digigrow-apply

<!-- GSD:project-start source:PROJECT.md -->
## Project

**digigrow-apply v2 — Conversational Hiring Funnel**

`apply.digigrow.uk` is DigiGrow's hiring intake. **v2 replaces the existing 5-step form with a conversational AI interviewer** that gathers the same applicant information (and more) through natural chat, ships with the official DigiGrow brand identity, and runs as a long-lived Node container on Coolify instead of Cloudflare Pages. The applicant never sees a "form" — they have a guided conversation, save progress automatically, and complete the application from any device.

**Core Value:** **An applicant finishes the application and lands in GHL as a properly-scored, high-context candidate — without ever filling a traditional form.** If chat fails, scoring fails, or GHL sync fails, the product fails. Everything else (motion, polish, pattern art, latency) is in service of that.

### Constraints

- **Tech stack**: Next.js 16 App Router + React 19 + TypeScript 5.7 + Tailwind 4 + shadcn/ui + Radix — per global instructions, no deviation
- **Package manager**: pnpm (replacing the current `package-lock.json` on this repo)
- **Deployment**: Dockerfile (NOT docker-compose) on Coolify behind Traefik — per global infra rules
- **Database**: PostgreSQL with raw SQL + Alembic-style migrations (Drizzle or node-pg-migrate; decide in research phase)
- **Cache/queue**: Redis (self-hosted on Coolify, not Upstash, unless ops cost forces otherwise)
- **AI**: Model `MiniMax-M2.7-highspeed` via Anthropic-compatible endpoint at `https://api.minimax.io/anthropic`; `@anthropic-ai/sdk` only…

## Architectural Constraints
- **No custom fields on contact** — GHL custom field set is being reorganized by another AI agent, form deliberately avoids writing them. All narrative answers go in the Note instead.
- **One opportunity per contact per pipeline** — GHL enforces this. Re-applications delete old opp and create new one at "Application Received".
- **Static export + Wrangler** — Next.js builds to static HTML/CSS/JS, deployed via Wrangler alongside Pages Functions. No SSR.
- **Global Turnstile state** — Widget is mounted once on review step via browser global `window.turnstile`. Lazy-loads the Turnstile script via document.head.appendChild().
- **Rate limiting at edge** — Per-IP throttle using KV store, not in-memory. No persistence between requests.
- **Server-side validation mandatory** — Client-side validation is UX-friendly, but Pages Function re-validates everything with same Zod schema.
## Anti-Patterns
### Exposing GHL IDs in Browser
### Storing Secrets in Env Variables Without .env.local
### Multiple Opportunities Per Contact
### Skipping Server-Side Validation
## Error Handling
- **Validation errors (422):** Return field-level errors from Zod, client displays inline next to field
- **Auth/permissions errors (401, 403):** Not applicable (Pages Function has env-injected credentials)
- **Rate limit (429):** Per-IP throttle, return message "Slow down"
- **External service errors (502):** GHL API unreachable or returned error, return 502 with message "Could not create contact in CRM"
- **Client errors (400):** Bad JSON, missing Turnstile token, honeypot triggere…