# Phase 14: PostgreSQL Migration - Context

**Gathered:** 2026-04-04
**Status:** Ready for planning

<domain>
## Phase Boundary

Replace SQLite with PostgreSQL as the sole database. Make all database operations async. Establish PGlite-based test infrastructure. Provide a one-time data migration script and Docker Compose for local Postgres development.

</domain>

<decisions>
## Implementation Decisions

### Migration Strategy
- **D-01:** Clean rewrite of `src/db/schema.ts` using `drizzle-orm/pg-core` (pgTable, serial, text, numeric, timestamp, etc.) — not a conversion of the SQLite schema
- **D-02:** Start fresh Postgres migration history in a new directory (e.g., `drizzle-pg/`) — keep existing `drizzle/` SQLite migrations archived for reference
- **D-03:** `src/db/index.ts` switches from `bun:sqlite` + `drizzle-orm/bun-sqlite` to `drizzle-orm/node-postgres` (or `drizzle-orm/postgres-js`) with async connection

### Data Migration Script
- **D-04:** Standalone TypeScript script (e.g., `scripts/migrate-sqlite-to-postgres.ts`) that reads from SQLite file and writes to Postgres — not a Drizzle migration
- **D-05:** Script handles type conversions: integer timestamps → proper Postgres `timestamp` columns, `real` weight → `numeric` or `double precision`, text → text
- **D-06:** Script preserves all IDs and foreign key relationships — no ID remapping

### Test Infrastructure
- **D-07:** `createTestDb()` returns an async PGlite-backed Drizzle instance — same API shape as current, but async
- **D-08:** Per-test fresh PGlite instance with migrations applied (matches current in-memory SQLite pattern, avoids test pollution)
- **D-09:** All service and route tests updated from sync to async database operations

### Docker Compose
- **D-10:** Separate `docker-compose.dev.yml` for development with Postgres service — keep existing `docker-compose.yml` for production (updated to include Postgres)
- **D-11:** PostgreSQL 16 (latest stable)
- **D-12:** Environment variable `DATABASE_URL` for Postgres connection string (replaces `DATABASE_PATH` for SQLite)

### Claude's Discretion
- Drizzle Postgres driver choice (`node-postgres` vs `postgres-js`) — pick based on Bun compatibility and async performance
- PGlite configuration details (version, extensions)
- Column type mapping specifics beyond the ones called out (e.g., whether to use `serial` vs `integer().primaryKey()`)
- Migration script error handling and progress reporting
- Whether to use `drizzle-orm/pglite` driver or generic pg driver for tests

</decisions>

<canonical_refs>
## Canonical References

**Downstream agents MUST read these before planning or implementing.**

### Database Schema & Config
- `src/db/schema.ts` — Current SQLite schema (source of truth for tables/columns to migrate)
- `src/db/index.ts` — Current database initialization (bun:sqlite + drizzle)
- `drizzle.config.ts` — Current Drizzle Kit config (sqlite dialect)
- `drizzle/` — Existing SQLite migration files (10 migrations, reference only)

### Test Infrastructure
- `tests/helpers/db.ts` — Current test database helper (in-memory SQLite, migration application, seed)

### Services (all need sync → async)
- `src/server/services/*.ts` — 9 service files that use synchronous Drizzle operations
- `src/server/routes/*.ts` — 9 route files that call services

### Tests (all need updating)
- `tests/services/*.test.ts` — 9 service test files
- `tests/routes/*.test.ts` — 8 route test files
- `tests/mcp/tools.test.ts` — MCP tools test

### Docker
- `docker-compose.yml` — Current production compose (SQLite volumes, no Postgres)

</canonical_refs>

<code_context>
## Existing Code Insights

### Reusable Assets
- Drizzle ORM already in use — schema definition pattern transfers directly to pg-core
- Service layer architecture with DI (db as first param) — makes swapping the db instance straightforward
- Zod schemas in `src/shared/schemas.ts` — validation layer is database-agnostic, no changes needed
- TanStack Query hooks — frontend is fully decoupled from database, no changes needed

### Established Patterns
- **Service DI pattern**: All services take `db` as first parameter — this means swapping SQLite for Postgres only requires changing what `db` is, not how services use it
- **Sync Drizzle calls**: Current code uses `.run()`, `.get()`, `.all()` synchronously — Postgres requires `.execute()` / await on all queries
- **Test pattern**: `createTestDb()` creates isolated DB, applies migrations, seeds — same pattern works with PGlite
- **Timestamps as integers**: `{ mode: "timestamp" }` on integer columns — Postgres can use native `timestamp` type

### Integration Points
- `src/db/index.ts` — Single point of database creation (good: only one file to change for connection)
- `src/server/index.ts` — Where db is provided to Hono context via middleware
- `tests/helpers/db.ts` — Single test DB factory (good: only one file to change for test infra)
- `drizzle.config.ts` — Needs dialect change from sqlite to postgresql

</code_context>

<specifics>
## Specific Ideas

No specific requirements — open to standard approaches for SQLite-to-Postgres migration with Drizzle ORM.

</specifics>

<deferred>
## Deferred Ideas

None — discussion stayed within phase scope

</deferred>

---

*Phase: 14-postgresql-migration*
*Context gathered: 2026-04-04*
