fix(background-agent): improve task completion detection and concurrency release

- manager.ts: Release concurrency key immediately on task completion, not after retention
- call-omo-agent: Add polling loop for sync agent completion detection
- sisyphus-task: Add abort handling, improve poll logging for debugging

src/tools/call-omo-agent/tools.ts

@@ -191,7 +191,58 @@ async function executeSync(
     return `Error: Failed to send prompt: ${errorMessage}\n\n<task_metadata>\nsession_id: ${sessionID}\n</task_metadata>`
   }
 
-  log(`[call_omo_agent] Prompt sent, fetching messages...`)
+  log(`[call_omo_agent] Prompt sent, polling for completion...`)
+
+  // Poll for session completion
+  const POLL_INTERVAL_MS = 500
+  const MAX_POLL_TIME_MS = 5 * 60 * 1000 // 5 minutes max
+  const pollStart = Date.now()
+  let lastMsgCount = 0
+  let stablePolls = 0
+  const STABILITY_REQUIRED = 3
+
+  while (Date.now() - pollStart < MAX_POLL_TIME_MS) {
+    // Check if aborted
+    if (toolContext.abort?.aborted) {
+      log(`[call_omo_agent] Aborted by user`)
+      return `Task aborted.\n\n<task_metadata>\nsession_id: ${sessionID}\n</task_metadata>`
+    }
+
+    await new Promise(resolve => setTimeout(resolve, POLL_INTERVAL_MS))
+
+    // Check session status
+    const statusResult = await ctx.client.session.status()
+    const allStatuses = (statusResult.data ?? {}) as Record<string, { type: string }>
+    const sessionStatus = allStatuses[sessionID]
+
+    // If session is actively running, reset stability counter
+    if (sessionStatus && sessionStatus.type !== "idle") {
+      stablePolls = 0
+      lastMsgCount = 0
+      continue
+    }
+
+    // Session is idle - check message stability
+    const messagesCheck = await ctx.client.session.messages({ path: { id: sessionID } })
+    const msgs = ((messagesCheck as { data?: unknown }).data ?? messagesCheck) as Array<unknown>
+    const currentMsgCount = msgs.length
+
+    if (currentMsgCount > 0 && currentMsgCount === lastMsgCount) {
+      stablePolls++
+      if (stablePolls >= STABILITY_REQUIRED) {
+        log(`[call_omo_agent] Session complete, ${currentMsgCount} messages`)
+        break
+      }
+    } else {
+      stablePolls = 0
+      lastMsgCount = currentMsgCount
+    }
+  }
+
+  if (Date.now() - pollStart >= MAX_POLL_TIME_MS) {
+    log(`[call_omo_agent] Timeout reached`)
+    return `Error: Agent task timed out after 5 minutes.\n\n<task_metadata>\nsession_id: ${sessionID}\n</task_metadata>`
+  }
 
   const messagesResult = await ctx.client.session.messages({
     path: { id: sessionID },