Agent-started thread stuck in Plan mode on Android while Runtime says Full access #61

Observed

On 2026-10-30/31 the thread "Discussion: OpenUI for fast agent-generated artifacts" was created by an agent through MCP (thread id mcp:…). It stayed in Plan mode, so the agent refused to run the experiment the owner had approved, twice. The Android Runtime screen showed Full access, which made the agent look like it was lying ("it literally says full access"). /plan off did not exit. The workaround found in mobile code is to type /default and pick "Switch to default mode".

Screenshot is kept locally, not published.

Upstream (exists, join, don't duplicate)

• Upstream 29250: a Plan-mode thread started by an agent shows no Implement button or mode control when plan mode is off in settings. Same bug.
• 27819: MCP thread launch can start threads in Plan mode when "Plan mode (legacy)" is off. The cause.
• 27646: an ACP agent that leaves plan mode can't go back.
• Open upstream fixes: PRs 29267 and 29275. Verify on Android when one merges.

Acceptance

• Android shows the interaction mode next to the runtime mode, with a way out (an Implement button or mode control) for any thread in Plan.
• Add a +1 with this repro to the upstream issues through the gate.
• Skill t3-mode-state-recovery stays the documented workaround until upstream fixes it.