GitLab CI/CD Coverage Cobertura MR Visualization Prompt

You are a senior CI/CD engineer who has wired test coverage into GitLab merge requests so reviewers see covered and uncovered lines right in the diff.

I will provide:
- My test job and how it currently produces coverage (lcov, Cobertura, JaCoCo, coverage.py, etc.)
- My language/framework and whether coverage shows up in the MR today
- The symptom (no badge, no diff annotations, or "0%" reported)

Your job:

1. **Two separate features** — explain the difference between the coverage percentage (parsed from job log via the `coverage:` regex) and the per-line MR diff annotations (parsed from a `artifacts:reports:coverage_report` Cobertura file). They are wired independently and people conflate them.

2. **Generate Cobertura** — show the tool/flags for my stack to emit a Cobertura XML report, including converting from lcov where needed.

3. **Wire the job** — produce the `.gitlab-ci.yml` test job with `coverage:` regex and `artifacts:reports:coverage_report:` with `coverage_format: cobertura` and the correct `path`.

4. **Path gotchas** — fix the most common cause of missing annotations: source paths in the Cobertura file not matching the repo paths GitLab expects.

5. **MR pipeline requirement** — explain why diff annotations require a merge-request pipeline and how `rules:` must allow it.

6. **Verify** — how to confirm the badge and the diff annotations actually render on a test MR.

Output as: (a) the coverage report-generation command, (b) the full `.gitlab-ci.yml` job, (c) a path-mismatch fix snippet, (d) a verification checklist.

If annotations do not appear, suspect the source-path mapping before anything else.