    document_id: {
+                                        if let Ok(Some(Ok(index))) = ctx
+                                            .index
+                                            .external_id_of(&index_rtxn, std::iter::once(docid))
+                                            .map(|it| it.into_iter().next())
+                                        {
+                                            index
+                                        } else {
+                                            format!("internal docid={docid}")
+                                        }
+                                    },
+                                    value: vectors.clone(),
+                                },
+                            )));
+                        };
+
+                        for (
+                            embedder_name,
+                            EmbeddingsWithMetadata { embeddings, regenerate, has_fragments },
+                        ) in embeddings
+                        {
+                            let embeddings = ExplicitVectors {
+                                embeddings: Some(VectorOrArrayOfVectors::from_array_of_vectors(
+                                    embeddings,
+                                )),
+                                regenerate: regenerate &&
+                                // Meilisearch does not handle well dumps with fragments, because as the fragments
+                                // are marked as user-provided,
+                                // all embeddings would be regenerated on any settings change or document update.
+                                // To prevent this, we mark embeddings has non regenerate in this case.
+                                !has_fragments,
+                            };
+                            vectors
+                                .insert(embedder_name, serde_json::to_value(embeddings).unwrap());
+                        }
+                    }
+
+                    tmp_buffer.clear();
+                    serde_json::to_writer(&mut tmp_buffer, &document)
+                        .map_err(milli::InternalError::from)
+                        .map_err(milli::Error::from)
+                        .map_err(err)?;
+
+                    // Make sure we put at least one document in the buffer even
+                    // though we might go above the buffer limit before sending
+                    if !buffer.is_empty() && buffer.len() + tmp_buffer.len() > limit {
+                        // We compress the documents before sending them
+                        let mut encoder =
+                            GzEncoder::new(&mut compressed_buffer, Compression::default());
+                        encoder.write_all(&buffer).map_err(milli::Error::from).map_err(err)?;
+                        encoder.finish().map_err(milli::Error::from).map_err(err)?;
+
+                        match retry(ctx.must_stop_processing, || {
+                            let mut request = ctx.agent.post(&documents_url);
+                            request = request.set("Content-Type", "application/x-ndjson");
+                            request = request.set("Content-Encoding", "gzip");
+                            if let Some(bearer) = &bearer {
+                                request = request.set("Authorization", bearer);
+                            }
+                            if let Some((import_data, origin, metadata)) = &task_network {
+                                request = set_network_ureq_headers(
+                                    request,
+                                    import_data,
+                                    origin,
+                                    metadata,
+                                );
+                            }
+                            request.send_bytes(&compressed_buffer).map_err(into_backoff_error)
+                        }) {
+                            Ok(_response) => {}
+                            Err(Error::FromRemoteWhenExporting { code, .. })
+                                if code == Code::ImportTaskAlreadyReceived.name() =>
+                            {
+                                continue;
+                            }
+                            Err(Error::FromRemoteWhenExporting { code, message, .. })
+                                if code == Code::ImportTaskUnknownRemote.name() =>
+                            {
+                                tracing::warn!("remote answered with: {message}");
+                                break;
+                            }
+                            Err(Error::FromRemoteWhenExporting { code, message, .. })
+                                if code == Code::ImportTaskWithoutNetworkTask.name() =>
+                            {
+                                tracing::warn!("remote answered with: {message}");
+                                break;
+                            }
+                            Err(e) => return Err(e),
+                        }
+                        buffer.clear();
+                        compressed_buffer.clear();
+                        if let Some((import_data, _, metadata)) = &mut task_network {
+                            import_data.document_count = 0;
+                            metadata.task_key = 0;
+                        }
+                    }
+                    buffer.extend_from_slice(&tmp_buffer);
+
+                    if i > 0 && i % 100 == 0 {
+                        step.fetch_add(100, atomic::Ordering::Relaxed);
+                    }
+                }
+
+                retry(ctx.must_stop_processing, || {
+                    let mut request = ctx.agent.post(&documents_url);
+                    request = request.set("Content-Type", "application/x-ndjson");
+                    if let Some((import_data, origin, metadata)) = &task_network {
+                        request = set_network_ureq_headers(request, import_data, origin, metadata);
+                    }
+                    if let Some(bearer) = &bearer {
+                        request = request.set("Authorization", bearer);
+                    }
+                    request.send_bytes(&buffer).map_err(into_backoff_error)
+                })?;
+
+                Ok(())
+            })
+            .map_err(|e| err(milli::Error::InternalError(InternalError::PanicInThreadPool(e))))?;
+        for result in results {
+            result?;
+        }
+        step.store(total_documents, atomic::Ordering::Relaxed);
+        Ok(total_documents as u64)
+    }
+}
+
+fn set_network_ureq_headers(
+    request: ureq::Request,
+    import_data: &ImportData,
+    origin: &Origin,
+    metadata: &ImportMetadata,
+) -> ureq::Request {
+    request
+        .set(headers::PROXY_ORIGIN_REMOTE_HEADER, &origin.remote_name)
+        .set(headers::PROXY_ORIGIN_TASK_UID_HEADER, &origin.task_uid.to_string())
+        .set(
+            headers::PROXY_ORIGIN_NETWORK_VERSION_HEADER,
+            &origin.network_version.to_u128_le().to_string(),
+        )
+        .set(headers::PROXY_IMPORT_REMOTE_HEADER, &import_data.remote_name)
+        .set(headers::PROXY_IMPORT_INDEX_HEADER, &import_data.index_name)
+        .set(headers::PROXY_IMPORT_TASK_KEY_HEADER, &metadata.task_key.to_string())
+        .set(headers::PROXY_IMPORT_DOCS_HEADER, &import_data.document_count.to_string())
+        .set(headers::PROXY_IMPORT_INDEX_COUNT_HEADER, &metadata.index_count.to_string())
+        .set(
+            headers::PROXY_IMPORT_TOTAL_INDEX_DOCS_HEADER,
+            &metadata.total_index_documents.to_string(),
+        )
 }

 fn retry<F>(must_stop_processing: &MustStopProcessing, send_request: F) -> Result<ureq::Response>
@@ -374,4 +459,37 @@ fn ureq_error_into_error(error: ureq::Error) -> Error {
    }
 }

+// export_one_index arguments
+pub(super) struct TargetInstance<'a> {
+    pub(super) base_url: &'a str,
+    pub(super) api_key: Option<&'a str>,
+}
+
+pub(super) struct ExportOptions<'a> {
+    pub(super) index_uid: &'a str,
+    pub(super) payload_size: Option<&'a Byte>,
+    pub(super) override_settings: bool,
+    pub(super) export_mode: ExportMode<'a>,
+}
+
+pub(super) struct ExportContext<'a> {
+    pub(super) index: &'a meilisearch_types::milli::Index,
+    pub(super) index_rtxn: &'a milli::heed::RoTxn<'a>,
+    pub(super) universe: &'a RoaringBitmap,
+    pub(super) progress: &'a Progress,
+    pub(super) agent: &'a ureq::Agent,
+    pub(super) must_stop_processing: &'a MustStopProcessing,
+}
+
+pub(super) enum ExportMode<'a> {
+    ExportRoute,
+    NetworkBalancing {
+        index_count: u64,
+
+        export_old_remote_name: &'a str,
+        network_change_origin: &'a Origin,
+    },
+}
+
+// progress related
 enum ExportIndex {}
--- a/crates/index-scheduler/src/scheduler/snapshots/test_failure.rs/upgrade_failure/after_processing_everything.snap
+++ b/crates/index-scheduler/src/scheduler/snapshots/test_failure.rs/upgrade_failure/after_processing_everything.snap
@@ -6,7 +6,7 @@ source: crates/index-scheduler/src/scheduler/test_failure.rs
 []
 ----------------------------------------------------------------------
 ### All Tasks:
-0 {uid: 0, batch_uid: 0, status: succeeded, details: { from: (1, 12, 0), to: (1, 24, 0) }, kind: UpgradeDatabase { from: (1, 12, 0) }}
+0 {uid: 0, batch_uid: 0, status: succeeded, details: { from: (1, 12, 0), to: (1, 26, 0) }, kind: UpgradeDatabase { from: (1, 12, 0) }}
 1 {uid: 1, batch_uid: 1, status: succeeded, details: { primary_key: Some("mouse"), old_new_uid: None, new_index_uid: None }, kind: IndexCreation { index_uid: "catto", primary_key: Some("mouse") }}
 2 {uid: 2, batch_uid: 2, status: succeeded, details: { primary_key: Some("bone"), old_new_uid: None, new_index_uid: None }, kind: IndexCreation { index_uid: "doggo", primary_key: Some("bone") }}
 3 {uid: 3, batch_uid: 3, status: failed, error: ResponseError { code: 200, message: "Index `doggo` already exists.", error_code: "index_already_exists", error_type: "invalid_request", error_link: "https://docs.meilisearch.com/errors#index_already_exists" }, details: { primary_key: Some("bone"), old_new_uid: None, new_index_uid: None }, kind: IndexCreation { index_uid: "doggo", primary_key: Some("bone") }}
@@ -57,7 +57,7 @@ girafo: { number_of_documents: 0, field_distribution: {} }
 [timestamp] [4,]
 ----------------------------------------------------------------------
 ### All Batches:
-0 {uid: 0, details: {"upgradeFrom":"v1.12.0","upgradeTo":"v1.24.0"}, stats: {"totalNbTasks":1,"status":{"succeeded":1},"types":{"upgradeDatabase":1},"indexUids":{}}, stop reason: "stopped after the last task of type `upgradeDatabase` because they cannot be batched with tasks of any other type.", }
+0 {uid: 0, details: {"upgradeFrom":"v1.12.0","upgradeTo":"v1.26.0"}, stats: {"totalNbTasks":1,"status":{"succeeded":1},"types":{"upgradeDatabase":1},"indexUids":{}}, stop reason: "stopped after the last task of type `upgradeDatabase` because they cannot be batched with tasks of any other type.", }
 1 {uid: 1, details: {"primaryKey":"mouse"}, stats: {"totalNbTasks":1,"status":{"succeeded":1},"types":{"indexCreation":1},"indexUids":{"catto":1}}, stop reason: "created batch containing only task with id 1 of type `indexCreation` that cannot be batched with any other task.", }
 2 {uid: 2, details: {"primaryKey":"bone"}, stats: {"totalNbTasks":1,"status":{"succeeded":1},"types":{"indexCreation":1},"indexUids":{"doggo":1}}, stop reason: "created batch containing only task with id 2 of type `indexCreation` that cannot be batched with any other task.", }
 3 {uid: 3, details: {"primaryKey":"bone"}, stats: {"totalNbTasks":1,"status":{"failed":1},"types":{"indexCreation":1},"indexUids":{"doggo":1}}, stop reason: "created batch containing only task with id 3 of type `indexCreation` that cannot be batched with any other task.", }
--- a/crates/index-scheduler/src/scheduler/snapshots/test_failure.rs/upgrade_failure/register_automatic_upgrade_task.snap
+++ b/crates/index-scheduler/src/scheduler/snapshots/test_failure.rs/upgrade_failure/register_automatic_upgrade_task.snap
@@ -6,7 +6,7 @@ source: crates/index-scheduler/src/scheduler/test_failure.rs
 []
 ----------------------------------------------------------------------
 ### All Tasks:
-0 {uid: 0, status: enqueued, details: { from: (1, 12, 0), to: (1, 24, 0) }, kind: UpgradeDatabase { from: (1, 12, 0) }}
+0 {uid: 0, status: enqueued, details: { from: (1, 12, 0), to: (1, 26, 0) }, kind: UpgradeDatabase { from: (1, 12, 0) }}
 ----------------------------------------------------------------------
 ### Status:
 enqueued [0,]
--- a/crates/index-scheduler/src/scheduler/snapshots/test_failure.rs/upgrade_failure/registered_a_task_while_the_upgrade_task_is_enqueued.snap
+++ b/crates/index-scheduler/src/scheduler/snapshots/test_failure.rs/upgrade_failure/registered_a_task_while_the_upgrade_task_is_enqueued.snap
@@ -6,7 +6,7 @@ source: crates/index-scheduler/src/scheduler/test_failure.rs
 []
 ----------------------------------------------------------------------
 ### All Tasks:
-0 {uid: 0, status: enqueued, details: { from: (1, 12, 0), to: (1, 24, 0) }, kind: UpgradeDatabase { from: (1, 12, 0) }}
+0 {uid: 0, status: enqueued, details: { from: (1, 12, 0), to: (1, 26, 0) }, kind: UpgradeDatabase { from: (1, 12, 0) }}
 1 {uid: 1, status: enqueued, details: { primary_key: Some("mouse"), old_new_uid: None, new_index_uid: None }, kind: IndexCreation { index_uid: "catto", primary_key: Some("mouse") }}
 ----------------------------------------------------------------------
 ### Status:
--- a/crates/index-scheduler/src/scheduler/snapshots/test_failure.rs/upgrade_failure/upgrade_task_failed.snap
+++ b/crates/index-scheduler/src/scheduler/snapshots/test_failure.rs/upgrade_failure/upgrade_task_failed.snap
@@ -6,7 +6,7 @@ source: crates/index-scheduler/src/scheduler/test_failure.rs
 []
 ----------------------------------------------------------------------
 ### All Tasks:
-0 {uid: 0, batch_uid: 0, status: failed, error: ResponseError { code: 200, message: "Planned failure for tests.", error_code: "internal", error_type: "internal", error_link: "https://docs.meilisearch.com/errors#internal" }, details: { from: (1, 12, 0), to: (1, 24, 0) }, kind: UpgradeDatabase { from: (1, 12, 0) }}
+0 {uid: 0, batch_uid: 0, status: failed, error: ResponseError { code: 200, message: "Planned failure for tests.", error_code: "internal", error_type: "internal", error_link: "https://docs.meilisearch.com/errors#internal" }, details: { from: (1, 12, 0), to: (1, 26, 0) }, kind: UpgradeDatabase { from: (1, 12, 0) }}
 1 {uid: 1, status: enqueued, details: { primary_key: Some("mouse"), old_new_uid: None, new_index_uid: None }, kind: IndexCreation { index_uid: "catto", primary_key: Some("mouse") }}
 ----------------------------------------------------------------------
 ### Status:
@@ -37,7 +37,7 @@ catto [1,]
 [timestamp] [0,]
 ----------------------------------------------------------------------
 ### All Batches:
-0 {uid: 0, details: {"upgradeFrom":"v1.12.0","upgradeTo":"v1.24.0"}, stats: {"totalNbTasks":1,"status":{"failed":1},"types":{"upgradeDatabase":1},"indexUids":{}}, stop reason: "stopped after the last task of type `upgradeDatabase` because they cannot be batched with tasks of any other type.", }
+0 {uid: 0, details: {"upgradeFrom":"v1.12.0","upgradeTo":"v1.26.0"}, stats: {"totalNbTasks":1,"status":{"failed":1},"types":{"upgradeDatabase":1},"indexUids":{}}, stop reason: "stopped after the last task of type `upgradeDatabase` because they cannot be batched with tasks of any other type.", }
 ----------------------------------------------------------------------
 ### Batch to tasks mapping:
 0 [0,]
--- a/crates/index-scheduler/src/scheduler/snapshots/test_failure.rs/upgrade_failure/upgrade_task_failed_again.snap
+++ b/crates/index-scheduler/src/scheduler/snapshots/test_failure.rs/upgrade_failure/upgrade_task_failed_again.snap
@@ -6,7 +6,7 @@ source: crates/index-scheduler/src/scheduler/test_failure.rs
 []
 ----------------------------------------------------------------------
 ### All Tasks:
-0 {uid: 0, batch_uid: 0, status: failed, error: ResponseError { code: 200, message: "Planned failure for tests.", error_code: "internal", error_type: "internal", error_link: "https://docs.meilisearch.com/errors#internal" }, details: { from: (1, 12, 0), to: (1, 24, 0) }, kind: UpgradeDatabase { from: (1, 12, 0) }}
+0 {uid: 0, batch_uid: 0, status: failed, error: ResponseError { code: 200, message: "Planned failure for tests.", error_code: "internal", error_type: "internal", error_link: "https://docs.meilisearch.com/errors#internal" }, details: { from: (1, 12, 0), to: (1, 26, 0) }, kind: UpgradeDatabase { from: (1, 12, 0) }}
 1 {uid: 1, status: enqueued, details: { primary_key: Some("mouse"), old_new_uid: None, new_index_uid: None }, kind: IndexCreation { index_uid: "catto", primary_key: Some("mouse") }}
 2 {uid: 2, status: enqueued, details: { primary_key: Some("bone"), old_new_uid: None, new_index_uid: None }, kind: IndexCreation { index_uid: "doggo", primary_key: Some("bone") }}
 ----------------------------------------------------------------------
@@ -40,7 +40,7 @@ doggo [2,]
 [timestamp] [0,]
 ----------------------------------------------------------------------
 ### All Batches:
-0 {uid: 0, details: {"upgradeFrom":"v1.12.0","upgradeTo":"v1.24.0"}, stats: {"totalNbTasks":1,"status":{"failed":1},"types":{"upgradeDatabase":1},"indexUids":{}}, stop reason: "stopped after the last task of type `upgradeDatabase` because they cannot be batched with tasks of any other type.", }
+0 {uid: 0, details: {"upgradeFrom":"v1.12.0","upgradeTo":"v1.26.0"}, stats: {"totalNbTasks":1,"status":{"failed":1},"types":{"upgradeDatabase":1},"indexUids":{}}, stop reason: "stopped after the last task of type `upgradeDatabase` because they cannot be batched with tasks of any other type.", }
 ----------------------------------------------------------------------
 ### Batch to tasks mapping:
 0 [0,]
--- a/crates/index-scheduler/src/scheduler/snapshots/test_failure.rs/upgrade_failure/upgrade_task_succeeded.snap
+++ b/crates/index-scheduler/src/scheduler/snapshots/test_failure.rs/upgrade_failure/upgrade_task_succeeded.snap
@@ -6,7 +6,7 @@ source: crates/index-scheduler/src/scheduler/test_failure.rs
 []
 ----------------------------------------------------------------------
 ### All Tasks:
-0 {uid: 0, batch_uid: 0, status: succeeded, details: { from: (1, 12, 0), to: (1, 24, 0) }, kind: UpgradeDatabase { from: (1, 12, 0) }}
+0 {uid: 0, batch_uid: 0, status: succeeded, details: { from: (1, 12, 0), to: (1, 26, 0) }, kind: UpgradeDatabase { from: (1, 12, 0) }}
 1 {uid: 1, status: enqueued, details: { primary_key: Some("mouse"), old_new_uid: None, new_index_uid: None }, kind: IndexCreation { index_uid: "catto", primary_key: Some("mouse") }}
 2 {uid: 2, status: enqueued, details: { primary_key: Some("bone"), old_new_uid: None, new_index_uid: None }, kind: IndexCreation { index_uid: "doggo", primary_key: Some("bone") }}
 3 {uid: 3, status: enqueued, details: { primary_key: Some("bone"), old_new_uid: None, new_index_uid: None }, kind: IndexCreation { index_uid: "doggo", primary_key: Some("bone") }}
@@ -43,7 +43,7 @@ doggo [2,3,]
 [timestamp] [0,]
 ----------------------------------------------------------------------
 ### All Batches:
-0 {uid: 0, details: {"upgradeFrom":"v1.12.0","upgradeTo":"v1.24.0"}, stats: {"totalNbTasks":1,"status":{"succeeded":1},"types":{"upgradeDatabase":1},"indexUids":{}}, stop reason: "stopped after the last task of type `upgradeDatabase` because they cannot be batched with tasks of any other type.", }
+0 {uid: 0, details: {"upgradeFrom":"v1.12.0","upgradeTo":"v1.26.0"}, stats: {"totalNbTasks":1,"status":{"succeeded":1},"types":{"upgradeDatabase":1},"indexUids":{}}, stop reason: "stopped after the last task of type `upgradeDatabase` because they cannot be batched with tasks of any other type.", }
 ----------------------------------------------------------------------
 ### Batch to tasks mapping:
 0 [0,]
--- a/crates/index-scheduler/src/upgrade/mod.rs
+++ b/crates/index-scheduler/src/upgrade/mod.rs
@@ -48,6 +48,8 @@ pub fn upgrade_index_scheduler(
        (1, 22, _) => 0,
        (1, 23, _) => 0,
        (1, 24, _) => 0,
+        (1, 25, _) => 0,
+        (1, 26, _) => 0,
        (major, minor, patch) => {
            if major > current_major
                || (major == current_major && minor > current_minor)
@@ -98,6 +100,7 @@ pub fn upgrade_index_scheduler(
            status: Status::Enqueued,
            kind: KindWithContent::UpgradeDatabase { from },
            network: None,
+            custom_metadata: None,
        },
    )?;
    wtxn.commit()?;
--- a/crates/index-scheduler/src/utils.rs
+++ b/crates/index-scheduler/src/utils.rs
@@ -286,6 +286,7 @@ pub fn swap_index_uid_in_task(task: &mut Task, swap: (&str, &str)) {
        | K::DumpCreation { .. }
        | K::Export { .. }
        | K::UpgradeDatabase { .. }
+        | K::NetworkTopologyChange(_)
        | K::SnapshotCreation => (),
    };
    if let Some(Details::IndexSwap { swaps }) = &mut task.details {
@@ -379,6 +380,7 @@ impl crate::IndexScheduler {
                status,
                kind,
                network: _,
+                custom_metadata: _,
            } = task;
            assert_eq!(uid, task.uid);
            if task.status != Status::Enqueued {
@@ -626,6 +628,13 @@ impl crate::IndexScheduler {
                    } => {
                        assert_eq!(kind.as_kind(), Kind::IndexCompaction);
                    }
+                    Details::NetworkTopologyChange {
+                        moved_documents: _,
+                        received_documents: _,
+                        message: _,
+                    } => {
+                        assert_eq!(kind.as_kind(), Kind::NetworkTopologyChange);
+                    }
                }
            }

--- a/crates/meilisearch-types/src/enterprise_edition/network.rs
+++ b/crates/meilisearch-types/src/enterprise_edition/network.rs
@@ -7,6 +7,7 @@ use std::collections::BTreeMap;

 use milli::update::new::indexer::enterprise_edition::sharding::Shards;
 use serde::{Deserialize, Serialize};
+use uuid::Uuid;

 #[derive(Serialize, Deserialize, Debug, Clone, PartialEq, Eq, Default)]
 #[serde(rename_all = "camelCase")]
@@ -16,20 +17,18 @@ pub struct Network {
    #[serde(default)]
    pub remotes: BTreeMap<String, Remote>,
    #[serde(default)]
-    pub sharding: bool,
+    pub leader: Option<String>,
+    #[serde(default)]
+    pub version: Uuid,
 }

 impl Network {
    pub fn shards(&self) -> Option<Shards> {
-        if self.sharding {
-            let this = self.local.as_deref().expect("Inconsistent `sharding` and `self`");
-            let others = self
-                .remotes
-                .keys()
-                .filter(|name| name.as_str() != this)
-                .map(|name| name.to_owned())
-                .collect();
-            Some(Shards { own: vec![this.to_owned()], others })
+        if self.leader.is_some() {
+            Some(Shards::from_remotes_local(
+                self.remotes.keys().map(String::as_str),
+                self.local.as_deref(),
+            ))
        } else {
            None
        }
--- a/crates/meilisearch-types/src/error.rs
+++ b/crates/meilisearch-types/src/error.rs
@@ -156,7 +156,7 @@ macro_rules! make_error_codes {
            }

            /// return error name, used as error code
-            fn name(&self) -> String {
+            pub fn name(&self) -> String {
                match self {
                    $(
                        Code::$code_ident => stringify!($code_ident).to_case(convert_case::Case::Snake)
@@ -214,6 +214,9 @@ ImmutableApiKeyUid                             , InvalidRequest       , BAD_REQU
 ImmutableApiKeyUpdatedAt                       , InvalidRequest       , BAD_REQUEST;
 ImmutableIndexCreatedAt                        , InvalidRequest       , BAD_REQUEST;
 ImmutableIndexUpdatedAt                        , InvalidRequest       , BAD_REQUEST;
+ImportTaskAlreadyReceived                      , InvalidRequest       , PRECONDITION_FAILED;
+ImportTaskUnknownRemote                        , InvalidRequest       , PRECONDITION_FAILED;
+ImportTaskWithoutNetworkTask                   , InvalidRequest       , SERVICE_UNAVAILABLE;
 IndexAlreadyExists                             , InvalidRequest       , CONFLICT ;
 IndexCreationFailed                            , Internal             , INTERNAL_SERVER_ERROR;
 IndexNotFound                                  , InvalidRequest       , NOT_FOUND;
@@ -254,6 +257,7 @@ InvalidSearchHybridQuery                       , InvalidRequest       , BAD_REQU
 InvalidIndexLimit                              , InvalidRequest       , BAD_REQUEST ;
 InvalidIndexOffset                             , InvalidRequest       , BAD_REQUEST ;
 InvalidIndexPrimaryKey                         , InvalidRequest       , BAD_REQUEST ;
+InvalidIndexCustomMetadata                     , InvalidRequest       , BAD_REQUEST ;
 InvalidIndexUid                                , InvalidRequest       , BAD_REQUEST ;
 InvalidMultiSearchFacets                       , InvalidRequest       , BAD_REQUEST ;
 InvalidMultiSearchFacetsByIndex                , InvalidRequest       , BAD_REQUEST ;
@@ -269,9 +273,9 @@ InvalidMultiSearchQueryRankingRules            , InvalidRequest       , BAD_REQU
 InvalidMultiSearchQueryPosition                , InvalidRequest       , BAD_REQUEST ;
 InvalidMultiSearchRemote                       , InvalidRequest       , BAD_REQUEST ;
 InvalidMultiSearchWeight                       , InvalidRequest       , BAD_REQUEST ;
+InvalidNetworkLeader                           , InvalidRequest       , BAD_REQUEST ;
 InvalidNetworkRemotes                          , InvalidRequest       , BAD_REQUEST ;
 InvalidNetworkSelf                             , InvalidRequest       , BAD_REQUEST ;
-InvalidNetworkSharding                         , InvalidRequest       , BAD_REQUEST ;
 InvalidNetworkSearchApiKey                     , InvalidRequest       , BAD_REQUEST ;
 InvalidNetworkWriteApiKey                      , InvalidRequest       , BAD_REQUEST ;
 InvalidNetworkUrl                              , InvalidRequest       , BAD_REQUEST ;
@@ -376,7 +380,9 @@ MissingPayload                                 , InvalidRequest       , BAD_REQU
 MissingSearchHybrid                            , InvalidRequest       , BAD_REQUEST ;
 MissingSwapIndexes                             , InvalidRequest       , BAD_REQUEST ;
 MissingTaskFilters                             , InvalidRequest       , BAD_REQUEST ;
+NetworkVersionMismatch                         , InvalidRequest       , PRECONDITION_FAILED ;
 NoSpaceLeftOnDevice                            , System               , UNPROCESSABLE_ENTITY;
+NotLeader                                      , InvalidRequest       , BAD_REQUEST ;
 PayloadTooLarge                                , InvalidRequest       , PAYLOAD_TOO_LARGE ;
 RemoteBadResponse                              , System               , BAD_GATEWAY ;
 RemoteBadRequest                               , InvalidRequest       , BAD_REQUEST ;
@@ -390,6 +396,7 @@ TaskFileNotFound                               , InvalidRequest       , NOT_FOUN
 BatchNotFound                                  , InvalidRequest       , NOT_FOUND ;
 TooManyOpenFiles                               , System               , UNPROCESSABLE_ENTITY ;
 TooManyVectors                                 , InvalidRequest       , BAD_REQUEST ;
+UnexpectedNetworkPreviousRemotes               , InvalidRequest       , BAD_REQUEST ;
 UnretrievableDocument                          , Internal             , BAD_REQUEST ;
 UnretrievableErrorCode                         , InvalidRequest       , BAD_REQUEST ;
 UnsupportedMediaType                           , InvalidRequest       , UNSUPPORTED_MEDIA_TYPE ;
--- a/crates/meilisearch-types/src/task_view.rs
+++ b/crates/meilisearch-types/src/task_view.rs
@@ -9,9 +9,9 @@ use utoipa::ToSchema;
 use crate::batches::BatchId;
 use crate::error::ResponseError;
 use crate::settings::{Settings, Unchecked};
+use crate::tasks::enterprise_edition::network::DbTaskNetwork;
 use crate::tasks::{
    serialize_duration, Details, DetailsExportIndexSettings, IndexSwap, Kind, Status, Task, TaskId,
-    TaskNetwork,
 };

 #[derive(Debug, Clone, PartialEq, Serialize, ToSchema)]
@@ -54,7 +54,10 @@ pub struct TaskView {
    pub finished_at: Option<OffsetDateTime>,

    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub network: Option<TaskNetwork>,
+    pub network: Option<DbTaskNetwork>,
+
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub custom_metadata: Option<String>,
 }

 impl TaskView {
@@ -73,6 +76,7 @@ impl TaskView {
            started_at: task.started_at,
            finished_at: task.finished_at,
            network: task.network.clone(),
+            custom_metadata: task.custom_metadata.clone(),
        }
    }
 }
@@ -147,6 +151,11 @@ pub struct DetailsView {
    pub pre_compaction_size: Option<String>,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub post_compaction_size: Option<String>,
+    // network topology change
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub moved_documents: Option<u64>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub message: Option<String>,
 }

 impl DetailsView {
@@ -157,6 +166,17 @@ impl DetailsView {
                (None, Some(doc)) | (Some(doc), None) => Some(doc),
                (Some(left), Some(right)) => Some(left + right),
            },
+            moved_documents: match (self.moved_documents, other.moved_documents) {
+                (None, None) => None,
+                (None, Some(doc)) | (Some(doc), None) => Some(doc),
+                (Some(left), Some(right)) => Some(left + right),
+            },
+            message: match (&mut self.message, &other.message) {
+                (None, None) => None,
+                (None, Some(message)) => Some(message.clone()),
+                (Some(message), None) => Some(std::mem::take(message)),
+                (Some(message), Some(_)) => Some(std::mem::take(message)),
+            },
            indexed_documents: match (self.indexed_documents, other.indexed_documents) {
                (None, None) => None,
                (None, Some(None)) | (Some(None), None) | (Some(None), Some(None)) => Some(None),
@@ -447,6 +467,14 @@ impl From<Details> for DetailsView {
                    ..Default::default()
                }
            }
+            Details::NetworkTopologyChange { moved_documents, received_documents, message } => {
+                DetailsView {
+                    moved_documents: Some(moved_documents),
+                    received_documents: Some(received_documents),
+                    message: Some(message),
+                    ..Default::default()
+                }
+            }
        }
    }
 }
--- a/crates/meilisearch-types/src/tasks/enterprise_edition/mod.rs
+++ b/crates/meilisearch-types/src/tasks/enterprise_edition/mod.rs
@@ -0,0 +1,6 @@
+// Copyright © 2025 Meilisearch Some Rights Reserved
+// This file is part of Meilisearch Enterprise Edition (EE).
+// Use of this source code is governed by the Business Source License 1.1,
+// as found in the LICENSE-EE file or at <https://mariadb.com/bsl11>
+
+pub mod network;
--- a/crates/meilisearch-types/src/tasks/enterprise_edition/network.rs
+++ b/crates/meilisearch-types/src/tasks/enterprise_edition/network.rs
@@ -0,0 +1,564 @@
+// Copyright © 2025 Meilisearch Some Rights Reserved
+// This file is part of Meilisearch Enterprise Edition (EE).
+// Use of this source code is governed by the Business Source License 1.1,
+// as found in the LICENSE-EE file or at <https://mariadb.com/bsl11>
+
+use std::collections::BTreeMap;
+
+use milli::DocumentId;
+use serde::{Deserialize, Serialize};
+use utoipa::ToSchema;
+use uuid::Uuid;
+
+use crate::enterprise_edition::network::{Network, Remote};
+use crate::error::ResponseError;
+use crate::tasks::{Details, TaskId};
+
+#[derive(Debug, PartialEq, Clone, Serialize, Deserialize, ToSchema)]
+#[serde(untagged, rename_all = "camelCase")]
+// This type is used in the database, care should be taken when modifying it.
+pub enum DbTaskNetwork {
+    /// Tasks that were duplicated from `origin`
+    Origin { origin: Origin },
+    /// Tasks that were duplicated as `remote_tasks`
+    Remotes {
+        remote_tasks: BTreeMap<String, RemoteTask>,
+        #[serde(default)]
+        network_version: Uuid,
+    },
+    /// Document import tasks sent in the context of `network_change`
+    Import { import_from: ImportData, network_change: Origin },
+}
+
+impl DbTaskNetwork {
+    pub fn network_version(&self) -> Uuid {
+        match self {
+            DbTaskNetwork::Origin { origin } => origin.network_version,
+            DbTaskNetwork::Remotes { remote_tasks: _, network_version } => *network_version,
+            DbTaskNetwork::Import { import_from: _, network_change } => {
+                network_change.network_version
+            }
+        }
+    }
+
+    pub fn import_data(&self) -> Option<&ImportData> {
+        match self {
+            DbTaskNetwork::Origin { .. } | DbTaskNetwork::Remotes { .. } => None,
+            DbTaskNetwork::Import { import_from, .. } => Some(import_from),
+        }
+    }
+
+    pub fn origin(&self) -> Option<&Origin> {
+        match self {
+            DbTaskNetwork::Origin { origin } => Some(origin),
+            DbTaskNetwork::Remotes { .. } => None,
+            DbTaskNetwork::Import { network_change, .. } => Some(network_change),
+        }
+    }
+}
+
+#[derive(Debug, PartialEq, Clone)]
+pub enum TaskNetwork {
+    /// Tasks that were duplicated from `origin`
+    Origin { origin: Origin },
+    /// Tasks that were duplicated as `remote_tasks`
+    Remotes { remote_tasks: BTreeMap<String, RemoteTask>, network_version: Uuid },
+    /// Document import tasks sent in the context of `network_change`
+    Import { import_from: ImportData, network_change: Origin, metadata: ImportMetadata },
+}
+
+impl From<TaskNetwork> for DbTaskNetwork {
+    fn from(value: TaskNetwork) -> Self {
+        match value {
+            TaskNetwork::Origin { origin } => DbTaskNetwork::Origin { origin },
+            TaskNetwork::Remotes { remote_tasks, network_version } => {
+                DbTaskNetwork::Remotes { remote_tasks, network_version }
+            }
+            TaskNetwork::Import { import_from, network_change, metadata: _ } => {
+                DbTaskNetwork::Import { import_from, network_change }
+            }
+        }
+    }
+}
+
+#[derive(Debug, PartialEq, Clone, Serialize, Deserialize, ToSchema)]
+#[serde(rename_all = "camelCase")]
+pub struct Origin {
+    pub remote_name: String,
+    pub task_uid: u32,
+    pub network_version: Uuid,
+}
+
+/// Import data stored in a task
+#[derive(Debug, PartialEq, Clone, Serialize, Deserialize, ToSchema)]
+#[serde(rename_all = "camelCase")]
+pub struct ImportData {
+    pub remote_name: String,
+    pub index_name: String,
+    pub document_count: u64,
+}
+
+/// Import metadata associated with a task but not stored in the task
+#[derive(Debug, PartialEq, Clone)]
+pub struct ImportMetadata {
+    /// Total number of indexes to import from this host
+    pub index_count: u64,
+    /// Key unique to this (network_change, index, host, key).
+    ///
+    /// In practice, an internal document id of one of the documents to import.
+    pub task_key: DocumentId,
+    /// Total number of documents to import for this index from this host.
+    pub total_index_documents: u64,
+}
+
+#[derive(Debug, PartialEq, Clone, Serialize, Deserialize, ToSchema)]
+#[serde(rename_all = "camelCase")]
+pub struct RemoteTask {
+    #[serde(skip_serializing_if = "Option::is_none")]
+    task_uid: Option<TaskId>,
+    error: Option<ResponseError>,
+}
+
+impl From<Result<TaskId, ResponseError>> for RemoteTask {
+    fn from(res: Result<TaskId, ResponseError>) -> RemoteTask {
+        match res {
+            Ok(task_uid) => RemoteTask { task_uid: Some(task_uid), error: None },
+            Err(err) => RemoteTask { task_uid: None, error: Some(err) },
+        }
+    }
+}
+
+/// Contains the full state of a network topology change.
+///
+/// A network topology change task is unique in that it can be processed in multiple different batches, as its resolution
+/// depends on various document additions tasks being processed.
+///
+/// A network topology task has 4 states:
+///
+/// 1. Processing any task that was meant for an earlier version of the network. This is necessary to know that we have the right version of
+/// documents.
+/// 2. Sending all documents that must be moved to other remotes.
+/// 3. Processing any task coming from the remotes.
+/// 4. Finished.
+///
+/// Furthermore, it maintains some stats
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct NetworkTopologyChange {
+    state: NetworkTopologyState,
+    // in name, `None` if the node is no longer part of the network
+    #[serde(skip_serializing_if = "Option::is_none")]
+    in_name: Option<String>,
+    // out name, `None` if the node is new to the network
+    #[serde(skip_serializing_if = "Option::is_none")]
+    out_name: Option<String>,
+    out_remotes: BTreeMap<String, Remote>,
+    in_remotes: BTreeMap<String, InRemote>,
+    stats: NetworkTopologyStats,
+}
+
+impl NetworkTopologyChange {
+    pub fn new(old_network: Network, new_network: Network) -> Self {
+        // we use our old name as export name
+        let out_name = old_network.local;
+        // we use our new name as import name
+        let in_name = new_network.local;
+        // we export to the new network
+        let mut out_remotes = new_network.remotes;
+        // don't export to ourselves
+        if let Some(in_name) = &in_name {
+            out_remotes.remove(in_name);
+        }
+        /// FIXME: doesn't work if the old network is not the same for old nodes
+        let in_remotes = old_network
+            .remotes
+            .into_keys()
+            // don't await imports from ourselves
+            .filter(|name| Some(name.as_str()) != out_name.as_deref())
+            .map(|name| (name, InRemote::new()))
+            .collect();
+        Self {
+            state: NetworkTopologyState::WaitingForOlderTasks,
+            in_name,
+            out_name,
+            out_remotes,
+            in_remotes,
+            stats: NetworkTopologyStats { received_documents: 0, moved_documents: 0 },
+        }
+    }
+
+    pub fn state(&self) -> NetworkTopologyState {
+        self.state
+    }
+
+    pub fn out_name(&self) -> Option<&str> {
+        // unwrap: one of out name or in_name must be defined
+        self.out_name.as_deref()
+    }
+
+    pub fn in_name(&self) -> Option<&str> {
+        self.in_name.as_deref()
+    }
+
+    pub fn export_to_process(&self) -> Option<(&BTreeMap<String, Remote>, &str)> {
+        if self.state != NetworkTopologyState::ExportingDocuments {
+            return None;
+        }
+
+        if self.out_remotes.is_empty() {
+            return None;
+        }
+
+        let out_name = self.out_name()?;
+        Some((&self.out_remotes, out_name))
+    }
+
+    /// Compute the next state from the current state of the task.
+    pub fn update_state(&mut self) {
+        self.state = match self.state {
+            NetworkTopologyState::WaitingForOlderTasks => {
+                // no more older tasks, so finished waiting
+                NetworkTopologyState::ExportingDocuments
+            }
+            NetworkTopologyState::ExportingDocuments => {
+                // processed all exported documents
+                NetworkTopologyState::ImportingDocuments
+            }
+            NetworkTopologyState::ImportingDocuments => {
+                if self.is_import_finished() {
+                    NetworkTopologyState::Finished
+                } else {
+                    NetworkTopologyState::ImportingDocuments
+                }
+            }
+            NetworkTopologyState::Finished => NetworkTopologyState::Finished,
+        };
+    }
+
+    pub fn receive_remote_task(
+        &mut self,
+        remote_name: &str,
+        index_name: &str,
+        task_key: DocumentId,
+        document_count: u64,
+        total_indexes: u64,
+        total_index_documents: u64,
+    ) -> Result<(), ReceiveTaskError> {
+        let remote = self
+            .in_remotes
+            .get_mut(remote_name)
+            .ok_or_else(|| ReceiveTaskError::UnknownRemote(remote_name.to_string()))?;
+        remote.import_state = match std::mem::take(&mut remote.import_state) {
+            ImportState::WaitingForInitialTask => {
+                let mut import_index_state = BTreeMap::new();
+                import_index_state.insert(
+                    index_name.to_owned(),
+                    ImportIndexState::Ongoing {
+                        total_documents: total_index_documents,
+                        received_documents: document_count,
+                        task_keys: vec![task_key],
+                        processed_documents: 0,
+                    },
+                );
+                ImportState::Ongoing { import_index_state, total_indexes }
+            }
+            ImportState::Ongoing { mut import_index_state, total_indexes } => {
+                if let Some((index_name, mut index_state)) =
+                    import_index_state.remove_entry(index_name)
+                {
+                    index_state = match index_state {
+                        ImportIndexState::Ongoing {
+                            total_documents,
+                            received_documents: previously_received,
+                            processed_documents,
+                            mut task_keys,
+                        } => {
+                            if task_keys.contains(&task_key) {
+                                return Err(ReceiveTaskError::DuplicateTask(task_key));
+                            }
+                            task_keys.push(task_key);
+                            ImportIndexState::Ongoing {
+                                total_documents,
+                                received_documents: previously_received + document_count,
+                                processed_documents,
+                                task_keys,
+                            }
+                        }
+                        ImportIndexState::Finished { total_documents } => {
+                            ImportIndexState::Finished { total_documents }
+                        }
+                    };
+                    import_index_state.insert(index_name, index_state);
+                } else {
+                    let state = ImportIndexState::Ongoing {
+                        total_documents: total_index_documents,
+                        received_documents: document_count,
+                        processed_documents: 0,
+                        task_keys: vec![task_key],
+                    };
+                    import_index_state.insert(index_name.to_string(), state);
+                }
+                ImportState::Ongoing { import_index_state, total_indexes: total_indexes }
+            }
+            ImportState::Finished { total_indexes, total_documents } => {
+                ImportState::Finished { total_indexes, total_documents }
+            }
+        };
+        Ok(())
+    }
+
+    pub fn process_remote_tasks(
+        &mut self,
+        remote_name: &str,
+        index_name: &str,
+        document_count: u64,
+    ) {
+        /// FIXME: unwraps and panics
+        let remote = self.in_remotes.get_mut(remote_name).unwrap();
+        remote.import_state = match std::mem::take(&mut remote.import_state) {
+            ImportState::WaitingForInitialTask => panic!("no task received yet one processed"),
+            ImportState::Ongoing { mut import_index_state, total_indexes } => {
+                let (index_name, mut index_state) =
+                    import_index_state.remove_entry(index_name).unwrap();
+                index_state = match index_state {
+                    ImportIndexState::Ongoing {
+                        total_documents,
+                        received_documents,
+                        processed_documents: previously_processed,
+                        task_keys,
+                    } => {
+                        let newly_processed_documents = previously_processed + document_count;
+                        if newly_processed_documents >= total_documents {
+                            ImportIndexState::Finished { total_documents }
+                        } else {
+                            ImportIndexState::Ongoing {
+                                total_documents,
+                                received_documents,
+                                processed_documents: newly_processed_documents,
+                                task_keys,
+                            }
+                        }
+                    }
+                    ImportIndexState::Finished { total_documents } => {
+                        ImportIndexState::Finished { total_documents }
+                    }
+                };
+                import_index_state.insert(index_name, index_state);
+                if import_index_state.len() as u64 == total_indexes
+                    && import_index_state.values().all(|index| index.is_finished())
+                {
+                    let total_documents =
+                        import_index_state.values().map(|index| index.total_documents()).sum();
+                    ImportState::Finished { total_indexes, total_documents }
+                } else {
+                    ImportState::Ongoing { import_index_state, total_indexes }
+                }
+            }
+            ImportState::Finished { total_indexes, total_documents } => {
+                ImportState::Finished { total_indexes, total_documents }
+            }
+        }
+    }
+
+    pub fn to_details(&self) -> Details {
+        let message = match self.state {
+            NetworkTopologyState::WaitingForOlderTasks => {
+                "Waiting for tasks enqueued before the network change to finish processing".into()
+            }
+            NetworkTopologyState::ExportingDocuments => "Exporting documents".into(),
+            NetworkTopologyState::ImportingDocuments => {
+                let mut finished_count = 0;
+                let mut first_ongoing = None;
+                let mut ongoing_total_indexes = 0;
+                let mut ongoing_processed_documents = 0;
+                let mut ongoing_missing_documents = 0;
+                let mut ongoing_total_documents = 0;
+                let mut other_ongoing_count = 0;
+                let mut first_waiting = None;
+                let mut other_waiting_count = 0;
+                for (remote_name, in_remote) in &self.in_remotes {
+                    match &in_remote.import_state {
+                        ImportState::WaitingForInitialTask => {
+                            first_waiting = match first_waiting {
+                                None => Some(remote_name),
+                                first_waiting => {
+                                    other_waiting_count += 1;
+                                    first_waiting
+                                }
+                            };
+                        }
+                        ImportState::Ongoing { import_index_state, total_indexes } => {
+                            first_ongoing = match first_ongoing {
+                                None => {
+                                    ongoing_total_indexes = *total_indexes;
+                                    Some(remote_name)
+                                }
+                                first_ongoing => {
+                                    other_ongoing_count += 1;
+                                    first_ongoing
+                                }
+                            };
+                            for import_state in import_index_state.values() {
+                                match import_state {
+                                    ImportIndexState::Ongoing {
+                                        total_documents,
+                                        processed_documents,
+                                        received_documents,
+                                        task_keys: _,
+                                    } => {
+                                        ongoing_total_documents += total_documents;
+                                        ongoing_processed_documents += processed_documents;
+                                        ongoing_missing_documents +=
+                                            total_documents.saturating_sub(*received_documents);
+                                    }
+                                    ImportIndexState::Finished { total_documents } => {
+                                        ongoing_total_documents += total_documents;
+                                        ongoing_processed_documents += total_documents;
+                                    }
+                                }
+                            }
+                        }
+                        ImportState::Finished { total_indexes, total_documents } => {
+                            finished_count += 1;
+                            ongoing_total_indexes = *total_indexes;
+                            ongoing_total_documents += *total_documents;
+                            ongoing_processed_documents += *total_documents;
+                        }
+                    }
+                }
+                format!(
+                    "Importing documents from {total} remotes{waiting}{ongoing}{finished}",
+                    total = self.in_remotes.len(),
+                    waiting = if let Some(first_waiting) = first_waiting {
+                        &format!(
+                            ", waiting on first task from `{}`{others}",
+                            first_waiting,
+                            others = if other_waiting_count > 0 {
+                                &format!(" and {other_waiting_count} other remotes")
+                            } else {
+                                ""
+                            }
+                        )
+                    } else {
+                        ""
+                    },
+                    ongoing = if let Some(first_ongoing) = first_ongoing {
+                        &format!(", awaiting {ongoing_missing_documents} and processed {ongoing_processed_documents} out of {ongoing_total_documents} documents in {ongoing_total_indexes} indexes from `{first_ongoing}`{others}",
+                others=if other_ongoing_count > 0 {&format!(" and {other_ongoing_count} other remotes")} else {""})
+                    } else {
+                        ""
+                    },
+                    finished = if finished_count >= 0 {
+                        &format!(", {finished_count} remotes finished processing")
+                    } else {
+                        ""
+                    }
+                )
+            }
+            NetworkTopologyState::Finished => "Finished".into(),
+        };
+        Details::NetworkTopologyChange {
+            moved_documents: self.stats.moved_documents,
+            received_documents: self.stats.received_documents,
+            message,
+        }
+    }
+
+    fn is_import_finished(&self) -> bool {
+        self.in_remotes.values().all(|remote| remote.is_finished())
+    }
+}
+
+pub enum ReceiveTaskError {
+    UnknownRemote(String),
+    DuplicateTask(DocumentId),
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub enum NetworkTopologyState {
+    WaitingForOlderTasks,
+    ExportingDocuments,
+    ImportingDocuments,
+    Finished,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct NetworkTopologyStats {
+    pub received_documents: u64,
+    pub moved_documents: u64,
+}
+
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct InRemote {
+    import_state: ImportState,
+}
+
+impl InRemote {
+    pub fn new() -> Self {
+        Self { import_state: ImportState::WaitingForInitialTask }
+    }
+
+    pub fn is_finished(&self) -> bool {
+        matches!(self.import_state, ImportState::Finished { .. })
+    }
+}
+
+#[derive(Default, Debug, Clone, PartialEq, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+enum ImportState {
+    /// Initially Meilisearch doesn't know how many documents it should expect from a remote.
+    /// The first task for each remote contains the information of how many indexes will be imported,
+    /// and the first task for each index contains the number of documents to import for that index.
+    #[default]
+    WaitingForInitialTask,
+    Ongoing {
+        import_index_state: BTreeMap<String, ImportIndexState>,
+        total_indexes: u64,
+    },
+    Finished {
+        total_indexes: u64,
+        total_documents: u64,
+    },
+}
+
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+enum ImportIndexState {
+    Ongoing {
+        total_documents: u64,
+        received_documents: u64,
+        processed_documents: u64,
+        task_keys: Vec<DocumentId>,
+    },
+    Finished {
+        total_documents: u64,
+    },
+}
+
+impl ImportIndexState {
+    pub fn is_finished(&self) -> bool {
+        matches!(self, ImportIndexState::Finished { .. })
+    }
+
+    fn total_documents(&self) -> u64 {
+        match *self {
+            ImportIndexState::Ongoing { total_documents, .. }
+            | ImportIndexState::Finished { total_documents } => total_documents,
+        }
+    }
+}
+
+pub mod headers {
+    pub const PROXY_ORIGIN_REMOTE_HEADER: &str = "Meili-Proxy-Origin-Remote";
+    pub const PROXY_ORIGIN_TASK_UID_HEADER: &str = "Meili-Proxy-Origin-TaskUid";
+    pub const PROXY_ORIGIN_NETWORK_VERSION_HEADER: &str = "Meili-Proxy-Origin-Network-Version";
+    pub const PROXY_IMPORT_REMOTE_HEADER: &str = "Meili-Proxy-Import-Remote";
+    pub const PROXY_IMPORT_INDEX_COUNT_HEADER: &str = "Meili-Proxy-Import-Index-Count";
+    pub const PROXY_IMPORT_INDEX_HEADER: &str = "Meili-Proxy-Import-Index";
+    pub const PROXY_IMPORT_TASK_KEY_HEADER: &str = "Meili-Proxy-Import-Task-Key";
+    pub const PROXY_IMPORT_DOCS_HEADER: &str = "Meili-Proxy-Import-Docs";
+    pub const PROXY_IMPORT_TOTAL_INDEX_DOCS_HEADER: &str = "Meili-Proxy-Import-Total-Index-Docs";
+}
--- a/crates/meilisearch-types/src/tasks/mod.rs
+++ b/crates/meilisearch-types/src/tasks/mod.rs
@@ -23,6 +23,8 @@ use crate::{versioning, InstanceUid};

 pub type TaskId = u32;

+pub mod enterprise_edition;
+
 #[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
 #[serde(rename_all = "camelCase")]
 pub struct Task {
@@ -44,7 +46,10 @@ pub struct Task {
    pub kind: KindWithContent,

    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub network: Option<TaskNetwork>,
+    pub network: Option<enterprise_edition::network::DbTaskNetwork>,
+
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub custom_metadata: Option<String>,
 }

 impl Task {
@@ -58,6 +63,7 @@ impl Task {
            | TaskDeletion { .. }
            | Export { .. }
            | UpgradeDatabase { .. }
+            | NetworkTopologyChange { .. }
            | IndexSwap { .. } => None,
            DocumentAdditionOrUpdate { index_uid, .. }
            | DocumentEdition { index_uid, .. }
@@ -96,6 +102,7 @@ impl Task {
            | KindWithContent::SnapshotCreation
            | KindWithContent::Export { .. }
            | KindWithContent::UpgradeDatabase { .. }
+            | KindWithContent::NetworkTopologyChange { .. }
            | KindWithContent::IndexCompaction { .. } => None,
        }
    }
@@ -175,6 +182,7 @@ pub enum KindWithContent {
    IndexCompaction {
        index_uid: String,
    },
+    NetworkTopologyChange(enterprise_edition::network::NetworkTopologyChange),
 }

 #[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize, ToSchema)]
@@ -212,6 +220,7 @@ impl KindWithContent {
            KindWithContent::Export { .. } => Kind::Export,
            KindWithContent::UpgradeDatabase { .. } => Kind::UpgradeDatabase,
            KindWithContent::IndexCompaction { .. } => Kind::IndexCompaction,
+            KindWithContent::NetworkTopologyChange { .. } => Kind::NetworkTopologyChange,
        }
    }

@@ -224,6 +233,7 @@ impl KindWithContent {
            | TaskCancelation { .. }
            | TaskDeletion { .. }
            | Export { .. }
+            | NetworkTopologyChange { .. }
            | UpgradeDatabase { .. } => vec![],
            DocumentAdditionOrUpdate { index_uid, .. }
            | DocumentEdition { index_uid, .. }
@@ -337,6 +347,11 @@ impl KindWithContent {
                pre_compaction_size: None,
                post_compaction_size: None,
            }),
+            KindWithContent::NetworkTopologyChange { .. } => Some(Details::NetworkTopologyChange {
+                moved_documents: 0,
+                received_documents: 0,
+                message: "processing tasks for previous network versions".into(),
+            }),
        }
    }

@@ -389,7 +404,7 @@ impl KindWithContent {
                })
            }
            KindWithContent::IndexSwap { .. } => {
-                todo!()
+                unimplemented!("do not call `default_finished_details` for `IndexSwap` tasks")
            }
            KindWithContent::TaskCancelation { query, tasks } => Some(Details::TaskCancelation {
                matched_tasks: tasks.len(),
@@ -424,6 +439,9 @@ impl KindWithContent {
                pre_compaction_size: None,
                post_compaction_size: None,
            }),
+            KindWithContent::NetworkTopologyChange(network_topology_change) => {
+                Some(network_topology_change.to_details())
+            }
        }
    }
 }
@@ -491,6 +509,9 @@ impl From<&KindWithContent> for Option<Details> {
                pre_compaction_size: None,
                post_compaction_size: None,
            }),
+            KindWithContent::NetworkTopologyChange(network_topology_change) => {
+                Some(network_topology_change.to_details())
+            }
        }
    }
 }
@@ -602,6 +623,7 @@ pub enum Kind {
    Export,
    UpgradeDatabase,
    IndexCompaction,
+    NetworkTopologyChange,
 }

 impl Kind {
@@ -621,6 +643,7 @@ impl Kind {
            | Kind::DumpCreation
            | Kind::Export
            | Kind::UpgradeDatabase
+            | Kind::NetworkTopologyChange
            | Kind::SnapshotCreation => false,
        }
    }
@@ -643,6 +666,7 @@ impl Display for Kind {
            Kind::Export => write!(f, "export"),
            Kind::UpgradeDatabase => write!(f, "upgradeDatabase"),
            Kind::IndexCompaction => write!(f, "indexCompaction"),
+            Kind::NetworkTopologyChange => write!(f, "networkTopologyChange"),
        }
    }
 }
@@ -680,6 +704,8 @@ impl FromStr for Kind {
            Ok(Kind::UpgradeDatabase)
        } else if kind.eq_ignore_ascii_case("indexCompaction") {
            Ok(Kind::IndexCompaction)
+        } else if kind.eq_ignore_ascii_case("networkTopologyChange") {
+            Ok(Kind::NetworkTopologyChange)
        } else {
            Err(ParseTaskKindError(kind.to_owned()))
        }
@@ -770,36 +796,11 @@ pub enum Details {
        pre_compaction_size: Option<Byte>,
        post_compaction_size: Option<Byte>,
    },
-}
-
-#[derive(Debug, PartialEq, Clone, Serialize, Deserialize, ToSchema)]
-#[serde(untagged, rename_all = "camelCase")]
-pub enum TaskNetwork {
-    Origin { origin: Origin },
-    Remotes { remote_tasks: BTreeMap<String, RemoteTask> },
-}
-#[derive(Debug, PartialEq, Clone, Serialize, Deserialize, ToSchema)]
-#[serde(rename_all = "camelCase")]
-pub struct Origin {
-    pub remote_name: String,
-    pub task_uid: usize,
-}
-
-#[derive(Debug, PartialEq, Clone, Serialize, Deserialize, ToSchema)]
-#[serde(rename_all = "camelCase")]
-pub struct RemoteTask {
-    #[serde(skip_serializing_if = "Option::is_none")]
-    task_uid: Option<TaskId>,
-    error: Option<ResponseError>,
-}
-
-impl From<Result<TaskId, ResponseError>> for RemoteTask {
-    fn from(res: Result<TaskId, ResponseError>) -> RemoteTask {
-        match res {
-            Ok(task_uid) => RemoteTask { task_uid: Some(task_uid), error: None },
-            Err(err) => RemoteTask { task_uid: None, error: Some(err) },
-        }
-    }
+    NetworkTopologyChange {
+        moved_documents: u64,
+        received_documents: u64,
+        message: String,
+    },
 }

 #[derive(Debug, PartialEq, Clone, Serialize, Deserialize, ToSchema)]
@@ -842,6 +843,9 @@ impl Details {
            | Self::Export { .. }
            | Self::UpgradeDatabase { .. }
            | Self::IndexSwap { .. } => (),
+            Self::NetworkTopologyChange { moved_documents: _, received_documents: _, message } => {
+                *message = format!("Failed. Previous status: {}", message);
+            }
        }

        details
--- a/crates/meilisearch/src/error.rs
+++ b/crates/meilisearch/src/error.rs
@@ -6,6 +6,10 @@ use meilisearch_types::error::{Code, ErrorCode, ResponseError};
 use meilisearch_types::index_uid::{IndexUid, IndexUidFormatError};
 use meilisearch_types::milli;
 use meilisearch_types::milli::OrderBy;
+use meilisearch_types::tasks::enterprise_edition::network::headers::{
+    PROXY_IMPORT_DOCS_HEADER, PROXY_IMPORT_INDEX_COUNT_HEADER, PROXY_IMPORT_INDEX_HEADER,
+    PROXY_IMPORT_REMOTE_HEADER, PROXY_IMPORT_TASK_KEY_HEADER, PROXY_IMPORT_TOTAL_INDEX_DOCS_HEADER,
+};
 use serde_json::Value;
 use tokio::task::JoinError;

@@ -93,8 +97,49 @@ pub enum MeilisearchHttpError {
    } else { PROXY_ORIGIN_TASK_UID_HEADER }
 )]
    InconsistentOriginHeaders { is_remote_missing: bool },
+    #[error("Inconsistent `Import` headers: {remote}: {remote_status}, {index}: {index_status}, {docs}: {docs_status}.\n - Hint: either all three headers should be provided, or none of them",
+        remote = PROXY_IMPORT_REMOTE_HEADER,
+        remote_status = if *is_remote_missing { "missing" } else{ "provided" },
+        index = PROXY_IMPORT_INDEX_HEADER,
+        index_status = if *is_index_missing { "missing" } else { "provided" },
+        docs = PROXY_IMPORT_DOCS_HEADER,
+        docs_status = if *is_docs_missing { "missing" } else { "provided" }
+    )]
+    InconsistentImportHeaders {
+        is_remote_missing: bool,
+        is_index_missing: bool,
+        is_docs_missing: bool,
+    },
+    #[error("Inconsistent `Import-Metadata` headers: {index_count}: {index_count_status}, {task_key}: {task_key_status}, {total_index_documents}: {total_index_documents_status}.\n - Hint: either all three headers should be provided, or none of them",
+        index_count = PROXY_IMPORT_INDEX_COUNT_HEADER,
+        index_count_status = if *is_index_count_missing { "missing" } else { "provided"},
+        task_key = PROXY_IMPORT_TASK_KEY_HEADER,
+        task_key_status = if *is_task_key_missing { "missing" } else { "provided"},
+        total_index_documents = PROXY_IMPORT_TOTAL_INDEX_DOCS_HEADER,
+        total_index_documents_status = if *is_total_index_documents_missing { "missing" } else { "provided"},
+    )]
+    InconsistentImportMetadataHeaders {
+        is_index_count_missing: bool,
+        is_task_key_missing: bool,
+        is_total_index_documents_missing: bool,
+    },
+
+    #[error(
+        "Inconsistent task network headers: origin headers: {origin_status}, import headers: {import_status}, import metadata: {import_metadata_status}",
+        origin_status =  if *is_missing_origin { "missing"} else { "present" },
+        import_status =  if *is_missing_import { "missing"} else { "present" },
+        import_metadata_status =  if *is_missing_import_metadata { "missing"} else { "present" })]
+    InconsistentTaskNetworkHeaders {
+        is_missing_origin: bool,
+        is_missing_import: bool,
+        is_missing_import_metadata: bool,
+    },
    #[error("Invalid value for header {header_name}: {msg}")]
    InvalidHeaderValue { header_name: &'static str, msg: String },
+    #[error("This remote is not the leader of the network.\n  - Note: only the leader `{leader}` can receive new tasks.")]
+    NotLeader { leader: String },
+    #[error("Unexpected `previousRemotes` in network call.\n  - Note: `previousRemote` is reserved for internal use.")]
+    UnexpectedNetworkPreviousRemotes,
 }

 impl MeilisearchHttpError {
@@ -142,10 +187,17 @@ impl ErrorCode for MeilisearchHttpError {
            MeilisearchHttpError::PersonalizationInFederatedQuery(_) => {
                Code::InvalidMultiSearchQueryPersonalization
            }
-            MeilisearchHttpError::InconsistentOriginHeaders { .. } => {
+            MeilisearchHttpError::InconsistentOriginHeaders { .. }
+            | MeilisearchHttpError::InconsistentImportHeaders { .. }
+            | MeilisearchHttpError::InconsistentImportMetadataHeaders { .. }
+            | MeilisearchHttpError::InconsistentTaskNetworkHeaders { .. } => {
                Code::InconsistentDocumentChangeHeaders
            }
            MeilisearchHttpError::InvalidHeaderValue { .. } => Code::InvalidHeaderValue,
+            MeilisearchHttpError::NotLeader { .. } => Code::NotLeader,
+            MeilisearchHttpError::UnexpectedNetworkPreviousRemotes => {
+                Code::UnexpectedNetworkPreviousRemotes
+            }
        }
    }
 }
--- a/crates/meilisearch/src/routes/indexes/documents.rs
+++ b/crates/meilisearch/src/routes/indexes/documents.rs
@@ -45,7 +45,9 @@ use crate::extractors::authentication::policies::*;
 use crate::extractors::authentication::GuardedData;
 use crate::extractors::payload::Payload;
 use crate::extractors::sequential_extractor::SeqHandler;
-use crate::routes::indexes::enterprise_edition::proxy::{proxy, Body};
+use crate::routes::indexes::enterprise_edition::proxy::{
+    proxy, task_network_and_check_leader, Body,
+};
 use crate::routes::indexes::search::fix_sort_query_parameters;
 use crate::routes::{
    get_task_id, is_dry_run, PaginationView, SummarizedTaskView, PAGINATION_DEFAULT_LIMIT,
@@ -333,13 +335,16 @@ impl Aggregate for DocumentsDeletionAggregator {
 pub async fn delete_document(
    index_scheduler: GuardedData<ActionPolicy<{ actions::DOCUMENTS_DELETE }>, Data<IndexScheduler>>,
    path: web::Path<DocumentParam>,
+    params: AwebQueryParameter<CustomMetadataQuery, DeserrQueryParamError>,
    req: HttpRequest,
    opt: web::Data<Opt>,
    analytics: web::Data<Analytics>,
 ) -> Result<HttpResponse, ResponseError> {
+    let CustomMetadataQuery { custom_metadata } = params.into_inner();
    let DocumentParam { index_uid, document_id } = path.into_inner();
    let index_uid = IndexUid::try_from(index_uid)?;
    let network = index_scheduler.network();
+    let task_network = task_network_and_check_leader(&req, &network)?;

    analytics.publish(
        DocumentsDeletionAggregator {
@@ -357,13 +362,23 @@ pub async fn delete_document(
    };
    let uid = get_task_id(&req, &opt)?;
    let dry_run = is_dry_run(&req, &opt)?;
-    let task = {
+    let mut task = {
        let index_scheduler = index_scheduler.clone();
-        tokio::task::spawn_blocking(move || index_scheduler.register(task, uid, dry_run)).await??
+        tokio::task::spawn_blocking(move || {
+            index_scheduler.register_with_custom_metadata(
+                task,
+                uid,
+                custom_metadata,
+                dry_run,
+                task_network,
+            )
+        })
+        .await??
    };

-    if network.sharding && !dry_run {
-        proxy(&index_scheduler, &index_uid, &req, network, Body::none(), &task).await?;
+    if let Some(task_network) = task.network.take() {
+        proxy(&index_scheduler, Some(&index_uid), &req, task_network, network, Body::none(), &task)
+            .await?;
    }

    let task: SummarizedTaskView = task.into();
@@ -678,6 +693,19 @@ pub struct UpdateDocumentsQuery {
    #[param(value_type = char, default = ",", example = ";")]
    #[deserr(default, try_from(char) = from_char_csv_delimiter -> DeserrQueryParamError<InvalidDocumentCsvDelimiter>, error = DeserrQueryParamError<InvalidDocumentCsvDelimiter>)]
    pub csv_delimiter: Option<u8>,
+
+    #[param(example = "custom")]
+    #[deserr(default, error = DeserrQueryParamError<InvalidIndexCustomMetadata>)]
+    pub custom_metadata: Option<String>,
+}
+
+#[derive(Deserialize, Debug, Deserr, IntoParams)]
+#[deserr(error = DeserrQueryParamError, rename_all = camelCase, deny_unknown_fields)]
+#[into_params(parameter_in = Query, rename_all = "camelCase")]
+pub struct CustomMetadataQuery {
+    #[param(example = "custom")]
+    #[deserr(default, error = DeserrQueryParamError<InvalidIndexCustomMetadata>)]
+    pub custom_metadata: Option<String>,
 }

 fn from_char_csv_delimiter(
@@ -819,6 +847,7 @@ pub async fn replace_documents(
        body,
        IndexDocumentsMethod::ReplaceDocuments,
        uid,
+        params.custom_metadata,
        dry_run,
        allow_index_creation,
        &req,
@@ -921,6 +950,7 @@ pub async fn update_documents(
        body,
        IndexDocumentsMethod::UpdateDocuments,
        uid,
+        params.custom_metadata,
        dry_run,
        allow_index_creation,
        &req,
@@ -940,12 +970,14 @@ async fn document_addition(
    body: Payload,
    method: IndexDocumentsMethod,
    task_id: Option<TaskId>,
+    custom_metadata: Option<String>,
    dry_run: bool,
    allow_index_creation: bool,
    req: &HttpRequest,
 ) -> Result<SummarizedTaskView, MeilisearchHttpError> {
    let mime_type = extract_mime_type(req)?;
    let network = index_scheduler.network();
+    let task_network = task_network_and_check_leader(&req, &network)?;

    let format = match (
        mime_type.as_ref().map(|m| (m.type_().as_str(), m.subtype().as_str())),
@@ -1064,9 +1096,18 @@ async fn document_addition(
        index_uid: index_uid.to_string(),
    };

+    /// FIXME: not new to this PR, but _any_ error here will cause the payload to unduly persist
    let scheduler = index_scheduler.clone();
-    let task = match tokio::task::spawn_blocking(move || scheduler.register(task, task_id, dry_run))
-        .await?
+    let mut task = match tokio::task::spawn_blocking(move || {
+        scheduler.register_with_custom_metadata(
+            task,
+            task_id,
+            custom_metadata,
+            dry_run,
+            task_network,
+        )
+    })
+    .await?
    {
        Ok(task) => task,
        Err(e) => {
@@ -1075,12 +1116,13 @@ async fn document_addition(
        }
    };

-    if network.sharding {
+    if let Some(task_network) = task.network.take() {
        if let Some(file) = file {
            proxy(
                &index_scheduler,
-                &index_uid,
+                Some(&index_uid),
                req,
+                task_network,
                network,
                Body::with_ndjson_payload(file),
                &task,
@@ -1130,7 +1172,7 @@ async fn copy_body_to_file(
 /// Delete a set of documents based on an array of document ids.
 #[utoipa::path(
    post,
-    path = "{indexUid}/delete-batch",
+    path = "{indexUid}/documents/delete-batch",
    tag = "Documents",
    security(("Bearer" = ["documents.delete", "documents.*", "*"])),
    params(
@@ -1161,13 +1203,17 @@ pub async fn delete_documents_batch(
    index_scheduler: GuardedData<ActionPolicy<{ actions::DOCUMENTS_DELETE }>, Data<IndexScheduler>>,
    index_uid: web::Path<String>,
    body: web::Json<Vec<Value>>,
+    params: AwebQueryParameter<CustomMetadataQuery, DeserrQueryParamError>,
    req: HttpRequest,
    opt: web::Data<Opt>,
    analytics: web::Data<Analytics>,
 ) -> Result<HttpResponse, ResponseError> {
    debug!(parameters = ?body, "Delete documents by batch");
+    let CustomMetadataQuery { custom_metadata } = params.into_inner();
+
    let index_uid = IndexUid::try_from(index_uid.into_inner())?;
    let network = index_scheduler.network();
+    let task_network = task_network_and_check_leader(&req, &network)?;

    analytics.publish(
        DocumentsDeletionAggregator {
@@ -1188,13 +1234,31 @@ pub async fn delete_documents_batch(
        KindWithContent::DocumentDeletion { index_uid: index_uid.to_string(), documents_ids: ids };
    let uid = get_task_id(&req, &opt)?;
    let dry_run = is_dry_run(&req, &opt)?;
-    let task = {
+    let mut task = {
        let index_scheduler = index_scheduler.clone();
-        tokio::task::spawn_blocking(move || index_scheduler.register(task, uid, dry_run)).await??
+        tokio::task::spawn_blocking(move || {
+            index_scheduler.register_with_custom_metadata(
+                task,
+                uid,
+                custom_metadata,
+                dry_run,
+                task_network,
+            )
+        })
+        .await??
    };

-    if network.sharding && !dry_run {
-        proxy(&index_scheduler, &index_uid, &req, network, Body::Inline(body), &task).await?;
+    if let Some(task_network) = task.network.take() {
+        proxy(
+            &index_scheduler,
+            Some(&index_uid),
+            &req,
+            task_network,
+            network,
+            Body::inline(body),
+            &task,
+        )
+        .await?;
    }

    let task: SummarizedTaskView = task.into();
@@ -1244,16 +1308,20 @@ pub struct DocumentDeletionByFilter {
 pub async fn delete_documents_by_filter(
    index_scheduler: GuardedData<ActionPolicy<{ actions::DOCUMENTS_DELETE }>, Data<IndexScheduler>>,
    index_uid: web::Path<String>,
+    params: AwebQueryParameter<CustomMetadataQuery, DeserrQueryParamError>,
    body: AwebJson<DocumentDeletionByFilter, DeserrJsonError>,
    req: HttpRequest,
    opt: web::Data<Opt>,
    analytics: web::Data<Analytics>,
 ) -> Result<HttpResponse, ResponseError> {
    debug!(parameters = ?body, "Delete documents by filter");
+    let CustomMetadataQuery { custom_metadata } = params.into_inner();
+
    let index_uid = IndexUid::try_from(index_uid.into_inner())?;
    let index_uid = index_uid.into_inner();
    let filter = body.into_inner();
    let network = index_scheduler.network();
+    let task_network = task_network_and_check_leader(&req, &network)?;

    analytics.publish(
        DocumentsDeletionAggregator {
@@ -1280,13 +1348,31 @@ pub async fn delete_documents_by_filter(

    let uid = get_task_id(&req, &opt)?;
    let dry_run = is_dry_run(&req, &opt)?;
-    let task = {
+    let mut task = {
        let index_scheduler = index_scheduler.clone();
-        tokio::task::spawn_blocking(move || index_scheduler.register(task, uid, dry_run)).await??
+        tokio::task::spawn_blocking(move || {
+            index_scheduler.register_with_custom_metadata(
+                task,
+                uid,
+                custom_metadata,
+                dry_run,
+                task_network,
+            )
+        })
+        .await??
    };

-    if network.sharding && !dry_run {
-        proxy(&index_scheduler, &index_uid, &req, network, Body::Inline(filter), &task).await?;
+    if let Some(task_network) = task.network.take() {
+        proxy(
+            &index_scheduler,
+            Some(&index_uid),
+            &req,
+            task_network,
+            network,
+            Body::inline(filter),
+            &task,
+        )
+        .await?;
    }

    let task: SummarizedTaskView = task.into();
@@ -1372,38 +1458,41 @@ impl Aggregate for EditDocumentsByFunctionAggregator {
 pub async fn edit_documents_by_function(
    index_scheduler: GuardedData<ActionPolicy<{ actions::DOCUMENTS_ALL }>, Data<IndexScheduler>>,
    index_uid: web::Path<String>,
-    params: AwebJson<DocumentEditionByFunction, DeserrJsonError>,
+    params: AwebQueryParameter<CustomMetadataQuery, DeserrQueryParamError>,
+    body: AwebJson<DocumentEditionByFunction, DeserrJsonError>,
    req: HttpRequest,
    opt: web::Data<Opt>,
    analytics: web::Data<Analytics>,
 ) -> Result<HttpResponse, ResponseError> {
-    debug!(parameters = ?params, "Edit documents by function");
+    debug!(parameters = ?body, "Edit documents by function");
+    let CustomMetadataQuery { custom_metadata } = params.into_inner();

    index_scheduler
        .features()
        .check_edit_documents_by_function("Using the documents edit route")?;

    let network = index_scheduler.network();
+    let task_network = task_network_and_check_leader(&req, &network)?;

    let index_uid = IndexUid::try_from(index_uid.into_inner())?;
    let index_uid = index_uid.into_inner();
-    let params = params.into_inner();
+    let body = body.into_inner();

    analytics.publish(
        EditDocumentsByFunctionAggregator {
-            filtered: params.filter.is_some(),
-            with_context: params.context.is_some(),
+            filtered: body.filter.is_some(),
+            with_context: body.context.is_some(),
            index_creation: index_scheduler.index(&index_uid).is_err(),
        },
        &req,
    );

    let engine = milli::rhai::Engine::new();
-    if let Err(e) = engine.compile(&params.function) {
+    if let Err(e) = engine.compile(&body.function) {
        return Err(ResponseError::from_msg(e.to_string(), Code::BadRequest));
    }

-    if let Some(ref filter) = params.filter {
+    if let Some(ref filter) = body.filter {
        // we ensure the filter is well formed before enqueuing it
        crate::search::parse_filter(
            filter,
@@ -1414,8 +1503,8 @@ pub async fn edit_documents_by_function(
    }
    let task = KindWithContent::DocumentEdition {
        index_uid: index_uid.clone(),
-        filter_expr: params.filter.clone(),
-        context: match params.context.clone() {
+        filter_expr: body.filter.clone(),
+        context: match body.context.clone() {
            Some(Value::Object(m)) => Some(m),
            None => None,
            _ => {
@@ -1425,18 +1514,36 @@ pub async fn edit_documents_by_function(
                ))
            }
        },
-        function: params.function.clone(),
+        function: body.function.clone(),
    };

    let uid = get_task_id(&req, &opt)?;
    let dry_run = is_dry_run(&req, &opt)?;
-    let task = {
+    let mut task = {
        let index_scheduler = index_scheduler.clone();
-        tokio::task::spawn_blocking(move || index_scheduler.register(task, uid, dry_run)).await??
+        tokio::task::spawn_blocking(move || {
+            index_scheduler.register_with_custom_metadata(
+                task,
+                uid,
+                custom_metadata,
+                dry_run,
+                task_network,
+            )
+        })
+        .await??
    };

-    if network.sharding && !dry_run {
-        proxy(&index_scheduler, &index_uid, &req, network, Body::Inline(params), &task).await?;
+    if let Some(task_network) = task.network.take() {
+        proxy(
+            &index_scheduler,
+            Some(&index_uid),
+            &req,
+            task_network,
+            network,
+            Body::inline(body),
+            &task,
+        )
+        .await?;
    }

    let task: SummarizedTaskView = task.into();
@@ -1477,12 +1584,15 @@ pub async fn edit_documents_by_function(
 pub async fn clear_all_documents(
    index_scheduler: GuardedData<ActionPolicy<{ actions::DOCUMENTS_DELETE }>, Data<IndexScheduler>>,
    index_uid: web::Path<String>,
+    params: AwebQueryParameter<CustomMetadataQuery, DeserrQueryParamError>,
    req: HttpRequest,
    opt: web::Data<Opt>,
    analytics: web::Data<Analytics>,
 ) -> Result<HttpResponse, ResponseError> {
    let index_uid = IndexUid::try_from(index_uid.into_inner())?;
    let network = index_scheduler.network();
+    let CustomMetadataQuery { custom_metadata } = params.into_inner();
+    let task_network = task_network_and_check_leader(&req, &network)?;

    analytics.publish(
        DocumentsDeletionAggregator {
@@ -1498,14 +1608,24 @@ pub async fn clear_all_documents(
    let uid = get_task_id(&req, &opt)?;
    let dry_run = is_dry_run(&req, &opt)?;

-    let task = {
+    let mut task = {
        let index_scheduler = index_scheduler.clone();

-        tokio::task::spawn_blocking(move || index_scheduler.register(task, uid, dry_run)).await??
+        tokio::task::spawn_blocking(move || {
+            index_scheduler.register_with_custom_metadata(
+                task,
+                uid,
+                custom_metadata,
+                dry_run,
+                task_network,
+            )
+        })
+        .await??
    };

-    if network.sharding && !dry_run {
-        proxy(&index_scheduler, &index_uid, &req, network, Body::none(), &task).await?;
+    if let Some(task_network) = task.network.take() {
+        proxy(&index_scheduler, Some(&index_uid), &req, task_network, network, Body::none(), &task)
+            .await?;
    }

    let task: SummarizedTaskView = task.into();
--- a/crates/meilisearch/src/routes/indexes/enterprise_edition/proxy.rs
+++ b/crates/meilisearch/src/routes/indexes/enterprise_edition/proxy.rs
@@ -3,6 +3,7 @@
 // Use of this source code is governed by the Business Source License 1.1,
 // as found in the LICENSE-EE file or at <https://mariadb.com/bsl11>

+use std::borrow::Cow;
 use std::collections::BTreeMap;
 use std::fs::File;

@@ -10,8 +11,18 @@ use actix_web::http::header::CONTENT_TYPE;
 use actix_web::HttpRequest;
 use bytes::Bytes;
 use index_scheduler::IndexScheduler;
+use meilisearch_types::enterprise_edition::network::Remote;
 use meilisearch_types::error::ResponseError;
-use meilisearch_types::tasks::{Origin, RemoteTask, TaskNetwork};
+use meilisearch_types::milli::DocumentId;
+use meilisearch_types::tasks::enterprise_edition::network::headers::{
+    PROXY_IMPORT_DOCS_HEADER, PROXY_IMPORT_INDEX_COUNT_HEADER, PROXY_IMPORT_INDEX_HEADER,
+    PROXY_IMPORT_REMOTE_HEADER, PROXY_IMPORT_TASK_KEY_HEADER, PROXY_IMPORT_TOTAL_INDEX_DOCS_HEADER,
+    PROXY_ORIGIN_NETWORK_VERSION_HEADER, PROXY_ORIGIN_REMOTE_HEADER, PROXY_ORIGIN_TASK_UID_HEADER,
+};
+use meilisearch_types::tasks::enterprise_edition::network::{
+    DbTaskNetwork, ImportData, ImportMetadata, Origin, TaskNetwork,
+};
+use meilisearch_types::tasks::Task;
 use reqwest::StatusCode;
 use serde::de::DeserializeOwned;
 use serde_json::Value;
@@ -22,13 +33,18 @@ use crate::routes::indexes::enterprise_edition::proxy::error::{
 };
 use crate::routes::SummarizedTaskView;

-pub enum Body<T: serde::Serialize> {
+pub enum Body<T, F>
+where
+    T: serde::Serialize,
+    F: FnMut(&str, &Remote, &mut T),
+{
    NdJsonPayload(File),
    Inline(T),
+    Generated(T, F),
    None,
 }

-impl Body<()> {
+impl Body<(), fn(&str, &Remote, &mut ())> {
    pub fn with_ndjson_payload(file: File) -> Self {
        Self::NdJsonPayload(file)
    }
@@ -38,7 +54,115 @@ impl Body<()> {
    }
 }

-/// If necessary, proxies the passed request to the network and update the task description.
+impl<T> Body<T, fn(&str, &Remote, &mut T)>
+where
+    T: serde::Serialize,
+{
+    pub fn inline(payload: T) -> Self {
+        Self::Inline(payload)
+    }
+}
+
+impl<T, F> Body<T, F>
+where
+    T: serde::Serialize,
+    F: FnMut(&str, &Remote, &mut T),
+{
+    pub fn generated(initial: T, f: F) -> Self {
+        Self::Generated(initial, f)
+    }
+}
+
+impl<T, F> Body<T, F>
+where
+    T: serde::Serialize,
+    F: FnMut(&str, &Remote, &mut T),
+{
+    pub fn into_bytes_iter(
+        self,
+        remotes: impl IntoIterator<Item = (String, Remote)>,
+    ) -> Result<
+        impl Iterator<Item = (Option<Bytes>, (String, Remote))>,
+        meilisearch_types::milli::Error,
+    > {
+        let bytes = match self {
+            Body::NdJsonPayload(file) => {
+                Some(Bytes::from_owner(unsafe { memmap2::Mmap::map(&file)? }))
+            }
+
+            Body::Inline(payload) => {
+                Some(Bytes::copy_from_slice(&serde_json::to_vec(&payload).unwrap()))
+            }
+
+            Body::None => None,
+
+            Body::Generated(mut initial, mut f) => {
+                return Ok(either::Right(remotes.into_iter().map(move |(name, remote)| {
+                    f(&name, &remote, &mut initial);
+                    let bytes =
+                        Some(Bytes::copy_from_slice(&serde_json::to_vec(&initial).unwrap()));
+                    (bytes, (name, remote))
+                })));
+            }
+        };
+        Ok(either::Left(std::iter::repeat(bytes).zip(remotes)))
+    }
+}
+
+/// Parses the header to determine if this task is a duplicate and originates with a remote.
+///
+/// If not, checks whether this remote is the leader and return `MeilisearchHttpError::NotLeader` if not.
+///
+/// If there is no leader, returns `Ok(None)`
+///
+/// # Errors
+///
+/// - `MeiliearchHttpError::NotLeader`: if the following are true simultaneously:
+///     1. The task originates with the current node
+///     2. There's a declared `leader`
+///     3. The declared leader is **not** the current node
+/// - `MeilisearchHttpError::InvalidHeaderValue`: if only parts of the headers are present, or if they cannot be parsed as a task network.
+/// - `MeilisearchHttpError::Inconsistent`
+pub fn task_network_and_check_leader(
+    req: &HttpRequest,
+    network: &meilisearch_types::enterprise_edition::network::Network,
+) -> Result<Option<TaskNetwork>, MeilisearchHttpError> {
+    match (origin_from_req(req)?, import_data_from_req(req)?, import_metadata_from_req(req)?) {
+        (Some(network_change), Some(import_from), Some(metadata)) => {
+            Ok(Some(TaskNetwork::Import { import_from, network_change, metadata }))
+        }
+        (Some(origin), None, None) => Ok(Some(TaskNetwork::Origin { origin })),
+        (None, None, None) => {
+            match (network.leader.as_deref(), network.local.as_deref()) {
+                // 1. Always allowed if there is no leader
+                (None, _) => return Ok(None),
+                // 2. Allowed if the leader is self
+                (Some(leader), Some(this)) if leader == this => (),
+                // 3. Any other change is disallowed
+                (Some(leader), _) => {
+                    return Err(
+                        MeilisearchHttpError::NotLeader { leader: leader.to_string() }.into()
+                    )
+                }
+            }
+
+            Ok(Some(TaskNetwork::Remotes {
+                remote_tasks: Default::default(),
+                network_version: network.version,
+            }))
+        }
+        // all good cases were matched, so this is always an error
+        (origin, import_from, metadata) => {
+            Err(MeilisearchHttpError::InconsistentTaskNetworkHeaders {
+                is_missing_origin: origin.is_none(),
+                is_missing_import: import_from.is_none(),
+                is_missing_import_metadata: metadata.is_none(),
+            })
+        }
+    }
+}
+
+/// Updates the task description and, if necessary, proxies the passed request to the network and update the task description.
 ///
 /// This function reads the custom headers from the request to determine if must proxy the request or if the request
 /// has already been proxied.
@@ -48,152 +172,139 @@ impl Body<()> {
 ///   with the task ids from the task queues of the remotes.
 /// - when the request has already been proxied, the custom headers contains information about the remote that created the initial task.
 ///   This information is copied to the passed task.
-pub async fn proxy<T: serde::Serialize>(
+///
+/// # Returns
+///
+/// The updated task. The task is read back from the database to avoid erasing concurrent changes.
+pub async fn proxy<T, F>(
    index_scheduler: &IndexScheduler,
-    index_uid: &str,
+    index_uid: Option<&str>,
    req: &HttpRequest,
+    mut task_network: DbTaskNetwork,
    network: meilisearch_types::enterprise_edition::network::Network,
-    body: Body<T>,
+    body: Body<T, F>,
    task: &meilisearch_types::tasks::Task,
-) -> Result<(), MeilisearchHttpError> {
-    match origin_from_req(req)? {
-        Some(origin) => {
-            index_scheduler.set_task_network(task.uid, TaskNetwork::Origin { origin })?
+) -> Result<Task, MeilisearchHttpError>
+where
+    T: serde::Serialize,
+    F: FnMut(&str, &Remote, &mut T),
+{
+    if let DbTaskNetwork::Remotes { remote_tasks, network_version: _ } = &mut task_network {
+        let this = network
+            .local
+            .as_deref()
+            .expect("inconsistent `network.sharding` and `network.self`")
+            .to_owned();
+
+        let content_type = match &body {
+            // for file bodies, force x-ndjson
+            Body::NdJsonPayload(_) => Some(b"application/x-ndjson".as_slice()),
+            // otherwise get content type from request
+            _ => req.headers().get(CONTENT_TYPE).map(|h| h.as_bytes()),
+        };
+
+        let mut in_flight_remote_queries = BTreeMap::new();
+        let client = reqwest::ClientBuilder::new()
+            .connect_timeout(std::time::Duration::from_secs(3))
+            .build()
+            .unwrap();
+
+        let method = from_old_http_method(req.method());
+
+        // send payload to all remotes
+        for (body, (node_name, node)) in body
+            .into_bytes_iter(network.remotes.into_iter().filter(|(name, _)| name.as_str() != this))
+            .map_err(|err| {
+                MeilisearchHttpError::from_milli(err, index_uid.map(ToOwned::to_owned))
+            })?
+        {
+            let client = client.clone();
+            let api_key = node.write_api_key;
+            let this = this.clone();
+            let method = method.clone();
+            let path_and_query = req.uri().path_and_query().map(|paq| paq.as_str()).unwrap_or("/");
+
+            in_flight_remote_queries.insert(
+                node_name,
+                tokio::spawn({
+                    let url = format!("{}{}", node.url, path_and_query);
+
+                    let url_encoded_this = urlencoding::encode(&this).into_owned();
+                    let url_encoded_task_uid = task.uid.to_string(); // it's url encoded i promize
+
+                    let content_type = content_type.map(|b| b.to_owned());
+
+                    let backoff = backoff::ExponentialBackoffBuilder::new()
+                        .with_max_elapsed_time(Some(std::time::Duration::from_secs(25)))
+                        .build();
+
+                    backoff::future::retry(backoff, move || {
+                        let url = url.clone();
+                        let client = client.clone();
+                        let url_encoded_this = url_encoded_this.clone();
+                        let url_encoded_task_uid = url_encoded_task_uid.clone();
+                        let content_type = content_type.clone();
+
+                        let body = body.clone();
+                        let api_key = api_key.clone();
+                        let method = method.clone();
+
+                        async move {
+                            try_proxy(
+                                method,
+                                &url,
+                                content_type.as_deref(),
+                                api_key.as_deref(),
+                                &client,
+                                &url_encoded_this,
+                                &url_encoded_task_uid,
+                                body,
+                            )
+                            .await
+                        }
+                    })
+                }),
+            );
        }
-        None => {
-            let this = network
-                .local
-                .as_deref()
-                .expect("inconsistent `network.sharding` and `network.self`")
-                .to_owned();

-            let content_type = match &body {
-                // for file bodies, force x-ndjson
-                Body::NdJsonPayload(_) => Some(b"application/x-ndjson".as_slice()),
-                // otherwise get content type from request
-                _ => req.headers().get(CONTENT_TYPE).map(|h| h.as_bytes()),
-            };
+        // wait for all in-flight queries to finish and collect their results
+        for (node_name, handle) in in_flight_remote_queries {
+            match handle.await {
+                Ok(Ok(res)) => {
+                    let task_uid = res.task_uid;

-            let body = match body {
-                Body::NdJsonPayload(file) => Some(Bytes::from_owner(unsafe {
-                    memmap2::Mmap::map(&file).map_err(|err| {
-                        MeilisearchHttpError::from_milli(err.into(), Some(index_uid.to_owned()))
-                    })?
-                })),
-
-                Body::Inline(payload) => {
-                    Some(Bytes::copy_from_slice(&serde_json::to_vec(&payload).unwrap()))
+                    remote_tasks.insert(node_name, Ok(task_uid).into());
                }
-
-                Body::None => None,
-            };
-
-            let mut in_flight_remote_queries = BTreeMap::new();
-            let client = reqwest::ClientBuilder::new()
-                .connect_timeout(std::time::Duration::from_secs(3))
-                .build()
-                .unwrap();
-
-            let method = from_old_http_method(req.method());
-
-            // send payload to all remotes
-            for (node_name, node) in
-                network.remotes.into_iter().filter(|(name, _)| name.as_str() != this)
-            {
-                let body = body.clone();
-                let client = client.clone();
-                let api_key = node.write_api_key;
-                let this = this.clone();
-                let method = method.clone();
-                let path_and_query =
-                    req.uri().path_and_query().map(|paq| paq.as_str()).unwrap_or("/");
-
-                in_flight_remote_queries.insert(
-                    node_name,
-                    tokio::spawn({
-                        let url = format!("{}{}", node.url, path_and_query);
-
-                        let url_encoded_this = urlencoding::encode(&this).into_owned();
-                        let url_encoded_task_uid = task.uid.to_string(); // it's url encoded i promize
-
-                        let content_type = content_type.map(|b| b.to_owned());
-
-                        let backoff = backoff::ExponentialBackoffBuilder::new()
-                            .with_max_elapsed_time(Some(std::time::Duration::from_secs(25)))
-                            .build();
-
-                        backoff::future::retry(backoff, move || {
-                            let url = url.clone();
-                            let client = client.clone();
-                            let url_encoded_this = url_encoded_this.clone();
-                            let url_encoded_task_uid = url_encoded_task_uid.clone();
-                            let content_type = content_type.clone();
-
-                            let body = body.clone();
-                            let api_key = api_key.clone();
-                            let method = method.clone();
-
-                            async move {
-                                try_proxy(
-                                    method,
-                                    &url,
-                                    content_type.as_deref(),
-                                    api_key.as_deref(),
-                                    &client,
-                                    &url_encoded_this,
-                                    &url_encoded_task_uid,
-                                    body,
-                                )
-                                .await
-                            }
-                        })
-                    }),
-                );
-            }
-
-            // wait for all in-flight queries to finish and collect their results
-            let mut remote_tasks: BTreeMap<String, RemoteTask> = BTreeMap::new();
-            for (node_name, handle) in in_flight_remote_queries {
-                match handle.await {
-                    Ok(Ok(res)) => {
-                        let task_uid = res.task_uid;
-
-                        remote_tasks.insert(node_name, Ok(task_uid).into());
-                    }
-                    Ok(Err(error)) => {
-                        remote_tasks.insert(node_name, Err(error.as_response_error()).into());
-                    }
-                    Err(panic) => match panic.try_into_panic() {
-                        Ok(panic) => {
-                            let msg = match panic.downcast_ref::<&'static str>() {
-                                Some(s) => *s,
-                                None => match panic.downcast_ref::<String>() {
-                                    Some(s) => &s[..],
-                                    None => "Box<dyn Any>",
-                                },
-                            };
-                            remote_tasks.insert(
-                                node_name,
-                                Err(ResponseError::from_msg(
-                                    msg.to_string(),
-                                    meilisearch_types::error::Code::Internal,
-                                ))
-                                .into(),
-                            );
-                        }
-                        Err(_) => {
-                            tracing::error!("proxy task was unexpectedly cancelled")
-                        }
-                    },
+                Ok(Err(error)) => {
+                    remote_tasks.insert(node_name, Err(error.as_response_error()).into());
                }
+                Err(panic) => match panic.try_into_panic() {
+                    Ok(panic) => {
+                        let msg = match panic.downcast_ref::<&'static str>() {
+                            Some(s) => *s,
+                            None => match panic.downcast_ref::<String>() {
+                                Some(s) => &s[..],
+                                None => "Box<dyn Any>",
+                            },
+                        };
+                        remote_tasks.insert(
+                            node_name,
+                            Err(ResponseError::from_msg(
+                                msg.to_string(),
+                                meilisearch_types::error::Code::Internal,
+                            ))
+                            .into(),
+                        );
+                    }
+                    Err(_) => {
+                        tracing::error!("proxy task was unexpectedly cancelled")
+                    }
+                },
            }
-
-            // edit details to contain the return values from the remotes
-            index_scheduler.set_task_network(task.uid, TaskNetwork::Remotes { remote_tasks })?;
        }
    }

-    Ok(())
+    Ok(index_scheduler.set_task_network(task.uid, task_network)?)
 }

 fn from_old_http_method(method: &actix_http::Method) -> reqwest::Method {
@@ -375,25 +486,23 @@ mod error {
    }
 }

-pub const PROXY_ORIGIN_REMOTE_HEADER: &str = "Meili-Proxy-Origin-Remote";
-pub const PROXY_ORIGIN_TASK_UID_HEADER: &str = "Meili-Proxy-Origin-TaskUid";
-
 pub fn origin_from_req(req: &HttpRequest) -> Result<Option<Origin>, MeilisearchHttpError> {
-    let (remote_name, task_uid) = match (
+    let (remote_name, task_uid, network_version) = match (
        req.headers().get(PROXY_ORIGIN_REMOTE_HEADER),
        req.headers().get(PROXY_ORIGIN_TASK_UID_HEADER),
+        req.headers().get(PROXY_ORIGIN_NETWORK_VERSION_HEADER),
    ) {
-        (None, None) => return Ok(None),
-        (None, Some(_)) => {
+        (None, None, _) => return Ok(None),
+        (None, Some(_), _) => {
            return Err(MeilisearchHttpError::InconsistentOriginHeaders { is_remote_missing: true })
        }
-        (Some(_), None) => {
+        (Some(_), None, _) => {
            return Err(MeilisearchHttpError::InconsistentOriginHeaders {
                is_remote_missing: false,
            })
        }
-        (Some(remote_name), Some(task_uid)) => (
-            urlencoding::decode(remote_name.to_str().map_err(|err| {
+        (Some(remote_name), Some(task_uid), network_version) => {
+            let remote_name = urlencoding::decode(remote_name.to_str().map_err(|err| {
                MeilisearchHttpError::InvalidHeaderValue {
                    header_name: PROXY_ORIGIN_REMOTE_HEADER,
                    msg: format!("while parsing remote name as UTF-8: {err}"),
@@ -402,8 +511,8 @@ pub fn origin_from_req(req: &HttpRequest) -> Result<Option<Origin>, MeilisearchH
            .map_err(|err| MeilisearchHttpError::InvalidHeaderValue {
                header_name: PROXY_ORIGIN_REMOTE_HEADER,
                msg: format!("while URL-decoding remote name: {err}"),
-            })?,
-            urlencoding::decode(task_uid.to_str().map_err(|err| {
+            })?;
+            let task_uid = urlencoding::decode(task_uid.to_str().map_err(|err| {
                MeilisearchHttpError::InvalidHeaderValue {
                    header_name: PROXY_ORIGIN_TASK_UID_HEADER,
                    msg: format!("while parsing task UID as UTF-8: {err}"),
@@ -412,15 +521,182 @@ pub fn origin_from_req(req: &HttpRequest) -> Result<Option<Origin>, MeilisearchH
            .map_err(|err| MeilisearchHttpError::InvalidHeaderValue {
                header_name: PROXY_ORIGIN_TASK_UID_HEADER,
                msg: format!("while URL-decoding task UID: {err}"),
-            })?,
-        ),
+            })?;
+            let network_version = match network_version {
+                Some(network_version) => {
+                    urlencoding::decode(network_version.to_str().map_err(|err| {
+                        MeilisearchHttpError::InvalidHeaderValue {
+                            header_name: PROXY_ORIGIN_NETWORK_VERSION_HEADER,
+                            msg: format!("while parsing network version as UTF-8: {err}"),
+                        }
+                    })?)
+                    .map_err(|err| {
+                        MeilisearchHttpError::InvalidHeaderValue {
+                            header_name: PROXY_ORIGIN_NETWORK_VERSION_HEADER,
+                            msg: format!("while URL-decoding network version: {err}"),
+                        }
+                    })?
+                }
+                None => Cow::Borrowed("0"),
+            };
+            (remote_name, task_uid, network_version)
+        }
    };

-    let task_uid: usize =
+    let task_uid: u32 =
        task_uid.parse().map_err(|err| MeilisearchHttpError::InvalidHeaderValue {
            header_name: PROXY_ORIGIN_TASK_UID_HEADER,
            msg: format!("while parsing the task UID as an integer: {err}"),
        })?;

-    Ok(Some(Origin { remote_name: remote_name.into_owned(), task_uid }))
+    let network_version: u128 =
+        network_version.parse().map_err(|err| MeilisearchHttpError::InvalidHeaderValue {
+            header_name: PROXY_ORIGIN_NETWORK_VERSION_HEADER,
+            msg: format!("while parsing the network version as a u128: {err}"),
+        })?;
+
+    let network_version = uuid::Uuid::from_u128(network_version);
+
+    Ok(Some(Origin { remote_name: remote_name.into_owned(), task_uid, network_version }))
+}
+
+pub fn import_data_from_req(req: &HttpRequest) -> Result<Option<ImportData>, MeilisearchHttpError> {
+    let (remote_name, index_name, documents) = match (
+        req.headers().get(PROXY_IMPORT_REMOTE_HEADER),
+        req.headers().get(PROXY_IMPORT_INDEX_HEADER),
+        req.headers().get(PROXY_IMPORT_DOCS_HEADER),
+    ) {
+        (None, None, None) => return Ok(None),
+        (Some(remote_name), Some(index_name), Some(documents)) => {
+            let remote_name = urlencoding::decode(remote_name.to_str().map_err(|err| {
+                MeilisearchHttpError::InvalidHeaderValue {
+                    header_name: PROXY_IMPORT_REMOTE_HEADER,
+                    msg: format!("while parsing import remote name as UTF-8: {err}"),
+                }
+            })?)
+            .map_err(|err| MeilisearchHttpError::InvalidHeaderValue {
+                header_name: PROXY_IMPORT_REMOTE_HEADER,
+                msg: format!("while URL-decoding import remote name: {err}"),
+            })?;
+
+            let index_name = urlencoding::decode(index_name.to_str().map_err(|err| {
+                MeilisearchHttpError::InvalidHeaderValue {
+                    header_name: PROXY_IMPORT_INDEX_HEADER,
+                    msg: format!("while parsing import index name as UTF-8: {err}"),
+                }
+            })?)
+            .map_err(|err| MeilisearchHttpError::InvalidHeaderValue {
+                header_name: PROXY_IMPORT_INDEX_HEADER,
+                msg: format!("while URL-decoding import index name: {err}"),
+            })?;
+
+            let documents = urlencoding::decode(documents.to_str().map_err(|err| {
+                MeilisearchHttpError::InvalidHeaderValue {
+                    header_name: PROXY_IMPORT_DOCS_HEADER,
+                    msg: format!("while parsing documents as UTF-8: {err}"),
+                }
+            })?)
+            .map_err(|err| MeilisearchHttpError::InvalidHeaderValue {
+                header_name: PROXY_IMPORT_DOCS_HEADER,
+                msg: format!("while URL-decoding documents: {err}"),
+            })?;
+            (remote_name, index_name, documents)
+        }
+        // catch-all pattern that has to contain an inconsistency since we already matched (None, None, None) and (Some, Some, Some)
+        (remote_name, index_name, documents) => {
+            return Err(MeilisearchHttpError::InconsistentImportHeaders {
+                is_remote_missing: remote_name.is_none(),
+                is_index_missing: index_name.is_none(),
+                is_docs_missing: documents.is_none(),
+            })
+        }
+    };
+
+    let document_count: u64 =
+        documents.parse().map_err(|err| MeilisearchHttpError::InvalidHeaderValue {
+            header_name: PROXY_IMPORT_DOCS_HEADER,
+            msg: format!("while parsing the documents as an integer: {err}"),
+        })?;
+
+    Ok(Some(ImportData {
+        remote_name: remote_name.to_string(),
+        index_name: index_name.to_string(),
+        document_count,
+    }))
+}
+
+pub fn import_metadata_from_req(
+    req: &HttpRequest,
+) -> Result<Option<ImportMetadata>, MeilisearchHttpError> {
+    let (index_count, task_key, total_index_documents) = match (
+        req.headers().get(PROXY_IMPORT_INDEX_COUNT_HEADER),
+        req.headers().get(PROXY_IMPORT_TASK_KEY_HEADER),
+        req.headers().get(PROXY_IMPORT_TOTAL_INDEX_DOCS_HEADER),
+    ) {
+        (None, None, None) => return Ok(None),
+        (Some(index_count), Some(task_key), Some(total_index_documents)) => {
+            let index_count = urlencoding::decode(index_count.to_str().map_err(|err| {
+                MeilisearchHttpError::InvalidHeaderValue {
+                    header_name: PROXY_IMPORT_REMOTE_HEADER,
+                    msg: format!("while parsing import index count as UTF-8: {err}"),
+                }
+            })?)
+            .map_err(|err| MeilisearchHttpError::InvalidHeaderValue {
+                header_name: PROXY_IMPORT_INDEX_COUNT_HEADER,
+                msg: format!("while URL-decoding import index count: {err}"),
+            })?;
+
+            let task_key = urlencoding::decode(task_key.to_str().map_err(|err| {
+                MeilisearchHttpError::InvalidHeaderValue {
+                    header_name: PROXY_IMPORT_TASK_KEY_HEADER,
+                    msg: format!("while parsing import task key as UTF-8: {err}"),
+                }
+            })?)
+            .map_err(|err| MeilisearchHttpError::InvalidHeaderValue {
+                header_name: PROXY_IMPORT_TASK_KEY_HEADER,
+                msg: format!("while URL-decoding import task key: {err}"),
+            })?;
+
+            let total_index_documents =
+                urlencoding::decode(total_index_documents.to_str().map_err(|err| {
+                    MeilisearchHttpError::InvalidHeaderValue {
+                        header_name: PROXY_IMPORT_TOTAL_INDEX_DOCS_HEADER,
+                        msg: format!("while parsing total index documents as UTF-8: {err}"),
+                    }
+                })?)
+                .map_err(|err| MeilisearchHttpError::InvalidHeaderValue {
+                    header_name: PROXY_IMPORT_TOTAL_INDEX_DOCS_HEADER,
+                    msg: format!("while URL-decoding total index documents: {err}"),
+                })?;
+            (index_count, task_key, total_index_documents)
+        }
+        // catch-all pattern that has to contain an inconsistency since we already matched (None, None, None) and (Some, Some, Some)
+        (index_count, task_key, total_index_documents) => {
+            return Err(MeilisearchHttpError::InconsistentImportMetadataHeaders {
+                is_index_count_missing: index_count.is_none(),
+                is_task_key_missing: task_key.is_none(),
+                is_total_index_documents_missing: total_index_documents.is_none(),
+            })
+        }
+    };
+
+    let index_count: u64 =
+        index_count.parse().map_err(|err| MeilisearchHttpError::InvalidHeaderValue {
+            header_name: PROXY_IMPORT_INDEX_COUNT_HEADER,
+            msg: format!("while parsing the index count as an integer: {err}"),
+        })?;
+
+    let task_key: DocumentId =
+        task_key.parse().map_err(|err| MeilisearchHttpError::InvalidHeaderValue {
+            header_name: PROXY_IMPORT_TASK_KEY_HEADER,
+            msg: format!("while parsing import task key as an integer: {err}"),
+        })?;
+
+    let total_index_documents: u64 =
+        total_index_documents.parse().map_err(|err| MeilisearchHttpError::InvalidHeaderValue {
+            header_name: PROXY_IMPORT_TOTAL_INDEX_DOCS_HEADER,
+            msg: format!("while parsing the total index documents as an integer: {err}"),
+        })?;
+
+    Ok(Some(ImportMetadata { index_count, task_key, total_index_documents }))
 }
--- a/crates/meilisearch/src/routes/indexes/mod.rs
+++ b/crates/meilisearch/src/routes/indexes/mod.rs
@@ -30,7 +30,7 @@ use crate::Opt;

 pub mod compact;
 pub mod documents;
-mod enterprise_edition;
+pub mod enterprise_edition;
 pub mod facet_search;
 pub mod search;
 mod search_analytics;
@@ -41,7 +41,9 @@ mod settings_analytics;
 pub mod similar;
 mod similar_analytics;

-pub use enterprise_edition::proxy::{PROXY_ORIGIN_REMOTE_HEADER, PROXY_ORIGIN_TASK_UID_HEADER};
+pub use meilisearch_types::tasks::enterprise_edition::network::headers::{
+    PROXY_ORIGIN_REMOTE_HEADER, PROXY_ORIGIN_TASK_UID_HEADER,
+};

 #[derive(OpenApi)]
 #[openapi(
--- a/crates/meilisearch/src/routes/mod.rs
+++ b/crates/meilisearch/src/routes/mod.rs
@@ -218,6 +218,8 @@ pub struct SummarizedTaskView {
        deserialize_with = "time::serde::rfc3339::deserialize"
    )]
    enqueued_at: OffsetDateTime,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    custom_metadata: Option<String>,
 }

 impl From<Task> for SummarizedTaskView {
@@ -228,6 +230,7 @@ impl From<Task> for SummarizedTaskView {
            status: task.status,
            kind: task.kind.as_kind(),
            enqueued_at: task.enqueued_at,
+            custom_metadata: task.custom_metadata,
        }
    }
 }
--- a/crates/meilisearch/src/routes/network.rs
+++ b/crates/meilisearch/src/routes/network.rs
@@ -9,20 +9,27 @@ use itertools::{EitherOrBoth, Itertools};
 use meilisearch_types::deserr::DeserrJsonError;
 use meilisearch_types::enterprise_edition::network::{Network as DbNetwork, Remote as DbRemote};
 use meilisearch_types::error::deserr_codes::{
-    InvalidNetworkRemotes, InvalidNetworkSearchApiKey, InvalidNetworkSelf, InvalidNetworkSharding,
+    InvalidNetworkLeader, InvalidNetworkRemotes, InvalidNetworkSearchApiKey, InvalidNetworkSelf,
    InvalidNetworkUrl, InvalidNetworkWriteApiKey,
 };
 use meilisearch_types::error::ResponseError;
 use meilisearch_types::keys::actions;
 use meilisearch_types::milli::update::Setting;
+use meilisearch_types::tasks::enterprise_edition::network::{
+    NetworkTopologyChange, Origin, DbTaskNetwork,
+};
+use meilisearch_types::tasks::KindWithContent;
 use serde::Serialize;
 use tracing::debug;
 use utoipa::{OpenApi, ToSchema};

 use crate::analytics::{Aggregate, Analytics};
+use crate::error::MeilisearchHttpError;
 use crate::extractors::authentication::policies::ActionPolicy;
 use crate::extractors::authentication::GuardedData;
 use crate::extractors::sequential_extractor::SeqHandler;
+use crate::routes::indexes::enterprise_edition::proxy::{proxy, Body};
+use crate::routes::SummarizedTaskView;

 #[derive(OpenApi)]
 #[openapi(
@@ -83,7 +90,7 @@ async fn get_network(
    Ok(HttpResponse::Ok().json(network))
 }

-#[derive(Debug, Deserr, ToSchema, Serialize)]
+#[derive(Clone, Debug, Deserr, ToSchema, Serialize)]
 #[deserr(error = DeserrJsonError<InvalidNetworkRemotes>, rename_all = camelCase, deny_unknown_fields)]
 #[serde(rename_all = "camelCase")]
 #[schema(rename_all = "camelCase")]
@@ -106,12 +113,19 @@ pub struct Remote {
    pub write_api_key: Setting<String>,
 }

-#[derive(Debug, Deserr, ToSchema, Serialize)]
+#[derive(Clone, Debug, Deserr, ToSchema, Serialize)]
 #[deserr(error = DeserrJsonError, rename_all = camelCase, deny_unknown_fields)]
 #[serde(rename_all = "camelCase")]
 #[schema(rename_all = "camelCase")]
 pub struct Network {
-    #[schema(value_type = Option<BTreeMap<String, Remote>>, example = json!("http://localhost:7700"))]
+    #[schema(value_type = Option<BTreeMap<String, Remote>>, example = json!({
+        "ms-00": {
+            "url": "http://localhost:7700"
+        },
+        "ms-01": {
+            "url": "http://localhost:7701"
+        }
+    }))]
    #[deserr(default, error = DeserrJsonError<InvalidNetworkRemotes>)]
    #[serde(default)]
    pub remotes: Setting<BTreeMap<String, Option<Remote>>>,
@@ -119,10 +133,21 @@ pub struct Network {
    #[serde(default, rename = "self")]
    #[deserr(default, rename = "self", error = DeserrJsonError<InvalidNetworkSelf>)]
    pub local: Setting<String>,
-    #[schema(value_type = Option<bool>, example = json!(true))]
+    #[schema(value_type = Option<String>, example = json!("ms-00"))]
    #[serde(default)]
-    #[deserr(default, error = DeserrJsonError<InvalidNetworkSharding>)]
-    pub sharding: Setting<bool>,
+    #[deserr(default, error = DeserrJsonError<InvalidNetworkLeader>)]
+    pub leader: Setting<String>,
+    #[schema(value_type = Option<BTreeMap<String, Remote>>, example = json!({
+        "ms-00": {
+            "url": "http://localhost:7700"
+        },
+        "ms-01": {
+            "url": "http://localhost:7701"
+        }
+    }))]
+    #[deserr(default, error = DeserrJsonError<InvalidNetworkRemotes>)]
+    #[serde(default)]
+    pub previous_remotes: Setting<BTreeMap<String, Option<Remote>>>,
 }

 impl Remote {
@@ -207,29 +232,203 @@ async fn patch_network(
 ) -> Result<HttpResponse, ResponseError> {
    index_scheduler.features().check_network("Using the /network route")?;

+    match crate::routes::indexes::enterprise_edition::proxy::origin_from_req(&req)? {
+        Some(origin) => {
+            patch_network_with_origin(index_scheduler, new_network, req, origin, analytics).await
+        }
+        None => patch_network_without_origin(index_scheduler, new_network, req, analytics).await,
+    }
+}
+
+async fn patch_network_without_origin(
+    index_scheduler: GuardedData<ActionPolicy<{ actions::NETWORK_UPDATE }>, Data<IndexScheduler>>,
+    new_network: AwebJson<Network, DeserrJsonError>,
+    req: HttpRequest,
+    analytics: Data<Analytics>,
+) -> Result<HttpResponse, ResponseError> {
    let new_network = new_network.0;
    let old_network = index_scheduler.network();
    debug!(parameters = ?new_network, "Patch network");

+    if !matches!(new_network.previous_remotes, Setting::NotSet) {
+        return Err(MeilisearchHttpError::UnexpectedNetworkPreviousRemotes.into());
+    }
+
+    let merged_network = merge_networks(old_network.clone(), new_network)?;
+    index_scheduler.put_network(merged_network.clone())?;
+
+    analytics.publish(
+        PatchNetworkAnalytics {
+            network_size: merged_network.remotes.len(),
+            network_has_self: merged_network.local.is_some(),
+        },
+        &req,
+    );
+
+    /// TODO: spawn task only if necessary
+    let network_topology_change =
+        NetworkTopologyChange::new(old_network.clone(), merged_network.clone());
+    let task = KindWithContent::NetworkTopologyChange(network_topology_change);
+    let task = {
+        let index_scheduler = index_scheduler.clone();
+        tokio::task::spawn_blocking(move || index_scheduler.register(task, None, false)).await??
+    };
+
+    let mut proxied_network = Network {
+        remotes: Setting::Set(to_settings_remotes(&merged_network.remotes)),
+        local: Setting::NotSet,
+        leader: Setting::some_or_not_set(merged_network.leader.clone()),
+        previous_remotes: Setting::Set(to_settings_remotes(&old_network.remotes)),
+    };
+    let mut deleted_network = old_network;
+
+    let deleted_remotes = &mut deleted_network.remotes;
+    deleted_remotes.retain(|node, _| !merged_network.remotes.contains_key(node));
+
+    // proxy network change to the remaining remotes.
+    let updated_task = proxy(
+        &index_scheduler,
+        None,
+        &req,
+        DbTaskNetwork::Remotes {
+            remote_tasks: Default::default(),
+            network_version: merged_network.version,
+        },
+        merged_network,
+        Body::generated(proxied_network.clone(), |name, _remote, network| {
+            network.local = Setting::Set(name.to_string());
+        }),
+        &task,
+    )
+    .await?;
+    // unwrap: network was set by `proxy`
+    let task_network = updated_task.network.unwrap();
+
+    proxied_network.previous_remotes = Setting::NotSet;
+
+    // proxy network change to the deleted remotes
+    proxy(
+        &index_scheduler,
+        None,
+        &req,
+        task_network,
+        deleted_network,
+        Body::generated(proxied_network.clone(), |_name, _remote, network| {
+            network.local = Setting::Reset;
+        }),
+        &task,
+    )
+    .await?;
+
+    let task: SummarizedTaskView = task.into();
+    debug!("returns: {:?}", task);
+    Ok(HttpResponse::Accepted().json(task))
+}
+
+async fn patch_network_with_origin(
+    index_scheduler: GuardedData<ActionPolicy<{ actions::NETWORK_UPDATE }>, Data<IndexScheduler>>,
+    merged_network: AwebJson<Network, DeserrJsonError>,
+    req: HttpRequest,
+    origin: Origin,
+    analytics: Data<Analytics>,
+) -> Result<HttpResponse, ResponseError> {
+    let merged_network = merged_network.into_inner();
+    debug!(parameters = ?merged_network, ?origin, "Patch network");
+    let mut remotes = BTreeMap::new();
+    let mut old_network = index_scheduler.network();
+
+    for (name, remote) in merged_network.remotes.set().into_iter().flat_map(|x| x.into_iter()) {
+        let Some(remote) = remote else { continue };
+        let remote = remote.try_into_db_node(&name)?;
+        remotes.insert(name, remote);
+    }
+    let mut previous_remotes = BTreeMap::new();
+    for (name, remote) in
+        merged_network.previous_remotes.set().into_iter().flat_map(|x| x.into_iter())
+    {
+        let Some(remote) = remote else {
+            continue;
+        };
+        let remote = remote.try_into_db_node(&name)?;
+        previous_remotes.insert(name, remote);
+    }
+
+    old_network.remotes = previous_remotes;
+
+    let new_network = DbNetwork {
+        local: merged_network.local.set(),
+        remotes,
+        leader: merged_network.leader.set(),
+        version: origin.network_version,
+    };
+    index_scheduler.put_network(new_network.clone())?;
+
+    analytics.publish(
+        PatchNetworkAnalytics {
+            network_size: new_network.remotes.len(),
+            network_has_self: new_network.local.is_some(),
+        },
+        &req,
+    );
+
+    /// TODO: spawn task only if necessary
+    let network_topology_change = NetworkTopologyChange::new(old_network, new_network);
+    let task = KindWithContent::NetworkTopologyChange(network_topology_change);
+    let task = {
+        let index_scheduler = index_scheduler.clone();
+        tokio::task::spawn_blocking(move || index_scheduler.register(task, None, false)).await??
+    };
+
+    index_scheduler.set_task_network(task.uid, DbTaskNetwork::Origin { origin })?;
+
+    let task: SummarizedTaskView = task.into();
+    debug!("returns: {:?}", task);
+    Ok(HttpResponse::Accepted().json(task))
+}
+
+fn to_settings_remotes(
+    db_remotes: &BTreeMap<String, DbRemote>,
+) -> BTreeMap<String, Option<Remote>> {
+    db_remotes
+        .iter()
+        .map(|(name, remote)| {
+            (
+                name.clone(),
+                Some(Remote {
+                    url: Setting::Set(remote.url.clone()),
+                    search_api_key: Setting::some_or_not_set(remote.search_api_key.clone()),
+                    write_api_key: Setting::some_or_not_set(remote.write_api_key.clone()),
+                }),
+            )
+        })
+        .collect()
+}
+
+fn merge_networks(
+    old_network: DbNetwork,
+    new_network: Network,
+) -> Result<DbNetwork, ResponseError> {
    let merged_self = match new_network.local {
        Setting::Set(new_self) => Some(new_self),
        Setting::Reset => None,
        Setting::NotSet => old_network.local,
    };
-
-    let merged_sharding = match new_network.sharding {
-        Setting::Set(new_sharding) => new_sharding,
-        Setting::Reset => false,
-        Setting::NotSet => old_network.sharding,
+    let merged_leader = match new_network.leader {
+        Setting::Set(new_leader) => Some(new_leader),
+        Setting::Reset => None,
+        Setting::NotSet => old_network.leader,
    };
-
-    if merged_sharding && merged_self.is_none() {
-        return Err(ResponseError::from_msg(
-            "`.sharding`: enabling the sharding requires `.self` to be set\n  - Hint: Disable `sharding` or set `self` to a value.".into(),
-            meilisearch_types::error::Code::InvalidNetworkSharding,
-        ));
+    match (merged_leader.as_deref(), merged_self.as_deref()) {
+        // 1. Always allowed if there is no leader
+        (None, _) => (),
+        // 2. Allowed if the leader is self
+        (Some(leader), Some(this)) if leader == this => (),
+        // 3. Any other change is disallowed
+        (Some(leader), _) => {
+            return Err(MeilisearchHttpError::NotLeader { leader: leader.to_string() }.into())
+        }
    }
-
+    let new_version = uuid::Uuid::now_v7();
    let merged_remotes = match new_network.remotes {
        Setting::Set(new_remotes) => {
            let mut merged_remotes = BTreeMap::new();
@@ -301,18 +500,11 @@ async fn patch_network(
        Setting::Reset => BTreeMap::new(),
        Setting::NotSet => old_network.remotes,
    };
-
-    analytics.publish(
-        PatchNetworkAnalytics {
-            network_size: merged_remotes.len(),
-            network_has_self: merged_self.is_some(),
-        },
-        &req,
-    );
-
-    let merged_network =
-        DbNetwork { local: merged_self, remotes: merged_remotes, sharding: merged_sharding };
-    index_scheduler.put_network(merged_network.clone())?;
-    debug!(returns = ?merged_network, "Patch network");
-    Ok(HttpResponse::Ok().json(merged_network))
+    let merged_network = DbNetwork {
+        local: merged_self,
+        remotes: merged_remotes,
+        leader: merged_leader,
+        version: new_version,
+    };
+    Ok(merged_network)
 }
--- a/crates/meilisearch/tests/common/index.rs
+++ b/crates/meilisearch/tests/common/index.rs
@@ -91,7 +91,16 @@ impl<'a> Index<'a, Owned> {
        documents: Value,
        primary_key: Option<&str>,
    ) -> (Value, StatusCode) {
-        self._add_documents(documents, primary_key).await
+        self._add_documents(documents, primary_key, None).await
+    }
+
+    pub async fn add_documents_with_custom_metadata(
+        &self,
+        documents: Value,
+        primary_key: Option<&str>,
+        custom_metadata: Option<&str>,
+    ) -> (Value, StatusCode) {
+        self._add_documents(documents, primary_key, custom_metadata).await
    }

    pub async fn raw_add_documents(
@@ -352,12 +361,25 @@ impl<State> Index<'_, State> {
        &self,
        documents: Value,
        primary_key: Option<&str>,
+        custom_metadata: Option<&str>,
    ) -> (Value, StatusCode) {
-        let url = match primary_key {
-            Some(key) => {
-                format!("/indexes/{}/documents?primaryKey={}", urlencode(self.uid.as_ref()), key)
+        let url = match (primary_key, custom_metadata) {
+            (Some(key), Some(meta)) => {
+                format!(
+                    "/indexes/{}/documents?primaryKey={key}&customMetadata={meta}",
+                    urlencode(self.uid.as_ref()),
+                )
            }
-            None => format!("/indexes/{}/documents", urlencode(self.uid.as_ref())),
+            (None, Some(meta)) => {
+                format!(
+                    "/indexes/{}/documents?&customMetadata={meta}",
+                    urlencode(self.uid.as_ref()),
+                )
+            }
+            (Some(key), None) => {
+                format!("/indexes/{}/documents?&primaryKey={key}", urlencode(self.uid.as_ref()),)
+            }
+            (None, None) => format!("/indexes/{}/documents", urlencode(self.uid.as_ref())),
        };
        self.service.post_encoded(url, documents, self.encoder).await
    }
--- a/crates/meilisearch/tests/common/mod.rs
+++ b/crates/meilisearch/tests/common/mod.rs
@@ -241,7 +241,7 @@ pub async fn shared_index_with_documents() -> &'static Index<'static, Shared> {
        let server = Server::new_shared();
        let index = server._index("SHARED_DOCUMENTS").to_shared();
        let documents = DOCUMENTS.clone();
-        let (response, _code) = index._add_documents(documents, None).await;
+        let (response, _code) = index._add_documents(documents, None, None).await;
        server.wait_task(response.uid()).await.succeeded();
        let (response, _code) = index
            ._update_settings(
@@ -284,7 +284,7 @@ pub async fn shared_index_with_score_documents() -> &'static Index<'static, Shar
        let server = Server::new_shared();
        let index = server._index("SHARED_SCORE_DOCUMENTS").to_shared();
        let documents = SCORE_DOCUMENTS.clone();
-        let (response, _code) = index._add_documents(documents, None).await;
+        let (response, _code) = index._add_documents(documents, None, None).await;
        server.wait_task(response.uid()).await.succeeded();
        let (response, _code) = index
            ._update_settings(
@@ -361,7 +361,7 @@ pub async fn shared_index_with_nested_documents() -> &'static Index<'static, Sha
        let server = Server::new_shared();
        let index = server._index("SHARED_NESTED_DOCUMENTS").to_shared();
        let documents = NESTED_DOCUMENTS.clone();
-        let (response, _code) = index._add_documents(documents, None).await;
+        let (response, _code) = index._add_documents(documents, None, None).await;
        server.wait_task(response.uid()).await.succeeded();
        let (response, _code) = index
            ._update_settings(
@@ -508,7 +508,7 @@ pub async fn shared_index_with_geo_documents() -> &'static Index<'static, Shared
        .get_or_init(|| async {
            let server = Server::new_shared();
            let index = server._index("SHARED_GEO_DOCUMENTS").to_shared();
-            let (response, _code) = index._add_documents(GEO_DOCUMENTS.clone(), None).await;
+            let (response, _code) = index._add_documents(GEO_DOCUMENTS.clone(), None, None).await;
            server.wait_task(response.uid()).await.succeeded();

            let (response, _code) = index
@@ -531,7 +531,7 @@ pub async fn shared_index_geojson_documents() -> &'static Index<'static, Shared>
            let index = server._index("SHARED_GEOJSON_DOCUMENTS").to_shared();
            let countries = include_str!("../documents/geojson/assets/countries.json");
            let lille = serde_json::from_str::<serde_json::Value>(countries).unwrap();
-            let (response, _code) = index._add_documents(Value(lille), Some("name")).await;
+            let (response, _code) = index._add_documents(Value(lille), Some("name"), None).await;
            server.wait_task(response.uid()).await.succeeded();

            let (response, _code) =
--- a/crates/meilisearch/tests/search/multi/proxy.rs
+++ b/crates/meilisearch/tests/search/multi/proxy.rs
@@ -3141,3 +3141,513 @@ fn fail(override_response_body: Option<&str>) -> ResponseTemplate {
        response.set_body_json(json!({"error": "provoked error", "code": "test_error", "link": "https://docs.meilisearch.com/errors#test_error"}))
    }
 }
+
+#[actix_rt::test]
+async fn remote_auto_sharding() {
+    let ms0 = Server::new().await;
+    let ms1 = Server::new().await;
+    let ms2 = Server::new().await;
+
+    // enable feature
+
+    let (response, code) = ms0.set_features(json!({"network": true})).await;
+    snapshot!(code, @"200 OK");
+    snapshot!(json_string!(response["network"]), @"true");
+    let (response, code) = ms1.set_features(json!({"network": true})).await;
+    snapshot!(code, @"200 OK");
+    snapshot!(json_string!(response["network"]), @"true");
+    let (response, code) = ms2.set_features(json!({"network": true})).await;
+    snapshot!(code, @"200 OK");
+    snapshot!(json_string!(response["network"]), @"true");
+
+    // set self & sharding
+
+    let (response, code) = ms0.set_network(json!({"self": "ms0", "sharding": true})).await;
+    snapshot!(code, @"200 OK");
+    snapshot!(json_string!(response), @r###"
+    {
+      "self": "ms0",
+      "remotes": {},
+      "sharding": true
+    }
+    "###);
+    let (response, code) = ms1.set_network(json!({"self": "ms1", "sharding": true})).await;
+    snapshot!(code, @"200 OK");
+    snapshot!(json_string!(response), @r###"
+    {
+      "self": "ms1",
+      "remotes": {},
+      "sharding": true
+    }
+    "###);
+    let (response, code) = ms2.set_network(json!({"self": "ms2", "sharding": true})).await;
+    snapshot!(code, @"200 OK");
+    snapshot!(json_string!(response), @r###"
+    {
+      "self": "ms2",
+      "remotes": {},
+      "sharding": true
+    }
+    "###);
+
+    // wrap servers
+    let ms0 = Arc::new(ms0);
+    let ms1 = Arc::new(ms1);
+    let ms2 = Arc::new(ms2);
+
+    let rms0 = LocalMeili::new(ms0.clone()).await;
+    let rms1 = LocalMeili::new(ms1.clone()).await;
+    let rms2 = LocalMeili::new(ms2.clone()).await;
+
+    // set network
+    let network = json!({"remotes": {
+        "ms0": {
+            "url": rms0.url()
+        },
+        "ms1": {
+            "url": rms1.url()
+        },
+        "ms2": {
+            "url": rms2.url()
+        }
+    }});
+
+    println!("{}", serde_json::to_string_pretty(&network).unwrap());
+
+    let (_response, status_code) = ms0.set_network(network.clone()).await;
+    snapshot!(status_code, @"200 OK");
+    let (_response, status_code) = ms1.set_network(network.clone()).await;
+    snapshot!(status_code, @"200 OK");
+    let (_response, status_code) = ms2.set_network(network.clone()).await;
+    snapshot!(status_code, @"200 OK");
+
+    // add documents
+    let documents = SCORE_DOCUMENTS.clone();
+    let documents = documents.as_array().unwrap();
+    let index0 = ms0.index("test");
+    let _index1 = ms1.index("test");
+    let _index2 = ms2.index("test");
+
+    let (task, _status_code) = index0.add_documents(json!(documents), None).await;
+
+    let t0 = task.uid();
+    let (t, _) = ms0.get_task(task.uid()).await;
+    let t1 = t["network"]["remote_tasks"]["ms1"]["taskUid"].as_u64().unwrap();
+    let t2 = t["network"]["remote_tasks"]["ms2"]["taskUid"].as_u64().unwrap();
+
+    ms0.wait_task(t0).await.succeeded();
+    ms1.wait_task(t1).await.succeeded();
+    ms2.wait_task(t2).await.succeeded();
+
+    // perform multi-search
+    let query = "badman returns";
+    let request = json!({
+        "federation": {},
+        "queries": [
+            {
+                "q": query,
+                "indexUid": "test",
+                "federationOptions": {
+                    "remote": "ms0"
+                }
+            },
+            {
+                "q": query,
+                "indexUid": "test",
+                "federationOptions": {
+                    "remote": "ms1"
+                }
+            },
+            {
+                "q": query,
+                "indexUid": "test",
+                "federationOptions": {
+                    "remote": "ms2"
+                }
+            },
+        ]
+    });
+
+    let (response, _status_code) = ms0.multi_search(request.clone()).await;
+    snapshot!(code, @"200 OK");
+    snapshot!(json_string!(response, { ".processingTimeMs" => "[time]", ".requestUid" => "[uuid]" }), @r###"
+    {
+      "hits": [
+        {
+          "title": "Batman Returns",
+          "id": "C",
+          "_federation": {
+            "indexUid": "test",
+            "queriesPosition": 2,
+            "weightedRankingScore": 0.8317901234567902,
+            "remote": "ms2"
+          }
+        },
+        {
+          "title": "Batman the dark knight returns: Part 1",
+          "id": "A",
+          "_federation": {
+            "indexUid": "test",
+            "queriesPosition": 1,
+            "weightedRankingScore": 0.7028218694885362,
+            "remote": "ms1"
+          }
+        },
+        {
+          "title": "Batman the dark knight returns: Part 2",
+          "id": "B",
+          "_federation": {
+            "indexUid": "test",
+            "queriesPosition": 1,
+            "weightedRankingScore": 0.7028218694885362,
+            "remote": "ms1"
+          }
+        },
+        {
+          "title": "Badman",
+          "id": "E",
+          "_federation": {
+            "indexUid": "test",
+            "queriesPosition": 2,
+            "weightedRankingScore": 0.5,
+            "remote": "ms2"
+          }
+        },
+        {
+          "title": "Batman",
+          "id": "D",
+          "_federation": {
+            "indexUid": "test",
+            "queriesPosition": 0,
+            "weightedRankingScore": 0.23106060606060605,
+            "remote": "ms0"
+          }
+        }
+      ],
+      "processingTimeMs": "[time]",
+      "limit": 20,
+      "offset": 0,
+      "estimatedTotalHits": 5,
+      "requestUid": "[uuid]",
+      "remoteErrors": {}
+    }
+    "###);
+    let (response, _status_code) = ms1.multi_search(request.clone()).await;
+    snapshot!(code, @"200 OK");
+    snapshot!(json_string!(response, { ".processingTimeMs" => "[time]", ".requestUid" => "[uuid]" }), @r###"
+    {
+      "hits": [
+        {
+          "title": "Batman Returns",
+          "id": "C",
+          "_federation": {
+            "indexUid": "test",
+            "queriesPosition": 2,
+            "weightedRankingScore": 0.8317901234567902,
+            "remote": "ms2"
+          }
+        },
+        {
+          "title": "Batman the dark knight returns: Part 1",
+          "id": "A",
+          "_federation": {
+            "indexUid": "test",
+            "queriesPosition": 1,
+            "weightedRankingScore": 0.7028218694885362,
+            "remote": "ms1"
+          }
+        },
+        {
+          "title": "Batman the dark knight returns: Part 2",
+          "id": "B",
+          "_federation": {
+            "indexUid": "test",
+            "queriesPosition": 1,
+            "weightedRankingScore": 0.7028218694885362,
+            "remote": "ms1"
+          }
+        },
+        {
+          "title": "Badman",
+          "id": "E",
+          "_federation": {
+            "indexUid": "test",
+            "queriesPosition": 2,
+            "weightedRankingScore": 0.5,
+            "remote": "ms2"
+          }
+        },
+        {
+          "title": "Batman",
+          "id": "D",
+          "_federation": {
+            "indexUid": "test",
+            "queriesPosition": 0,
+            "weightedRankingScore": 0.23106060606060605,
+            "remote": "ms0"
+          }
+        }
+      ],
+      "processingTimeMs": "[time]",
+      "limit": 20,
+      "offset": 0,
+      "estimatedTotalHits": 5,
+      "requestUid": "[uuid]",
+      "remoteErrors": {}
+    }
+    "###);
+    let (response, _status_code) = ms2.multi_search(request.clone()).await;
+    snapshot!(code, @"200 OK");
+    snapshot!(json_string!(response, { ".processingTimeMs" => "[time]", ".requestUid" => "[uuid]" }), @r###"
+    {
+      "hits": [
+        {
+          "title": "Batman Returns",
+          "id": "C",
+          "_federation": {
+            "indexUid": "test",
+            "queriesPosition": 2,
+            "weightedRankingScore": 0.8317901234567902,
+            "remote": "ms2"
+          }
+        },
+        {
+          "title": "Batman the dark knight returns: Part 1",
+          "id": "A",
+          "_federation": {
+            "indexUid": "test",
+            "queriesPosition": 1,
+            "weightedRankingScore": 0.7028218694885362,
+            "remote": "ms1"
+          }
+        },
+        {
+          "title": "Batman the dark knight returns: Part 2",
+          "id": "B",
+          "_federation": {
+            "indexUid": "test",
+            "queriesPosition": 1,
+            "weightedRankingScore": 0.7028218694885362,
+            "remote": "ms1"
+          }
+        },
+        {
+          "title": "Badman",
+          "id": "E",
+          "_federation": {
+            "indexUid": "test",
+            "queriesPosition": 2,
+            "weightedRankingScore": 0.5,
+            "remote": "ms2"
+          }
+        },
+        {
+          "title": "Batman",
+          "id": "D",
+          "_federation": {
+            "indexUid": "test",
+            "queriesPosition": 0,
+            "weightedRankingScore": 0.23106060606060605,
+            "remote": "ms0"
+          }
+        }
+      ],
+      "processingTimeMs": "[time]",
+      "limit": 20,
+      "offset": 0,
+      "estimatedTotalHits": 5,
+      "requestUid": "[uuid]",
+      "remoteErrors": {}
+    }
+    "###);
+}
+
+#[actix_rt::test]
+async fn remote_auto_sharding_with_custom_metadata() {
+    let ms0 = Server::new().await;
+    let ms1 = Server::new().await;
+    let ms2 = Server::new().await;
+
+    // enable feature
+
+    let (response, code) = ms0.set_features(json!({"network": true})).await;
+    snapshot!(code, @"200 OK");
+    snapshot!(json_string!(response["network"]), @"true");
+    let (response, code) = ms1.set_features(json!({"network": true})).await;
+    snapshot!(code, @"200 OK");
+    snapshot!(json_string!(response["network"]), @"true");
+    let (response, code) = ms2.set_features(json!({"network": true})).await;
+    snapshot!(code, @"200 OK");
+    snapshot!(json_string!(response["network"]), @"true");
+
+    // set self & sharding
+
+    let (response, code) = ms0.set_network(json!({"self": "ms0", "sharding": true})).await;
+    snapshot!(code, @"200 OK");
+    snapshot!(json_string!(response), @r###"
+    {
+      "self": "ms0",
+      "remotes": {},
+      "sharding": true
+    }
+    "###);
+    let (response, code) = ms1.set_network(json!({"self": "ms1", "sharding": true})).await;
+    snapshot!(code, @"200 OK");
+    snapshot!(json_string!(response), @r###"
+    {
+      "self": "ms1",
+      "remotes": {},
+      "sharding": true
+    }
+    "###);
+    let (response, code) = ms2.set_network(json!({"self": "ms2", "sharding": true})).await;
+    snapshot!(code, @"200 OK");
+    snapshot!(json_string!(response), @r###"
+    {
+      "self": "ms2",
+      "remotes": {},
+      "sharding": true
+    }
+    "###);
+
+    // wrap servers
+    let ms0 = Arc::new(ms0);
+    let ms1 = Arc::new(ms1);
+    let ms2 = Arc::new(ms2);
+
+    let rms0 = LocalMeili::new(ms0.clone()).await;
+    let rms1 = LocalMeili::new(ms1.clone()).await;
+    let rms2 = LocalMeili::new(ms2.clone()).await;
+
+    // set network
+    let network = json!({"remotes": {
+        "ms0": {
+            "url": rms0.url()
+        },
+        "ms1": {
+            "url": rms1.url()
+        },
+        "ms2": {
+            "url": rms2.url()
+        }
+    }});
+
+    println!("{}", serde_json::to_string_pretty(&network).unwrap());
+
+    let (_response, status_code) = ms0.set_network(network.clone()).await;
+    snapshot!(status_code, @"200 OK");
+    let (_response, status_code) = ms1.set_network(network.clone()).await;
+    snapshot!(status_code, @"200 OK");
+    let (_response, status_code) = ms2.set_network(network.clone()).await;
+    snapshot!(status_code, @"200 OK");
+
+    // add documents
+    let documents = SCORE_DOCUMENTS.clone();
+    let documents = documents.as_array().unwrap();
+    let index0 = ms0.index("test");
+    let _index1 = ms1.index("test");
+    let _index2 = ms2.index("test");
+
+    let (task, _status_code) = index0
+        .add_documents_with_custom_metadata(
+            json!(documents),
+            None,
+            Some("remote_auto_sharding_with_custom_metadata"),
+        )
+        .await;
+
+    let t0 = task.uid();
+    let (t, _) = ms0.get_task(task.uid()).await;
+    let t1 = t["network"]["remote_tasks"]["ms1"]["taskUid"].as_u64().unwrap();
+    let t2 = t["network"]["remote_tasks"]["ms2"]["taskUid"].as_u64().unwrap();
+
+    let t = ms0.wait_task(t0).await.succeeded();
+    snapshot!(t, @r###"
+    {
+      "uid": "[uid]",
+      "batchUid": "[batch_uid]",
+      "indexUid": "test",
+      "status": "succeeded",
+      "type": "documentAdditionOrUpdate",
+      "canceledBy": null,
+      "details": {
+        "receivedDocuments": 5,
+        "indexedDocuments": 1
+      },
+      "error": null,
+      "duration": "[duration]",
+      "enqueuedAt": "[date]",
+      "startedAt": "[date]",
+      "finishedAt": "[date]",
+      "network": {
+        "remote_tasks": {
+          "ms1": {
+            "taskUid": 0,
+            "error": null
+          },
+          "ms2": {
+            "taskUid": 0,
+            "error": null
+          }
+        }
+      },
+      "customMetadata": "remote_auto_sharding_with_custom_metadata"
+    }
+    "###);
+
+    let t = ms1.wait_task(t1).await.succeeded();
+    snapshot!(t, @r###"
+    {
+      "uid": "[uid]",
+      "batchUid": "[batch_uid]",
+      "indexUid": "test",
+      "status": "succeeded",
+      "type": "documentAdditionOrUpdate",
+      "canceledBy": null,
+      "details": {
+        "receivedDocuments": 5,
+        "indexedDocuments": 2
+      },
+      "error": null,
+      "duration": "[duration]",
+      "enqueuedAt": "[date]",
+      "startedAt": "[date]",
+      "finishedAt": "[date]",
+      "network": {
+        "origin": {
+          "remoteName": "ms0",
+          "taskUid": 0
+        }
+      },
+      "customMetadata": "remote_auto_sharding_with_custom_metadata"
+    }
+    "###);
+
+    let t = ms2.wait_task(t2).await.succeeded();
+    snapshot!(t, @r###"
+    {
+      "uid": "[uid]",
+      "batchUid": "[batch_uid]",
+      "indexUid": "test",
+      "status": "succeeded",
+      "type": "documentAdditionOrUpdate",
+      "canceledBy": null,
+      "details": {
+        "receivedDocuments": 5,
+        "indexedDocuments": 2
+      },
+      "error": null,
+      "duration": "[duration]",
+      "enqueuedAt": "[date]",
+      "startedAt": "[date]",
+      "finishedAt": "[date]",
+      "network": {
+        "origin": {
+          "remoteName": "ms0",
+          "taskUid": 0
+        }
+      },
+      "customMetadata": "remote_auto_sharding_with_custom_metadata"
+    }
+    "###);
+}
--- a/crates/meilisearch/tests/tasks/webhook.rs
+++ b/crates/meilisearch/tests/tasks/webhook.rs
@@ -656,3 +656,119 @@ async fn forbidden_fields() {
    }
    "#);
 }
+
+#[actix_web::test]
+async fn receive_custom_metadata() {
+    let WebhookHandle { server_handle: handle1, url: url1, receiver: mut receiver1 } =
+        create_webhook_server().await;
+    let WebhookHandle { server_handle: handle2, url: url2, receiver: mut receiver2 } =
+        create_webhook_server().await;
+    let WebhookHandle { server_handle: handle3, url: url3, receiver: mut receiver3 } =
+        create_webhook_server().await;
+
+    let db_path = tempfile::tempdir().unwrap();
+    let server = Server::new_with_options(Opt {
+        task_webhook_url: Some(Url::parse(&url3).unwrap()),
+        ..default_settings(db_path.path())
+    })
+    .await
+    .unwrap();
+
+    for url in [url1, url2] {
+        let (value, code) = server.create_webhook(json!({ "url": url })).await;
+        snapshot!(code, @"201 Created");
+        snapshot!(json_string!(value, { ".uuid" => "[uuid]", ".url" => "[ignored]" }), @r#"
+        {
+          "uuid": "[uuid]",
+          "isEditable": true,
+          "url": "[ignored]",
+          "headers": {}
+        }
+        "#);
+    }
+    let index = server.index("tamo");
+    let (response, code) = index
+        .add_documents_with_custom_metadata(
+            json!({ "id": 1, "doggo": "bone" }),
+            None,
+            Some("test_meta"),
+        )
+        .await;
+
+    snapshot!(response, @r###"
+    {
+      "taskUid": 0,
+      "indexUid": "tamo",
+      "status": "enqueued",
+      "type": "documentAdditionOrUpdate",
+      "enqueuedAt": "[date]",
+      "customMetadata": "test_meta"
+    }
+    "###);
+    snapshot!(code, @"202 Accepted");
+
+    let mut count1 = 0;
+    let mut count2 = 0;
+    let mut count3 = 0;
+    while count1 == 0 || count2 == 0 || count3 == 0 {
+        tokio::select! {
+            msg = receiver1.recv() => {
+              if let Some(msg) = msg {
+                count1 += 1;
+                check_metadata(msg);
+              }
+           },
+            msg = receiver2.recv() => {
+              if let Some(msg) = msg {
+                count2 += 1;
+                check_metadata(msg);
+              }
+             },
+            msg = receiver3.recv() => {
+              if let Some(msg) = msg {
+                count3 += 1;
+                check_metadata(msg);
+              }
+            },
+        }
+    }
+
+    assert_eq!(count1, 1);
+    assert_eq!(count2, 1);
+    assert_eq!(count3, 1);
+
+    handle1.abort();
+    handle2.abort();
+    handle3.abort();
+}
+
+fn check_metadata(msg: Vec<u8>) {
+    let msg = String::from_utf8(msg).unwrap();
+    let tasks = msg.split('\n');
+    for task in tasks {
+        if task.is_empty() {
+            continue;
+        }
+        let task: serde_json::Value = serde_json::from_str(task).unwrap();
+        snapshot!(common::Value(task), @r###"
+        {
+          "uid": "[uid]",
+          "batchUid": "[batch_uid]",
+          "indexUid": "tamo",
+          "status": "succeeded",
+          "type": "documentAdditionOrUpdate",
+          "canceledBy": null,
+          "details": {
+            "receivedDocuments": 1,
+            "indexedDocuments": 1
+          },
+          "error": null,
+          "duration": "[duration]",
+          "enqueuedAt": "[date]",
+          "startedAt": "[date]",
+          "finishedAt": "[date]",
+          "customMetadata": "test_meta"
+        }
+        "###);
+    }
+}
--- a/crates/meilisearch/tests/upgrade/mod.rs
+++ b/crates/meilisearch/tests/upgrade/mod.rs
@@ -43,7 +43,7 @@ async fn version_too_old() {
    std::fs::write(db_path.join("VERSION"), "1.11.9999").unwrap();
    let options = Opt { experimental_dumpless_upgrade: true, ..default_settings };
    let err = Server::new_with_options(options).await.map(|_| ()).unwrap_err();
-    snapshot!(err, @"Database version 1.11.9999 is too old for the experimental dumpless upgrade feature. Please generate a dump using the v1.11.9999 and import it in the v1.24.0");
+    snapshot!(err, @"Database version 1.11.9999 is too old for the experimental dumpless upgrade feature. Please generate a dump using the v1.11.9999 and import it in the v1.26.0");
 }

 #[actix_rt::test]
@@ -58,7 +58,7 @@ async fn version_requires_downgrade() {
    std::fs::write(db_path.join("VERSION"), format!("{major}.{minor}.{patch}")).unwrap();
    let options = Opt { experimental_dumpless_upgrade: true, ..default_settings };
    let err = Server::new_with_options(options).await.map(|_| ()).unwrap_err();
-    snapshot!(err, @"Database version 1.24.1 is higher than the Meilisearch version 1.24.0. Downgrade is not supported");
+    snapshot!(err, @"Database version 1.26.1 is higher than the Meilisearch version 1.26.0. Downgrade is not supported");
 }

 #[actix_rt::test]
--- a/crates/meilisearch/tests/upgrade/v1_12/snapshots/v1_12_0.rs/check_the_index_scheduler/batches_filter_afterEnqueuedAt_equal_2025-01-16T16_47_41.snap
+++ b/crates/meilisearch/tests/upgrade/v1_12/snapshots/v1_12_0.rs/check_the_index_scheduler/batches_filter_afterEnqueuedAt_equal_2025-01-16T16_47_41.snap
@@ -8,7 +8,7 @@ source: crates/meilisearch/tests/upgrade/v1_12/v1_12_0.rs
      "progress": null,
      "details": {
        "upgradeFrom": "v1.12.0",
-        "upgradeTo": "v1.24.0"
+        "upgradeTo": "v1.26.0"
      },
      "stats": {
        "totalNbTasks": 1,
--- a/crates/meilisearch/tests/upgrade/v1_12/snapshots/v1_12_0.rs/check_the_index_scheduler/batches_filter_afterFinishedAt_equal_2025-01-16T16_47_41.snap
+++ b/crates/meilisearch/tests/upgrade/v1_12/snapshots/v1_12_0.rs/check_the_index_scheduler/batches_filter_afterFinishedAt_equal_2025-01-16T16_47_41.snap
@@ -8,7 +8,7 @@ source: crates/meilisearch/tests/upgrade/v1_12/v1_12_0.rs
      "progress": null,
      "details": {
        "upgradeFrom": "v1.12.0",
-        "upgradeTo": "v1.24.0"
+        "upgradeTo": "v1.26.0"
      },
      "stats": {
        "totalNbTasks": 1,
--- a/crates/meilisearch/tests/upgrade/v1_12/snapshots/v1_12_0.rs/check_the_index_scheduler/batches_filter_afterStartedAt_equal_2025-01-16T16_47_41.snap
+++ b/crates/meilisearch/tests/upgrade/v1_12/snapshots/v1_12_0.rs/check_the_index_scheduler/batches_filter_afterStartedAt_equal_2025-01-16T16_47_41.snap
@@ -8,7 +8,7 @@ source: crates/meilisearch/tests/upgrade/v1_12/v1_12_0.rs
      "progress": null,
      "details": {
        "upgradeFrom": "v1.12.0",
-        "upgradeTo": "v1.24.0"
+        "upgradeTo": "v1.26.0"
      },
      "stats": {
        "totalNbTasks": 1,
--- a/crates/meilisearch/tests/upgrade/v1_12/snapshots/v1_12_0.rs/check_the_index_scheduler/tasks_filter_afterEnqueuedAt_equal_2025-01-16T16_47_41.snap
+++ b/crates/meilisearch/tests/upgrade/v1_12/snapshots/v1_12_0.rs/check_the_index_scheduler/tasks_filter_afterEnqueuedAt_equal_2025-01-16T16_47_41.snap
@@ -12,7 +12,7 @@ source: crates/meilisearch/tests/upgrade/v1_12/v1_12_0.rs
      "canceledBy": null,
      "details": {
        "upgradeFrom": "v1.12.0",
-        "upgradeTo": "v1.24.0"
+        "upgradeTo": "v1.26.0"
      },
      "error": null,
      "duration": "[duration]",
--- a/crates/meilisearch/tests/upgrade/v1_12/snapshots/v1_12_0.rs/check_the_index_scheduler/tasks_filter_afterFinishedAt_equal_2025-01-16T16_47_41.snap
+++ b/crates/meilisearch/tests/upgrade/v1_12/snapshots/v1_12_0.rs/check_the_index_scheduler/tasks_filter_afterFinishedAt_equal_2025-01-16T16_47_41.snap
@@ -12,7 +12,7 @@ source: crates/meilisearch/tests/upgrade/v1_12/v1_12_0.rs
      "canceledBy": null,
      "details": {
        "upgradeFrom": "v1.12.0",
-        "upgradeTo": "v1.24.0"
+        "upgradeTo": "v1.26.0"
      },
      "error": null,
      "duration": "[duration]",
--- a/crates/meilisearch/tests/upgrade/v1_12/snapshots/v1_12_0.rs/check_the_index_scheduler/tasks_filter_afterStartedAt_equal_2025-01-16T16_47_41.snap
+++ b/crates/meilisearch/tests/upgrade/v1_12/snapshots/v1_12_0.rs/check_the_index_scheduler/tasks_filter_afterStartedAt_equal_2025-01-16T16_47_41.snap
@@ -12,7 +12,7 @@ source: crates/meilisearch/tests/upgrade/v1_12/v1_12_0.rs
      "canceledBy": null,
      "details": {
        "upgradeFrom": "v1.12.0",
-        "upgradeTo": "v1.24.0"
+        "upgradeTo": "v1.26.0"
      },
      "error": null,
      "duration": "[duration]",
--- a/crates/meilisearch/tests/upgrade/v1_12/snapshots/v1_12_0.rs/check_the_index_scheduler/the_whole_batch_queue_once_everything_has_been_processed.snap
+++ b/crates/meilisearch/tests/upgrade/v1_12/snapshots/v1_12_0.rs/check_the_index_scheduler/the_whole_batch_queue_once_everything_has_been_processed.snap
@@ -8,7 +8,7 @@ source: crates/meilisearch/tests/upgrade/v1_12/v1_12_0.rs
      "progress": null,
      "details": {
        "upgradeFrom": "v1.12.0",
-        "upgradeTo": "v1.24.0"
+        "upgradeTo": "v1.26.0"
      },
      "stats": {
        "totalNbTasks": 1,
--- a/crates/meilisearch/tests/upgrade/v1_12/snapshots/v1_12_0.rs/check_the_index_scheduler/the_whole_task_queue_once_everything_has_been_processed.snap
+++ b/crates/meilisearch/tests/upgrade/v1_12/snapshots/v1_12_0.rs/check_the_index_scheduler/the_whole_task_queue_once_everything_has_been_processed.snap
@@ -12,7 +12,7 @@ source: crates/meilisearch/tests/upgrade/v1_12/v1_12_0.rs
      "canceledBy": null,
      "details": {
        "upgradeFrom": "v1.12.0",
-        "upgradeTo": "v1.24.0"
+        "upgradeTo": "v1.26.0"
      },
      "error": null,
      "duration": "[duration]",
--- a/crates/milli/Cargo.toml
+++ b/crates/milli/Cargo.toml
@@ -74,12 +74,13 @@ csv = "1.3.1"
 candle-core = { version = "0.9.1" }
 candle-transformers = { version = "0.9.1" }
 candle-nn = { version = "0.9.1" }
-tokenizers = { git = "https://github.com/huggingface/tokenizers.git", tag = "v0.15.2", version = "0.15.2", default-features = false, features = [
+tokenizers = { version = "0.22.1", default-features = false, features = [
    "onig",
 ] }
 hf-hub = { git = "https://github.com/dureuill/hf-hub.git", branch = "rust_tls", default-features = false, features = [
    "online",
 ] }
+safetensors = "0.6.2"
 tiktoken-rs = "0.7.0"
 liquid = "0.26.11"
 rhai = { version = "1.22.2", features = [
@@ -100,7 +101,6 @@ bumpalo = "3.18.1"
 bumparaw-collections = "0.1.4"
 steppe = { version = "0.4", default-features = false }
 thread_local = "1.1.9"
-allocator-api2 = "0.3.0"
 rustc-hash = "2.1.1"
 enum-iterator = "2.1.0"
 bbqueue = { git = "https://github.com/meilisearch/bbqueue" }
--- a/crates/milli/src/update/index_documents/extract/extract_vector_points.rs
+++ b/crates/milli/src/update/index_documents/extract/extract_vector_points.rs
@@ -1173,6 +1173,7 @@ pub fn extract_embeddings_from_fragments<R: io::Read + io::Seek>(
        request_threads,
        &doc_alloc,
        embedder_stats,
+        false,
        on_embed,
    );

--- a/crates/milli/src/update/new/extract/vectors/mod.rs
+++ b/crates/milli/src/update/new/extract/vectors/mod.rs
@@ -35,6 +35,7 @@ pub struct EmbeddingExtractor<'a, 'b> {
    possible_embedding_mistakes: PossibleEmbeddingMistakes,
    embedder_stats: &'a EmbedderStats,
    threads: &'a ThreadPoolNoAbort,
+    failure_modes: EmbedderFailureModes,
 }

 impl<'a, 'b> EmbeddingExtractor<'a, 'b> {
@@ -46,7 +47,15 @@ impl<'a, 'b> EmbeddingExtractor<'a, 'b> {
        threads: &'a ThreadPoolNoAbort,
    ) -> Self {
        let possible_embedding_mistakes = PossibleEmbeddingMistakes::new(field_distribution);
-        Self { embedders, sender, threads, possible_embedding_mistakes, embedder_stats }
+        let failure_modes = EmbedderFailureModes::from_env();
+        Self {
+            embedders,
+            sender,
+            threads,
+            possible_embedding_mistakes,
+            embedder_stats,
+            failure_modes,
+        }
    }
 }

@@ -91,6 +100,7 @@ impl<'extractor> Extractor<'extractor> for EmbeddingExtractor<'_, '_> {
                self.threads,
                self.sender,
                &context.doc_alloc,
+                self.failure_modes,
            ))
        }

@@ -267,6 +277,7 @@ pub struct SettingsChangeEmbeddingExtractor<'a, 'b, SD> {
    sender: EmbeddingSender<'a, 'b>,
    possible_embedding_mistakes: PossibleEmbeddingMistakes,
    threads: &'a ThreadPoolNoAbort,
+    failure_modes: EmbedderFailureModes,
 }

 impl<'a, 'b, SD: SettingsDelta> SettingsChangeEmbeddingExtractor<'a, 'b, SD> {
@@ -279,7 +290,16 @@ impl<'a, 'b, SD: SettingsDelta> SettingsChangeEmbeddingExtractor<'a, 'b, SD> {
        threads: &'a ThreadPoolNoAbort,
    ) -> Self {
        let possible_embedding_mistakes = PossibleEmbeddingMistakes::new(field_distribution);
-        Self { settings_delta, embedder_stats, sender, threads, possible_embedding_mistakes }
+        let failure_modes = EmbedderFailureModes::from_env();
+
+        Self {
+            settings_delta,
+            embedder_stats,
+            sender,
+            threads,
+            possible_embedding_mistakes,
+            failure_modes,
+        }
    }
 }

@@ -336,6 +356,7 @@ impl<'extractor, SD: SettingsDelta + Sync> SettingsChangeExtractor<'extractor>
                    self.threads,
                    self.sender,
                    &context.doc_alloc,
+                    self.failure_modes,
                ),
                reindex_action,
            ));
@@ -539,6 +560,7 @@ struct Chunks<'a, 'b, 'extractor> {
 enum ChunkType<'a, 'b> {
    DocumentTemplate {
        document_template: &'a Prompt,
+        ignore_document_template_failures: bool,
        session: EmbedSession<'a, OnEmbeddingDocumentUpdates<'a, 'b>, &'a str>,
    },
    Fragments {
@@ -559,6 +581,7 @@ impl<'a, 'b, 'extractor> Chunks<'a, 'b, 'extractor> {
        threads: &'a ThreadPoolNoAbort,
        sender: EmbeddingSender<'a, 'b>,
        doc_alloc: &'a Bump,
+        failure_modes: EmbedderFailureModes,
    ) -> Self {
        let embedder = &runtime.embedder;
        let dimensions = embedder.dimensions();
@@ -567,12 +590,14 @@ impl<'a, 'b, 'extractor> Chunks<'a, 'b, 'extractor> {
        let kind = if fragments.is_empty() {
            ChunkType::DocumentTemplate {
                document_template: &runtime.document_template,
+                ignore_document_template_failures: failure_modes.ignore_document_template_failures,
                session: EmbedSession::new(
                    &runtime.embedder,
                    embedder_name,
                    threads,
                    doc_alloc,
                    embedder_stats,
+                    failure_modes.ignore_embedder_failures,
                    OnEmbeddingDocumentUpdates {
                        embedder_id: embedder_info.embedder_id,
                        sender,
@@ -589,6 +614,7 @@ impl<'a, 'b, 'extractor> Chunks<'a, 'b, 'extractor> {
                    threads,
                    doc_alloc,
                    embedder_stats,
+                    failure_modes.ignore_embedder_failures,
                    OnEmbeddingDocumentUpdates {
                        embedder_id: embedder_info.embedder_id,
                        sender,
@@ -693,7 +719,11 @@ impl<'a, 'b, 'extractor> Chunks<'a, 'b, 'extractor> {
                    },
                )?;
            }
-            ChunkType::DocumentTemplate { document_template, session } => {
+            ChunkType::DocumentTemplate {
+                document_template,
+                ignore_document_template_failures,
+                session,
+            } => {
                let doc_alloc = session.doc_alloc();

                let old_embedder = settings_delta.old_embedders().get(session.embedder_name());
@@ -702,6 +732,7 @@ impl<'a, 'b, 'extractor> Chunks<'a, 'b, 'extractor> {
                } else {
                    old_embedder.as_ref().map(|old_embedder| &old_embedder.document_template)
                };
+
                let extractor =
                    DocumentTemplateExtractor::new(document_template, doc_alloc, fields_ids_map);
                let old_extractor = old_document_template.map(|old_document_template| {
@@ -710,7 +741,15 @@ impl<'a, 'b, 'extractor> Chunks<'a, 'b, 'extractor> {
                let metadata =
                    Metadata { docid, external_docid, extractor_id: extractor.extractor_id() };

-                match extractor.diff_settings(document, &external_docid, old_extractor.as_ref())? {
+                let extractor_diff = if *ignore_document_template_failures {
+                    let extractor = extractor.ignore_errors();
+                    let old_extractor = old_extractor.map(DocumentTemplateExtractor::ignore_errors);
+                    extractor.diff_settings(document, &external_docid, old_extractor.as_ref())?
+                } else {
+                    extractor.diff_settings(document, &external_docid, old_extractor.as_ref())?
+                };
+
+                match extractor_diff {
                    ExtractorDiff::Removed => {
                        if old_is_user_provided || full_reindex {
                            session.on_embed_mut().clear_vectors(docid);
@@ -758,7 +797,11 @@ impl<'a, 'b, 'extractor> Chunks<'a, 'b, 'extractor> {
            new_must_regenerate,
        );
        match &mut self.kind {
-            ChunkType::DocumentTemplate { document_template, session } => {
+            ChunkType::DocumentTemplate {
+                document_template,
+                ignore_document_template_failures,
+                session,
+            } => {
                let doc_alloc = session.doc_alloc();
                let ex = DocumentTemplateExtractor::new(
                    document_template,
@@ -766,18 +809,33 @@ impl<'a, 'b, 'extractor> Chunks<'a, 'b, 'extractor> {
                    new_fields_ids_map,
                );

-                update_autogenerated(
-                    docid,
-                    external_docid,
-                    [ex],
-                    old_document,
-                    new_document,
-                    &external_docid,
-                    old_must_regenerate,
-                    old_is_user_provided,
-                    session,
-                    unused_vectors_distribution,
-                )?
+                if *ignore_document_template_failures {
+                    update_autogenerated(
+                        docid,
+                        external_docid,
+                        [ex.ignore_errors()],
+                        old_document,
+                        new_document,
+                        &external_docid,
+                        old_must_regenerate,
+                        old_is_user_provided,
+                        session,
+                        unused_vectors_distribution,
+                    )
+                } else {
+                    update_autogenerated(
+                        docid,
+                        external_docid,
+                        [ex],
+                        old_document,
+                        new_document,
+                        &external_docid,
+                        old_must_regenerate,
+                        old_is_user_provided,
+                        session,
+                        unused_vectors_distribution,
+                    )
+                }?
            }
            ChunkType::Fragments { fragments, session } => {
                let doc_alloc = session.doc_alloc();
@@ -844,23 +902,38 @@ impl<'a, 'b, 'extractor> Chunks<'a, 'b, 'extractor> {
        );

        match &mut self.kind {
-            ChunkType::DocumentTemplate { document_template, session } => {
+            ChunkType::DocumentTemplate {
+                document_template,
+                ignore_document_template_failures,
+                session,
+            } => {
                let doc_alloc = session.doc_alloc();
                let ex = DocumentTemplateExtractor::new(
                    document_template,
                    doc_alloc,
                    new_fields_ids_map,
                );
-
-                insert_autogenerated(
-                    docid,
-                    external_docid,
-                    [ex],
-                    new_document,
-                    &external_docid,
-                    session,
-                    unused_vectors_distribution,
-                )?;
+                if *ignore_document_template_failures {
+                    insert_autogenerated(
+                        docid,
+                        external_docid,
+                        [ex.ignore_errors()],
+                        new_document,
+                        &external_docid,
+                        session,
+                        unused_vectors_distribution,
+                    )?;
+                } else {
+                    insert_autogenerated(
+                        docid,
+                        external_docid,
+                        [ex],
+                        new_document,
+                        &external_docid,
+                        session,
+                        unused_vectors_distribution,
+                    )?;
+                }
            }
            ChunkType::Fragments { fragments, session } => {
                let doc_alloc = session.doc_alloc();
@@ -884,7 +957,11 @@ impl<'a, 'b, 'extractor> Chunks<'a, 'b, 'extractor> {

    pub fn drain(self, unused_vectors_distribution: &UnusedVectorsDistributionBump) -> Result<()> {
        match self.kind {
-            ChunkType::DocumentTemplate { document_template: _, session } => {
+            ChunkType::DocumentTemplate {
+                document_template: _,
+                ignore_document_template_failures: _,
+                session,
+            } => {
                session.drain(unused_vectors_distribution)?;
            }
            ChunkType::Fragments { fragments: _, session } => {
@@ -896,9 +973,11 @@ impl<'a, 'b, 'extractor> Chunks<'a, 'b, 'extractor> {

    pub fn embedder_name(&self) -> &'a str {
        match &self.kind {
-            ChunkType::DocumentTemplate { document_template: _, session } => {
-                session.embedder_name()
-            }
+            ChunkType::DocumentTemplate {
+                document_template: _,
+                ignore_document_template_failures: _,
+                session,
+            } => session.embedder_name(),
            ChunkType::Fragments { fragments: _, session } => session.embedder_name(),
        }
    }
@@ -967,7 +1046,11 @@ impl<'a, 'b, 'extractor> Chunks<'a, 'b, 'extractor> {
            }
        }
        match &mut self.kind {
-            ChunkType::DocumentTemplate { document_template: _, session } => {
+            ChunkType::DocumentTemplate {
+                document_template: _,
+                ignore_document_template_failures: _,
+                session,
+            } => {
                session.on_embed_mut().process_embeddings(
                    Metadata { docid, external_docid, extractor_id: 0 },
                    embeddings,
@@ -1078,3 +1161,41 @@ where

    Ok(())
 }
+
+#[derive(Clone, Copy, PartialEq, Eq, Default)]
+struct EmbedderFailureModes {
+    pub ignore_document_template_failures: bool,
+    pub ignore_embedder_failures: bool,
+}
+
+impl EmbedderFailureModes {
+    fn from_env() -> Self {
+        match std::env::var("MEILI_EXPERIMENTAL_CONFIG_EMBEDDER_FAILURE_MODES") {
+            Ok(failure_modes) => Self::parse_from_str(
+                &failure_modes,
+                "`MEILI_EXPERIMENTAL_CONFIG_EMBEDDER_FAILURE_MODES`",
+            ),
+            Err(std::env::VarError::NotPresent) => Self::default(),
+            Err(std::env::VarError::NotUnicode(_)) => panic!(
+                "`MEILI_EXPERIMENTAL_CONFIG_EMBEDDER_FAILURE_MODES` contains a non-unicode value"
+            ),
+        }
+    }
+
+    fn parse_from_str(failure_modes: &str, provenance: &'static str) -> Self {
+        let Self { mut ignore_document_template_failures, mut ignore_embedder_failures } =
+            Default::default();
+        for segment in failure_modes.split(',') {
+            let segment = segment.trim();
+            match segment {
+                "ignore_document_template_failures" => {
+                    ignore_document_template_failures = true;
+                }
+                "ignore_embedder_failures" => ignore_embedder_failures = true,
+                "" => continue,
+                segment => panic!("Unrecognized segment value for {provenance}: {segment}"),
+            }
+        }
+        Self { ignore_document_template_failures, ignore_embedder_failures }
+    }
+}
--- a/crates/milli/src/update/new/indexer/enterprise_edition/sharding.rs
+++ b/crates/milli/src/update/new/indexer/enterprise_edition/sharding.rs
@@ -5,18 +5,36 @@

 use std::hash::{BuildHasher as _, BuildHasherDefault};

-pub struct Shards {
-    pub own: Vec<String>,
-    pub others: Vec<String>,
+pub struct Shards(pub Vec<Shard>);
+
+pub struct Shard {
+    pub is_own: bool,
+    pub name: String,
 }

 impl Shards {
+    pub fn from_remotes_local<'a>(
+        remotes: impl IntoIterator<Item = &'a str>,
+        local: Option<&str>,
+    ) -> Self {
+        Shards(
+            remotes
+                .into_iter()
+                .map(|name| Shard { is_own: Some(name) == local, name: name.to_owned() })
+                .collect(),
+        )
+    }
+
    pub fn must_process(&self, docid: &str) -> bool {
+        self.processing_shard(docid).map(|shard| shard.is_own).unwrap_or_default()
+    }
+
+    pub fn processing_shard<'a>(&'a self, docid: &str) -> Option<&'a Shard> {
        let hasher = BuildHasherDefault::<twox_hash::XxHash3_64>::new();
-        let to_hash = |shard: &String| hasher.hash_one((shard, docid));
+        let to_hash = |shard: &'a Shard| (shard, hasher.hash_one((&shard.name, docid)));

-        let max_hash = self.others.iter().map(to_hash).max().unwrap_or_default();
-
-        self.own.iter().map(to_hash).any(|hash| hash > max_hash)
+        let shard =
+            self.0.iter().map(to_hash).max_by_key(|(_, hash)| *hash).map(|(shard, _)| shard);
+        shard
    }
 }
--- a/crates/milli/src/update/settings.rs
+++ b/crates/milli/src/update/settings.rs
@@ -1631,8 +1631,11 @@ impl<'a, 't, 'i> Settings<'a, 't, 'i> {

            // Update index settings
            let embedding_config_updates = self.update_embedding_configs()?;
+            self.update_user_defined_searchable_attributes()?;

-            let new_inner_settings = InnerIndexSettings::from_index(self.index, self.wtxn, None)?;
+            let mut new_inner_settings =
+                InnerIndexSettings::from_index(self.index, self.wtxn, None)?;
+            new_inner_settings.recompute_searchables(self.wtxn, self.index)?;

            let primary_key_id = self
                .index
--- a/crates/milli/src/update/upgrade/mod.rs
+++ b/crates/milli/src/update/upgrade/mod.rs
@@ -42,6 +42,8 @@ const UPGRADE_FUNCTIONS: &[&dyn UpgradeIndex] = &[
    &ToTargetNoOp { target: (1, 22, 0) },
    &ToTargetNoOp { target: (1, 23, 0) },
    &ToTargetNoOp { target: (1, 24, 0) },
+    &ToTargetNoOp { target: (1, 25, 0) },
+    &ToTargetNoOp { target: (1, 26, 0) },
    // This is the last upgrade function, it will be called when the index is up to date.
    // any other upgrade function should be added before this one.
    &ToCurrentNoOp {},
@@ -77,6 +79,8 @@ const fn start(from: (u32, u32, u32)) -> Option<usize> {
        (1, 22, _) => function_index!(12),
        (1, 23, _) => function_index!(13),
        (1, 24, _) => function_index!(14),
+        (1, 25, _) => function_index!(15),
+        (1, 26, _) => function_index!(16),
        // We deliberately don't add a placeholder with (VERSION_MAJOR, VERSION_MINOR, VERSION_PATCH) here to force manually
        // considering dumpless upgrade.
        (_major, _minor, _patch) => return None,
--- a/crates/milli/src/vector/embedder/hf.rs
+++ b/crates/milli/src/vector/embedder/hf.rs
@@ -1,9 +1,11 @@
 use candle_core::Tensor;
 use candle_nn::VarBuilder;
-use candle_transformers::models::bert::{BertModel, Config, DTYPE};
+use candle_transformers::models::bert::{BertModel, Config as BertConfig, DTYPE};
+use candle_transformers::models::modernbert::{Config as ModernConfig, ModernBert};
 // FIXME: currently we'll be using the hub to retrieve model, in the future we might want to embed it into Meilisearch itself
 use hf_hub::api::sync::Api;
 use hf_hub::{Repo, RepoType};
+use safetensors::SafeTensors;
 use tokenizers::{PaddingParams, Tokenizer};

 use super::EmbeddingCache;
@@ -84,14 +86,21 @@ impl Default for EmbedderOptions {
    }
 }

+enum ModelKind {
+    Bert(BertModel),
+    Modern(ModernBert),
+}
+
 /// Perform embedding of documents and queries
 pub struct Embedder {
-    model: BertModel,
+    model: ModelKind,
    tokenizer: Tokenizer,
    options: EmbedderOptions,
    dimensions: usize,
    pooling: Pooling,
    cache: EmbeddingCache,
+    device: candle_core::Device,
+    max_len: usize,
 }

 impl std::fmt::Debug for Embedder {
@@ -101,10 +110,60 @@ impl std::fmt::Debug for Embedder {
            .field("tokenizer", &self.tokenizer)
            .field("options", &self.options)
            .field("pooling", &self.pooling)
+            .field("device", &self.device)
+            .field("max_len", &self.max_len)
            .finish()
    }
 }

+// some models do not have the "model." prefix in their safetensors weights
+fn change_tensor_names(
+    weights_path: &std::path::Path,
+) -> Result<std::path::PathBuf, NewEmbedderError> {
+    let data = std::fs::read(weights_path)
+        .map_err(|e| NewEmbedderError::safetensor_weight(candle_core::Error::Io(e)))?;
+
+    let tensors = SafeTensors::deserialize(&data)
+        .map_err(|e| NewEmbedderError::safetensor_weight(candle_core::Error::Msg(e.to_string())))?;
+
+    let names = tensors.names();
+    let has_model_prefix = names.iter().any(|n| n.starts_with("model."));
+
+    if has_model_prefix {
+        return Ok(weights_path.to_path_buf());
+    }
+
+    let fixed_path = weights_path.with_extension("fixed.safetensors");
+
+    if fixed_path.exists() {
+        return Ok(fixed_path);
+    }
+
+    let mut new_tensors = vec![];
+    for name in names {
+        let tensor_view = tensors.tensor(name).map_err(|e| {
+            NewEmbedderError::safetensor_weight(candle_core::Error::Msg(e.to_string()))
+        })?;
+
+        let new_name = format!("model.{}", name);
+        let data_offset = tensor_view.data();
+        let shape = tensor_view.shape();
+        let dtype = tensor_view.dtype();
+
+        new_tensors.push((new_name, shape.to_vec(), dtype, data_offset));
+    }
+
+    use safetensors::tensor::TensorView;
+    let views = new_tensors.iter().map(|(name, shape, dtype, data)| {
+        (name.as_str(), TensorView::new(*dtype, shape.clone(), data).unwrap())
+    });
+
+    safetensors::serialize_to_file(views, None, &fixed_path)
+        .map_err(|e| NewEmbedderError::safetensor_weight(candle_core::Error::Msg(e.to_string())))?;
+
+    Ok(fixed_path)
+}
+
 #[derive(Clone, Copy, serde::Deserialize)]
 struct PoolingConfig {
    #[serde(default)]
@@ -220,19 +279,42 @@ impl Embedder {
            (config, tokenizer, weights, source, pooling)
        };

-        let config = std::fs::read_to_string(&config_filename)
+        let config_str = std::fs::read_to_string(&config_filename)
            .map_err(|inner| NewEmbedderError::open_config(config_filename.clone(), inner))?;
-        let config: Config = serde_json::from_str(&config).map_err(|inner| {
-            NewEmbedderError::deserialize_config(
-                options.model.clone(),
-                config,
-                config_filename,
-                inner,
-            )
-        })?;
+
+        let cfg_val: serde_json::Value = match serde_json::from_str(&config_str) {
+            Ok(v) => v,
+            Err(inner) => {
+                return Err(NewEmbedderError::deserialize_config(
+                    options.model.clone(),
+                    config_str.clone(),
+                    config_filename.clone(),
+                    inner,
+                ));
+            }
+        };
+
+        let model_type = cfg_val.get("model_type").and_then(|v| v.as_str()).unwrap_or_default();
+        let arch_arr = cfg_val.get("architectures").and_then(|v| v.as_array());
+        let has_arch = |needle: &str| {
+            model_type.eq_ignore_ascii_case(needle)
+                || arch_arr.is_some_and(|arr| {
+                    arr.iter().filter_map(|v| v.as_str()).any(|s| s.to_lowercase().contains(needle))
+                })
+        };
+
+        let is_modern = has_arch("modernbert");
+        tracing::debug!(is_modern, model_type, "detected HF architecture");
+
        let mut tokenizer = Tokenizer::from_file(&tokenizer_filename)
            .map_err(|inner| NewEmbedderError::open_tokenizer(tokenizer_filename, inner))?;

+        let weights_filename = if is_modern && weight_source == WeightSource::Safetensors {
+            change_tensor_names(&weights_filename)?
+        } else {
+            weights_filename
+        };
+
        let vb = match weight_source {
            WeightSource::Pytorch => VarBuilder::from_pth(&weights_filename, DTYPE, &device)
                .map_err(NewEmbedderError::pytorch_weight)?,
@@ -244,7 +326,31 @@ impl Embedder {

        tracing::debug!(model = options.model, weight=?weight_source, pooling=?pooling, "model config");

-        let model = BertModel::load(vb, &config).map_err(NewEmbedderError::load_model)?;
+        // max length from config, fallback to 512
+        let max_len =
+            cfg_val.get("max_position_embeddings").and_then(|v| v.as_u64()).unwrap_or(512) as usize;
+
+        let model = if is_modern {
+            let config: ModernConfig = serde_json::from_str(&config_str).map_err(|inner| {
+                NewEmbedderError::deserialize_config(
+                    options.model.clone(),
+                    config_str.clone(),
+                    config_filename.clone(),
+                    inner,
+                )
+            })?;
+            ModelKind::Modern(ModernBert::load(vb, &config).map_err(NewEmbedderError::load_model)?)
+        } else {
+            let config: BertConfig = serde_json::from_str(&config_str).map_err(|inner| {
+                NewEmbedderError::deserialize_config(
+                    options.model.clone(),
+                    config_str.clone(),
+                    config_filename.clone(),
+                    inner,
+                )
+            })?;
+            ModelKind::Bert(BertModel::load(vb, &config).map_err(NewEmbedderError::load_model)?)
+        };

        if let Some(pp) = tokenizer.get_padding_mut() {
            pp.strategy = tokenizers::PaddingStrategy::BatchLongest
@@ -263,6 +369,8 @@ impl Embedder {
            dimensions: 0,
            pooling,
            cache: EmbeddingCache::new(cache_cap),
+            device,
+            max_len,
        };

        let embeddings = this
@@ -321,15 +429,29 @@ impl Embedder {
    pub fn embed_one(&self, text: &str) -> std::result::Result<Embedding, EmbedError> {
        let tokens = self.tokenizer.encode(text, true).map_err(EmbedError::tokenize)?;
        let token_ids = tokens.get_ids();
-        let token_ids = if token_ids.len() > 512 { &token_ids[..512] } else { token_ids };
        let token_ids =
-            Tensor::new(token_ids, &self.model.device).map_err(EmbedError::tensor_shape)?;
+            if token_ids.len() > self.max_len { &token_ids[..self.max_len] } else { token_ids };
+        let token_ids = Tensor::new(token_ids, &self.device).map_err(EmbedError::tensor_shape)?;
        let token_ids = Tensor::stack(&[token_ids], 0).map_err(EmbedError::tensor_shape)?;
-        let token_type_ids = token_ids.zeros_like().map_err(EmbedError::tensor_shape)?;
-        let embeddings = self
-            .model
-            .forward(&token_ids, &token_type_ids, None)
-            .map_err(EmbedError::model_forward)?;
+
+        let embeddings = match &self.model {
+            ModelKind::Bert(model) => {
+                let token_type_ids = token_ids.zeros_like().map_err(EmbedError::tensor_shape)?;
+                model
+                    .forward(&token_ids, &token_type_ids, None)
+                    .map_err(EmbedError::model_forward)?
+            }
+            ModelKind::Modern(model) => {
+                let mut mask_vec = tokens.get_attention_mask().to_vec();
+                if mask_vec.len() > self.max_len {
+                    mask_vec.truncate(self.max_len);
+                }
+                let mask = Tensor::new(mask_vec.as_slice(), &self.device)
+                    .map_err(EmbedError::tensor_shape)?;
+                let mask = Tensor::stack(&[mask], 0).map_err(EmbedError::tensor_shape)?;
+                model.forward(&token_ids, &mask).map_err(EmbedError::model_forward)?
+            }
+        };

        let embedding = Self::pooling(embeddings, self.pooling)?;

--- a/crates/milli/src/vector/embedder/rest.rs
+++ b/crates/milli/src/vector/embedder/rest.rs
@@ -91,6 +91,7 @@ struct EmbedderData {
    request: RequestData,
    response: Response,
    configuration_source: ConfigurationSource,
+    max_retry_duration: std::time::Duration,
 }

 #[derive(Debug)]
@@ -182,10 +183,15 @@ impl Embedder {
    ) -> Result<Self, NewEmbedderError> {
        let bearer = options.api_key.as_deref().map(|api_key| format!("Bearer {api_key}"));

+        let timeout = std::env::var("MEILI_EXPERIMENTAL_REST_EMBEDDER_TIMEOUT_SECONDS")
+            .ok()
+            .map(|p| p.parse().unwrap())
+            .unwrap_or(30);
+
        let client = ureq::AgentBuilder::new()
            .max_idle_connections(REQUEST_PARALLELISM * 2)
            .max_idle_connections_per_host(REQUEST_PARALLELISM * 2)
-            .timeout(std::time::Duration::from_secs(30))
+            .timeout(std::time::Duration::from_secs(timeout))
            .build();

        let request = RequestData::new(
@@ -196,6 +202,14 @@ impl Embedder {

        let response = Response::new(options.response, &request)?;

+        let max_retry_duration =
+            std::env::var("MEILI_EXPERIMENTAL_REST_EMBEDDER_MAX_RETRY_DURATION_SECONDS")
+                .ok()
+                .map(|p| p.parse().unwrap())
+                .unwrap_or(60);
+
+        let max_retry_duration = std::time::Duration::from_secs(max_retry_duration);
+
        let data = EmbedderData {
            client,
            bearer,
@@ -204,6 +218,7 @@ impl Embedder {
            response,
            configuration_source,
            headers: options.headers,
+            max_retry_duration,
        };

        let dimensions = if let Some(dimensions) = options.dimensions {
@@ -457,7 +472,7 @@ where
            }
        }?;

-        let retry_duration = retry_duration.min(std::time::Duration::from_secs(60)); // don't wait more than a minute
+        let retry_duration = retry_duration.min(data.max_retry_duration); // don't wait more than the max duration

        // randomly up to double the retry duration
        let retry_duration = retry_duration
--- a/crates/milli/src/vector/error.rs
+++ b/crates/milli/src/vector/error.rs
@@ -550,9 +550,9 @@ pub struct DeserializePoolingConfig {
 #[derive(Debug, thiserror::Error)]
 #[error("model `{model_name}` appears to be unsupported{}\n  - inner error: {inner}",
 if architectures.is_empty() {
-    "\n  - Note: only models with architecture \"BertModel\" are supported.".to_string()
+    "\n  - Note: only models with architecture \"BertModel\" or \"ModernBert\" are supported.".to_string()
 } else {
-    format!("\n  - Note: model has declared architectures `{architectures:?}`, only models with architecture `\"BertModel\"` are supported.")
+    format!("\n  - Note: model has declared architectures `{architectures:?}`, only models with architecture `\"BertModel\"` or `\"ModernBert\"` are supported.")
 })]
 pub struct UnsupportedModel {
    pub model_name: String,
--- a/crates/milli/src/vector/session.rs
+++ b/crates/milli/src/vector/session.rs
@@ -44,6 +44,7 @@ pub struct EmbedSession<'doc, C, I> {
    embedder_name: &'doc str,

    embedder_stats: &'doc EmbedderStats,
+    ignore_embedding_failures: bool,

    on_embed: C,
 }
@@ -87,6 +88,7 @@ impl<'doc, C: OnEmbed<'doc>, I: Input> EmbedSession<'doc, C, I> {
        threads: &'doc ThreadPoolNoAbort,
        doc_alloc: &'doc Bump,
        embedder_stats: &'doc EmbedderStats,
+        ignore_embedding_failures: bool,
        on_embed: C,
    ) -> Self {
        let capacity = embedder.prompt_count_in_chunk_hint() * embedder.chunk_count_hint();
@@ -99,6 +101,7 @@ impl<'doc, C: OnEmbed<'doc>, I: Input> EmbedSession<'doc, C, I> {
            threads,
            embedder_name,
            embedder_stats,
+            ignore_embedding_failures,
            on_embed,
        }
    }
@@ -144,24 +147,33 @@ impl<'doc, C: OnEmbed<'doc>, I: Input> EmbedSession<'doc, C, I> {
                Ok(())
            }
            Err(error) => {
-                // reset metadata and inputs, and send metadata to the error processing.
+                // send metadata to the error processing.
                let doc_alloc = self.metadata.bump();
                let metadata = std::mem::replace(
                    &mut self.metadata,
                    BVec::with_capacity_in(self.inputs.capacity(), doc_alloc),
                );
-                self.inputs.clear();
-                return Err(self.on_embed.process_embedding_error(
+                Err(self.on_embed.process_embedding_error(
                    error,
                    self.embedder_name,
                    unused_vectors_distribution,
                    metadata,
-                ));
+                ))
            }
        };
        self.inputs.clear();
        self.metadata.clear();
-        res
+        if self.ignore_embedding_failures {
+            if let Err(err) = res {
+                tracing::warn!(
+                    %err,
+                    "ignored error embedding batch of documents due to failure policy"
+                );
+            }
+            Ok(())
+        } else {
+            res
+        }
    }

    pub(crate) fn embedder_name(&self) -> &'doc str {
Author	SHA1	Message	Date
Louis Dureuil	1bf6e5030a	WIP	2025-11-18 17:56:01 +01:00
Louis Dureuil	b757db5cf6	Pass task network at registration time	2025-11-18 10:37:54 +01:00
Louis Dureuil	47f87ba17d	WIP	2025-11-17 15:48:43 +01:00
Clément Renault	ea70a7d1c9	Merge pull request #5969 from xuhongxu96/main Remove unused dependency `allocator-api2`	2025-11-15 10:03:15 +00:00
Clément Renault	9304f8e586	Merge pull request #5991 from meilisearch/release-v1.26.0 Release v1.26.0	2025-11-13 17:54:01 +00:00
Louis Dureuil	495db080ec	Upgrade snap	2025-11-13 17:52:34 +01:00
Louis Dureuil	d71341fa48	Suport upgrade to v1.26.0	2025-11-13 17:52:02 +01:00
Louis Dureuil	5b3070d8c3	Update version in toml and lock	2025-11-13 17:35:26 +01:00
Louis Dureuil	89006fd4b3	Merge pull request #5980 from hayatosc/feat/hugging-face-modernbert Support ModernBERT architecture on `huggingface` embedder	2025-11-10 18:03:35 +00:00
Louis Dureuil	49f50a0a21	Don't collect the views	2025-11-10 17:55:44 +01:00
Louis Dureuil	1104f00803	happy clippy	2025-11-10 16:59:12 +01:00
Louis Dureuil	33fa564a9c	rustfmt	2025-11-10 16:56:13 +01:00
Clément Renault	a097b254f8	Merge pull request #5963 from meilisearch/engprod-2128-allow-attaching-user-defined-metadata-to-tasks-and-return Allow to attach `customMetadata` in the document addition or update tasks	2025-11-10 15:48:46 +00:00
Clément Renault	54cb0ec437	Merge pull request #5984 from meilisearch/embedder-error-modes Embedder failure modes	2025-11-10 15:34:01 +00:00
Louis Dureuil	38ed1f1dbb	Change parsing of environment variable	2025-11-10 15:08:24 +01:00
Clément Renault	643dd33358	Merge pull request #5982 from meilisearch/bump-meilisearch-v1.25.0 Bump meilisearch v1.25.0	2025-11-10 14:04:17 +00:00
Louis Dureuil	32f9fb6ab2	fix environment variable values	2025-11-10 14:54:25 +01:00
Louis Dureuil	b5966f82e8	Make max retry duration configurable with MEILI_EXPERIMENTAL_REST_EMBEDDER_MAX_RETRY_DURATION_SECONDS	2025-11-10 14:29:27 +01:00
Louis Dureuil	5e54063aab	Configurable timeout with MEILI_EXPERIMENTAL_REST_EMBEDDER_TIMEOUT_SECONDS	2025-11-10 14:29:20 +01:00
Louis Dureuil	40456795d0	Allow to customize failure modes with `MEILI_EXPERIMENTAL_CONFIG_EMBEDDER_FAILURE_MODES`	2025-11-10 14:23:51 +01:00
ManyTheFish	40e60c6f52	Fix dumpless upgrade	2025-11-10 14:03:17 +01:00
ManyTheFish	eeae6383d0	Bump Meilisearch version v1.25.0	2025-11-10 14:03:17 +01:00
Hayato Sakaguchi	9f7172f6ab	chage tensor names	2025-11-09 01:06:04 +09:00
Hayato Sakaguchi	d6eca83cfa	Support modernbert architecture in hugging face embedder	2025-11-08 20:53:47 +09:00
Louis Dureuil	fc3508c8c8	Fix route path	2025-11-06 18:08:50 +01:00
Louis Dureuil	747476a225	Add customMetadata to all documents routes	2025-11-06 17:07:18 +01:00
Louis Dureuil	4b72e54ca7	Test webhook with metadata	2025-11-04 17:41:29 +01:00
Louis Dureuil	adef2cc132	test remote auto sharding with and without metadata	2025-11-04 17:41:28 +01:00
Louis Dureuil	533b9951b1	Allow adding custom metadata in tests	2025-11-04 17:41:28 +01:00
Louis Dureuil	9103cbc9db	Add custom metadata to payload	2025-11-04 17:41:28 +01:00
Louis Dureuil	083de2bfc1	Allow to attach `customMetadata`in the document addition or update tasks	2025-11-04 17:41:28 +01:00
Hongxu Xu	08bc982748	Remove unused dependency `allocator-api2`	2025-11-04 03:29:24 +00:00