# CLAUDE.md — Padelnomics

This file tells Claude Code how to work in this repository.

## Project Overview

Padelnomics is a SaaS application built with Quart (async Python), HTMX, and SQLite.

It includes a full data pipeline:

```
External APIs → extract → landing zone → SQLMesh transform → DuckDB → web app
```


**Packages** (uv workspace):
- `web/` — Quart + HTMX web application (auth, billing, dashboard)

- `extract/padelnomics_extract/` — data extraction to local landing zone
- `transform/sqlmesh_padelnomics/` — 4-layer SQL transformation (raw → staging → foundation → serving)
- `src/padelnomics/` — CLI utilities, export_serving helper


## Skills: invoke these for domain tasks

### Working on extraction or transformation?

Use the **`data-engineer`** skill for:
- Designing or reviewing SQLMesh model logic
- Adding a new data source (extract + raw + staging models)
- Performance tuning DuckDB queries
- Data modeling decisions (dimensions, facts, aggregates)
- Understanding the 4-layer architecture

```
/data-engineer  (or ask Claude to invoke it)
```


### Working on the web app UI or frontend?

Use the **`frontend-design`** skill for UI components, templates, or dashboard layouts.

### Working on payments or subscriptions?

Use the **`paddle-integration`** skill for billing, webhooks, and subscription logic.

## Key commands

```bash
# Install all dependencies
uv sync --all-packages

# Lint & format
ruff check .
ruff format .

# Run tests
uv run pytest tests/ -v

# Dev server
./scripts/dev_run.sh

# Extract data
LANDING_DIR=data/landing uv run extract

# SQLMesh plan + run (from repo root)
uv run sqlmesh -p transform/sqlmesh_padelnomics plan
uv run sqlmesh -p transform/sqlmesh_padelnomics plan prod

# Export serving tables (run after SQLMesh)
DUCKDB_PATH=local.duckdb SERVING_DUCKDB_PATH=analytics.duckdb \
    uv run python -m padelnomics.export_serving

```

## Architecture documentation

| Topic | File |
|-------|------|
| Extraction patterns, state tracking, adding new sources | `extract/padelnomics_extract/README.md` |
| 4-layer SQLMesh architecture, materialization strategy | `transform/sqlmesh_padelnomics/README.md` |
| Two-file DuckDB architecture (SQLMesh lock isolation) | `src/padelnomics/export_serving.py` docstring |

## Pipeline data flow

```
data/landing/
  └── padelnomics/{year}/{etag}.csv.gz   ← extraction output

local.duckdb                ← SQLMesh exclusive (raw → staging → foundation → serving)

analytics.duckdb            ← serving tables only, web app read-only
  └── serving.*             ← atomically replaced by export_serving.py
```

## Environment variables

| Variable | Default | Description |
|----------|---------|-------------|
| `LANDING_DIR` | `data/landing` | Landing zone root (extraction writes here) |
| `DUCKDB_PATH` | `local.duckdb` | SQLMesh pipeline DB (exclusive write) |
| `SERVING_DUCKDB_PATH` | `analytics.duckdb` | Read-only DB for web app |


## Coding philosophy

- **Simple and procedural** — functions over classes, no "Manager" patterns
- **Idempotent operations** — running twice produces the same result
- **Explicit assertions** — assert preconditions at function boundaries
- **Bounded operations** — set timeouts, page limits, buffer sizes

Read `coding_philosophy.md` (if present) for the full guide.