Interrupts, restart interrupts, and steers now carry the same two-minute
per-call deadline as starts, so the twelve-minute worker backstop is only
a backstop. That backstop now covers provider-turn control effects only;
runtime-request.respond keeps its previous behavior.

A start that outlives its deadline releases the provider session before
the run is marked failed, so a turn the provider accepted without
answering cannot keep editing the workspace. A steer that timed out is not
retried, since providers do not deduplicate steering input. A restart
whose retries are exhausted fails its still-starting replacement run.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>