Merge pull request #5775 from meilisearch/experimental-search-personnalization

Experimental search personalization

crates/meilisearch-types/src/error.rs

@@ -258,6 +258,7 @@ InvalidIndexUid                                , InvalidRequest       , BAD_REQU
 InvalidMultiSearchFacets                       , InvalidRequest       , BAD_REQUEST ;
 InvalidMultiSearchFacetsByIndex                , InvalidRequest       , BAD_REQUEST ;
 InvalidMultiSearchFacetOrder                   , InvalidRequest       , BAD_REQUEST ;
+InvalidMultiSearchQueryPersonalization         , InvalidRequest       , BAD_REQUEST ;
 InvalidMultiSearchFederated                    , InvalidRequest       , BAD_REQUEST ;
 InvalidMultiSearchFederationOptions            , InvalidRequest       , BAD_REQUEST ;
 InvalidMultiSearchMaxValuesPerFacet            , InvalidRequest       , BAD_REQUEST ;
@@ -315,6 +316,8 @@ InvalidSearchShowRankingScoreDetails           , InvalidRequest       , BAD_REQU
 InvalidSimilarShowRankingScoreDetails          , InvalidRequest       , BAD_REQUEST ;
 InvalidSearchSort                              , InvalidRequest       , BAD_REQUEST ;
 InvalidSearchDistinct                          , InvalidRequest       , BAD_REQUEST ;
+InvalidSearchPersonalize                       , InvalidRequest       , BAD_REQUEST ;
+InvalidSearchPersonalizeUserContext            , InvalidRequest       , BAD_REQUEST ;
 InvalidSearchMediaAndVector                    , InvalidRequest       , BAD_REQUEST ;
 InvalidSettingsDisplayedAttributes             , InvalidRequest       , BAD_REQUEST ;
 InvalidSettingsDistinctAttribute               , InvalidRequest       , BAD_REQUEST ;
@@ -682,6 +685,18 @@ impl fmt::Display for deserr_codes::InvalidNetworkSearchApiKey {
     }
 }
 
+impl fmt::Display for deserr_codes::InvalidSearchPersonalize {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "the value of `personalize` is invalid, expected a JSON object with `userContext` string.")
+    }
+}
+
+impl fmt::Display for deserr_codes::InvalidSearchPersonalizeUserContext {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "the value of `userContext` is invalid, expected a string.")
+    }
+}
+
 #[macro_export]
 macro_rules! internal_error {
     ($target:ty : $($other:path), *) => {

crates/meilisearch/src/analytics/segment_analytics.rs

@@ -208,6 +208,7 @@ struct Infos {
     experimental_no_edition_2024_for_prefix_post_processing: bool,
     experimental_no_edition_2024_for_facet_post_processing: bool,
     experimental_vector_store_setting: bool,
+    experimental_personalization: bool,
     gpu_enabled: bool,
     db_path: bool,
     import_dump: bool,
@@ -286,6 +287,7 @@ impl Infos {
             indexer_options,
             config_file_path,
             no_analytics: _,
+            experimental_personalization_api_key,
             s3_snapshot_options,
         } = options;
 
@@ -374,6 +376,7 @@ impl Infos {
             experimental_no_edition_2024_for_settings,
             experimental_no_edition_2024_for_prefix_post_processing,
             experimental_no_edition_2024_for_facet_post_processing,
+            experimental_personalization: experimental_personalization_api_key.is_some(),
         }
     }
 }

crates/meilisearch/src/error.rs

@@ -38,6 +38,8 @@ pub enum MeilisearchHttpError {
     PaginationInFederatedQuery(usize, &'static str),
     #[error("Inside `.queries[{0}]`: Using facet options is not allowed in federated queries.\n - Hint: remove `facets` from query #{0} or remove `federation` from the request\n - Hint: pass `federation.facetsByIndex.{1}: {2:?}` for facets in federated search")]
     FacetsInFederatedQuery(usize, String, Vec<String>),
+    #[error("Inside `.queries[{0}]`: Using `.personalize` is not allowed in federated queries.\n - Hint: remove `personalize` from query #{0} or remove `federation` from the request")]
+    PersonalizationInFederatedQuery(usize),
     #[error("Inconsistent order for values in facet `{facet}`: index `{previous_uid}` orders {previous_facet_order}, but index `{current_uid}` orders {index_facet_order}.\n - Hint: Remove `federation.mergeFacets` or change `faceting.sortFacetValuesBy` to be consistent in settings.")]
     InconsistentFacetOrder {
         facet: String,
@@ -137,6 +139,9 @@ impl ErrorCode for MeilisearchHttpError {
             MeilisearchHttpError::InconsistentFacetOrder { .. } => {
                 Code::InvalidMultiSearchFacetOrder
             }
+            MeilisearchHttpError::PersonalizationInFederatedQuery(_) => {
+                Code::InvalidMultiSearchQueryPersonalization
+            }
             MeilisearchHttpError::InconsistentOriginHeaders { .. } => {
                 Code::InconsistentDocumentChangeHeaders
             }

crates/meilisearch/src/lib.rs

@@ -11,6 +11,7 @@ pub mod middleware;
 pub mod option;
 #[cfg(test)]
 mod option_test;
+pub mod personalization;
 pub mod routes;
 pub mod search;
 pub mod search_queue;
@@ -58,6 +59,7 @@ use tracing::{error, info_span};
 use tracing_subscriber::filter::Targets;
 
 use crate::error::MeilisearchHttpError;
+use crate::personalization::PersonalizationService;
 
 /// Default number of simultaneously opened indexes.
 ///
@@ -128,12 +130,8 @@ pub type LogStderrType = tracing_subscriber::filter::Filtered<
 >;
 
 pub fn create_app(
-    index_scheduler: Data<IndexScheduler>,
-    auth_controller: Data<AuthController>,
-    search_queue: Data<SearchQueue>,
+    services: ServicesData,
     opt: Opt,
-    logs: (LogRouteHandle, LogStderrHandle),
-    analytics: Data<Analytics>,
     enable_dashboard: bool,
 ) -> actix_web::App<
     impl ServiceFactory<
@@ -145,17 +143,7 @@ pub fn create_app(
     >,
 > {
     let app = actix_web::App::new()
-        .configure(|s| {
-            configure_data(
-                s,
-                index_scheduler.clone(),
-                auth_controller.clone(),
-                search_queue.clone(),
-                &opt,
-                logs,
-                analytics.clone(),
-            )
-        })
+        .configure(|s| configure_data(s, services, &opt))
         .configure(routes::configure)
         .configure(|s| dashboard(s, enable_dashboard));
 
@@ -690,23 +678,26 @@ fn import_dump(
     Ok(index_scheduler_dump.finish()?)
 }
 
-pub fn configure_data(
-    config: &mut web::ServiceConfig,
-    index_scheduler: Data<IndexScheduler>,
-    auth: Data<AuthController>,
-    search_queue: Data<SearchQueue>,
-    opt: &Opt,
-    (logs_route, logs_stderr): (LogRouteHandle, LogStderrHandle),
-    analytics: Data<Analytics>,
-) {
+pub fn configure_data(config: &mut web::ServiceConfig, services: ServicesData, opt: &Opt) {
+    let ServicesData {
+        index_scheduler,
+        auth,
+        search_queue,
+        personalization_service,
+        logs_route_handle,
+        logs_stderr_handle,
+        analytics,
+    } = services;
+
     let http_payload_size_limit = opt.http_payload_size_limit.as_u64() as usize;
     config
         .app_data(index_scheduler)
         .app_data(auth)
         .app_data(search_queue)
         .app_data(analytics)
-        .app_data(web::Data::new(logs_route))
-        .app_data(web::Data::new(logs_stderr))
+        .app_data(personalization_service)
+        .app_data(logs_route_handle)
+        .app_data(logs_stderr_handle)
         .app_data(web::Data::new(opt.clone()))
         .app_data(
             web::JsonConfig::default()
@@ -767,3 +758,14 @@ pub fn dashboard(config: &mut web::ServiceConfig, enable_frontend: bool) {
 pub fn dashboard(config: &mut web::ServiceConfig, _enable_frontend: bool) {
     config.service(web::resource("/").route(web::get().to(routes::running)));
 }
+
+#[derive(Clone)]
+pub struct ServicesData {
+    pub index_scheduler: Data<IndexScheduler>,
+    pub auth: Data<AuthController>,
+    pub search_queue: Data<SearchQueue>,
+    pub personalization_service: Data<PersonalizationService>,
+    pub logs_route_handle: Data<LogRouteHandle>,
+    pub logs_stderr_handle: Data<LogStderrHandle>,
+    pub analytics: Data<Analytics>,
+}

crates/meilisearch/src/main.rs

@@ -14,10 +14,11 @@ use index_scheduler::IndexScheduler;
 use is_terminal::IsTerminal;
 use meilisearch::analytics::Analytics;
 use meilisearch::option::LogMode;
+use meilisearch::personalization::PersonalizationService;
 use meilisearch::search_queue::SearchQueue;
 use meilisearch::{
     analytics, create_app, setup_meilisearch, LogRouteHandle, LogRouteType, LogStderrHandle,
-    LogStderrType, Opt, SubscriberForSecondLayer,
+    LogStderrType, Opt, ServicesData, SubscriberForSecondLayer,
 };
 use meilisearch_auth::{generate_master_key, AuthController, MASTER_KEY_MIN_SIZE};
 use termcolor::{Color, ColorChoice, ColorSpec, StandardStream, WriteColor};
@@ -152,8 +153,15 @@ async fn run_http(
     let enable_dashboard = &opt.env == "development";
     let opt_clone = opt.clone();
     let index_scheduler = Data::from(index_scheduler);
-    let auth_controller = Data::from(auth_controller);
+    let auth = Data::from(auth_controller);
     let analytics = Data::from(analytics);
+    // Create personalization service with API key from options
+    let personalization_service = Data::new(
+        opt.experimental_personalization_api_key
+            .clone()
+            .map(PersonalizationService::cohere)
+            .unwrap_or_else(PersonalizationService::disabled),
+    );
     let search_queue = SearchQueue::new(
         opt.experimental_search_queue_size,
         available_parallelism()
@@ -165,21 +173,25 @@ async fn run_http(
         usize::from(opt.experimental_drop_search_after) as u64
     ));
     let search_queue = Data::new(search_queue);
+    let (logs_route_handle, logs_stderr_handle) = logs;
+    let logs_route_handle = Data::new(logs_route_handle);
+    let logs_stderr_handle = Data::new(logs_stderr_handle);
 
-    let http_server = HttpServer::new(move || {
-        create_app(
-            index_scheduler.clone(),
-            auth_controller.clone(),
-            search_queue.clone(),
-            opt.clone(),
-            logs.clone(),
-            analytics.clone(),
-            enable_dashboard,
-        )
-    })
-    // Disable signals allows the server to terminate immediately when a user enter CTRL-C
-    .disable_signals()
-    .keep_alive(KeepAlive::Os);
+    let services = ServicesData {
+        index_scheduler,
+        auth,
+        search_queue,
+        personalization_service,
+        logs_route_handle,
+        logs_stderr_handle,
+        analytics,
+    };
+
+    let http_server =
+        HttpServer::new(move || create_app(services.clone(), opt.clone(), enable_dashboard))
+            // Disable signals allows the server to terminate immediately when a user enter CTRL-C
+            .disable_signals()
+            .keep_alive(KeepAlive::Os);
 
     if let Some(config) = opt_clone.get_ssl_config()? {
         http_server.bind_rustls_0_23(opt_clone.http_addr, config)?.run().await?;

crates/meilisearch/src/metrics.rs

@@ -114,4 +114,9 @@ lazy_static! {
             "Meilisearch Task Queue Size Until Stop Registering",
         ))
         .expect("Can't create a metric");
+    pub static ref MEILISEARCH_PERSONALIZED_SEARCH_REQUESTS: IntGauge = register_int_gauge!(opts!(
+        "meilisearch_personalized_search_requests",
+        "Meilisearch number of search requests with personalization"
+    ))
+    .expect("Can't create a metric");
 }

crates/meilisearch/src/option.rs

@@ -75,6 +75,8 @@ const MEILI_EXPERIMENTAL_EMBEDDING_CACHE_ENTRIES: &str =
 const MEILI_EXPERIMENTAL_NO_SNAPSHOT_COMPACTION: &str = "MEILI_EXPERIMENTAL_NO_SNAPSHOT_COMPACTION";
 const MEILI_EXPERIMENTAL_NO_EDITION_2024_FOR_DUMPS: &str =
     "MEILI_EXPERIMENTAL_NO_EDITION_2024_FOR_DUMPS";
+const MEILI_EXPERIMENTAL_PERSONALIZATION_API_KEY: &str =
+    "MEILI_EXPERIMENTAL_PERSONALIZATION_API_KEY";
 
 // Related to S3 snapshots
 const MEILI_S3_BUCKET_URL: &str = "MEILI_S3_BUCKET_URL";
@@ -494,6 +496,12 @@ pub struct Opt {
     #[serde(default)]
     pub experimental_no_snapshot_compaction: bool,
 
+    /// Experimental personalization API key feature.
+    ///
+    /// Sets the API key for personalization features.
+    #[clap(long, env = MEILI_EXPERIMENTAL_PERSONALIZATION_API_KEY)]
+    pub experimental_personalization_api_key: Option<String>,
+
     #[serde(flatten)]
     #[clap(flatten)]
     pub indexer_options: IndexerOpts,
@@ -603,6 +611,7 @@ impl Opt {
             experimental_limit_batched_tasks_total_size,
             experimental_embedding_cache_entries,
             experimental_no_snapshot_compaction,
+            experimental_personalization_api_key,
             s3_snapshot_options,
         } = self;
         export_to_env_if_not_present(MEILI_DB_PATH, db_path);
@@ -704,6 +713,12 @@ impl Opt {
             MEILI_EXPERIMENTAL_NO_SNAPSHOT_COMPACTION,
             experimental_no_snapshot_compaction.to_string(),
         );
+        if let Some(experimental_personalization_api_key) = experimental_personalization_api_key {
+            export_to_env_if_not_present(
+                MEILI_EXPERIMENTAL_PERSONALIZATION_API_KEY,
+                experimental_personalization_api_key,
+            );
+        }
         indexer_options.export_to_env();
         if let Some(s3_snapshot_options) = s3_snapshot_options {
             #[cfg(not(unix))]

crates/meilisearch/src/personalization/mod.rs

@@ -0,0 +1,366 @@
+use crate::search::{Personalize, SearchResult};
+use meilisearch_types::{
+    error::{Code, ErrorCode, ResponseError},
+    milli::TimeBudget,
+};
+use rand::Rng;
+use reqwest::Client;
+use serde::{Deserialize, Serialize};
+use std::time::Duration;
+use tracing::{debug, info, warn};
+
+const COHERE_API_URL: &str = "https://api.cohere.ai/v1/rerank";
+const MAX_RETRIES: u32 = 10;
+
+#[derive(Debug, thiserror::Error)]
+enum PersonalizationError {
+    #[error("Personalization service: HTTP request failed: {0}")]
+    Request(#[from] reqwest::Error),
+    #[error("Personalization service: Failed to parse response: {0}")]
+    Parse(String),
+    #[error("Personalization service: Cohere API error: {0}")]
+    Api(String),
+    #[error("Personalization service: Unauthorized: invalid API key")]
+    Unauthorized,
+    #[error("Personalization service: Rate limited: too many requests")]
+    RateLimited,
+    #[error("Personalization service: Bad request: {0}")]
+    BadRequest(String),
+    #[error("Personalization service: Internal server error: {0}")]
+    InternalServerError(String),
+    #[error("Personalization service: Network error: {0}")]
+    Network(String),
+    #[error("Personalization service: Deadline exceeded")]
+    DeadlineExceeded,
+    #[error(transparent)]
+    FeatureNotEnabled(#[from] index_scheduler::error::FeatureNotEnabledError),
+}
+
+impl ErrorCode for PersonalizationError {
+    fn error_code(&self) -> Code {
+        match self {
+            PersonalizationError::FeatureNotEnabled { .. } => Code::FeatureNotEnabled,
+            PersonalizationError::Unauthorized => Code::RemoteInvalidApiKey,
+            PersonalizationError::RateLimited => Code::TooManySearchRequests,
+            PersonalizationError::BadRequest(_) => Code::RemoteBadRequest,
+            PersonalizationError::InternalServerError(_) => Code::RemoteRemoteError,
+            PersonalizationError::Network(_) | PersonalizationError::Request(_) => {
+                Code::RemoteCouldNotSendRequest
+            }
+            PersonalizationError::Parse(_) | PersonalizationError::Api(_) => {
+                Code::RemoteBadResponse
+            }
+            PersonalizationError::DeadlineExceeded => Code::Internal, // should not be returned to the client
+        }
+    }
+}
+
+pub struct CohereService {
+    client: Client,
+    api_key: String,
+}
+
+impl CohereService {
+    pub fn new(api_key: String) -> Self {
+        info!("Personalization service initialized with Cohere API");
+        let client = Client::builder()
+            .timeout(Duration::from_secs(30))
+            .build()
+            .expect("Failed to create HTTP client");
+        Self { client, api_key }
+    }
+
+    pub async fn rerank_search_results(
+        &self,
+        search_result: SearchResult,
+        personalize: &Personalize,
+        query: Option<&str>,
+        time_budget: TimeBudget,
+    ) -> Result<SearchResult, ResponseError> {
+        if time_budget.exceeded() {
+            warn!("Could not rerank due to deadline");
+            // If the deadline is exceeded, return the original search result instead of an error
+            return Ok(search_result);
+        }
+
+        // Extract user context from personalization
+        let user_context = personalize.user_context.as_str();
+
+        // Build the prompt by merging query and user context
+        let prompt = match query {
+            Some(q) => format!("User Context: {user_context}\nQuery: {q}"),
+            None => format!("User Context: {user_context}"),
+        };
+
+        // Extract documents for reranking
+        let documents: Vec<String> = search_result
+            .hits
+            .iter()
+            .map(|hit| {
+                // Convert the document to a string representation for reranking
+                serde_json::to_string(&hit.document).unwrap_or_else(|_| "{}".to_string())
+            })
+            .collect();
+
+        if documents.is_empty() {
+            return Ok(search_result);
+        }
+
+        // Call Cohere's rerank API with retry logic
+        let reranked_indices =
+            match self.call_rerank_with_retry(&prompt, &documents, time_budget).await {
+                Ok(indices) => indices,
+                Err(PersonalizationError::DeadlineExceeded) => {
+                    // If the deadline is exceeded, return the original search result instead of an error
+                    return Ok(search_result);
+                }
+                Err(e) => return Err(e.into()),
+            };
+
+        debug!("Cohere rerank successful, reordering {} results", search_result.hits.len());
+
+        // Reorder the hits based on Cohere's reranking
+        let mut reranked_hits = Vec::new();
+        for index in reranked_indices.iter() {
+            if let Some(hit) = search_result.hits.get(*index) {
+                reranked_hits.push(hit.clone());
+            }
+        }
+
+        Ok(SearchResult { hits: reranked_hits, ..search_result })
+    }
+
+    async fn call_rerank_with_retry(
+        &self,
+        query: &str,
+        documents: &[String],
+        time_budget: TimeBudget,
+    ) -> Result<Vec<usize>, PersonalizationError> {
+        let request_body = CohereRerankRequest {
+            query: query.to_string(),
+            documents: documents.to_vec(),
+            model: "rerank-english-v3.0".to_string(),
+        };
+
+        // Retry loop similar to vector extraction
+        for attempt in 0..MAX_RETRIES {
+            let response_result = self.send_rerank_request(&request_body).await;
+
+            let retry_duration = match self.handle_response(response_result).await {
+                Ok(indices) => return Ok(indices),
+                Err(retry) => {
+                    warn!("Cohere rerank attempt #{} failed: {}", attempt, retry.error);
+
+                    if time_budget.exceeded() {
+                        warn!("Could not rerank due to deadline");
+                        return Err(PersonalizationError::DeadlineExceeded);
+                    } else {
+                        match retry.into_duration(attempt) {
+                            Ok(d) => d,
+                            Err(error) => return Err(error),
+                        }
+                    }
+                }
+            };
+
+            // randomly up to double the retry duration
+            let retry_duration = retry_duration
+                + rand::thread_rng().gen_range(std::time::Duration::ZERO..retry_duration);
+
+            warn!("Retrying after {}ms", retry_duration.as_millis());
+            tokio::time::sleep(retry_duration).await;
+        }
+
+        // Final attempt without retry
+        let response_result = self.send_rerank_request(&request_body).await;
+
+        match self.handle_response(response_result).await {
+            Ok(indices) => Ok(indices),
+            Err(retry) => Err(retry.into_error()),
+        }
+    }
+
+    async fn send_rerank_request(
+        &self,
+        request_body: &CohereRerankRequest,
+    ) -> Result<reqwest::Response, reqwest::Error> {
+        self.client
+            .post(COHERE_API_URL)
+            .header("Authorization", format!("Bearer {}", self.api_key))
+            .header("Content-Type", "application/json")
+            .json(request_body)
+            .send()
+            .await
+    }
+
+    async fn handle_response(
+        &self,
+        response_result: Result<reqwest::Response, reqwest::Error>,
+    ) -> Result<Vec<usize>, Retry> {
+        let response = match response_result {
+            Ok(r) => r,
+            Err(e) if e.is_timeout() => {
+                return Err(Retry::retry_later(PersonalizationError::Network(format!(
+                    "Request timeout: {}",
+                    e
+                ))));
+            }
+            Err(e) => {
+                return Err(Retry::retry_later(PersonalizationError::Network(format!(
+                    "Network error: {}",
+                    e
+                ))));
+            }
+        };
+
+        let status = response.status();
+        let status_code = status.as_u16();
+
+        if status.is_success() {
+            let rerank_response: CohereRerankResponse = match response.json().await {
+                Ok(r) => r,
+                Err(e) => {
+                    return Err(Retry::retry_later(PersonalizationError::Parse(format!(
+                        "Failed to parse response: {}",
+                        e
+                    ))));
+                }
+            };
+
+            // Extract indices from rerank results
+            let indices: Vec<usize> =
+                rerank_response.results.iter().map(|result| result.index as usize).collect();
+
+            return Ok(indices);
+        }
+
+        // Handle error status codes
+        let error_body = response.text().await.unwrap_or_else(|_| "Unknown error".to_string());
+
+        let retry = match status_code {
+            401 => Retry::give_up(PersonalizationError::Unauthorized),
+            429 => Retry::rate_limited(PersonalizationError::RateLimited),
+            400 => Retry::give_up(PersonalizationError::BadRequest(error_body)),
+            500..=599 => Retry::retry_later(PersonalizationError::InternalServerError(format!(
+                "Status {}: {}",
+                status_code, error_body
+            ))),
+            402..=499 => Retry::give_up(PersonalizationError::Api(format!(
+                "Status {}: {}",
+                status_code, error_body
+            ))),
+            _ => Retry::retry_later(PersonalizationError::Api(format!(
+                "Unexpected status {}: {}",
+                status_code, error_body
+            ))),
+        };
+
+        Err(retry)
+    }
+}
+
+#[derive(Serialize)]
+struct CohereRerankRequest {
+    query: String,
+    documents: Vec<String>,
+    model: String,
+}
+
+#[derive(Deserialize)]
+struct CohereRerankResponse {
+    results: Vec<CohereRerankResult>,
+}
+
+#[derive(Deserialize)]
+struct CohereRerankResult {
+    index: u32,
+}
+
+// Retry strategy similar to vector extraction
+struct Retry {
+    error: PersonalizationError,
+    strategy: RetryStrategy,
+}
+
+enum RetryStrategy {
+    GiveUp,
+    Retry,
+    RetryAfterRateLimit,
+}
+
+impl Retry {
+    fn give_up(error: PersonalizationError) -> Self {
+        Self { error, strategy: RetryStrategy::GiveUp }
+    }
+
+    fn retry_later(error: PersonalizationError) -> Self {
+        Self { error, strategy: RetryStrategy::Retry }
+    }
+
+    fn rate_limited(error: PersonalizationError) -> Self {
+        Self { error, strategy: RetryStrategy::RetryAfterRateLimit }
+    }
+
+    fn into_duration(self, attempt: u32) -> Result<Duration, PersonalizationError> {
+        match self.strategy {
+            RetryStrategy::GiveUp => Err(self.error),
+            RetryStrategy::Retry => {
+                // Exponential backoff: 10^attempt milliseconds
+                Ok(Duration::from_millis((10u64).pow(attempt)))
+            }
+            RetryStrategy::RetryAfterRateLimit => {
+                // Longer backoff for rate limits: 100ms + exponential
+                Ok(Duration::from_millis(100 + (10u64).pow(attempt)))
+            }
+        }
+    }
+
+    fn into_error(self) -> PersonalizationError {
+        self.error
+    }
+}
+
+pub enum PersonalizationService {
+    Cohere(CohereService),
+    Disabled,
+}
+
+impl PersonalizationService {
+    pub fn cohere(api_key: String) -> Self {
+        // If the API key is empty, consider the personalization service as disabled
+        if api_key.trim().is_empty() {
+            Self::disabled()
+        } else {
+            Self::Cohere(CohereService::new(api_key))
+        }
+    }
+
+    pub fn disabled() -> Self {
+        debug!("Personalization service disabled");
+        Self::Disabled
+    }
+
+    pub async fn rerank_search_results(
+        &self,
+        search_result: SearchResult,
+        personalize: &Personalize,
+        query: Option<&str>,
+        time_budget: TimeBudget,
+    ) -> Result<SearchResult, ResponseError> {
+        match self {
+            Self::Cohere(cohere_service) => {
+                cohere_service
+                    .rerank_search_results(search_result, personalize, query, time_budget)
+                    .await
+            }
+            Self::Disabled => Err(PersonalizationError::FeatureNotEnabled(
+                index_scheduler::error::FeatureNotEnabledError {
+                    disabled_action: "reranking search results",
+                    feature: "personalization",
+                    issue_link: "https://github.com/orgs/meilisearch/discussions/866",
+                },
+            )
+            .into()),
+        }
+    }
+}

crates/meilisearch/src/routes/indexes/facet_search.rs

@@ -343,6 +343,7 @@ impl From<FacetSearchQuery> for SearchQuery {
             hybrid,
             ranking_score_threshold,
             locales,
+            personalize: None,
         }
     }
 }

crates/meilisearch/src/routes/indexes/search.rs

@@ -24,9 +24,9 @@ use crate::metrics::MEILISEARCH_DEGRADED_SEARCH_REQUESTS;
 use crate::routes::indexes::search_analytics::{SearchAggregator, SearchGET, SearchPOST};
 use crate::routes::parse_include_metadata_header;
 use crate::search::{
-    add_search_rules, perform_search, HybridQuery, MatchingStrategy, RankingScoreThreshold,
-    RetrieveVectors, SearchKind, SearchParams, SearchQuery, SearchResult, SemanticRatio,
-    DEFAULT_CROP_LENGTH, DEFAULT_CROP_MARKER, DEFAULT_HIGHLIGHT_POST_TAG,
+    add_search_rules, perform_search, HybridQuery, MatchingStrategy, Personalize,
+    RankingScoreThreshold, RetrieveVectors, SearchKind, SearchParams, SearchQuery, SearchResult,
+    SemanticRatio, DEFAULT_CROP_LENGTH, DEFAULT_CROP_MARKER, DEFAULT_HIGHLIGHT_POST_TAG,
     DEFAULT_HIGHLIGHT_PRE_TAG, DEFAULT_SEARCH_LIMIT, DEFAULT_SEARCH_OFFSET, DEFAULT_SEMANTIC_RATIO,
 };
 use crate::search_queue::SearchQueue;
@@ -134,6 +134,8 @@ pub struct SearchQueryGet {
     #[deserr(default, error = DeserrQueryParamError<InvalidSearchLocales>)]
     #[param(value_type = Vec<Locale>, explode = false)]
     pub locales: Option<CS<Locale>>,
+    #[deserr(default, error = DeserrQueryParamError<InvalidSearchPersonalizeUserContext>)]
+    pub personalize_user_context: Option<String>,
 }
 
 #[derive(Debug, Clone, Copy, PartialEq, deserr::Deserr)]
@@ -205,6 +207,9 @@ impl TryFrom<SearchQueryGet> for SearchQuery {
             ));
         }
 
+        let personalize =
+            other.personalize_user_context.map(|user_context| Personalize { user_context });
+
         Ok(Self {
             q: other.q,
             // `media` not supported for `GET`
@@ -234,6 +239,7 @@ impl TryFrom<SearchQueryGet> for SearchQuery {
             hybrid,
             ranking_score_threshold: other.ranking_score_threshold.map(|o| o.0),
             locales: other.locales.map(|o| o.into_iter().collect()),
+            personalize,
         })
     }
 }
@@ -322,6 +328,7 @@ pub fn fix_sort_query_parameters(sort_query: &str) -> Vec<String> {
 pub async fn search_with_url_query(
     index_scheduler: GuardedData<ActionPolicy<{ actions::SEARCH }>, Data<IndexScheduler>>,
     search_queue: web::Data<SearchQueue>,
+    personalization_service: web::Data<crate::personalization::PersonalizationService>,
     index_uid: web::Path<String>,
     params: AwebQueryParameter<SearchQueryGet, DeserrQueryParamError>,
     req: HttpRequest,
@@ -342,9 +349,16 @@ pub async fn search_with_url_query(
 
     let index = index_scheduler.index(&index_uid)?;
 
+    // Extract personalization and query string before moving query
+    let personalize = query.personalize.take();
+
     let search_kind =
         search_kind(&query, index_scheduler.get_ref(), index_uid.to_string(), &index)?;
     let retrieve_vector = RetrieveVectors::new(query.retrieve_vectors);
+
+    // Save the query string for personalization if requested
+    let personalize_query = personalize.is_some().then(|| query.q.clone()).flatten();
+
     let permit = search_queue.try_get_search_permit().await?;
     let include_metadata = parse_include_metadata_header(&req);
 
@@ -365,12 +379,24 @@ pub async fn search_with_url_query(
     .await;
     permit.drop().await;
     let search_result = search_result?;
-    if let Ok(ref search_result) = search_result {
+    if let Ok((search_result, _)) = search_result.as_ref() {
         aggregate.succeed(search_result);
     }
     analytics.publish(aggregate, &req);
 
-    let search_result = search_result?;
+    let (mut search_result, time_budget) = search_result?;
+
+    // Apply personalization if requested
+    if let Some(personalize) = personalize.as_ref() {
+        search_result = personalization_service
+            .rerank_search_results(
+                search_result,
+                personalize,
+                personalize_query.as_deref(),
+                time_budget,
+            )
+            .await?;
+    }
 
     debug!(request_uid = ?request_uid, returns = ?search_result, "Search get");
     Ok(HttpResponse::Ok().json(search_result))
@@ -435,6 +461,7 @@ pub async fn search_with_url_query(
 pub async fn search_with_post(
     index_scheduler: GuardedData<ActionPolicy<{ actions::SEARCH }>, Data<IndexScheduler>>,
     search_queue: web::Data<SearchQueue>,
+    personalization_service: web::Data<crate::personalization::PersonalizationService>,
     index_uid: web::Path<String>,
     params: AwebJson<SearchQuery, DeserrJsonError>,
     req: HttpRequest,
@@ -455,12 +482,18 @@ pub async fn search_with_post(
 
     let index = index_scheduler.index(&index_uid)?;
 
+    // Extract personalization and query string before moving query
+    let personalize = query.personalize.take();
+
     let search_kind =
         search_kind(&query, index_scheduler.get_ref(), index_uid.to_string(), &index)?;
     let retrieve_vectors = RetrieveVectors::new(query.retrieve_vectors);
 
     let include_metadata = parse_include_metadata_header(&req);
 
+    // Save the query string for personalization if requested
+    let personalize_query = personalize.is_some().then(|| query.q.clone()).flatten();
+
     let permit = search_queue.try_get_search_permit().await?;
     let search_result = tokio::task::spawn_blocking(move || {
         perform_search(
@@ -479,7 +512,7 @@ pub async fn search_with_post(
     .await;
     permit.drop().await;
     let search_result = search_result?;
-    if let Ok(ref search_result) = search_result {
+    if let Ok((ref search_result, _)) = search_result {
         aggregate.succeed(search_result);
         if search_result.degraded {
             MEILISEARCH_DEGRADED_SEARCH_REQUESTS.inc();
@@ -487,7 +520,19 @@ pub async fn search_with_post(
     }
     analytics.publish(aggregate, &req);
 
-    let search_result = search_result?;
+    let (mut search_result, time_budget) = search_result?;
+
+    // Apply personalization if requested
+    if let Some(personalize) = personalize.as_ref() {
+        search_result = personalization_service
+            .rerank_search_results(
+                search_result,
+                personalize,
+                personalize_query.as_deref(),
+                time_budget,
+            )
+            .await?;
+    }
 
     debug!(request_uid = ?request_uid, returns = ?search_result, "Search post");
     Ok(HttpResponse::Ok().json(search_result))

crates/meilisearch/src/routes/indexes/search_analytics.rs

@@ -7,6 +7,7 @@ use serde_json::{json, Value};
 
 use crate::aggregate_methods;
 use crate::analytics::{Aggregate, AggregateMethod};
+use crate::metrics::MEILISEARCH_PERSONALIZED_SEARCH_REQUESTS;
 use crate::search::{
     SearchQuery, SearchResult, DEFAULT_CROP_LENGTH, DEFAULT_CROP_MARKER,
     DEFAULT_HIGHLIGHT_POST_TAG, DEFAULT_HIGHLIGHT_PRE_TAG, DEFAULT_SEARCH_LIMIT,
@@ -95,6 +96,9 @@ pub struct SearchAggregator<Method: AggregateMethod> {
     show_ranking_score_details: bool,
     ranking_score_threshold: bool,
 
+    // personalization
+    total_personalized: usize,
+
     marker: std::marker::PhantomData<Method>,
 }
 
@@ -129,6 +133,7 @@ impl<Method: AggregateMethod> SearchAggregator<Method> {
             hybrid,
             ranking_score_threshold,
             locales,
+            personalize,
         } = query;
 
         let mut ret = Self::default();
@@ -204,6 +209,12 @@ impl<Method: AggregateMethod> SearchAggregator<Method> {
             ret.locales = locales.iter().copied().collect();
         }
 
+        // personalization
+        if personalize.is_some() {
+            ret.total_personalized = 1;
+            MEILISEARCH_PERSONALIZED_SEARCH_REQUESTS.inc();
+        }
+
         ret.highlight_pre_tag = *highlight_pre_tag != DEFAULT_HIGHLIGHT_PRE_TAG();
         ret.highlight_post_tag = *highlight_post_tag != DEFAULT_HIGHLIGHT_POST_TAG();
         ret.crop_marker = *crop_marker != DEFAULT_CROP_MARKER();
@@ -296,6 +307,7 @@ impl<Method: AggregateMethod> Aggregate for SearchAggregator<Method> {
             total_used_negative_operator,
             ranking_score_threshold,
             mut locales,
+            total_personalized,
             marker: _,
         } = *new;
 
@@ -381,6 +393,9 @@ impl<Method: AggregateMethod> Aggregate for SearchAggregator<Method> {
         // locales
         self.locales.append(&mut locales);
 
+        // personalization
+        self.total_personalized = self.total_personalized.saturating_add(total_personalized);
+
         self
     }
 
@@ -426,6 +441,7 @@ impl<Method: AggregateMethod> Aggregate for SearchAggregator<Method> {
             total_used_negative_operator,
             ranking_score_threshold,
             locales,
+            total_personalized,
             marker: _,
         } = *self;
 
@@ -499,6 +515,9 @@ impl<Method: AggregateMethod> Aggregate for SearchAggregator<Method> {
                 "show_ranking_score_details": show_ranking_score_details,
                 "ranking_score_threshold": ranking_score_threshold,
             },
+            "personalization": {
+                "total_personalized": total_personalized,
+            },
         })
     }
 }

crates/meilisearch/src/routes/multi_search.rs

@@ -146,6 +146,7 @@ pub struct SearchResults {
 pub async fn multi_search_with_post(
     index_scheduler: GuardedData<ActionPolicy<{ actions::SEARCH }>, Data<IndexScheduler>>,
     search_queue: Data<SearchQueue>,
+    personalization_service: web::Data<crate::personalization::PersonalizationService>,
     params: AwebJson<FederatedSearch, DeserrJsonError>,
     req: HttpRequest,
     analytics: web::Data<Analytics>,
@@ -236,7 +237,7 @@ pub async fn multi_search_with_post(
             // changes.
             let search_results: Result<_, (ResponseError, usize)> = async {
                 let mut search_results = Vec::with_capacity(queries.len());
-                for (query_index, (index_uid, query, federation_options)) in queries
+                for (query_index, (index_uid, mut query, federation_options)) in queries
                     .into_iter()
                     .map(SearchQueryWithIndex::into_index_query_federation)
                     .enumerate()
@@ -269,6 +270,13 @@ pub async fn multi_search_with_post(
                         })
                         .with_index(query_index)?;
 
+                    // Extract personalization and query string before moving query
+                    let personalize = query.personalize.take();
+
+                    // Save the query string for personalization if requested
+                    let personalize_query =
+                        personalize.is_some().then(|| query.q.clone()).flatten();
+
                     let index_uid_str = index_uid.to_string();
 
                     let search_kind = search_kind(
@@ -280,7 +288,7 @@ pub async fn multi_search_with_post(
                     .with_index(query_index)?;
                     let retrieve_vector = RetrieveVectors::new(query.retrieve_vectors);
 
-                    let search_result = tokio::task::spawn_blocking(move || {
+                    let (mut search_result, time_budget) = tokio::task::spawn_blocking(move || {
                         perform_search(
                             SearchParams {
                                 index_uid: index_uid_str.clone(),
@@ -295,11 +303,25 @@ pub async fn multi_search_with_post(
                         )
                     })
                     .await
+                    .with_index(query_index)?
                     .with_index(query_index)?;
 
+                    // Apply personalization if requested
+                    if let Some(personalize) = personalize.as_ref() {
+                        search_result = personalization_service
+                            .rerank_search_results(
+                                search_result,
+                                personalize,
+                                personalize_query.as_deref(),
+                                time_budget,
+                            )
+                            .await
+                            .with_index(query_index)?;
+                    }
+
                     search_results.push(SearchResultWithIndex {
                         index_uid: index_uid.into_inner(),
-                        result: search_result.with_index(query_index)?,
+                        result: search_result,
                     });
                 }
                 Ok(search_results)

crates/meilisearch/src/routes/multi_search_analytics.rs

@@ -67,6 +67,7 @@ impl MultiSearchAggregator {
             hybrid: _,
             ranking_score_threshold: _,
             locales: _,
+            personalize: _,
         } in &federated_search.queries
         {
             if let Some(federation_options) = federation_options {

crates/meilisearch/src/search/federated/perform.rs

@@ -601,6 +601,10 @@ impl PartitionedQueries {
             .into());
         }
 
+        if federated_query.has_personalize() {
+            return Err(MeilisearchHttpError::PersonalizationInFederatedQuery(query_index).into());
+        }
+
         let (index_uid, query, federation_options) = federated_query.into_index_query_federation();
 
         let federation_options = federation_options.unwrap_or_default();

crates/meilisearch/src/search/mod.rs

@@ -59,6 +59,13 @@ pub const DEFAULT_HIGHLIGHT_POST_TAG: fn() -> String = || "</em>".to_string();
 pub const DEFAULT_SEMANTIC_RATIO: fn() -> SemanticRatio = || SemanticRatio(0.5);
 pub const INCLUDE_METADATA_HEADER: &str = "Meili-Include-Metadata";
 
+#[derive(Clone, Default, PartialEq, Deserr, ToSchema, Debug)]
+#[deserr(error = DeserrJsonError<InvalidSearchPersonalize>, rename_all = camelCase, deny_unknown_fields)]
+pub struct Personalize {
+    #[deserr(error = DeserrJsonError<InvalidSearchPersonalizeUserContext>)]
+    pub user_context: String,
+}
+
 #[derive(Clone, Default, PartialEq, Deserr, ToSchema)]
 #[deserr(error = DeserrJsonError, rename_all = camelCase, deny_unknown_fields)]
 pub struct SearchQuery {
@@ -122,6 +129,8 @@ pub struct SearchQuery {
     pub ranking_score_threshold: Option<RankingScoreThreshold>,
     #[deserr(default, error = DeserrJsonError<InvalidSearchLocales>)]
     pub locales: Option<Vec<Locale>>,
+    #[deserr(default, error = DeserrJsonError<InvalidSearchPersonalize>, default)]
+    pub personalize: Option<Personalize>,
 }
 
 impl From<SearchParameters> for SearchQuery {
@@ -169,6 +178,7 @@ impl From<SearchParameters> for SearchQuery {
             highlight_post_tag: DEFAULT_HIGHLIGHT_POST_TAG(),
             crop_marker: DEFAULT_CROP_MARKER(),
             locales: None,
+            personalize: None,
         }
     }
 }
@@ -250,6 +260,7 @@ impl fmt::Debug for SearchQuery {
             attributes_to_search_on,
             ranking_score_threshold,
             locales,
+            personalize,
         } = self;
 
         let mut debug = f.debug_struct("SearchQuery");
@@ -338,6 +349,10 @@ impl fmt::Debug for SearchQuery {
             debug.field("locales", &locales);
         }
 
+        if let Some(personalize) = personalize {
+            debug.field("personalize", &personalize);
+        }
+
         debug.finish()
     }
 }
@@ -543,6 +558,9 @@ pub struct SearchQueryWithIndex {
     pub ranking_score_threshold: Option<RankingScoreThreshold>,
     #[deserr(default, error = DeserrJsonError<InvalidSearchLocales>, default)]
     pub locales: Option<Vec<Locale>>,
+    #[deserr(default, error = DeserrJsonError<InvalidSearchPersonalize>, default)]
+    #[serde(skip)]
+    pub personalize: Option<Personalize>,
 
     #[deserr(default)]
     pub federation_options: Option<FederationOptions>,
@@ -567,6 +585,10 @@ impl SearchQueryWithIndex {
         self.facets.as_deref().filter(|v| !v.is_empty())
     }
 
+    pub fn has_personalize(&self) -> bool {
+        self.personalize.is_some()
+    }
+
     pub fn from_index_query_federation(
         index_uid: IndexUid,
         query: SearchQuery,
@@ -600,6 +622,7 @@ impl SearchQueryWithIndex {
             attributes_to_search_on,
             ranking_score_threshold,
             locales,
+            personalize,
         } = query;
 
         SearchQueryWithIndex {
@@ -631,6 +654,7 @@ impl SearchQueryWithIndex {
             attributes_to_search_on,
             ranking_score_threshold,
             locales,
+            personalize,
             federation_options,
         }
     }
@@ -666,6 +690,7 @@ impl SearchQueryWithIndex {
             hybrid,
             ranking_score_threshold,
             locales,
+            personalize,
         } = self;
         (
             index_uid,
@@ -697,6 +722,7 @@ impl SearchQueryWithIndex {
                 hybrid,
                 ranking_score_threshold,
                 locales,
+                personalize,
                 // do not use ..Default::default() here,
                 // rather add any missing field from `SearchQuery` to `SearchQueryWithIndex`
             },
@@ -1149,7 +1175,10 @@ pub struct SearchParams {
     pub include_metadata: bool,
 }
 
-pub fn perform_search(params: SearchParams, index: &Index) -> Result<SearchResult, ResponseError> {
+pub fn perform_search(
+    params: SearchParams,
+    index: &Index,
+) -> Result<(SearchResult, TimeBudget), ResponseError> {
     let SearchParams {
         index_uid,
         query,
@@ -1168,7 +1197,7 @@ pub fn perform_search(params: SearchParams, index: &Index) -> Result<SearchResul
     };
 
     let (search, is_finite_pagination, max_total_hits, offset) =
-        prepare_search(index, &rtxn, &query, &search_kind, time_budget, features)?;
+        prepare_search(index, &rtxn, &query, &search_kind, time_budget.clone(), features)?;
 
     let (
         milli::SearchResult {
@@ -1226,6 +1255,7 @@ pub fn perform_search(params: SearchParams, index: &Index) -> Result<SearchResul
         attributes_to_search_on: _,
         filter: _,
         distinct: _,
+        personalize: _,
     } = query;
 
     let format = AttributesFormat {
@@ -1291,7 +1321,7 @@ pub fn perform_search(params: SearchParams, index: &Index) -> Result<SearchResul
         request_uid: Some(request_uid),
         metadata,
     };
-    Ok(result)
+    Ok((result, time_budget))
 }
 
 #[derive(Debug, Clone, Default, Serialize, Deserialize, ToSchema)]

crates/meilisearch/tests/common/service.rs

@@ -10,8 +10,9 @@ use actix_web::test::TestRequest;
 use actix_web::web::Data;
 use index_scheduler::IndexScheduler;
 use meilisearch::analytics::Analytics;
+use meilisearch::personalization::PersonalizationService;
 use meilisearch::search_queue::SearchQueue;
-use meilisearch::{create_app, Opt, SubscriberForSecondLayer};
+use meilisearch::{create_app, Opt, ServicesData, SubscriberForSecondLayer};
 use meilisearch_auth::AuthController;
 use tracing::level_filters::LevelFilter;
 use tracing_subscriber::Layer;
@@ -135,14 +136,24 @@ impl Service {
             self.options.experimental_search_queue_size,
             NonZeroUsize::new(1).unwrap(),
         );
+        let personalization_service = self
+            .options
+            .experimental_personalization_api_key
+            .clone()
+            .map(PersonalizationService::cohere)
+            .unwrap_or_else(PersonalizationService::disabled);
 
         actix_web::test::init_service(create_app(
-            self.index_scheduler.clone().into(),
-            self.auth.clone().into(),
-            Data::new(search_queue),
+            ServicesData {
+                index_scheduler: self.index_scheduler.clone().into(),
+                auth: self.auth.clone().into(),
+                search_queue: Data::new(search_queue),
+                personalization_service: Data::new(personalization_service),
+                logs_route_handle: Data::new(route_layer_handle),
+                logs_stderr_handle: Data::new(stderr_layer_handle),
+                analytics: Data::new(Analytics::no_analytics()),
+            },
             self.options.clone(),
-            (route_layer_handle, stderr_layer_handle),
-            Data::new(Analytics::no_analytics()),
             true,
         ))
         .await

crates/meilisearch/tests/features/mod.rs

@@ -207,3 +207,118 @@ async fn errors() {
     }
     "###);
 }
+
+#[actix_rt::test]
+async fn search_with_personalization_without_enabling_the_feature() {
+    let server = Server::new().await;
+    let index = server.unique_index();
+
+    // Create the index and add some documents
+    let (task, _code) = index.create(None).await;
+    server.wait_task(task.uid()).await.succeeded();
+
+    let (task, _code) = index
+        .add_documents(
+            json!([
+                {"id": 1, "title": "The Dark Knight", "genre": "Action"},
+                {"id": 2, "title": "Inception", "genre": "Sci-Fi"},
+                {"id": 3, "title": "The Matrix", "genre": "Sci-Fi"}
+            ]),
+            None,
+        )
+        .await;
+    server.wait_task(task.uid()).await.succeeded();
+
+    // Try to search with personalization - should return feature_not_enabled error
+    let (response, code) = index
+        .search_post(json!({
+            "q": "movie",
+            "personalize": {
+                "userContext": "I love science fiction movies"
+            }
+        }))
+        .await;
+
+    meili_snap::snapshot!(code, @"400 Bad Request");
+    meili_snap::snapshot!(meili_snap::json_string!(response), @r###"
+    {
+      "message": "reranking search results requires enabling the `personalization` experimental feature. See https://github.com/orgs/meilisearch/discussions/866",
+      "code": "feature_not_enabled",
+      "type": "invalid_request",
+      "link": "https://docs.meilisearch.com/errors#feature_not_enabled"
+    }
+    "###);
+}
+
+#[actix_rt::test]
+async fn multi_search_with_personalization_without_enabling_the_feature() {
+    let server = Server::new().await;
+    let index = server.unique_index();
+
+    // Create the index and add some documents
+    let (task, _code) = index.create(None).await;
+    server.wait_task(task.uid()).await.succeeded();
+
+    let (task, _code) = index
+        .add_documents(
+            json!([
+                {"id": 1, "title": "The Dark Knight", "genre": "Action"},
+                {"id": 2, "title": "Inception", "genre": "Sci-Fi"},
+                {"id": 3, "title": "The Matrix", "genre": "Sci-Fi"}
+            ]),
+            None,
+        )
+        .await;
+    server.wait_task(task.uid()).await.succeeded();
+
+    // Try to multi-search with personalization - should return feature_not_enabled error
+    let (response, code) = server
+        .multi_search(json!({
+            "queries": [
+                {
+                    "indexUid": index.uid,
+                    "q": "movie",
+                    "personalize": {
+                        "userContext": "I love science fiction movies"
+                    }
+                }
+            ]
+        }))
+        .await;
+
+    meili_snap::snapshot!(code, @"400 Bad Request");
+    meili_snap::snapshot!(meili_snap::json_string!(response), @r###"
+    {
+      "message": "Inside `.queries[0]`: reranking search results requires enabling the `personalization` experimental feature. See https://github.com/orgs/meilisearch/discussions/866",
+      "code": "feature_not_enabled",
+      "type": "invalid_request",
+      "link": "https://docs.meilisearch.com/errors#feature_not_enabled"
+    }
+    "###);
+
+    // Try to federated search with personalization - should return feature_not_enabled error
+    let (response, code) = server
+        .multi_search(json!({
+          "federation": {},
+            "queries": [
+                {
+                    "indexUid": index.uid,
+                    "q": "movie",
+                    "personalize": {
+                        "userContext": "I love science fiction movies"
+                    }
+                }
+            ]
+        }))
+        .await;
+
+    meili_snap::snapshot!(code, @"400 Bad Request");
+    meili_snap::snapshot!(meili_snap::json_string!(response), @r###"
+    {
+      "message": "Inside `.queries[0]`: Using `.personalize` is not allowed in federated queries.\n - Hint: remove `personalize` from query #0 or remove `federation` from the request",
+      "code": "invalid_multi_search_query_personalization",
+      "type": "invalid_request",
+      "link": "https://docs.meilisearch.com/errors#invalid_multi_search_query_personalization"
+    }
+    "###);
+}

crates/meilisearch/tests/logs/mod.rs

@@ -8,8 +8,9 @@ use actix_web::http::header::ContentType;
 use actix_web::web::Data;
 use meili_snap::snapshot;
 use meilisearch::analytics::Analytics;
+use meilisearch::personalization::PersonalizationService;
 use meilisearch::search_queue::SearchQueue;
-use meilisearch::{create_app, Opt, SubscriberForSecondLayer};
+use meilisearch::{create_app, Opt, ServicesData, SubscriberForSecondLayer};
 use tracing::level_filters::LevelFilter;
 use tracing_subscriber::layer::SubscriberExt;
 use tracing_subscriber::Layer;
@@ -50,12 +51,16 @@ async fn basic_test_log_stream_route() {
     );
 
     let app = actix_web::test::init_service(create_app(
-        server.service.index_scheduler.clone().into(),
-        server.service.auth.clone().into(),
-        Data::new(search_queue),
+        ServicesData {
+            index_scheduler: server.service.index_scheduler.clone().into(),
+            auth: server.service.auth.clone().into(),
+            search_queue: Data::new(search_queue),
+            personalization_service: Data::new(PersonalizationService::disabled()),
+            logs_route_handle: Data::new(route_layer_handle),
+            logs_stderr_handle: Data::new(stderr_layer_handle),
+            analytics: Data::new(Analytics::no_analytics()),
+        },
         server.service.options.clone(),
-        (route_layer_handle, stderr_layer_handle),
-        Data::new(Analytics::no_analytics()),
         true,
     ))
     .await;

crates/meilisearch/tests/search/errors.rs

@@ -1,7 +1,11 @@
 use meili_snap::*;
+use meilisearch::Opt;
+use tempfile::TempDir;
 
 use super::test_settings_documents_indexing_swapping_and_search;
-use crate::common::{shared_does_not_exists_index, Server, DOCUMENTS, NESTED_DOCUMENTS};
+use crate::common::{
+    default_settings, shared_does_not_exists_index, Server, DOCUMENTS, NESTED_DOCUMENTS,
+};
 use crate::json;
 
 #[actix_rt::test]
@@ -1320,3 +1324,98 @@ async fn search_with_contains_without_enabling_the_feature() {
     }
     "#);
 }
+
+#[actix_rt::test]
+#[ignore]
+async fn search_with_personalization_invalid_api_key() {
+    // Create a server with a fake personalization API key
+    let dir = TempDir::new().unwrap();
+    let options = Opt {
+        experimental_personalization_api_key: Some("fake-api-key-12345".to_string()),
+        ..default_settings(dir.path())
+    };
+    let server = Server::new_with_options(options).await.unwrap();
+    let index = server.unique_index();
+
+    // Create the index and add some documents
+    let (task, _code) = index.create(None).await;
+    server.wait_task(task.uid()).await.succeeded();
+
+    let (task, _code) = index
+        .add_documents(
+            json!([
+                {"id": 1, "title": "The Dark Knight", "genre": "Action"},
+                {"id": 2, "title": "Inception", "genre": "Sci-Fi"},
+                {"id": 3, "title": "The Matrix", "genre": "Sci-Fi"}
+            ]),
+            None,
+        )
+        .await;
+    server.wait_task(task.uid()).await.succeeded();
+
+    // Try to search with personalization - should return remote_invalid_api_key error
+    let (response, code) = index
+        .search_post(json!({
+            "q": "the",
+            "personalize": {
+                "userContext": "I love science fiction movies"
+            }
+        }))
+        .await;
+
+    snapshot!(code, @"403 Forbidden");
+    snapshot!(json_string!(response), @r#"
+    {
+      "message": "Personalization service: Unauthorized: invalid API key",
+      "code": "remote_invalid_api_key",
+      "type": "auth",
+      "link": "https://docs.meilisearch.com/errors#remote_invalid_api_key"
+    }
+    "#);
+}
+
+#[actix_rt::test]
+async fn search_with_personalization_no_user_context() {
+    // Create a server with a fake personalization API key
+    let dir = TempDir::new().unwrap();
+    let options = Opt {
+        experimental_personalization_api_key: Some("fake-api-key-12345".to_string()),
+        ..default_settings(dir.path())
+    };
+    let server = Server::new_with_options(options).await.unwrap();
+    let index = server.unique_index();
+
+    // Create the index and add some documents
+    let (task, _code) = index.create(None).await;
+    server.wait_task(task.uid()).await.succeeded();
+
+    let (task, _code) = index
+        .add_documents(
+            json!([
+                {"id": 1, "title": "The Dark Knight", "genre": "Action"},
+                {"id": 2, "title": "Inception", "genre": "Sci-Fi"},
+                {"id": 3, "title": "The Matrix", "genre": "Sci-Fi"}
+            ]),
+            None,
+        )
+        .await;
+    server.wait_task(task.uid()).await.succeeded();
+
+    // Try to search with personalization - should return remote_invalid_api_key error
+    let (response, code) = index
+        .search_post(json!({
+            "q": "the",
+            "personalize": {}
+        }))
+        .await;
+
+    snapshot!(code, @"400 Bad Request");
+    snapshot!(json_string!(response), @r###"
+    {
+      "message": "Missing field `userContext` inside `.personalize`",
+      "code": "invalid_search_personalize",
+      "type": "invalid_request",
+      "link": "https://docs.meilisearch.com/errors#invalid_search_personalize"
+    }
+    "###);
+}