Messages get stuck in input buffer when "Create a plan?" prompt appears

Bug Description

When sending a long multi-line message to Codex via terminal (pasted or piped from another tool), Codex sometimes detects it as a potential planning task and shows a Create a plan? shift + tab use Plan mode esc dismiss prompt overlay. The message appears in the input buffer but does not get submitted — it just sits there until the user manually presses Escape then Enter.

Steps to Reproduce

1. Send a long, structured prompt to Codex (e.g., via cmux send or terminal paste)
2. The prompt contains instructions that look like a multi-step task
3. Codex displays the "Create a plan?" suggestion overlay
4. The message remains in the input buffer and is never submitted automatically

Expected Behavior

The message should be submitted normally. The "Create a plan?" prompt should either:

• Not trigger on programmatically-sent input (e.g., when text is piped/pasted rather than typed interactively), OR
• Auto-dismiss after a short timeout and submit the message, OR
• Not block submission — show the suggestion without intercepting Enter

Actual Behavior

The message gets stuck in the input buffer. The user (or an orchestrating agent) has to manually press Escape to dismiss the overlay, then Enter to submit. This is especially problematic in multi-agent workflows where Codex receives tasks from an orchestrator — the orchestrator has no way to know the message got stuck.

Environment

• Codex CLI version: latest (gpt-5.5, xhigh fast mode)
• OS: macOS (Darwin 25.5.0)
• Terminal: cmux (terminal multiplexer)
• Input method: cmux send (programmatic text injection, not interactive typing)

Frequency

This happens intermittently — not every long message triggers it, but it occurs often enough to be disruptive in automated workflows. The user reports this is a recurring frustration.

Workaround

Press Escape to dismiss the plan mode prompt, then Enter to submit the message.