fix: stop agent crashing on Mongo errors during live loop

A Mongo auth/connection failure in getGitStates escaped uncaught and
killed the agent process on the first screen frame, so collision
detection never ran. Make git-state fusion best-effort (degrade to
vision-only) and wrap the whole onScreenFrame loop so no per-frame
Gemini/GitHub/Mongo error can crash the long-running agent.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AaCFWMkYQmTcuPsxaaACft

backend/src/agent/podman.ts

@@ -43,6 +43,9 @@ export class PodMan {
   }
 
   async onScreenFrame(engineerId: string, jpeg: Buffer): Promise<void> {
+    // Whole-frame guard: a Gemini/GitHub/Mongo failure on one frame must degrade
+    // gracefully, never crash the long-running live agent loop.
+    try {
       const ctx = await analyzeFrame(engineerId, this.podId, jpeg);
       this.contexts.set(engineerId, ctx);
       await recordObservation(ctx);
@@ -58,6 +61,9 @@ export class PodMan {
       const github = await getGithubState(); // cached
       const collisions = detectCollisions([...this.contexts.values()], github);
       for (const collision of collisions) await this.handle(collision);
+    } catch (err) {
+      console.warn(`[agent] frame from ${engineerId} skipped: ${(err as Error).message}`);
+    }
   }
 
   private async handle(collision: Collision): Promise<void> {

backend/src/memory/db.ts

@@ -69,8 +69,9 @@ export async function getGitStates(podId: string): Promise<Map<string, GitState>
     recentCommit?: string | null;
     gitUpdatedAt?: Date;
   }>('engineer_states');
-  const docs = await col.find({ podId }).toArray();
   const map = new Map<string, GitState>();
+  try {
+    const docs = await col.find({ podId }).toArray();
     for (const doc of docs) {
       map.set(doc.name, {
         changedFiles: doc.changedFiles ?? [],
@@ -79,6 +80,11 @@ export async function getGitStates(podId: string): Promise<Map<string, GitState>
         gitUpdatedAt: doc.gitUpdatedAt ?? null,
       });
     }
+  } catch (err) {
+    // Best-effort: a Mongo hiccup degrades git fusion, it must not crash the
+    // live agent loop. Detection falls back to vision-only signals.
+    console.warn(`[memory] getGitStates failed: ${(err as Error).message}`);
+  }
   return map;
 }