v0.9.14: unanswered user-input prompts stick in pending_user_inputs forever when their turn dies without the terminal settle

[Hmbown]

Why this matters

pending_user_inputs is the engine→user question surface that runtime clients render (the GPUI app turns it into a question sheet and hides the pet). An entry whose turn dies through a path that skips settle_user_inputs_for_terminal_turn never settles: it renders forever, and repeated prompts accumulate — the user sees "stuck pending inputs" they cannot clear except by answering a question the turn is no longer waiting for.

Current behavior

• crates/tui/src/runtime_threads.rs:11684 — EngineEvent::UserInputRequired registers the entry.
• Settlement paths: user answers (submit_user_input route) or settle_user_inputs_for_terminal_turn at runtime_threads.rs:6510, :8705, :12004.
• Turns that end through interrupt/cancel/failure paths which skip those three call sites leak their entries. The map is in-memory, so a leaked entry also survives until process restart.

Repro (live)

This session (GPUI client): plugin-install prompts fired by the overactive matcher (#6274) parked as pending user inputs; after the underlying turns ended the prompts remained rendered and further inputs kept arriving. Session record: ~/.codewhale/sessions/6453856f-10b5-4a9b-947c-dcac902071d3.json.

Desired behavior

1. Every turn-death path (complete, interrupt, cancel, failure) settles that turn's pending user inputs with user_input.canceled events — no path may leave an entry.
2. claim_pending_user_inputs_for_turn bailing on indeterminate entries should stay loud, but indeterminate entries must also be resolvable, not permanent.

Acceptance criteria

• Regression test: a turn with an outstanding user-input request that ends via the interrupt path emits user_input.canceled and leaves pending_user_inputs empty for that thread
• No call path from EngineEvent::TurnComplete/interrupt handling to a terminal state can skip the settle (assertion or exhaustive audit note in the PR)
• Focused cargo test -p codewhale-tui --lib --locked green for runtime_threads/runtime_api tests

Related

• v0.9.14: plugin suggestion matcher nags every turn on topic keywords — gate to once-per-session and skip domains a loaded skill covers #6274 (upstream source of the prompts in the live repro)
• Engine silently freezes mid-run: user messages are persisted but never answered; no error, no log line, no crash entry #6184 (adjacent persisted-but-unanswered shape)