FeedTLDR — agent guardrails

Start with these three, in order. They are guardrails, not suggestions.

docs/ENGINEERING.md — how code is written here: clean-code baseline, modularity and layering, tokens-only styling, component reuse, enforcement.
CLAUDE.md — what the project is, hard rules, commands, Firestore shape.
docs/DESIGN.md — the design system every pixel follows.

Per-app detail lives in apps/web/AGENTS.md and apps/api/AGENTS.md.

The short version

Reuse before you create. A token, a shadcn primitive, a composite, a hook, a service function — search for it before writing a new one.
No hard-coded design values in apps/web. Colours, radii, shadows, easings, type sizes and widths come from tokens in app/globals.css. pnpm check:tokens enforces it and runs in CI.
No hand-rolled primitives. If shadcn ships it, add it and restyle through tokens (swapping lucide imports for Phosphor).
Layering holds. Web: pages compose, hooks fetch, components/ui/ knows nothing about the product. API: routers are thin, services never import fastapi, backend/ and config/ are frozen.
One thing per function, intention-revealing names, no magic values.

cd apps/web && pnpm lint && pnpm typecheck && pnpm check:tokens
cd apps/api && uv run pytest -q