Operational Lesson: Always Screenshot During Frontend Testing (2026-04-06)

## Rule
Any step involving frontend testing, visual QA, or agentic browser viewing MUST capture screenshots and save them to the server. Screenshots are evidence — without them, visual validation is unverifiable and claims of "all routes 200" or "visual QA 93/100" lack proof.

## Implementation
- Save to: `static-site/screenshots/` (browsable at cms.chem.dev/ref/screenshots/) or `handoffs/screenshots/`
- Filename format: `YYYY-MM-DD_route-name_status.png` (e.g., `2026-04-06_dashboard_200.png`)
- Capture method: Playwright MCP `screenshot` tool, or headless browser via CLI
- Capture at minimum: every route after deploy, any visual regression check, any component showcase

## Added To
- CLAUDE.md Milestone/Decision Loop step 4 (of 5): QUERY → PROCEED → DEPLOY → SCREENSHOT → PUSH
- MEMORY.md Lessons Learned
- This brain source