# Contributing to Alfred

## Settings Management System

Alfred uses a **declarative, schema-based configuration system** that ensures type safety, validation, and maintainability.

### Architecture Overview

```
settings.toml          # Schema definitions (single source of truth)
    ↓
settings_schema.py     # Parser & validation
    ↓
settings_bootstrap.py  # Generation & resolution
    ↓
.env                   # Runtime configuration
.env.make              # Build variables for Makefile
    ↓
settings.py            # Pydantic Settings (runtime validation)
```

### Key Files

- **`settings.toml`** — Declarative schema for all settings
- **`alfred/settings_schema.py`** — Schema parser and validation logic
- **`alfred/settings_bootstrap.py`** — Bootstrap logic (generates `.env` and `.env.make`)
- **`alfred/settings.py`** — Pydantic Settings class (runtime)
- **`.env`** — Generated configuration file (gitignored)
- **`.env.make`** — Build variables for Makefile (gitignored)

### Setting Sources

Settings can come from different sources:

| Source | Description | Example |
|--------|-------------|---------|
| `toml` | From `pyproject.toml` | Version numbers, build config |
| `env` | From `.env` file | User-provided values, API keys |
| `generated` | Auto-generated secrets | JWT secrets, passwords |
| `computed` | Calculated from other settings | Database URIs |

### How to Add a New Setting

#### 1. Define in `settings.toml`

```toml
[tool.alfred.settings_schema.MY_NEW_SETTING]
type = "string"                    # string, integer, float, boolean, secret, computed
source = "env"                     # env, toml, generated, computed
default = "default_value"          # Optional: default value
description = "Description here"   # Required: clear description
category = "app"                   # app, api, database, security, build
required = true                    # Optional: default is true
validator = "range:1:100"          # Optional: validation rule
export_to_env_make = false         # Optional: export to .env.make for Makefile
```

#### 2. Regenerate Configuration

```bash
make bootstrap
```

This will:
- Read the schema from `settings.toml`
- Generate/update `.env` with the new setting
- Generate/update `.env.make` if `export_to_env_make = true`
- Preserve existing secrets

#### 3. Validate

```bash
make validate
```

This ensures all settings are valid according to the schema.

#### 4. Use in Code

The setting is automatically available in `settings.py`:

```python
from alfred.settings import settings

print(settings.my_new_setting)
```

### Setting Types

#### String Setting

```toml
[tool.alfred.settings_schema.API_URL]
type = "string"
source = "env"
default = "https://api.example.com"
description = "API base URL"
category = "api"
```

#### Integer Setting with Validation

```toml
[tool.alfred.settings_schema.MAX_RETRIES]
type = "integer"
source = "env"
default = 3
description = "Maximum retry attempts"
category = "app"
validator = "range:1:10"
```

#### Secret (Auto-generated)

```toml
[tool.alfred.settings_schema.API_SECRET]
type = "secret"
source = "generated"
secret_rule = "32:b64"  # 32 bytes, base64 encoded
description = "API secret key"
category = "security"
```

Secret rules:
- `"32:b64"` — 32 bytes, URL-safe base64
- `"16:hex"` — 16 bytes, hexadecimal

#### Computed Setting

```toml
[tool.alfred.settings_schema.DATABASE_URL]
type = "computed"
source = "computed"
compute_from = ["DB_HOST", "DB_PORT", "DB_NAME"]
compute_template = "postgresql://{DB_HOST}:{DB_PORT}/{DB_NAME}"
description = "Database connection URL"
category = "database"
```

#### From TOML (Build Variables)

```toml
[tool.alfred.settings_schema.APP_VERSION]
type = "string"
source = "toml"
toml_path = "tool.poetry.version"
description = "Application version"
category = "build"
export_to_env_make = true  # Available in Makefile
```

### Validators

Available validators:

- **`range:min:max`** — Numeric range validation
  ```toml
  validator = "range:0.0:2.0"  # For floats
  validator = "range:1:100"    # For integers
  ```

### Categories

Organize settings by category:

- **`app`** — Application settings
- **`api`** — API keys and external services
- **`database`** — Database configuration
- **`security`** — Secrets and security keys
- **`build`** — Build-time configuration

### Best Practices

1. **Always add a description** — Make it clear what the setting does
2. **Use appropriate types** — Don't use strings for numbers
3. **Add validation** — Use validators for numeric ranges
4. **Categorize properly** — Helps with organization
5. **Use computed settings** — For values derived from others (e.g., URIs)
6. **Mark secrets as generated** — Let the system handle secret generation
7. **Export build vars** — Set `export_to_env_make = true` for Makefile variables

### Workflow Example

```bash
# 1. Edit settings.toml
vim settings.toml

# 2. Regenerate configuration
make bootstrap

# 3. Validate
make validate

# 4. Test
python -c "from alfred.settings import settings; print(settings.my_new_setting)"

# 5. Commit (settings.toml only, not .env)
git add settings.toml
git commit -m "Add MY_NEW_SETTING"
```

### Commands

```bash
make bootstrap  # Generate .env and .env.make from schema
make validate   # Validate all settings against schema
make help       # Show all available commands
```

### Troubleshooting

**Setting not found in schema:**
```
KeyError: Missing [tool.alfred.settings_schema] section
```
→ Check that `settings.toml` exists and has the correct structure

**Validation error:**
```
ValueError: MY_SETTING must be between 1 and 100, got 150
```
→ Check the validator in `settings.toml` and adjust the value in `.env`

**Secret not preserved:**
→ Secrets are automatically preserved during `make bootstrap`. If lost, they were never in `.env` (check `.env` exists before running bootstrap)

### Testing

When adding a new setting, consider adding tests:

```python
# tests/test_settings_schema.py
def test_my_new_setting(self, create_schema_file):
    """Test MY_NEW_SETTING definition."""
    schema_toml = """
[tool.alfred.settings_schema.MY_NEW_SETTING]
type = "string"
source = "env"
default = "test"
"""
    base_dir = create_schema_file(schema_toml)
    schema = load_schema(base_dir)

    definition = schema.get("MY_NEW_SETTING")
    assert definition.default == "test"
```

### Migration from Old System

If you're migrating from the old system:

1. Settings are now in `settings.toml` instead of scattered across files
2. No more `.env.example` — schema is the source of truth
3. Secrets are auto-generated and preserved
4. Validation happens at bootstrap time, not just runtime

---

## Questions?

Open an issue or check the existing settings in `settings.toml` for examples.