## What
Adds the project's first **CI test workflow** —
`.github/workflows/test.yml` (job "CI"). Until now the only workflow was
`publish.yml`; tests never ran in CI. This gates every push to
`main`/`master` and every PR on (a) the full suite passing and (b)
**>90% by-branch coverage on changed code**.
## The workflow
- **Triggers:** `push` to `main`/`master`, and all `pull_request`s.
- **Env:** Python 3.12 (reliable CPU torch wheels),
`actions/checkout@v5` with `fetch-depth: 0` (diff-cover needs
base-branch history), `actions/setup-python@v5` with pip cache.
- **Real torch:** installs the CPU wheel from
`download.pytorch.org/whl/cpu`, so `tests/test_pack_split.py` (which
swaps the mock torch for real torch) actually executes rather than
skipping — its branch coverage counts.
- **Tests + coverage:** `pytest --cov=NRS --cov-branch --cov-report=xml
--cov-report=term-missing`. Any test failure fails the job.
- **Branch-coverage gate on the diff:** `diff-cover coverage.xml
--compare-branch=<base> --branch-coverage --fail-under=90`. Base is
`origin/${{ github.base_ref }}` for PRs (falling back to `origin/main`).
The `--branch-coverage` flag is required — diff-cover otherwise scores
only line coverage even when fed branch data in the Cobertura XML. Gate
is on **changed** code, not total project coverage, so a no-Python PR
passes trivially.
## Deliberately NOT touched
`pyproject.toml` is untouched (test deps live in the workflow), so this
change cannot trigger `publish.yml` or the held v1.0.0 version bump.
## Local validation
- `pytest --cov=NRS --cov-branch ...` → **42 passed**; total NRS branch
coverage ~79% (informational; the gate is diff-only, not total).
- `diff-cover coverage.xml --compare-branch=origin/main
--branch-coverage --fail-under=90` → passes (this branch changes no
Python).
- YAML parses cleanly; `coverage.xml`/`.coverage` already gitignored —
no artifacts committed.
## Note
Making this check **required** is a branch-protection repo setting you
control (GitHub → Settings → Branches).
Reithan
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