diff --git a/docs/api/file-rotation-config-to-json.md b/docs/api/file-rotation-config-to-json.md
index ebbc370..b95ff5d 100644
--- a/docs/api/file-rotation-config-to-json.md
+++ b/docs/api/file-rotation-config-to-json.md
@@ -33,8 +33,9 @@ pub fn file_rotation_config_to_json(config : FileRotation) -> @json_parser.JsonV
 
 Detailed rules explaining key parameters and behaviors
 
-- The output includes `max_bytes` and `max_backups`.
-- Both numeric fields are exported as JSON numbers.
+- The output always includes `max_bytes` and `max_backups`.
+- Both of those compatibility fields are exported as JSON numbers.
+- If the policy carries a wide threshold from `file_rotation_i64(...)`, the output also includes `max_bytes_i64` as a JSON string for exact roundtrip transport.
 - This helper serializes the rotation config object itself rather than sink availability, failure counters, or file state.
 - The same JSON shape is reused by `sink_config_to_json(...)`, file sink state export helpers, and larger logger config serialization paths.
 
@@ -61,6 +62,16 @@ let rotation_json = file_rotation_config_to_json(rotation)
 
 In this example, callers can carry the nested rotation shape without exporting a full sink config.
 
+#### When Need Exact Wide-threshold Roundtrip
+
+When a native large-file policy should preserve the original `Int64` threshold in JSON:
+```moonbit
+let rotation = file_rotation_i64(4294967296L, max_backups=2)
+let rotation_json = file_rotation_config_to_json(rotation)
+```
+
+In this example, the JSON value includes the compatibility `max_bytes` view plus `max_bytes_i64` as a string.
+
 ### Error Case
 
 e.g.:
@@ -73,3 +84,5 @@ e.g.:
 1. Use this helper when downstream code expects `JsonValue` rather than a typed `FileRotation` value.
 
 2. Pair it with `file_rotation(...)` when building rotation policy in code before export.
+
+3. For `file_rotation_i64(...)`, treat `max_bytes_i64` as the exact roundtrip field and `max_bytes` as the compatibility view.
diff --git a/docs/api/file-rotation-i64.md b/docs/api/file-rotation-i64.md
new file mode 100644
index 0000000..6b9bab8
--- /dev/null
+++ b/docs/api/file-rotation-i64.md
@@ -0,0 +1,74 @@
+---
+name: file-rotation-i64
+group: api
+category: sink
+update-time: 20260705
+description: Create a native-focused large-file rotation policy using an Int64 byte threshold.
+key-word:
+    - file
+    - rotation
+    - i64
+    - native
+---
+
+## File-rotation-i64
+
+Create a size-based file rotation policy with an `Int64` byte threshold. This helper is the opt-in native-focused path for large-file rotation scenarios that exceed the default `Int`-based contract.
+
+### Interface
+
+```moonbit
+pub fn file_rotation_i64(max_bytes : Int64, max_backups~ : Int = 1) -> FileRotation {}
+```
+
+#### input
+
+- `max_bytes : Int64` - Maximum active file size threshold before rotation on the native-focused wide path.
+- `max_backups : Int` - Number of retained backup files.
+
+#### output
+
+- `FileRotation` - Rotation policy value that preserves a native wide threshold while staying compatible with the existing file sink API surface.
+
+### Explanation
+
+- `max_bytes <= 0L` is normalized to `1L`.
+- `max_backups <= 0` is normalized to `1`.
+- Rotation is size-based only.
+- This helper keeps the existing `FileRotation` type but stores an additional native wide threshold internally for runtime rotation checks.
+- The helper is intended for native file backends and advanced large-file scenarios.
+- JSON config export helpers preserve the exact threshold through `max_bytes_i64` while still exposing a compatibility `max_bytes` view.
+
+### How to Use
+
+#### When Need Native Large-file Rotation Thresholds
+
+```moonbit
+let sink = file_sink(
+  "app.log",
+  rotation=Some(file_rotation_i64(5368709120L, max_backups=4)),
+)
+```
+
+In this example, the active rotation threshold is expressed with `Int64` rather than the default `Int` path.
+
+#### When Need A Wide Policy Value First
+
+```moonbit
+let rotation = file_rotation_i64(3221225472L, max_backups=2)
+let sink = file_sink("app.log", rotation=Some(rotation))
+```
+
+In this example, the wide threshold policy is assembled separately and then reused.
+
+### Error Case
+
+- If `max_bytes` is non-positive, it is clamped to `1L`.
+- This API does not make non-native targets gain real file support; callers should still use `native_files_supported()` when portability matters.
+
+### Notes
+
+1. This API is additive and does not replace the default `file_rotation(...)` contract.
+2. Prefer the default `Int` path unless a native large-file threshold is actually required.
+3. String-based JSON roundtrip uses `max_bytes_i64` for the exact threshold and keeps `max_bytes` as the compatibility field.
+4. This helper is designed for advanced use and target-aware code.
diff --git a/docs/api/file-rotation-type.md b/docs/api/file-rotation-type.md
index 410e691..369a022 100644
--- a/docs/api/file-rotation-type.md
+++ b/docs/api/file-rotation-type.md
@@ -13,7 +13,7 @@ key-word:
 
 ## File-rotation-type
 
-`FileRotation` is the public file sink rotation policy type used for native size-based log file rollover. It is a direct alias to the sink model that stores the byte limit and retained backup count.
+`FileRotation` is the public file sink rotation policy type used for native size-based log file rollover. It is a direct alias to the sink model that stores the standard byte limit, retained backup count, and additive native wide-threshold metadata for the optional `Int64` path.
 
 ### Interface
 
@@ -23,14 +23,14 @@ pub type FileRotation = @utils.FileRotation
 
 #### output
 
-- `FileRotation` - Public file rotation policy object containing `max_bytes` and `max_backups`.
+- `FileRotation` - Public file rotation policy object containing the standard `max_bytes` view, `max_backups`, and additive native wide-threshold support for advanced rotation flows.
 
 ### Explanation
 
 Detailed rules explaining key parameters and behaviors
 
 - This is a type alias, not a file sink or rotation trigger by itself.
-- The current fields are `max_bytes : Int` and `max_backups : Int`.
+- The current fields are `max_bytes : Int`, `max_backups : Int`, and additive native wide-threshold metadata used by the optional `file_rotation_i64(...)` path.
 - `file_rotation(...)` constructs this type as the main public helper.
 - The same value type is consumed by `file_sink(...)`, `FileSinkPolicy::new(...)`, `SinkConfig`, file runtime inspection APIs, and logger config serialization helpers.
 
@@ -65,6 +65,8 @@ e.g.:
 
 ### Notes
 
-1. Use `file_rotation(...)` when you need a value of this type in code.
+1. Use `file_rotation(...)` when you need the default `Int`-based value of this type in code.
 
-2. Use `native_files_supported()` or the target verification guidance when portability matters across non-native targets.
+2. Use `file_rotation_i64(...)` when a native large-file threshold must exceed the default `Int` contract.
+
+3. Use `native_files_supported()` or the target verification guidance when portability matters across non-native targets.
diff --git a/docs/api/file-rotation.md b/docs/api/file-rotation.md
index a3ed8e5..a83da09 100644
--- a/docs/api/file-rotation.md
+++ b/docs/api/file-rotation.md
@@ -38,6 +38,9 @@ Detailed rules explaining key parameters and behaviors
 - `max_backups <= 0` is normalized to `1`.
 - Rotation is size-based only.
 - This policy is consumed by `file_sink(...)`, file policy helpers, and config-driven file sink assembly.
+- The default `max_bytes : Int` path follows the current 32-bit `Int` contract used by the standard file rotation APIs.
+- On native targets, that default path is intended for ordinary log-file ranges rather than explicit large-file guarantees beyond the 32-bit `Int` boundary.
+- If a native large-file threshold is required, prefer `file_rotation_i64(...)`.
 
 ### How to Use
 
@@ -79,3 +82,5 @@ e.g.:
 
 2. Rotation currently focuses on size thresholds rather than time schedules or compression.
 
+3. The default API keeps the portable `Int`-based contract stable; the wider native-only path is exposed separately through `file_rotation_i64(...)`.
+
diff --git a/docs/api/file-sink-policy-to-json.md b/docs/api/file-sink-policy-to-json.md
index f6d86ee..bf6a304 100644
--- a/docs/api/file-sink-policy-to-json.md
+++ b/docs/api/file-sink-policy-to-json.md
@@ -38,6 +38,7 @@ Detailed rules explaining key parameters and behaviors
 - This helper exports runtime file policy, not current file health counters or availability.
 - The JSON value is useful for policy snapshots, comparisons, and diagnostics payloads.
 - Typical inputs come from `FileSink::policy()`, `RuntimeSink::file_policy()`, or `ConfiguredLogger::file_policy()`.
+- If the active rotation policy originated from `file_rotation_i64(...)`, the nested rotation JSON includes both the compatibility `max_bytes` number and `max_bytes_i64` as the exact string form.
 
 ### How to Use
 
@@ -74,3 +75,5 @@ e.g.:
 1. Use this helper when downstream code expects `JsonValue` rather than text.
 
 2. It pairs naturally with `FileSink::policy()`, `RuntimeSink::file_policy()`, and related default-policy accessors.
+
+3. For wide native rotation policies, downstream code should read `rotation.max_bytes_i64` when exact threshold recovery matters.
diff --git a/docs/api/file-sink-state-to-json.md b/docs/api/file-sink-state-to-json.md
index ab4cfc5..f394db7 100644
--- a/docs/api/file-sink-state-to-json.md
+++ b/docs/api/file-sink-state-to-json.md
@@ -38,6 +38,7 @@ Detailed rules explaining key parameters and behaviors
 - This helper exports state snapshots, not mutable runtime control handles.
 - It is useful when file sink state should be embedded into larger diagnostics payloads.
 - Typical inputs come from `FileSink::state()`, `RuntimeSink::file_state()`, or `ConfiguredLogger::file_state()`.
+- If the live rotation policy was created from `file_rotation_i64(...)`, the nested `rotation` JSON includes `max_bytes_i64` as a string alongside the compatibility `max_bytes` number.
 
 ### How to Use
 
@@ -73,3 +74,5 @@ e.g.:
 1. Use this helper when diagnostics consumers expect `JsonValue`.
 
 2. It pairs naturally with `FileSink::state()`, `RuntimeSink::file_state()`, and `ConfiguredLogger::file_state()`.
+
+3. For wide native rotation policies, `rotation.max_bytes_i64` is the exact roundtrip field.
diff --git a/docs/api/file-sink.md b/docs/api/file-sink.md
index 057f914..1a7b42c 100644
--- a/docs/api/file-sink.md
+++ b/docs/api/file-sink.md
@@ -32,7 +32,7 @@ pub fn file_sink(
 - `path : String` - Destination file path.
 - `append : Bool` - Whether opening/reopening should append rather than truncate.
 - `auto_flush : Bool` - Whether flush is attempted after each write.
-- `rotation : FileRotation?` - Optional size-based rotation policy.
+- `rotation : FileRotation?` - Optional size-based rotation policy. The default helper path is `file_rotation(...)`; advanced native large-file callers can also pass a policy created by `file_rotation_i64(...)`.
 - `formatter : RecordFormatter` - Formatter used to render each record before writing.
 
 #### output
diff --git a/docs/api/file.md b/docs/api/file.md
index df4f931..ee91c52 100644
--- a/docs/api/file.md
+++ b/docs/api/file.md
@@ -38,7 +38,7 @@ pub fn file(
 - `timestamp : Bool` - Whether the built logger should emit timestamps.
 - `append : Bool` - Whether file writes should append instead of truncate-on-open behavior.
 - `auto_flush : Bool` - Whether writes should be flushed automatically.
-- `rotation : FileRotation?` - Optional size-based file rotation policy.
+- `rotation : FileRotation?` - Optional size-based file rotation policy. The default `file_rotation(...)` path uses the standard `Int`-based threshold contract, while advanced native large-file callers can opt into `file_rotation_i64(...)`.
 - `text_formatter : TextFormatterConfig` - Formatter config used for file text rendering.
 
 #### output
diff --git a/docs/api/index.md b/docs/api/index.md
index 165503c..e6c5636 100644
--- a/docs/api/index.md
+++ b/docs/api/index.md
@@ -178,6 +178,7 @@ BitLogger API navigation.
 - [file-sink-type.md](./file-sink-type.md)
 - [native-files-supported.md](./native-files-supported.md)
 - [file-rotation.md](./file-rotation.md)
+- [file-rotation-i64.md](./file-rotation-i64.md)
 - [file-rotation-type.md](./file-rotation-type.md)
 - [file-sink-policy-to-json.md](./file-sink-policy-to-json.md)
 - [file-sink-policy.md](./file-sink-policy.md)
@@ -244,6 +245,7 @@ BitLogger API navigation.
 - [file.md](./file.md)
 - [with-queue.md](./with-queue.md)
 - [with-file-rotation.md](./with-file-rotation.md)
+- [with-file-rotation-i64.md](./with-file-rotation-i64.md)
 
 ## Async logger
 
diff --git a/docs/api/runtime-file-state-to-json.md b/docs/api/runtime-file-state-to-json.md
index 602fde3..e5ee687 100644
--- a/docs/api/runtime-file-state-to-json.md
+++ b/docs/api/runtime-file-state-to-json.md
@@ -37,6 +37,7 @@ Detailed rules explaining key parameters and behaviors
 - `file` is itself exported as a nested file sink state object.
 - This helper is richer than `file_sink_state_to_json(...)` because it also carries queue wrapping context.
 - It is useful for `RuntimeSink::file_runtime_state()`, `ConfiguredLogger::file_runtime_state()`, and similar queued-file diagnostics flows.
+- Any `file_rotation_i64(...)` policy nested under `file` includes both the compatibility `max_bytes` number and `max_bytes_i64` as a string.
 
 ### How to Use
 
@@ -78,3 +79,5 @@ e.g.:
 1. Use this helper when file and queue runtime context should stay together.
 
 2. It is especially useful for queued file runtime paths, whether accessed directly or through configured loggers.
+
+3. For wide native rotation policies nested under `file.rotation`, use `max_bytes_i64` when exact threshold recovery matters.
diff --git a/docs/api/with-file-rotation-i64.md b/docs/api/with-file-rotation-i64.md
new file mode 100644
index 0000000..5203101
--- /dev/null
+++ b/docs/api/with-file-rotation-i64.md
@@ -0,0 +1,78 @@
+---
+name: with-file-rotation-i64
+group: api
+category: config
+update-time: 20260705
+description: Add or replace native-focused Int64 file rotation on an existing file logger config preset.
+key-word:
+    - preset
+    - file
+    - rotation
+    - i64
+---
+
+## With-file-rotation-i64
+
+Add or replace a size-based file rotation policy with an `Int64` byte threshold on an existing `LoggerConfig`. This helper is the additive native-focused counterpart to `with_file_rotation(...)` for large-file rotation thresholds.
+
+### Interface
+
+```moonbit
+pub fn with_file_rotation_i64(
+  config : LoggerConfig,
+  max_bytes : Int64,
+  max_backups~ : Int = 1,
+) -> LoggerConfig {
+```
+
+#### input
+
+- `config : LoggerConfig` - Base logger config to inspect and possibly update.
+- `max_bytes : Int64` - Native-focused wide file size threshold.
+- `max_backups : Int` - Number of rotated backup files to retain.
+
+#### output
+
+- `LoggerConfig` - Updated file config with a wide rotation policy, or the original config unchanged when the sink is not file-based.
+
+### Explanation
+
+- `with_file_rotation_i64(...)` only applies to file presets or other configs whose `sink.kind=SinkKind::File`.
+- If the input config is not file-based, the helper returns the config unchanged.
+- When the input config is file-based, the helper preserves all existing config fields while replacing `sink.rotation` with a wide native-focused policy.
+- Rotation policy creation follows `file_rotation_i64(...)` normalization rules.
+- When the resulting config is exported to JSON, the nested rotation object preserves the exact threshold through `max_bytes_i64` and keeps `max_bytes` as the compatibility view.
+
+### How to Use
+
+#### When Need A Wide Threshold On A File Preset
+
+```moonbit
+let config = with_file_rotation_i64(file("service.log"), 4294967296L, max_backups=3)
+```
+
+In this example, the file preset gains an `Int64` rotation threshold.
+
+#### When Compose Queue And Wide Rotation Together
+
+```moonbit
+let config = with_file_rotation_i64(
+  with_queue(file("service.log"), max_pending=32),
+  3221225472L,
+  max_backups=2,
+)
+```
+
+In this example, queue settings are preserved while a wide native-focused rotation policy is added.
+
+### Error Case
+
+- If the input config is not file-based, no error is raised and the config is returned unchanged.
+- If `max_bytes` is non-positive, normalization behavior follows `file_rotation_i64(...)`.
+
+### Notes
+
+1. This helper is additive and does not replace `with_file_rotation(...)`.
+2. Prefer the default helper unless the file size threshold must exceed the standard `Int` contract.
+3. JSON roundtrip preserves the exact wide threshold through `max_bytes_i64`.
+4. This helper is intended for advanced, native-aware configuration flows.
diff --git a/docs/api/with-file-rotation.md b/docs/api/with-file-rotation.md
index ae446bf..b1e610b 100644
--- a/docs/api/with-file-rotation.md
+++ b/docs/api/with-file-rotation.md
@@ -43,6 +43,8 @@ Detailed rules explaining key parameters and behaviors
 - If the input config is not file-based, the helper returns the config unchanged.
 - When the input config is file-based, the helper preserves `min_level`, `target`, `timestamp`, file path, append mode, auto-flush, formatter, and queue settings while replacing `sink.rotation`.
 - Rotation policy creation follows `file_rotation(...)` normalization rules for `max_bytes` and `max_backups`.
+- The default `max_bytes : Int` path keeps the standard 32-bit `Int` contract for config-built file rotation.
+- If a native-only large-file threshold is required, use `with_file_rotation_i64(...)` rather than overloading the default `Int` path.
 
 ### How to Use
 
@@ -84,3 +86,5 @@ e.g.:
 1. This helper is a no-op for `console(...)`, `json_console(...)`, and `text_console(...)` presets.
 
 2. Use `file(...)` when you need to provide the initial file path, because `with_file_rotation(...)` does not create a file sink from a non-file config.
+
+3. The wider `with_file_rotation_i64(...)` path is additive and native-focused; it does not replace the default config contract.
diff --git a/docs/changes/1.0.1(0.6.1).md b/docs/changes/1.0.1(0.6.1).md
new file mode 100644
index 0000000..3deca94
--- /dev/null
+++ b/docs/changes/1.0.1(0.6.1).md
@@ -0,0 +1,36 @@
+## BitLogger Update Changes
+
+version 1.0.1(0.6.1)
+
+### Runtime
+
+- feat: add an additive `file_rotation_i64(...)` path so native large-file thresholds can exceed the default `Int` contract without replacing the existing API
+- feat: add `with_file_rotation_i64(...)` for file preset and config composition on the same wide-threshold path
+- fix: switch native file-size checks used by rotation decisions to 64-bit file positions so wide thresholds are enforced by the runtime backend
+
+### Config
+
+- feat: allow logger config parsing to prefer `max_bytes_i64` when present and keep `max_bytes` as the compatibility numeric view
+- feat: export wide rotation thresholds through `file_rotation_config_to_json(...)` using `max_bytes_i64` as a string for exact JSON roundtrip
+- feat: propagate the same wide-threshold JSON shape through sink config, file sink policy/state, and runtime file-state helpers
+
+### Docs
+
+- docs: add dedicated API references for `file_rotation_i64(...)` and `with_file_rotation_i64(...)`
+- docs: clarify the default `Int`-based file rotation contract versus the advanced native wide-threshold path across file sink and preset APIs
+- docs: document that JSON export keeps `max_bytes` as the compatibility field and `max_bytes_i64` as the exact roundtrip field
+
+### Test
+
+- test: cover wide-threshold metadata preservation in direct rotation helpers and preset helpers
+- test: cover logger config parse/stringify roundtrip behavior for `max_bytes_i64`
+- test: cover nested wide-threshold JSON export in config, file policy, file state, and runtime file-state helpers
+
+### Verification
+
+- verify: keep the repository passing `moon fmt`, `moon check`, and `moon test` after the wide-threshold rotation update
+
+### Notes
+
+- the default public contract remains the existing `Int`-based file rotation API; the `Int64` route is additive and opt-in
+- wide-threshold JSON transport now uses `max_bytes_i64` as a string to avoid precision loss in JavaScript-shaped consumers
diff --git a/docs/changes/index.md b/docs/changes/index.md
index d2ccabf..572bfe0 100644
--- a/docs/changes/index.md
+++ b/docs/changes/index.md
@@ -2,7 +2,8 @@
 
 Versioned BitLogger change summaries.
 
-- [1.0.0](./1.0.0.md)
+- [1.0.1](./1.0.1(0.6.1).md)
+- [1.0.0](./1.0.0(0.6.0).md)
 - [0.5.3](./0.5.3.md)
 - [0.5.2](./0.5.2.md)
 - [0.5.1](./0.5.1.md)