[Windows][Desktop 26.818 + app-server 0.149.0-alpha.4] Conversation renderer crashes: Cannot read properties of undefined (reading 'enable_message_feedback') - conversation shows 'this turn's content cannot be displayed'

Environment

• Windows x64, MSIX OpenAI.Codex 26.818.3698.0, UI release 26.818.31338
• Bundled app-server: codex-cli 0.149.0-alpha.4
• Account: personal ChatGPT Plus (subscription purchased via mobile IAP)

Summary
Desktop conversations render "this turn's content cannot be displayed" for every new turn, even a trivial Reply only with: ok. The app-server completes the turn correctly (session rollout shows final_answer with content "ok"), but the Electron renderer crashes with:

error boundary componentStack="... at JS (subagent-activity-chip-group-CEtIMCfG.js:13:11232) ... at Gi (local-conversation-turn-BBMTaze8.js:1:11992) ... at mD (local-conversation-thread-DCzS0Y-V.js:13:14447) ..."
errorMessage: "Cannot read properties of undefined (reading 'enable_message_feedback')"

A/B control (same account, same network, minutes apart):

• Desktop app (brand-new conversation): fails with the renderer error above.
• Browser chatgpt.com/codex: renders the identical conversation fine.

Root-cause evidence — data-contract mismatch
The desktop pipeline's response item for the crashing turn (redacted):

{
  "type": "response_item",
  "payload": {
    "type": "message",
    "content": [ { "type": "output_text", "text": "ok" } ],
    "phase": "final_answer",
    "internal_chat_message_metadata_passthrough": {
      "turn_id": "01a024ab-...",
      "create_time": 1787321625.123
    }
  }
}

internal_chat_message_metadata_passthrough contains only turn_id / create_time — enable_message_feedback is absent. The renderer dereferences it without a null-guard. The web path includes the field, so the server-side contract has it; the bundled app-server drops it when serializing response items for the desktop UI.

Version banner from the desktop log:

[AppServerConnection] Current reported app-server version: currentVersion=0.149.0-alpha.4 hostId=local
[AppServerConnection] Codex CLI initialized
[browser-session-registry] ... release=26.818.31338

Suggested fix: either include enable_message_feedback in the app-server's per-message metadata passthrough, or add a null-guard in subagent-activity-chip-group.

Related: #39850 (same build, auth issue), #31090 (desktop renderer crashes, subagent context).