claude.ai Cowork: create_pull_request renders an editable PR card that later shows a false "failed to create pull request" error

Surface: claude.ai web, Cowork session in a Project (Chrome on macOS). It's the web UI, not the CLI, so the CLI-only template fields don't apply.

What happened (9 Oct 2026):

1. The agent called the GitHub connector's create_pull_request (my private skills repo, a new head branch, base main). It returned a new PR, and the agent then merged it with merge_pull_request (merged: true).
2. The conversation still shows a full editable pull request form for that call (repo picker, base and compare dropdowns, Title, a Write/Preview description editor).
3. That card now shows a red banner: failed to create pull request: Validation Failed PullRequest (custom): No commits between main and the new head branch.

Why it's a bug: the PR was created and merged. The card is apparently trying to create it again from the UI, or re-validating after the merge, and reports a failure that never happened. That reads as if the agent's work failed. It also puts an interactive form in the transcript that the user never asked for and has no reason to touch.

Expected: a completed tool call renders as a compact, read-only result ("Created PR"), or doesn't render at all. It never offers a form that re-submits, and it never shows an error for an operation that succeeded. There should also be a setting to turn these cards off.

Screenshot available on request. Filed by the account owner, TheAviv.