[Bug]: Review submission fails on lines outside the PR diff and hides GitHub’s validation error

Before submitting

• I searched existing issues and did not find a duplicate.
• I included enough detail to reproduce or investigate the problem.

Area

apps/web

Steps to reproduce

1. Open a GitHub pull request in T3 Code and start a review.
2. Add an inline comment to unchanged context outside the diff hunks returned by GitHub. In my case, the comment was on line 1 of a modified file, while the first diff hunk started at line 2.
3. Add other valid inline comments and submit the review using Comment.
4. The entire review fails with a generic error.
5. Move the out-of-diff comment to a valid line in the same file and submit again. In my case, moving it to the class declaration at line 24 made the review submit successfully.

The line-1 anchor was confirmed in the extracted draft as: { "kind": "context", "oldLine": 1, "newLine": 1, "side": "right" }.

Expected behavior

T3 should prevent or flag inline comment anchors that GitHub cannot accept. If submission is rejected, show the useful GitHub validation error and help identify the affected comment so it can be moved, while preserving the rest of the draft.

Actual behavior

The UI only reports “the review could not be submitted.” The server trace reports “GitHub CLI command failed” and a non-zero exit, without the useful validation message.

Submitting the same payload directly through gh api returned HTTP 422 with errors: ["Line could not be resolved"]. Comparing the comment anchors with GitHub’s PR diff identified one comment on line 1 outside the returned hunk. Moving that comment to line 24 (within the diff) resolved the problem.

Impact

Minor bug or occasional failure

Version or commit

Installed macOS app bundle reports 0.0.42 (T3 Code Alpha)

Environment

macOS; T3 Code (Alpha) desktop app; GitHub pull request review submitted through the GitHub CLI.

Logs or stack traces

UI: the review could not be submitted.

Server trace:
PullRequestOperationError: Pull request operation submitReview failed: GitHub CLI command failed.
VcsProcessExitError: gh exited with 1 - Process exited with a non-zero status.

Direct POST /repos/{owner}/{repo}/pulls/{number}/reviews:
HTTP 422 Unprocessable Entity
{
  "message": "Unprocessable Entity",
  "errors": ["Line could not be resolved"],
  "documentation_url": "https://docs.github.com/rest/pulls/reviews#create-a-review-for-a-pull-request",
  "status": "422"
}

Screenshots, recordings, or supporting files

No response

Workaround

Move the comment from the unchanged line outside GitHub’s diff hunk to a valid line within the same file’s diff. Moving my comment from line 1 to the class declaration at line 24 allowed the review to submit successfully.

Start in apps/web and trace the GitHub pull request review submission through the GitHub CLI path described in the issue. Reproduce the HTTP 422 “Line could not be resolved” case with an out-of-diff anchor, then verify that the affected comment is identified, the useful validation error is shown, and the remaining draft is preserved.