opencode run exits 1 after auto-compaction recovers from a provider 413 #39573

Description

opencode run exits 1 (and the TUI shows an error toast) when a provider rejects a request for size (HTTP 413 / ContextOverflowError), even though auto-compaction recovers: the session compacts, retries, and produces a complete correct answer. Anything scripting opencode run or tailing --format json sees the run as failed.

Cause: the auto-compact branch in processor.ts halt() publishes Session.Event.Error before attempting recovery:

ctx.needsCompaction = true
yield* events.publish(Session.Event.Error, { sessionID: ctx.sessionID, error })
return

Consumers (cli/cmd/run.ts, tui/app.tsx, app/context/notification.tsx) all treat session.error as the run's outcome. This publish is inconsistent with the rest of the codebase: it doesn't set message.error (the durable message says no error), it isn't followed by idle or a throw, and nothing consumes it — compaction is triggered by the "compact" return value. Retried 429s and the proactive overflow check are both silent.

Steps to reproduce

1. Run a non-interactive prompt against a session large enough that the provider returns 413, with auto-compaction enabled
2. Compaction recovers and the final answer is produced
3. opencode run exits 1; --format json stdout contains an error event

Reproducible with the test-LLM harness: push a 413 (request_too_large), then two text replies; opencode run --format json exits 1 despite emitting the recovered output.

OpenCode version

dev (processor.ts:616)