session.error events are ignored by global sync (stuck busy, no error shown)

[CannonRS]

Description

A failed session turn is not reflected in the UI's session state and produces no visible error.

When the server emits a session.error event, the global sync reducer ignores it. The session stays in its last non-idle status (busy) and the failed assistant message keeps no error marker, so the user is not told that the turn failed.

Plugins

n/a

OpenCode version

latest dev

Steps to reproduce

1. Trigger a session that fails with an error event.
2. The session status stays busy and no error toast appears; the last assistant message does not get an error marker.

Screenshot and/or share link

n/a

Operating System

n/a (all)

Terminal

n/a

[github-actions]

This issue might be a duplicate of existing issues. Please check:

• Session run defects are silently dropped — UI shows no error, session just goes idle #42259: Session run defects are silently dropped — UI shows no error, session just goes idle — describes the same root cause: session.error events not being properly surfaced to the UI, leaving the session appearing to succeed or staying in an incorrect state.
• bug: UI stuck on 'thinking' indefinitely after stream error, no error displayed or state recovery #32366: UI stuck on 'thinking' indefinitely after stream error, no error displayed or state recovery — similar symptom of the session/UI getting stuck with no error shown after a failure.

[CannonRS]

Not a duplicate of #42259 or #32366; both are related but describe different layers.

#42259 is a server-side event-ordering problem: \session.error\ is published after \session.status idle, so UI consumers that stop processing on idle never render the error. Its fix (PR #42253) reorders the SSE stream and does not touch the client-side global sync reducer.

#32366 is a desktop 'stuck on thinking' case after a dropped stream (no state recovery, no retry), a different symptom and environment.

This issue (#48530) is the client-side counterpart: when a \session.error\ event reaches the store, the global sync reducer (\�pplyDirectoryEvent) ignores it — the session status stays busy, the last assistant message gets no error marker, and no toast is shown. The fix is purely in \�vent-reducer.ts\ / \server-sync.tsx; even with correct server ordering the reducer must first handle the event. The companion PR #48534 touches no file that #42253 touches.