# Hardening Fixes

## Architectural Decisions

### Canonical migration runner
`server/plugins/migrate.ts` is the canonical migration runner (Nitro plugin, runs on server start). `server/db/migrate.ts` is the standalone CLI script kept for manual use via `npm run db:migrate`, but the plugin is authoritative.

### SQLite
Appropriate for single-user/small-team. For multi-user production, evaluate PostgreSQL with Drizzle's pg adapter.

### Audio serving
Currently served from `/public/audio`. To complete the private audio migration:
1. Move audio generation output directory from `public/audio` to `private/audio`
2. Update all `audioPath` values stored in lesson content JSON — paths are stored as `/audio/...` and need to become `/api/audio/...`
3. This requires a one-time data migration script

### inFlightCourses Set
In-process only — does not survive server restarts. For multi-process deployments, use a DB flag or Redis.

### Per-topic mutex
Same limitation — in-process only.

---

## .env git history
`git log --all -- .env` returned no output — `.env` has never been committed to this repository. No key rotation required.

---

## Rate limiting
Not yet implemented. Marked for manual addition via a Nitro middleware using a simple Map-based token bucket.

---

## Cost tracking
`costAI` and `costAudio` fields are estimated values based on API-reported costs. Reconcile against OpenRouter and TTS provider dashboards monthly.

---

## Items that could NOT be fixed automatically

- **Full audio path migration** (public → private/audio + updating stored JSON paths): requires a one-time data migration script
- **Drizzle migration for ON DELETE CASCADE on foreign keys**: SQLite doesn't support `ALTER TABLE ... ADD FOREIGN KEY`, so CASCADE would require recreating all tables. Recommend doing this on next schema version if needed.
- **Full composable extraction from `learn/[id]/index.vue`** (`useLessonState`, `useFocusMode`, `useBranchPoll`): architectural refactor deferred, not a correctness issue.
- **Prompt versioning** (`server/prompts/` directory): deferred, not a correctness issue.
- **Full consola migration**: deferred tech debt.