Queued user messages are silently dropped and missing from durable session history

Short summary

Queued messages can disappear without being delivered to the agent or persisted in local session history, causing unrecoverable user-instruction data loss.

Affected version or release

GitHub Copilot App 1.0.83-5

Installation context

GitHub Copilot desktop app on Microsoft Windows 11 Pro, version 10.0.26200 (build 26200), 64-bit. The failure occurred in a local project session using a Git worktree.

What happened?

While an agent was working, the app UI showed "3 queued messages." One visible queued user instruction was:

If there is no way how to make it one-time setup, let's not do that at all

The agent never received that original message. After the user sent "WAKE UP", the agent received only that new message and repeated task-completion reminders; it did not receive the missing queued instruction.

The missing instruction was also absent from durable local session history. The local turns history contained the surrounding conversation, but not the original queued message. A local full-text search for "one-time setup" found only a later discussion quoting the screenshot, not the original queued message.

At least one additional queued message could not be identified because it was neither delivered nor persisted and was not fully visible in the screenshot.

This is data loss, not only a rendering or queue-display defect: user instructions can be silently dropped and cannot be recovered from durable local history.

Steps to reproduce

A deterministic reproduction is not yet known. The observed sequence was:

1. Run an agent in a local project session.
2. Send multiple follow-up messages while the agent is active so the app queues them.
3. Observe the UI showing "3 queued messages."
4. Allow the active work to continue. The queued instruction shown in the screenshot is never delivered to the agent.
5. Send another message (WAKE UP) to prompt the session.
6. Observe that the new message is delivered, but the earlier queued content is not.
7. Inspect the local turns history and search the local full-text index for text from the missing queued message.
8. Observe that the original queued message is absent from both durable stores.

The exact trigger that caused the queued messages to be dropped is unknown.

Expected behavior

Every queued user message should be delivered exactly once as an agent turn. Until delivery succeeds, the complete queued content should remain durably persisted and recoverable across UI updates, session wake-ups, restarts, and failures. If delivery cannot succeed, the app should keep the message visible and clearly report the failure rather than silently discarding it.

Additional context

• Project session ID: bc71ad03-5e0a-4e21-80d4-7b7f1b55d298
• Conversation/session ID: b665ef11-fd30-4acb-822b-503bcfc570f9
• Screenshot evidence: the provided screenshot shows "3 queued messages" and the visible missing instruction quoted above.
• Persistence check: the original queued instruction was absent from local turns history.
• Full-text check: searching for "one-time setup" found only later messages discussing the screenshot, not the original queued message.
• Related issue: github/app#1298 reported dropped messages and was closed as fixed in version 1.0.13. This observation on 1.0.83-5 may be a regression or a remaining queue-specific data-loss path.
• github/app#3525 and github/app#3564 concern queued messages getting stuck; this report is specifically about queued content disappearing from both delivery and durable history.
• Impact: silently lost instructions can make the agent continue with stale or incorrect requirements. Because the original content is not persisted, the user may be unable to determine what was lost or recover it.