Resume session with session id fails with "no session matched"

Start by reproducing /resume with the reported session ID on the affected versions, then trace how the CLI resolves session IDs versus task IDs. Done means a valid session ID resumes the matching session and the failure is covered by a regression test.

Describe the bug

Repeatedly, I've asked Copilot to help me find an old session, and it does, providing details about the session it found. For example:

The session is “Investigate Computer Shutdown Issues”:

• Session ID:  a2e4ec55-7ece-4c5b-b8ed-7c9b6d5ef25f 
• Date: July 20, 2026
• Key finding: Modern Standby/sleep failure, followed by  DRIVER_POWER_STATE_FAILURE (0x0000009F)  and battery drain while the lid was closed.

But then I try to resume that session and it fails.

How to resume that session?
Checking my documentation  # GitHub Copilot CLI Documentation

Use the  /resume  command and provide the session ID:

/resume a2e4ec55-7ece-4c5b-b8ed-7c9b6d5ef25f

You can also resume it by name:

/resume Investigate Computer Shutdown Issues

If  /resume  opens a selector, choose the July 20, 2026 session.

No session, task, or name matched 'a2e4ec55-7ece-4c5b-b8ed-7c9b6d5ef25f' 

The help seems to indicate that a session ID should be sufficient:

/resume                             Switch to a different session (optionally specify session ID, task ID, or name)

If I prompt Copilot, it can find the task ID instead, and that works:

Yes—the alternate **task ID** is:

69efac91-fce7-44fb-a7c0-2371c0201ded

Try:

/resume 69efac91-fce7-44fb-a7c0-2371c0201ded

The original session ID is `a2e4ec55-7ece-4c5b-b8ed-7c9b6d5ef25f`; depending on the CLI version, `/resume` may require the task ID instead.

This flow is super clumsy. Why can't Copilot resume a session by ID?

Affected version

1.0.74-3 and 1.0.86-2

Steps to reproduce the behavior

No response

Expected behavior

No response

Additional context

No response