# CLAUDE.md

Working context for Claude Code on the Analytics Portfolio project.

---

## Project Status

**Current Sprint**: 1 (Project Bootstrap)
**Phase**: 1 - Toronto Housing Dashboard
**Branch**: `development` (feature branches merge here)

---

## Quick Reference

### Run Commands

```bash
make setup          # Install deps, create .env, init pre-commit
make docker-up      # Start PostgreSQL + PostGIS
make docker-down    # Stop containers
make db-init        # Initialize database schema
make run            # Start Dash dev server
make test           # Run pytest
make lint           # Run ruff linter
make format         # Run ruff formatter
make ci             # Run all checks
```

### Branch Workflow

1. Create feature branch FROM `development`: `git checkout -b feature/{sprint}-{description}`
2. Work and commit on feature branch
3. Merge INTO `development` when complete
4. `development` -> `staging` -> `main` for releases

---

## Code Conventions

### Import Style

| Context | Style | Example |
|---------|-------|---------|
| Same directory | Single dot | `from .trreb import TRREBParser` |
| Sibling directory | Double dot | `from ..schemas.trreb import TRREBRecord` |
| External packages | Absolute | `import pandas as pd` |

### Module Responsibilities

| Directory | Contains | Purpose |
|-----------|----------|---------|
| `schemas/` | Pydantic models | Data validation |
| `models/` | SQLAlchemy ORM | Database persistence |
| `parsers/` | PDF/CSV extraction | Raw data ingestion |
| `loaders/` | Database operations | Data loading |
| `figures/` | Chart factories | Plotly figure generation |
| `callbacks/` | Dash callbacks | In `pages/{dashboard}/callbacks/` |
| `errors/` | Exceptions + handlers | Error handling |

### Type Hints

Use Python 3.10+ style:
```python
def process(items: list[str], config: dict[str, int] | None = None) -> bool:
    ...
```

### Error Handling

```python
# errors/exceptions.py
class PortfolioError(Exception):
    """Base exception."""

class ParseError(PortfolioError):
    """PDF/CSV parsing failed."""

class ValidationError(PortfolioError):
    """Pydantic or business rule validation failed."""

class LoadError(PortfolioError):
    """Database load operation failed."""
```

### Code Standards

- Single responsibility functions with verb naming
- Early returns over deep nesting
- Google-style docstrings only for non-obvious behavior
- Module-level constants for magic values
- Pydantic BaseSettings for runtime config

---

## Application Structure

```
portfolio_app/
├── app.py                    # Dash app factory with Pages routing
├── config.py                 # Pydantic BaseSettings
├── assets/                   # CSS, images (auto-served)
├── pages/
│   ├── home.py              # Bio landing page -> /
│   └── toronto/
│       ├── dashboard.py     # Layout only -> /toronto
│       └── callbacks/       # Interaction logic
├── components/              # Shared UI (navbar, footer, cards)
├── figures/                 # Shared chart factories
├── toronto/                 # Toronto data logic
│   ├── parsers/
│   ├── loaders/
│   ├── schemas/             # Pydantic
│   └── models/              # SQLAlchemy
└── errors/
```

### URL Routing

| URL | Page | Sprint |
|-----|------|--------|
| `/` | Bio landing page | 2 |
| `/toronto` | Toronto Housing Dashboard | 6 |

---

## Tech Stack (Locked)

| Layer | Technology | Version |
|-------|------------|---------|
| Database | PostgreSQL + PostGIS | 16.x |
| Validation | Pydantic | >=2.0 |
| ORM | SQLAlchemy | >=2.0 (2.0-style API only) |
| Transformation | dbt-postgres | >=1.7 |
| Data Processing | Pandas | >=2.1 |
| Geospatial | GeoPandas + Shapely | >=0.14 |
| Visualization | Dash + Plotly | >=2.14 |
| UI Components | dash-mantine-components | Latest stable |
| Testing | pytest | >=7.0 |
| Python | 3.11+ | Via pyenv |

**Notes**:
- SQLAlchemy 2.0 + Pydantic 2.0 only (never mix 1.x APIs)
- PostGIS extension required in database
- Docker Compose V2 format (no `version` field)

---

## Data Model Overview

### Geographic Reality (Toronto Housing)

```
TRREB Districts (~35)     - Purchase data (W01, C01, E01...)
CMHC Zones (~20)          - Rental data (Census Tract aligned)
City Neighbourhoods (158) - Enrichment/overlay only
```

**Critical**: These geographies do NOT align. Display as separate layers—do not force crosswalks.

### Star Schema

| Table | Type | Keys |
|-------|------|------|
| `fact_purchases` | Fact | -> dim_time, dim_trreb_district |
| `fact_rentals` | Fact | -> dim_time, dim_cmhc_zone |
| `dim_time` | Dimension | date_key (PK) |
| `dim_trreb_district` | Dimension | district_key (PK), geometry |
| `dim_cmhc_zone` | Dimension | zone_key (PK), geometry |
| `dim_neighbourhood` | Dimension | neighbourhood_id (PK), geometry |
| `dim_policy_event` | Dimension | event_id (PK) |

**V1 Rule**: `dim_neighbourhood` has NO FK to fact tables—reference overlay only.

### dbt Layers

| Layer | Naming | Purpose |
|-------|--------|---------|
| Staging | `stg_{source}__{entity}` | 1:1 source, cleaned, typed |
| Intermediate | `int_{domain}__{transform}` | Business logic |
| Marts | `mart_{domain}` | Final analytical tables |

---

## DO NOT BUILD (Phase 1)

**Stop and flag if a task seems to require these**:

| Feature | Reason |
|---------|--------|
| `bridge_district_neighbourhood` table | Area-weighted aggregation is Phase 4 |
| Crime data integration | Deferred to Phase 4 |
| Historical boundary reconciliation (140->158) | 2021+ data only for V1 |
| ML prediction models | Energy project scope (Phase 3) |
| Multi-project shared infrastructure | Build first, abstract second (Phase 2) |

---

## Sprint 1 Deliverables

| Category | Tasks |
|----------|-------|
| **Bootstrap** | Git init, pyproject.toml, .env.example, Makefile, CLAUDE.md |
| **Infrastructure** | Docker Compose (PostgreSQL + PostGIS), scripts/ directory |
| **App Foundation** | portfolio_app/ structure, config.py, error handling |
| **Tests** | tests/ directory, conftest.py, pytest config |
| **Data Acquisition** | Download TRREB PDFs, START boundary digitization (HUMAN task) |

### Human Tasks (Cannot Automate)

| Task | Tool | Effort |
|------|------|--------|
| Digitize TRREB district boundaries | QGIS | 3-4 hours |
| Research policy events (10-20) | Manual | 2-3 hours |
| Replace social link placeholders | Manual | 5 minutes |

---

## Environment Variables

Required in `.env`:

```bash
DATABASE_URL=postgresql://user:pass@localhost:5432/portfolio
POSTGRES_USER=portfolio
POSTGRES_PASSWORD=<secure>
POSTGRES_DB=portfolio
DASH_DEBUG=true
SECRET_KEY=<random>
LOG_LEVEL=INFO
```

---

## Script Standards

All scripts in `scripts/`:
- Include usage comments at top
- Idempotent where possible
- Exit codes: 0 = success, 1 = error
- Use `set -euo pipefail` for bash
- Log to stdout, errors to stderr

---

## Reference Documents

| Document | Location | Use When |
|----------|----------|----------|
| Full specification | `docs/PROJECT_REFERENCE.md` | Architecture decisions |
| Data schemas | `docs/toronto_housing_dashboard_spec_v5.md` | Parser/model tasks |
| WBS details | `docs/wbs_sprint_plan_v4.md` | Sprint planning |

---

*Last Updated: Sprint 1*
