v2: fix agent-runner lifecycle and session DB reliability

- Use DELETE journal mode for session DBs instead of WAL. WAL doesn't
  sync reliably across Docker volume mounts (VirtioFS), causing dropped
  writes and duplicate deliveries.
- Add 20s idle detection to end the query stream. The concurrent poll
  tracks SDK activity via a new 'activity' provider event. When no SDK
  events arrive for 20s and no messages are pending, the stream ends
  and the poll loop continues.
- Add touchProcessing heartbeat so the host can distinguish active
  agents from idle ones by checking status_changed recency.
- Catch query errors in the poll loop and write error responses to
  messages_out instead of crashing the process.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

container/agent-runner/src/providers/claude.ts

@@ -200,6 +200,9 @@ export class ClaudeProvider implements AgentProvider {
         if (aborted) return;
         messageCount++;
 
+        // Yield activity for every SDK event so the poll loop knows the agent is working
+        yield { type: 'activity' };
+
         if (message.type === 'system' && message.subtype === 'init') {
           yield { type: 'init', sessionId: message.session_id };
         } else if (message.type === 'result') {
@@ -213,7 +216,6 @@ export class ClaudeProvider implements AgentProvider {
           const tn = message as { summary?: string };
           yield { type: 'progress', message: tn.summary || 'Task notification' };
         }
-        // All other message types are logged but not emitted
       }
       log(`Query completed after ${messageCount} SDK messages`);
     }

container/agent-runner/src/providers/mock.ts

@@ -20,9 +20,11 @@ export class MockProvider implements AgentProvider {
 
     const events: AsyncIterable<ProviderEvent> = {
       async *[Symbol.asyncIterator]() {
+        yield { type: 'activity' };
         yield { type: 'init', sessionId: `mock-session-${Date.now()}` };
 
         // Process initial prompt
+        yield { type: 'activity' };
         yield { type: 'result', text: responseFactory(input.prompt) };
 
         // Process any pushed follow-ups

container/agent-runner/src/providers/types.ts

@@ -53,4 +53,5 @@ export type ProviderEvent =
   | { type: 'init'; sessionId: string }
   | { type: 'result'; text: string | null }
   | { type: 'error'; message: string; retryable: boolean; classification?: string }
-  | { type: 'progress'; message: string };
+  | { type: 'progress'; message: string }
+  | { type: 'activity' };