pcbjam/tests/tools/screenshots/README.md
Viktor Vaczi 13551f4f22 feat(tests): screenshot regression + Discord review, perf-tracked
New tooling in tests/tools/screenshots/ (TypeScript via tsx):
- compare.ts: one pixelmatch engine (AA-excluded), connected-component
  "where to look" boxes, old|new+boxes|heatmap triptych, per-engine floors.
- promote.ts: churn-free updater — overwrite a baseline only when decoded
  pixels differ beyond the floor, copying CI bytes verbatim (no re-encode
  churn); pulls a CI run via `gh run download` or a local --from dir.
- post-discord.ts: always-on CI-on-main report (SHA + e2e status + the
  track-only runtime-perf table), then screenshot triptychs, batched +
  size-capped + flood-collapsed + 429-aware.
- perf-report.ts: perf table with Δ vs the previous main run (via gh).
- changelog.ts: no-build git-history baseline differ (Discord trigger B).
- noise.ts / gen-manifest.ts: calibration + manifest generation.

CI wiring:
- wasm-build.yml: post-test step runs the gate + report on the already-
  produced test-results (no extra build); report-only (continue-on-error),
  posts only on push to main, inert without DISCORD_WEBHOOK_URL.
- ci-ubicloud.yml: secrets: inherit (pass the webhook through).
- screenshot-changelog.yml: ~30s no-build changelog on baseline changes.

screenshot-manifest.json: canonical 354-name set + best-effort engine tags
(313 chromium-swiftshader / 41 firefox-llvmpipe).

Normalize scale:'device'->'css' across 18 spec files (no-op at CI DSF=1)
so committed baselines are uniformly css-scaled.

Design: CI's Linux render is the single source of truth; no pinned
container (accept rare env drift -> re-promote); dev commits via promote.
Replaces the byte-cmp compare-screenshots.sh + file-size-proxy
update-baseline-screenshots.sh (kept for now until the first re-baseline).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
2026-07-01 18:17:20 +02:00

40 lines
3.1 KiB
Markdown

# Screenshot regression + Discord review tooling
One comparison engine + a churn-free updater + a Discord reporter for the e2e
screenshots. Design and rationale: `~/.claude/plans/…snowglobe.md` (or ask).
**Source of truth = CI's Linux render.** The dev never authors baselines on the
Mac (Mac fonts/GL ≠ CI). Instead, CI renders on every push; when a render change
is intentional you *promote* CI's artifact into the committed baselines. The
environment isn't pinned — if the host's Mesa/fonts drift, the gate lights up in
Discord and you just re-promote (broad + low-intensity change ⇒ likely drift).
## Files
- `config.ts` — thresholds, baseline dirs, per-engine floors (calibrate!), clustering knobs.
- `image-ops.ts` — PNG load/save, pixelmatch diff (AA-excluded), connected-component boxes, triptych compositing, size-cap resize.
- `compare.ts` — the engine: classify baselines vs `test-results/``test-results/screenshot-diff/report.json` + triptych/heatmap PNGs. `--pair` diffs two files.
- `promote.ts` — churn-free updater: pull a CI run's shots (`gh run download`) or `--from DIR`; overwrite a baseline only when pixels differ beyond the floor (verbatim bytes, no re-encode) → no git churn.
- `perf-report.ts` — renders the track-only runtime-perf table (loadMs/openMs/FPS) with Δ vs the previous main run (fetched via `gh`).
- `post-discord.ts` — the always-on CI-on-main report: SHA + e2e status + perf table, then screenshot triptychs (batched, size-capped, flood-collapsed).
- `changelog.ts` — Discord trigger B: git-history diff of committed baseline PNGs (no build/GPU).
- `noise.ts` — calibration: diff two identical-input renders → per-engine noise floor.
- `gen-manifest.ts` — regenerate `screenshot-manifest.json` (canonical name list + best-effort engine tag) by scanning the committed baselines + specs.
## npm scripts (run from `tests/`)
```
npm run screenshots:check # gate: baselines vs test-results → report.json (exit 0; add --fail-on-change to gate)
npm run screenshots:promote -- --run <ci-run-id> # churn-free re-baseline from a CI run (or --from DIR)
npm run screenshots:report -- --e2e pass # post the CI report to Discord (main+push only; needs DISCORD_WEBHOOK_URL)
npm run screenshots:changelog # post the baseline changelog (main+push only)
npm run screenshots:noise -- run1/ run2/ # calibrate floors
npm run screenshots:manifest # regenerate the manifest (--check to verify it's fresh)
```
## Activation checklist
- [x] `screenshot-manifest.json` generated (name list authoritative; engine tags best-effort until calibration).
- [x] `scale:'device'``'css'` normalized (no-op at CI's DSF=1).
1. Add the `DISCORD_WEBHOOK_URL` repo secret — until then everything is inert.
2. Calibrate: run the suite twice in CI, `screenshots:noise` the two dirs, set `FLOORS` in `config.ts`.
3. First re-baseline: `promote` a clean CI run's render, commit (expect a big, one-time chrome-font diff vs the Mac baselines).
4. Delete the old `scripts/{compare,update-baseline}-screenshots.sh`.
5. Once floors are proven stable, flip the gate to `--fail-on-change`.