fix(codex): surface thread system errors

[Liu-KM]

Summary

• convert Codex app-server thread/status/changed systemError notifications into terminal task failures
• allow explicitly thread-scoped terminal failures to complete the active turn even when they do not carry a turn id
• show the failure as a visible HAPI session message and avoid resurrecting a stale turn id after the terminal event races with startTurn()

Why

Codex app-server can report thread-level systemError without a turn id. Previously HAPI ignored/filtered that terminal signal while a turn was in flight, leaving the UI looking disconnected instead of surfacing the failure and returning to ready.

Test plan

• cd cli && bun run vitest run src/codex/codexRemoteLauncher.test.ts src/codex/utils/appServerEventConverter.test.ts src/codex/utils/terminalEventGuard.test.ts
• cd cli && bun run typecheck

[github-actions]

Findings

• [Major] Thread remains reusable after a thread-scoped systemError — the new thread/status/changed mapping only emits task_failed, but the launcher keeps hasThread/currentThreadId and will reuse that same thread on the next turn (cli/src/codex/utils/appServerEventConverter.ts:269, cli/src/codex/codexRemoteLauncher.ts:629, cli/src/codex/codexRemoteLauncher.ts:687). See inline comment for a minimal fix.

Summary
Review mode: initial

• 1 Major issue found in the Codex thread-system-error recovery path.

Testing

• Not run (automation; review instruction forbids executing PR code)

HAPI Bot

[github-actions]

[MAJOR] thread/status/changed is a thread-scoped failure, but this new path only converts it into task_failed. The launcher never clears currentThreadId or hasThread, so the next queued message will still call turn/start on the same thread that already entered systemError (cli/src/codex/codexRemoteLauncher.ts:629, cli/src/codex/codexRemoteLauncher.ts:687). That leaves the session stuck on a broken thread instead of recovering on the next turn.

Suggested fix:

const isThreadStatusFailure = msgType === 'task_failed' && msg.terminal_source === 'thread_status';

if (isTerminalEvent) {
    this.currentTurnId = null;
    allowAnonymousTerminalEvent = false;
    if (isThreadStatusFailure) {
        this.currentThreadId = null;
        hasThread = false;
    }
}

[github-actions]

Findings

• No actionable issues found in the updated diff.

Summary
Review mode: follow-up after new commits

• No actionable issues found on the latest head.
• Residual risk: added coverage is unit-level only; not found in repo/docs: integration coverage against a real app-server thread/status/changed sequence.

Testing

• Not run (automation)

HAPI Bot