Use the Node.js version pinned in .node-version (24) and the pnpm version pinned in package.json, run pnpm install, and read AGENTS.md, DESIGN.md and docs/architecture.md before editing. Keep changes small and in scope; all code, UI copy and documentation are English.
Start PostgreSQL with docker compose up -d, then run pnpm db:migrate and pnpm db:seed. Before opening a pull request, run pnpm check, pnpm format:check, pnpm build and pnpm test:e2e. Pricing changes need unit tests that assert exact cents. Interface changes need desktop and mobile screenshots and a note on the loading, empty, error, read-only and conflict states you checked; document changes need a rendered PDF page.
Never commit real proposals, client data, credentials, customer code or build output. New dependencies require a demonstrated need and a license review. AI-assisted contributions require human review of the diff and the same verification as any other contribution.