gitlab-mr-diff

GitLab MR Diff

Overview

Show the unified diff for an existing GitLab merge request. The skill uses the GitLab CLI when GITLAB_TOKEN is not set and the REST API when the token is available.

When to Use

• The user asks to show or review an MR diff
• The user provides a merge request IID such as 42
• The user needs a changed-files summary with additions and removals

Instructions

Inputs

$ARGUMENTS contains the merge request IID.

Step 1: Read the IID

Extract the merge request IID from $ARGUMENTS.

Step 2: Select the access path

Check whether GITLAB_TOKEN is set.

• If it is not set, use the GitLab CLI path.
• If it is set, use the REST API path.

Step 3: GitLab CLI path

Run:

glab mr diff {iid}

Display the unified diff output as returned.

Step 4: REST API path

Require these environment variables and fail clearly if any are missing:

• GITLAB_HOST
• GITLAB_TOKEN

Determine the project path from git remote get-url origin, strip the host prefix and .git suffix, then URL-encode / as %2F.

Fetch MR details:

GET {GITLAB_HOST}/api/v4/projects/{encoded_project_path}/merge_requests/{iid}
Headers: PRIVATE-TOKEN: {GITLAB_TOKEN}

Display a header with the title, author, branch mapping, and state.

Fetch MR changes:

GET {GITLAB_HOST}/api/v4/projects/{encoded_project_path}/merge_requests/{iid}/changes
Headers: PRIVATE-TOKEN: {GITLAB_TOKEN}

For each entry in changes, display:

• The file path, or old_path -> new_path for renames
• Whether it is a new, deleted, or renamed file
• The unified diff content

At the end, summarize:

• Total files changed
• Total lines added, excluding +++ headers
• Total lines removed, excluding --- headers

Output Format

Return a readable MR header, the per-file diffs, and the summary counts. On failure, include the HTTP status or CLI error output.

Examples

/gitlab-mr-diff 42
show the diff for MR 42
review merge request 105

Notes

• Preserve unified diff formatting so reviewers can read the patch directly.
• Count additions and removals from the diff body, not file header markers.
• Stop on API errors instead of returning partial results.