root — a personal companion AI

A companion AI you chat with by text, voice, or image. It has a personality you configure, remembers things about you across conversations, and can reach out with proactive check-ins. Built to be cheap but not dumb.

Stack

• Next.js 16 (App Router) + TypeScript + Tailwind + shadcn/ui
• Supabase — Postgres + pgvector, Auth, Storage (all on the free tier to start)
• Vercel AI SDK v6 via Vercel AI Gateway (provider/model strings)
• Chat: anthropic/claude-haiku-4-5 (cheap-but-smart; one-line swap to Sonnet)
• Embeddings: openai/text-embedding-3-small for long-term memory
• Voice: OpenAI Whisper (STT) + gpt-4o-mini-tts (opt-in TTS)

Cost design

• Haiku 4.5 as the default chat model (~3× cheaper than Sonnet)
• The persona/system prompt is prompt-cached (cached prefix bills at ~0.1×)
• Memory injects only the top ~6 relevant facts per turn; history is trimmed
• Voice is opt-in (record to talk, tap to hear) — no always-on audio
• Runs entirely on Vercel Hobby + Supabase Free in development

Setup

1. Install: pnpm install
2. Supabase: create a project, then run the SQL in supabase/migrations/ (in order) via the SQL editor or supabase db push. This creates the schema, RLS policies, the match_memories / due_proactive_companions functions, and the private media storage bucket.
   • For quick local testing, disable email confirmation in Supabase → Authentication → Providers → Email.
3. Env: copy .env.example to .env.local and fill in:
   • NEXT_PUBLIC_SUPABASE_URL, NEXT_PUBLIC_SUPABASE_ANON_KEY, SUPABASE_SERVICE_ROLE_KEY
   • AI_GATEWAY_API_KEY (Vercel AI Gateway — auto-injected on Vercel)
   • OPENAI_API_KEY (voice)
   • CRON_SECRET (any long random string; protects the proactive cron)
4. Run: pnpm dev → http://localhost:3000

How it works

• app/(auth) — email/password auth via @supabase/ssr; proxy.ts guards routes.
• app/(app)/onboarding — create a companion (name, tone, traits, backstory, voice).
• app/(app)/chat/[companionId] — the chat surface (components/chat.tsx).
• app/api/chat — streamText with the cached persona, memory tools, and history trimming.
• lib/ai/memory.ts — embeddings + match_memories RPC for top-K retrieval.
• app/api/{transcribe,speak,upload} — voice in/out and image upload.
• app/api/cron/proactive — daily Vercel Cron that messages companions that are due.

Deploy

Deploy to Vercel, add the env vars (vercel env), and connect a Supabase integration or paste the keys. The cron in vercel.json runs daily (Hobby-tier compatible); bump it to hourly on Pro for finer-grained check-ins.