fix: add content-hash dedup to batch observation store methods (#1302)

storeObservations() and storeObservationsAndMarkComplete() were missing
the content-hash deduplication that storeObservation() (singular) already
had via computeObservationContentHash() and findDuplicateObservation().

This caused the Gemini provider (and potentially others that return
multiple observations per response) to insert 2-10x duplicate rows per
tool use, since the batch methods inserted unconditionally without
checking content_hash.

The fix adds the same dedup pattern from storeObservation() to both
batch methods:
1. Compute content hash via computeObservationContentHash()
2. Check for existing observation within 30s window via findDuplicateObservation()
3. Skip insert and reuse existing ID if duplicate found
4. Include content_hash column in INSERT statement

Fixes #1158 (duplicate observations with Gemini provider)

Co-authored-by: Enzo Ricciulli <e.ricciulli@systhema.ai>

src/services/sqlite/SessionStore.ts

@@ -1659,15 +1659,23 @@ export class SessionStore {
     const storeTx = this.db.transaction(() => {
       const observationIds: number[] = [];
 
-      // 1. Store all observations
+      // 1. Store all observations (with content-hash deduplication)
       const obsStmt = this.db.prepare(`
         INSERT INTO observations
         (memory_session_id, project, type, title, subtitle, facts, narrative, concepts,
-         files_read, files_modified, prompt_number, discovery_tokens, created_at, created_at_epoch)
-        VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
+         files_read, files_modified, prompt_number, discovery_tokens, content_hash, created_at, created_at_epoch)
+        VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
       `);
 
       for (const observation of observations) {
+        // Content-hash deduplication (same logic as storeObservation singular)
+        const contentHash = computeObservationContentHash(memorySessionId, observation.title, observation.narrative);
+        const existing = findDuplicateObservation(this.db, contentHash, timestampEpoch);
+        if (existing) {
+          observationIds.push(existing.id);
+          continue;
+        }
+
         const result = obsStmt.run(
           memorySessionId,
           project,
@@ -1681,6 +1689,7 @@ export class SessionStore {
           JSON.stringify(observation.files_modified),
           promptNumber || null,
           discoveryTokens,
+          contentHash,
           timestampIso,
           timestampEpoch
         );
@@ -1779,15 +1788,23 @@ export class SessionStore {
     const storeAndMarkTx = this.db.transaction(() => {
       const observationIds: number[] = [];
 
-      // 1. Store all observations
+      // 1. Store all observations (with content-hash deduplication)
       const obsStmt = this.db.prepare(`
         INSERT INTO observations
         (memory_session_id, project, type, title, subtitle, facts, narrative, concepts,
-         files_read, files_modified, prompt_number, discovery_tokens, created_at, created_at_epoch)
-        VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
+         files_read, files_modified, prompt_number, discovery_tokens, content_hash, created_at, created_at_epoch)
+        VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
       `);
 
       for (const observation of observations) {
+        // Content-hash deduplication (same logic as storeObservation singular)
+        const contentHash = computeObservationContentHash(memorySessionId, observation.title, observation.narrative);
+        const existing = findDuplicateObservation(this.db, contentHash, timestampEpoch);
+        if (existing) {
+          observationIds.push(existing.id);
+          continue;
+        }
+
         const result = obsStmt.run(
           memorySessionId,
           project,
@@ -1801,6 +1818,7 @@ export class SessionStore {
           JSON.stringify(observation.files_modified),
           promptNumber || null,
           discoveryTokens,
+          contentHash,
           timestampIso,
           timestampEpoch
         );