---
id: T02
parent: S01
milestone: M001
provides: []
requires: []
affects: []
key_files: ["backend/models.py", "backend/database.py", "alembic/versions/001_initial.py", "alembic/env.py", "alembic.ini", "alembic/script.py.mako", "docker-compose.yml", ".gsd/KNOWLEDGE.md"]
key_decisions: ["Renamed relationship import to sa_relationship to avoid name clash with RelatedTechniqueLink.relationship column", "POSTGRES_PASSWORD default changed from :? to :-changeme to fix docker compose config validation without .env", "Separate enum names for key_moment_content_type vs content_type and page_review_status vs review_status to avoid PostgreSQL enum name collisions"]
patterns_established: []
drill_down_paths: []
observability_surfaces: []
duration: ""
verification_result: "docker compose config exits 0 (fixed from failing state). alembic upgrade head runs successfully against PostgreSQL 16-alpine test container. All 7 tables confirmed via \dt. Column types, constraints, indexes, and FK relationships verified via \d for all tables. alembic current confirms head at 001_initial."
completed_at: 2026-03-29T21:48:33.781Z
blocker_discovered: false
---

# T02: Created SQLAlchemy models for all 7 entities, Alembic async migration infrastructure, and initial migration with full PostgreSQL schema; fixed docker compose config validation failure

> Created SQLAlchemy models for all 7 entities, Alembic async migration infrastructure, and initial migration with full PostgreSQL schema; fixed docker compose config validation failure

## What Happened
---
id: T02
parent: S01
milestone: M001
key_files:
  - backend/models.py
  - backend/database.py
  - alembic/versions/001_initial.py
  - alembic/env.py
  - alembic.ini
  - alembic/script.py.mako
  - docker-compose.yml
  - .gsd/KNOWLEDGE.md
key_decisions:
  - Renamed relationship import to sa_relationship to avoid name clash with RelatedTechniqueLink.relationship column
  - POSTGRES_PASSWORD default changed from :? to :-changeme to fix docker compose config validation without .env
  - Separate enum names for key_moment_content_type vs content_type and page_review_status vs review_status to avoid PostgreSQL enum name collisions
duration: ""
verification_result: passed
completed_at: 2026-03-29T21:48:33.782Z
blocker_discovered: false
---

# T02: Created SQLAlchemy models for all 7 entities, Alembic async migration infrastructure, and initial migration with full PostgreSQL schema; fixed docker compose config validation failure

**Created SQLAlchemy models for all 7 entities, Alembic async migration infrastructure, and initial migration with full PostgreSQL schema; fixed docker compose config validation failure**

## What Happened

Created backend/database.py with async SQLAlchemy engine, session factory, and declarative base. Created backend/models.py with all 7 entities from chrysopedia-spec.md §6.1: Creator, SourceVideo, TranscriptSegment, KeyMoment, TechniquePage, RelatedTechniqueLink, and Tag. Each model uses UUID primary keys with gen_random_uuid(), proper FK constraints (CASCADE deletes, SET NULL for technique_page_id), PostgreSQL-native types (ARRAY, JSONB), and 7 custom enum types. Set up Alembic with async support and wrote the initial migration 001_initial.py. Also fixed the T01 verification failure by changing POSTGRES_PASSWORD from :? (required) to :-changeme default in docker-compose.yml.

## Verification

docker compose config exits 0 (fixed from failing state). alembic upgrade head runs successfully against PostgreSQL 16-alpine test container. All 7 tables confirmed via \dt. Column types, constraints, indexes, and FK relationships verified via \d for all tables. alembic current confirms head at 001_initial.

## Verification Evidence

| # | Command | Exit Code | Verdict | Duration |
|---|---------|-----------|---------|----------|
| 1 | `docker compose config > /dev/null 2>&1` | 0 | ✅ pass | 500ms |
| 2 | `DATABASE_URL=postgresql+asyncpg://chrysopedia:testpass@localhost:5434/chrysopedia alembic upgrade head` | 0 | ✅ pass | 2000ms |
| 3 | `docker exec chrysopedia-test-db psql -U chrysopedia -d chrysopedia -c '\dt'` | 0 | ✅ pass | 200ms |
| 4 | `alembic current` | 0 | ✅ pass | 500ms |


## Deviations

Fixed docker-compose.yml POSTGRES_PASSWORD from :? to :-changeme default — this was a T01 bug causing slice verification failure. canonical_tags.yaml already existed from T01.

## Known Issues

None.

## Files Created/Modified

- `backend/models.py`
- `backend/database.py`
- `alembic/versions/001_initial.py`
- `alembic/env.py`
- `alembic.ini`
- `alembic/script.py.mako`
- `docker-compose.yml`
- `.gsd/KNOWLEDGE.md`


## Deviations
Fixed docker-compose.yml POSTGRES_PASSWORD from :? to :-changeme default — this was a T01 bug causing slice verification failure. canonical_tags.yaml already existed from T01.

## Known Issues
None.
