Two-workflow split per ADR-020:
.github/workflows/ci.yml (existing, extended):
- checkout now uses fetch-depth: 0 so coverage:diff can resolve
origin/<base-ref>...HEAD against the PR's base branch
- new step "Coverage — aggregate (L2)" runs after the test step
(with `if: always()` so the artifact still captures partial state
on test failures)
- new step "Coverage — diff (L1)" runs only on pull_request events,
diffing against origin/${{ github.base_ref }}
- artifact upload extended to include the aggregated
coverage/lcov.info and coverage/summary.json alongside the
per-package files
.github/workflows/coverage-snapshot.yml (new):
- dedicated workflow with `permissions: contents: write` so it can
commit the aggregated coverage/summary.json back to main after
each merge — the committed trend store (ADR-020 L2)
- runs full test + aggregate, then commits summary.json only if it
actually changed (commit body marked [skip ci] so the snapshot
doesn't recurse into itself)
- concurrency: coverage-snapshot ensures only one snapshot at a time
This closes the CI side of the coverage architecture. PRs now fail
fast when changed lines are uncovered, and main's trend history
accumulates automatically.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Danijel Martinek
39e33eb634