## Description
Hardens two routine PR-review pain points from the recent open-PR sweep:
- PR Governance reruns could keep validating the stale
`pull_request_target` event body even after the live PR description had
been fixed.
- Main CI model-cache misses could surface as dozens of unrelated
memory-test failures instead of one clear cache-preflight failure.
This intentionally avoids PyPI/package-bloat and release/nightly
workflow changes so the PR stays scoped to review and CI stabilization.
## Type of Change
- [x] Bug fix
- [ ] New feature
- [ ] Documentation
- [x] Refactor
- [x] Tests only
## Changes Made
- Added `--body-file` support to `scripts/pr-governance.py` so workflows
can validate the current PR body rather than stale rerun payloads.
- Updated PR Governance to fetch the live PR body via the GitHub API
before validating template fields.
- Added a CI preflight script that loads the default
sentence-transformer model in offline mode and verifies the expected
embedding dimension.
- Wired that preflight into the sharded CI job before pytest starts,
turning missing/corrupt Hugging Face caches into one early, actionable
failure.
- Added workflow/script regression tests for the live-body override and
model-cache preflight placement.
## Testing
- [x] Unit tests
- [x] Lint/static checks
- [ ] Integration tests
- [ ] Manual testing
### Test Output
```text
uv run --with pytest --with pytest-asyncio python -m pytest scripts/tests/test_pr_governance.py scripts/tests/test_pr_health_workflow.py scripts/tests/test_ci_workflow.py -q
9 passed in 0.04s
uv run ruff check scripts/pr-governance.py scripts/ci/verify_hf_model_cache.py scripts/tests/test_pr_governance.py scripts/tests/test_pr_health_workflow.py scripts/tests/test_ci_workflow.py
All checks passed!
python -m py_compile scripts\ci\verify_hf_model_cache.py scripts\pr-governance.py
# passed
```
## Real Behavior Proof
- Environment: Windows 11, Python 3.13.3, isolated worktree
`C:\git\headroom\.worktrees\stabilization-hardening`.
- Exact command / steps: Ran the focused governance/workflow tests, ruff
on touched Python files, and `py_compile` for the executable scripts.
- Observed result: Governance tests prove a stale event body can be
overridden by the live PR body; workflow tests prove CI validates live
PR body and runs the Hugging Face offline-cache preflight before pytest
shards.
- Not tested: Full GitHub CI before PR creation; that will run on this
PR. The new Hugging Face preflight itself is intentionally not run
locally because it depends on the CI-warmed offline model cache.
## Review Readiness
- [x] I have performed a self-review
- [x] This PR is ready for human review
## Description
Make the PR Governance workflow advisory for incomplete pull request
bodies. The workflow still validates the template, writes the run
summary, comments on the PR, and syncs governance labels, but it no
longer marks the check red for expected author follow-up.
## Type of Change
- [x] Bug fix (non-breaking change that fixes an issue)
## Changes Made
- Replaced the failing incomplete-template step with a reporting step
that exits successfully.
- Added a regression test that guards against reintroducing the hard
failure path.
## Testing
- [x] Unit tests pass (`pytest`)
- [x] Manual testing performed
### Test Output
```text
pytest scripts/tests/test_pr_governance.py scripts/tests/test_pr_health_labels.py scripts/tests/test_pr_health_workflow.py -q
# 7 passed
act pull_request_target -W .github/workflows/pr-health.yml -e .github/act/pr-governance-invalid.json -n
# Job succeeded
act pull_request_target -W .github/workflows/pr-health.yml -e .github/act/pr-governance-valid.json -n
# Job succeeded
```
## Real Behavior Proof
- Environment: Windows 11, Python 3.13.13, act 0.2.87, Docker Desktop
via npipe.
- Exact command / steps: Ran the focused governance/label tests and
`act` dry-runs for the valid and invalid PR governance payloads.
- Observed result: Tests passed, the invalid payload's reporting step
completed successfully, and both PR Governance dry-runs ended with job
success.
- Not tested: Full non-dry-run `act` execution against GitHub API
side-effect steps, to avoid mutating real labels/comments from a local
run.
## Review Readiness
- [x] I have performed a self-review
- [x] This PR is ready for human review
