Inspect the local surface before changing code:
- Packages: react-email (components + CLI + render), optional @react-email/editor, @react-email/ui, peers react / react-dom 18+. CLI needs Node 20.19+.
- Legacy installs still on @react-email/components or renderAsync → treat as a v5→v6 migration (see setup-cli.md).
- Emails directory (default emails/), static/ assets, email script, shared Tailwind config if any.
- How mail is sent: render + ESP HTML, Resend react: prop, or static email export.
Refresh docs when versions are unclear or work touches Tailwind 4 email behavior, the editor, monorepos, or major upgrades. Start from source-map.md.
Route deeper detail:
- Install, CLI, monorepo, PreviewProps, static files: setup-cli.md.
- Components API and structure: components.md.
- Tailwind, pixelBasedPreset, client CSS limits: styling.md.
- render, plain text, ESP integrations: render-send.md.
- Embeddable TipTap editor: editor.md.
- i18n and common template shapes: patterns.md.
Prefer the project's existing email folder layout, brand tokens, and ESP. Do not invent a second emails package unless asked.
Verify the smallest useful surface (preview, render smoke, typecheck, send dry-run).

Core Judgment

Import components and render from react-email, not @react-email/components (removed as the primary entry in v6).
render is async. Never use renderAsync (removed). Prefer await render(<Email />) at send time over email export unless a non-JS backend forces static HTML.
Style with <Tailwind config={{ presets: [pixelBasedPreset] }}> — email clients do not support rem. Avoid flex/grid, sm:/md:/dark: utilities, SVG/WEBP images.
Structure: <Html> → <Tailwind> → <Head /> → <Body> with <Preview> first inside <Body>. One <Container> for the main column (~600px / max-w-xl). Use Section / Row / Column for layout tables.
Buttons need box-border. Borders need an explicit style (border-solid). Linked images need meaningful alt (never decorative-empty alt on a link).
Props are TypeScript — never put ESP mustache ({{name}}) in JSX. If a host requires mustache samples, put them only in .PreviewProps.
Images: absolute CDN URLs in production; local emails/static/ only works in email dev. Gate with a production base URL env.
Always ship HTML and plain text (render(..., { plainText: true }) or ESP auto-plaintext). Keep HTML under ~102KB (Gmail clip).
Use verified sending domains. Prefer bun / bunx in command examples.

Clarifying Before New Templates

If the user did not specify brand/assets, ask briefly (or proceed with placeholders they can swap):

Prefer repository-owned commands. Cover the relevant subset:

bun pm ls react-email (and @react-email/editor / @react-email/ui if used).
bun run email / bunx email dev --dir emails — preview compiles and PreviewProps render.
await render(<Template {...props} />) and optional { plainText: true } smoke in a script or test.
Typecheck template props and default exports.
ESP dry-run or sandbox send when changing send paths (Resend react:, Nodemailer html, etc.).
Client spot-check notes for Outlook/Gmail when layout or borders change.

Report which checks ran, which did not, and version assumptions that remain.