[Windows 26.903.9818.0] Recent task messages missing after reconnect; read_thread fails with MCP -32000

Environment

• Codex desktop on Windows, installed package 26.903.9818.0.
• Running executable: ChatGPT.exe, product name Codex. Separate executable file/product version: 152.0.7977.83.
• Observed September 11, 2026.

Issue

Recent assistant completion messages and output links are missing from the user's conversation view after an earlier reconnect episode. The current assistant context contains later completion messages, and the completed local artifacts still exist with hashes matching their release receipt.

A user screenshot showed an older progress message followed by Reconnecting 3/5 and Thinking. A later screenshot showed that older assistant response directly above a new user prompt asking for the latest output; the later completion was absent from the captured area.

Observed sequence

1. Continue a long-running, image-assisted local task.
2. The app displays a reconnect indicator during an earlier response.
3. Work subsequently completes and local output files are produced.
4. Return to the conversation: the user cannot find the later completion messages or output links.
5. A read-only attempt to retrieve the latest three turns through the app's read_thread tool fails.

This is an incident sequence, not a deterministic minimal reproduction. It has not been independently replayed in a fresh task or after restart.

Available error trace

The history-retrieval request returned:

Mcp error: -32000:
MCP error -32000:
Codex app tool request failed

No history or stack trace was returned. The full private request arguments, task ID and file paths are omitted. This error is an additional observation, not proof of the root cause.

Expected behavior

The conversation should show the later completed assistant responses and artifact links in order. If history loading fails, expose an actionable error and a supported recovery path.

Scope and related report

Completed local work is intact. Backend persistence of the missing messages has not been independently verified. Rendering, history retrieval, synchronization and persistence remain possible explanations; no specific cause is confirmed.

Possibly related symptom: #44562. That report identifies an ordinal-mismatch projection error on macOS. No such ordinal error has been established in this Windows incident, so the same cause is not asserted.

This report was prepared with Codex assistance. It includes no screenshots, private conversation content, project details, account information, credentials or raw logs. No app caches, settings or conversation data were modified during this investigation.

Start with the app's read_thread history-retrieval path and the MCP -32000 error, then compare the reconnect sequence with the missing conversation messages and artifact links. Reproduce the incident if possible and trace whether rendering, retrieval, synchronization, or persistence is responsible; done means later completions appear in order or history failure exposes an actionable recovery path.