Memory leak fixes

src/ai/conversation.ts

@@ -1,4 +1,4 @@
-import { getSaver } from "#chaincraft/ai/memory/checkpoint-memory.js";
+import { listThreadIds } from "#chaincraft/ai/memory/checkpoint-memory.js";
 
 // Map of conversation IDs by graph type
 const conversationIds = new Map<string, Set<string>>();
@@ -30,16 +30,7 @@ async function bootstrapConversationIds(graphType: string): Promise<void> {
         return;
     }
 
-    const saver = await getSaver('list-conversations', graphType);
-    const ids = new Set<string>();
-
-    for await (const checkpoint of saver.list({}, {})) {
-        const threadId = checkpoint.config?.configurable?.thread_id;
-        if (threadId) {
-            ids.add(threadId);
-        }
-    }
-
-    conversationIds.set(graphType, ids);
+    const threadIds = await listThreadIds(graphType);
+    conversationIds.set(graphType, new Set(threadIds));
     bootstrappedTypes.add(graphType);
 }

src/ai/design/design-workflow.ts

@@ -262,6 +262,8 @@ export async function getDesignByVersion(
   conversationId: string,
   version: number
 ): Promise<(DesignState | undefined)> {
+  // TODO - Consider paginating through checkpoints if we expect many versions, 
+  // to avoid excessive memory usage. 
   // Check if conversation exists
   if (!(await isActiveConversation(conversationId))) {
     throw new Error(`Conversation ${conversationId} not found`);

src/ai/memory/checkpoint-memory.ts

@@ -147,6 +147,40 @@ export async function getSaver(
   }
 }
 
+/**
+ * List all thread IDs for a given graph type.
+ * Uses efficient direct SQL query for PostgreSQL, falls back to checkpoint list for SQLite.
+ */
+export async function listThreadIds(graphType: string): Promise<string[]> {
+  await initialize();
+
+  const db = await getOrCreateDatabase(graphType);
+  const ids = new Set<string>();
+
+  if (db.backend === "postgres" && db.sharedSaver) {
+    // For PostgreSQL: query distinct thread_ids directly (much more efficient than loading checkpoints)
+    const postgresaver = db.sharedSaver as PostgresSaver;
+    const pool = (postgresaver as any).pool as Pool;
+    const result = await pool.query(
+      'SELECT DISTINCT thread_id FROM checkpoints ORDER BY thread_id'
+    );
+    for (const row of result.rows) {
+      ids.add(row.thread_id);
+    }
+  } else {
+    // For SQLite: use limited checkpoint list
+    const saver = await getSaver('list-threads', graphType);
+    for await (const checkpoint of saver.list({}, { limit: 100 })) {
+      const threadId = checkpoint.config?.configurable?.thread_id;
+      if (threadId) {
+        ids.add(threadId);
+      }
+    }
+  }
+
+  return Array.from(ids).sort();
+}
+
 export async function deleteThread(
   threadId: string,
   graphType: string