feat: add Playwright E2E agent check for reviewing browser tests

Add .agents/checks/playwright-e2e.md with 19 reviewer-focused checks
covering flakiness risks, fixture misuse, convention violations, and
test design issues. Hyperlinks to existing docs rather than duplicating.

.agents/checks/playwright-e2e.md

@@ -0,0 +1,75 @@
+---
+name: playwright-e2e
+description: Reviews Playwright E2E test code for ComfyUI-specific patterns, flakiness risks, and fixture misuse
+severity-default: medium
+tools: [Read, Grep]
+---
+
+You are reviewing Playwright E2E test code in `browser_tests/`. Focus on issues a **reviewer** would catch that an author might miss — flakiness risks, fixture misuse, test isolation problems, and convention violations.
+
+Reference docs (read if you need full context):
+- `browser_tests/README.md` — setup, patterns, screenshot workflow
+- `browser_tests/AGENTS.md` — directory structure, fixture overview
+- `docs/guidance/playwright.md` — type assertion rules, test tags, forbidden patterns
+- `.claude/skills/writing-playwright-tests/SKILL.md` — anti-patterns, retry patterns, Vue Nodes vs LiteGraph decision guide
+
+## Checks
+
+### Flakiness Risks (Major)
+
+1. **`waitForTimeout` usage** — Always wrong. Must use retrying assertions (`toBeVisible`, `toHaveText`), `expect.poll()`, or `expect().toPass()`. See retry patterns in `.claude/skills/writing-playwright-tests/SKILL.md`.
+
+2. **Missing `nextFrame()` after canvas ops** — Any `drag`, `click` on canvas, `resizeNode`, `pan`, `zoom`, or programmatic graph mutation via `page.evaluate` that changes visual state needs `await comfyPage.nextFrame()` before assertions. `loadWorkflow()` does NOT need it.
+
+3. **Keyboard actions without prior focus** — `page.keyboard.press()` without a preceding `comfyPage.canvas.click()` or element `.focus()` will silently send keys to nothing.
+
+4. **Coordinate-based interactions where node refs exist** — Raw `{ x, y }` clicks on canvas are fragile. If the test targets a node, use `comfyPage.nodeOps.getNodeRefById()` / `getNodeRefsByTitle()` / `getNodeRefsByType()` instead.
+
+5. **Shared mutable state between tests** — Variables declared outside `test()` blocks, `let` state mutated across tests, or tests depending on execution order. Each test must be independently runnable.
+
+6. **Missing cleanup of server-persisted state** — Settings changed via `comfyPage.settings.setSetting()` persist across tests. Must be reset in `afterEach` or at test start. Same for uploaded files or saved workflows.
+
+7. **Double-click without `{ delay }` option** — `dblclick()` without `{ delay: 5 }` or similar can be too fast for the canvas event handler.
+
+### Fixture & API Misuse (Medium)
+
+8. **Reimplementing existing fixture helpers** — Before flagging, grep `browser_tests/fixtures/` for the functionality. Common missed helpers:
+   - `comfyPage.command.executeCommand()` for menu/command actions
+   - `comfyPage.workflow.loadWorkflow()` for loading test workflows
+   - `comfyPage.canvasOps.resetView()` for view reset
+   - `comfyPage.settings.setSetting()` for settings
+   - Component page objects in `browser_tests/fixtures/components/`
+
+9. **Wrong import** — Tests must use `comfyPageFixture as test` and `comfyExpect as expect` from `../fixtures/ComfyPage`, not raw `@playwright/test` imports (exception: `expect` from `@playwright/test` is acceptable when `comfyExpect` doesn't provide needed matchers).
+
+10. **Building workflows programmatically when a JSON asset would work** — Complex `page.evaluate` chains to construct a graph should use a premade JSON workflow in `browser_tests/assets/` loaded via `comfyPage.workflow.loadWorkflow()`.
+
+11. **Selectors not using `TestIds`** — Hard-coded `data-testid` strings should reference `browser_tests/fixtures/selectors.ts` when a matching entry exists. Check `selectors.ts` before flagging.
+
+### Convention Violations (Minor)
+
+12. **Missing test tags** — Every `test.describe` should have `tag` with at least one of: `@smoke`, `@slow`, `@screenshot`, `@canvas`, `@node`, `@widget`, `@mobile`, `@2x`. See `.claude/skills/writing-playwright-tests/SKILL.md` for when to use each.
+
+13. **`as any` type assertions** — Forbidden in E2E tests. Use specific type assertions or test-local type helpers. See `docs/guidance/playwright.md` for acceptable patterns.
+
+14. **Screenshot tests without masking dynamic content** — Timestamps, version numbers, or other non-deterministic content in screenshots will cause flakes. Use `mask` option.
+
+15. **`test.describe` without `afterEach` cleanup when canvas state changes** — Tests that manipulate canvas view (drag, zoom, pan) should include `afterEach` with `comfyPage.canvasOps.resetView()`.
+
+16. **Debug helpers left in committed code** — `debugAddMarker`, `debugAttachScreenshot`, `debugShowCanvasOverlay`, `debugGetCanvasDataURL` are for local debugging only.
+
+### Test Design (Nitpick)
+
+17. **Screenshot-only assertions where functional assertions are possible** — Prefer `expect(await node.isPinned()).toBe(true)` over screenshot comparison when testing non-visual behavior.
+
+18. **Overly large test workflows** — Test should load the minimal workflow needed. If a test only needs one node, don't load the full default graph.
+
+19. **Vue Nodes / LiteGraph mismatch** — If testing Vue-rendered node UI (DOM widgets, CSS states), should use `comfyPage.vueNodes.*`. If testing canvas interactions/connections, should use `comfyPage.nodeOps.*`. Mixing both in one test is a smell.
+
+## Rules
+
+- Only review `.spec.ts` files and supporting code in `browser_tests/`
+- Do NOT flag patterns in fixture/helper code (`browser_tests/fixtures/`) — those are shared infrastructure with different rules
+- "Major" for flakiness risks (items 1-7), "medium" for fixture misuse (8-11), "minor" for convention violations (12-16), "nitpick" for test design (17-19)
+- When flagging missing fixture usage (item 8), confirm the helper exists by checking the fixture code — don't assume
+- Existing tests that predate conventions are acceptable to modify but not required to fix