fix: prevent chroma-mcp process leaks on worker restart

Critical bugfix: ChromaSync now properly cleans up chroma-mcp subprocesses
when the worker is restarted, preventing memory exhaustion from orphaned
processes accumulating over time.

Changes:
- Store reference to StdioClientTransport subprocess
- Explicitly close transport in close() method to kill subprocess
- Add error handling to ensure cleanup even on failures
- Reset all state in finally block

Problem:
Each worker restart spawned a new chroma-mcp process but never killed the
old one. After multiple restarts, orphaned processes accumulated (16+ seen
in production), consuming 900MB+ RAM and eventually causing OOM kills that
silently failed backfills.

Impact:
- Eliminates process accumulation
- Prevents memory exhaustion from leaked subprocesses
- Fixes silent backfill failures caused by OOM kills
- Ensures graceful cleanup on worker shutdown

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

src/services/sync/ChromaSync.ts

@@ -73,6 +73,7 @@ interface StoredUserPrompt {
 
 export class ChromaSync {
   private client: Client | null = null;
+  private transport: StdioClientTransport | null = null;
   private connected: boolean = false;
   private project: string;
   private collectionName: string;
@@ -101,7 +102,7 @@ export class ChromaSync {
       // See: https://github.com/thedotmack/claude-mem/issues/170 (Python 3.14 incompatibility)
       const settings = SettingsDefaultsManager.loadFromFile(USER_SETTINGS_PATH);
       const pythonVersion = settings.CLAUDE_MEM_PYTHON_VERSION;
-      const transport = new StdioClientTransport({
+      this.transport = new StdioClientTransport({
         command: 'uvx',
         args: [
           '--python', pythonVersion,
@@ -119,7 +120,7 @@ export class ChromaSync {
         capabilities: {}
       });
 
-      await this.client.connect(transport);
+      await this.client.connect(this.transport);
       this.connected = true;
 
       logger.info('CHROMA_SYNC', 'Connected to Chroma MCP server', { project: this.project });
@@ -815,14 +816,38 @@ export class ChromaSync {
   }
 
   /**
-   * Close the Chroma client connection
+   * Close the Chroma client connection and cleanup subprocess
    */
   async close(): Promise<void> {
-    if (this.client && this.connected) {
-      await this.client.close();
+    if (!this.connected && !this.client && !this.transport) {
+      return;
+    }
+
+    try {
+      // Close client first
+      if (this.client) {
+        try {
+          await this.client.close();
+        } catch (error) {
+          logger.warn('CHROMA_SYNC', 'Error closing Chroma client', { project: this.project }, error as Error);
+        }
+      }
+
+      // Explicitly close transport to kill subprocess
+      if (this.transport) {
+        try {
+          await this.transport.close();
+        } catch (error) {
+          logger.warn('CHROMA_SYNC', 'Error closing transport', { project: this.project }, error as Error);
+        }
+      }
+
+      logger.info('CHROMA_SYNC', 'Chroma client and subprocess closed', { project: this.project });
+    } finally {
+      // Always reset state, even if errors occurred
       this.connected = false;
       this.client = null;
-      logger.info('CHROMA_SYNC', 'Chroma client closed', { project: this.project });
+      this.transport = null;
     }
   }
 }