[AI] Add running-vrts skill for visual regression testing (#8477)

* [AI] Add running-vrts skill for visual regression testing

Documents how VRTs work in this repo (toMatchThemeScreenshots matcher,
three-theme snapshots, data-vrt-mask, strict diff tolerance), the
docker-based snapshot generation workflow, and the /update-vrt CI
fallback.

Co-Authored-By: Claude Fable 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01AZAw7AR6LMHTGss1BtnBDT

* [AI] Add codex skill symlink for running-vrts

Co-Authored-By: Claude Fable 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01AZAw7AR6LMHTGss1BtnBDT

* [AI] Add release note for running-vrts skill

Co-Authored-By: Claude Fable 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01AZAw7AR6LMHTGss1BtnBDT

---------

Co-authored-by: Claude <[email protected]>

.agents/skills/running-vrts

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+../../.claude/skills/running-vrts

.claude/skills/running-vrts/SKILL.md

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+---
+name: running-vrts
+description: Use whenever adding, updating, regenerating, running, or debugging visual regression tests (VRTs) / screenshot tests in the Actual Budget repo — including phrases like "add a VRT", "add a screenshot test", "update the snapshots", "regenerate the VRT screenshots", "the VRT is failing", "yarn vrt", "vrt:docker", or "/update-vrt", and any time a UI change needs screenshot coverage. VRT snapshots must be generated inside the Linux docker image (never on the host) and snapshot updates must be scoped to the changed test only — getting either wrong produces snapshots CI ignores or rewrites every screenshot in the repo.
+---
+
+# Running VRTs (Visual Regression Tests) in actualbudget/actual
+
+VRTs are ordinary Playwright e2e tests in `packages/desktop-client/e2e/*.test.ts` that call:
+
+```ts
+await expect(target).toMatchThemeScreenshots();
+```
+
+`toMatchThemeScreenshots()` is a custom matcher defined in
+`packages/desktop-client/e2e/fixtures.ts`. `target` is a `Page` or a `Locator` —
+**prefer a tight locator** (e.g. a popover or panel) over the whole page to
+reduce noise from charts and data.
+
+## Key mechanics
+
+- **No-op without `VRT=true`.** In a plain e2e run the matcher passes
+  immediately, so `yarn workspace @actual-app/web run playwright test <file> -g "<name>"`
+  verifies the interaction flow cheaply without needing snapshots — always do
+  this first.
+- **With `VRT=true`, each call captures three themes** (`auto` i.e. light,
+  `dark`, `midnight`), producing numbered snapshots:
+  `<file>.test.ts-snapshots/<Describe>-<test-name>-N-chromium-linux.png`.
+  One test with 2 assertions → 6 PNGs.
+- **Masking:** elements with `data-vrt-mask="true"` are masked out of
+  screenshots. Use it for volatile content (real dates, version numbers).
+- **Diff tolerance is strict:** `maxDiffPixels: 5`, `threshold: 0.05`
+  (`packages/desktop-client/playwright.config.ts`).
+- **Snapshots are Linux-only.** Committed snapshots end in
+  `-chromium-linux.png` and must be generated inside the Playwright docker
+  image. A host run on macOS writes `-chromium-darwin.png`, which CI ignores.
+
+## Writing a new VRT
+
+Import from the local fixtures, not `@playwright/test`:
+
+```ts
+import { expect, test } from './fixtures';
+```
+
+Patterns to copy:
+
+- Date-picker popover VRT: `e2e/transactions.test.ts` ("by date").
+- Report VRTs: `e2e/reports.test.ts`.
+- Tests use the demo budget (`ConfigurationPage.createTestFile()`), whose data
+  is pinned (date ranges show 2016), so snapshots are largely date-stable.
+- Popovers render with a `[data-popover]` attribute — a good screenshot
+  locator.
+- Page models live in `e2e/page-models/`.
+
+## Generating snapshots locally (docker)
+
+Run all yarn commands from the repo root.
+
+1. Start the dev server with HTTPS (background it; ready when
+   `https://localhost:3001` returns 200 — `ignoreHTTPSErrors` is already set in
+   the Playwright config):
+
+   ```sh
+   HTTPS=true yarn start
+   ```
+
+2. The container runs with `--network host`. On Linux it can reach
+   `https://localhost:3001` directly. On macOS/Windows it cannot — get the
+   machine's LAN IP (`ipconfig getifaddr en0` on macOS) and use
+   `https://<LAN_IP>:3001` instead.
+
+3. Run the Playwright docker image directly. The `bin/run-vrt` wrapper passes
+   `-it`, which fails without a TTY, so in an agent shell invoke docker
+   yourself:
+
+   ```sh
+   docker run --rm --network host -v "$(pwd)":/work/ -w /work/ \
+     mcr.microsoft.com/playwright:v1.59.1-jammy /bin/bash -c \
+     "E2E_START_URL=https://<HOST>:3001 yarn vrt --update-snapshots -g '<test name>' <file>.test.ts"
+   ```
+
+   Pin the image tag to the repo's Playwright version (`@playwright/test` in
+   `packages/desktop-client/package.json` — currently 1.59.1 →
+   `v1.59.1-jammy`). The equivalent user-facing wrapper is
+   `yarn vrt:docker --e2e-start-url https://<HOST>:3001 --update-snapshots`.
+
+4. **Always scope `--update-snapshots`** with `-g`/file args to the new or
+   changed test only — an unscoped update rewrites every screenshot in the
+   repo.
+
+5. Verify by re-running the exact same command **without**
+   `--update-snapshots`; it must pass.
+
+6. Optionally Read one generated PNG to sanity-check it shows the intended UI,
+   then commit the test + PNGs (commit messages need the `[AI]` prefix — see
+   the committing-actual-changes skill).
+
+## Fallback without docker
+
+Commit only the test file; CI generates the snapshots when someone comments
+`/update-vrt` on the PR (`.github/workflows/vrt-update-generate.yml`).

upcoming-release-notes/add-vrt-skill.md

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+---
+category: Maintenance
+authors: [MatissJanis]
+---
+
+Add an agent skill documenting how to run and update visual regression tests