🔎 fix: Specify Explicit Primary Key for Meilisearch Document Operations

[danny-avila]

Summary

Fixed message search returning empty results on Meilisearch v1.0+ and resolved several pre-existing bugs in the mongoMeili Mongoose plugin discovered during review.

Meilisearch v1.0 tightened primary key inference: when a document contains multiple fields ending with id, it refuses to auto-infer and requires the primary key to be specified explicitly. The messages index contains both conversationId and messageId, causing every addDocuments / addDocumentsInBatches / updateDocuments call to silently fail with index_primary_key_multiple_candidates_found. Documents get marked as _meiliIndex: true in MongoDB but never actually reach Meilisearch, leaving message search empty while conversation search continues working.

• Pass { primaryKey } to index.addDocumentsInBatches() in processSyncBatch (bulk sync path).
• Pass { primaryKey } to index.addDocuments() in addObjectToMeili (per-save hook path).
• Pass { primaryKey } to index.updateDocuments() in updateObjectToMeili (per-update hook path).
• Fix deleteObjectFromMeili using MongoDB _id instead of the Meilisearch primary key (conversationId/messageId), which caused post-remove cleanup to silently no-op and leave orphaned documents in the index.
• Pass options.primaryKey explicitly to the createMeiliMongooseModel factory function instead of deriving it from attributesToIndex[0] (schema field order), eliminating a fragile implicit contract.
• Fix updateObjectToMeili skipping preprocessObjectForIndex(), which meant updates bypassed content array-to-text conversion and conversationId pipe character escaping.
• Change collection.updateMany to collection.updateOne in addObjectToMeili since _id is unique.
• Add primaryKey to validateOptions required keys to fail fast if omitted.
• Strengthen test assertions to verify { primaryKey } argument is passed to addDocuments, addDocumentsInBatches, and updateDocuments. Add tests for the update path including preprocessObjectForIndex pipe escaping.

Closes #12538

Change Type

• Bug fix (non-breaking change which fixes an issue)

Testing

All 43 tests pass in the mongoMeili.spec.ts suite.

To verify the primary fix on a live deployment:

1. Deploy with Meilisearch v1.12+ (e.g., v1.35.1).
2. Clear the Meilisearch messages index (or start with a fresh volume).
3. Reset _meiliIndex flags in MongoDB: db.messages.updateMany({}, { $set: { _meiliIndex: false } }).
4. Restart LibreChat and confirm the sync completes.
5. Check Meilisearch tasks — addDocuments tasks should now succeed instead of failing with index_primary_key_multiple_candidates_found.
6. Verify message search returns results in the UI.

Checklist

• My code adheres to this project's style guidelines
• I have performed a self-review of my own code
• My changes do not introduce new warnings
• I have written tests demonstrating that my changes are effective or that my feature works
• Local unit tests pass with my changes

[Copilot]

Pull request overview

Fixes MeiliSearch message indexing/search on MeiliSearch v1.0+ by explicitly passing the index primaryKey to all document mutation calls in the mongoMeili Mongoose plugin, avoiding primary-key inference failures when multiple *id fields exist (e.g., messageId + conversationId).

Changes:

• Pass { primaryKey } to addDocumentsInBatches in the bulk sync path (processSyncBatch).
• Pass { primaryKey } to addDocuments (post-save hook) and updateDocuments (post-update hook).
• Replace this.collection.updateMany with Model.updateMany(..., { timestamps: false }) to avoid raw driver calls that bypass Mongoose middleware (tenant isolation).

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[Copilot]

Test coverage: the new behavior relies on passing { primaryKey } into Meili document mutation calls. The existing mongoMeili.spec.ts assertions only check that addDocuments*/updateDocuments were called, so this regression could reappear without failing tests. Please extend the spec(s) to assert that addDocumentsInBatches, addDocuments, and updateDocuments are invoked with the expected primaryKey option (e.g., messageId for messages, conversationId for convos).

[danny-avila]

@codex review

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. Hooray!

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