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Visual regression tests

Apollon's visual regression tests run as part of pr-health-checks.yml on every PR. They use Playwright with the mcr.microsoft.com/playwright:v1.59.1-noble Docker image so snapshots are pinned to one Linux rendering stack regardless of contributor OS.

Regenerating baselines​

Snapshots must be regenerated inside the same Playwright container CI uses, otherwise CI will diff against macOS/Windows-rendered pixels. From the repo root:

docker run --rm -v "$(pwd)":/work -w /work --ipc=host \
  mcr.microsoft.com/playwright:v1.59.1-noble \
  bash -c "curl -fsSL https://deb.nodesource.com/setup_24.x | bash - \
    && apt-get install -y nodejs \
    && npm install -g pnpm@11.1.3 \
    && pnpm install --frozen-lockfile \
    && pnpm run build:lib \
    && cd standalone/webapp \
    && pnpm exec playwright test tests/visual/ --update-snapshots"

SVG export baselines​

SVG export baselines do not depend on the rendering engine — they can be regenerated on any OS:

cd standalone/webapp
pnpm exec playwright test tests/visual/svg-export --update-snapshots

Triage​

If visual-regression-tests fails on CI, download the playwright-report-visual artifact from the workflow run, open playwright-report/index.html locally, and inspect the actual-vs-expected diff before deciding whether to update the baseline or fix the regression.