autopilot_fleet plan approval may not activate fleet mode immediately (race condition)

[Arithmomaniac]

Describe the bug

When selecting "Accept plan and build on autopilot + /fleet" (autopilot_fleet) from the plan approval menu, fleet mode may not activate immediately. In my case, the agent continued working interactively for ~50 minutes, and fleet mode only activated after the interactive loop fully completed.

It appears the exit_plan_mode tool result tells the LLM "parallel subagent execution has started," but the /fleet message gets queued behind the already-running agentic loop and isn't processed until the loop finishes. Since this appears to be a race condition, it may not reproduce every time.

Affected version

0.0.422

Steps to reproduce the behavior

1. Start a session with /plan on a task with parallelizable work
2. Agent creates a plan and calls exit_plan_mode with autopilot_fleet as the recommended action
3. Select "Accept plan and build on autopilot + /fleet"
4. Confirm autopilot permissions when prompted
5. Observe: In my case, the agent immediately started working interactively (reading files, making edits) instead of entering fleet mode and dispatching sub-agents
6. Fleet mode only activated ~50 minutes later, after the interactive agentic loop fully completed

Expected behavior

After selecting autopilot_fleet, the session should immediately enter fleet mode and the agent should begin dispatching parallel sub-agents via the task tool. The fleet mode prompt ("You are now in fleet mode. Dispatch sub-agents...") should be injected before the next model turn, not queued behind it.

Additional context

• OS: Windows 11 (x64)
• Terminal: Windows Terminal
• Shell: PowerShell 7
• Model: claude-opus-4.6-1m
• Session ID: 24873767-9ee6-4297-8678-5866320fb3ab

Evidence from ~/.copilot/logs/:

Timestamp (UTC)	Event
14:47:57	Model calls exit_plan_mode with autopilot_fleet
14:55:55	User approves plan -> tool returns "parallel subagent execution has started"
14:56:07	Model responds by reading files interactively (not fleet mode)
15:09-15:41	Sub-agents dispatched manually hit cascading API timeouts
15:46:05	Fleet mode finally activates (~50 min after approval)

The events.jsonl shows the exit_plan_mode tool with selected_action: "autopilot_fleet" immediately followed by regular view tool calls, confirming the agent was not in fleet mode.

The fleet mode statement first appears in the log at 15:46:05 -- a new configured settings group starts at that point, indicating a fresh non-interactive session was created for fleet mode only after the interactive loop drained. This suggests a race condition where the fleet start message is queued behind the already-processing agentic loop.