[Windows Desktop] Long local task can remain stuck at Thinking after reconnect/resume

No source files or tests are named. Start by tracing Windows Desktop reconnect/resume handling and the app-server turn lifecycle, focusing on the logged turn/interrupt and duplicate turn/start sequence; use the reproduction pattern and sanitized logs to follow state transitions. Done means one active turn survives reconnect without prompt duplication or interruption, or a recoverable error is shown.

Environment

• Surface: Codex Desktop for Windows (Microsoft Store package 26.721.3996.0)
• Bundled Codex runtime observed by the app: 26.721.31836
• Model: GPT-5.6 Terra, medium reasoning effort
• Platform: Windows 11 x64

Summary

Fresh local tasks respond normally, but an existing long local task can become permanently stuck at “Thinking” after a reconnect/resume. The affected task cannot accept a reliable follow-up; the desktop client may duplicate the prompt/turn or interrupt the active task instead of resuming it.

Reproduction pattern

1. Start a local Codex Desktop task and use it over a long project workflow.
2. A reconnect/resume occurs while the task has substantial history.
3. Send a normal follow-up, or reopen/resume the task.
4. The UI remains at “Thinking” indefinitely. In the affected case, the same diagnostic prompt appeared twice and two turns were left in progress.

Observed evidence

• Desktop/app-server logs show client-issued turn/interrupt events for the active task, followed after resume by a duplicate turn/start.
• The resulting stream retried after a WebSocket close without reaching response.completed.
• Fresh tasks and a direct ephemeral Codex CLI request against the same local project, account, model family, and network completed successfully. This points to desktop task recovery/state handling rather than the workspace sandbox or general connectivity.
• No project files need to be read or included to reproduce the symptom.

Expected behavior

A reconnect should preserve one active turn, avoid replaying or duplicating prompts, and either continue the task or expose a recoverable error. Long-running project work must retain a safe continuation path without relying on an unrecoverable old chat.

User impact

This blocks long-running project work and risks loss of unrecorded decisions. A new task is an imperfect workaround because it cannot restore the old task's in-flight reasoning or task-local state.

Request

Please investigate Windows Desktop task resume/reconnect idempotency, especially duplicate turn/start / interrupt transitions for older long tasks. A feedback session and sanitized log timestamps can be supplied through the in-app feedback flow if needed.