VS Code extension drops turn-scoped items and recent chat history during active thread

Start by tracing the components named in the logs: CodexMcpConnection, codex_app_server_protocol::protocol::thread_history, the analytics reducer, and IpcClient. Compare how turn state and thread-read-state-changed broadcasts are handled when tool items arrive late; done means active threads retain and render all conversation and tool items, recovering missing turn state instead of dropping them.

What version of the IDE extension are you using?

v26.721.30844

What subscription do you have?

ChatGPT Business

Which IDE are you using?

Visual Studio Code

What platform is your computer?

Darwin 25.5.0 arm64 arm (macOS 26.5)

What issue are you seeing?

Summary

While using a long-running active Codex thread in the VS Code extension, recent conversation/tool items disappeared from the visible chat history. This happened during the active session, not only after a VS Code restart.

The issue appears to be a mismatch between the extension UI, the Codex app-server connection, and turn state. Tool-related items arrive after the client has lost the associated turn state, so they are dropped.

Relevant logs

Local timestamps, with thread and item identifiers redacted:

2026-07-25 08:38:05.527 [warning] [CodexMcpConnection] cli:
dropping turn-scoped item for unknown turn id `<redacted>`
item_id="exec-<redacted>"

2026-07-25 08:38:05.528 [error] [CodexMcpConnection] cli:
codex_app_server_protocol::protocol::thread_history:
dropping turn-scoped item for unknown turn id `<redacted>`

codex_analytics::reducer:
dropping turn tool count update: missing turn state
thread_id=<redacted> turn_id=<redacted> item_id="exec-<redacted>"

2026-07-25 08:38:05.534 [error]
Item not found in turn state itemId=exec-<redacted>

2026-07-25 08:39:27.102 [warning] [IpcClient]
Received broadcast but no handler is configured
method=thread-read-state-changed

### What steps can reproduce the bug?

Open VS Code with the Codex extension signed in.
Work in a long-running thread with tool calls and multiple turns.
Continue working for an extended period.
Observe that recent conversation or tool items can disappear from the visible thread.
Check the VS Code Extension Host output.

### What is the expected behavior?

The extension should retain and render all turns and tool results belonging to the active thread. If state recovery is needed, it should rehydrate the missing turn instead of silently dropping associated items.

### Additional information

This was observed on macOS while working in an active long-running thread with tool calls. I did not manually edit or delete Codex session/state files.

I can provide additional sanitized VS Code Extension Host logs if needed.

Related issue: #14812