tui: pending question form lost after client reconnect — unexitable modal (FormNotFoundError loop)

Summary

When the TUI's connection to the shared background service drops while an agent-initiated interactive question form is pending, the server discards the pending form and does not restore it on reconnect. The TUI keeps its stale modal mounted; every subsequent keypress produces a 404 FormNotFoundError unhandled rejection, keyboard input stays trapped in the dead modal, and the terminal must be killed to recover.

Environment

• opencode version: opencode2 v0.0.0-beta-17963 (channel: beta)
• OS: Darwin 25.5.0 arm64
• Terminal: WarpTerminal
• Shell: /bin/zsh
• Install/channel: beta, shared background service (opencode2 service status reported http://127.0.0.1:)
• Active plugins: several local plugins are configured, but all failed schema validation at load time in this session ("Expected object at ["default"]"), so the failure occurred with no custom plugins active.

Reproduction

1. Start the TUI against the shared background service.
2. Trigger a tool call that opens an interactive question form and leave it pending.
3. Drop the client↔server connection while the form is open. In my case the drop happened on its own ~10 minutes into the wait; server logged location services evicted for the project directory.
4. Client silently reconnects (~45 s later; server re-runs location services boot and plugin load).
5. Press any key in the still-displayed form (Enter or Esc).

Observed once so far; likely reproducible whenever the connection drops while a form is pending.

Expected Behavior

Either the server persists and restores pending forms across client reconnects, or the client detects the stale form (404 / FormNotFoundError) and dismisses the modal, returning keyboard control to the user.

Actual Behavior

• On reconnect the TUI replayed its pending answer: POST /api/session/:id/form/:formId/reply → 404.

• Every later keypress produced another 404 on /reply or /cancel plus an unhandled rejection in the CLI log:

  level=ERROR role=cli message="unhandled rejection" cause._tag=FormNotFoundError cause.message="Form not found: frm_…"
  

• 77 such rejections over ~100 seconds.

• The modal remained mounted and captured all keyboard input; Esc/Ctrl+C did not work; only killing the terminal recovered.

• The assistant message was left incomplete with the tool stuck in running; the session ended as interrupted.

Additional Context

• Server side of the same window: repeated Sent HTTP response … http.url=/api/session/<id>/form/<formId>/reply http.status=404 and matching /cancel 404s after the reconnect.
• No pending permission remains queryable afterwards (GET /api/session/:id/permission → empty).
• Workaround: kill the terminal, start a new session. The run's completed work is intact; only the unanswered question is lost.
• Session/form IDs redacted. Happy to provide a fuller sanitized log excerpt.