The button doesn't auto-generate a commit when I click it.

### Describe the bug

copilot chat log:
2026-07-31 11:12:21.582 [info] Request ID for failed request: 1354e645-7186-48ff-91c8-9054b88f296e
2026-07-31 11:12:21.583 [error] Server error: 422 Unprocessable Entity
2026-07-31 11:12:21.584 [info] ccreq:6d224459.copilotmd | promptFiltered | gpt-4o-mini-2024-07-18 | 949ms | [gitCommitMessageGenerator]

### Affected version

_No response_

### Steps to reproduce the behavior

1、I change some words
2、I click the star btn
3、Clicking the button doesn't generate any commit message

### Expected behavior

_No response_

### Additional context

Reproduce the issue by changing some words and clicking the star button, then inspect the gitCommitMessageGenerator request and the reported 422 Unprocessable Entity response. Done means the button generates a commit message instead of failing.

Written by the indexing model from the issue text.