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Overview

The configuration manager handles loading and merging settings from multiple sources with a well-defined precedence order. It supports TOML configuration files, environment variables, and .env files. Source: docugen/utils/config_manager.py

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RuntimeConfig

@dataclass(frozen=True)
class RuntimeConfig:
    api_key: str
    model: str
    output: str
Immutable dataclass containing resolved runtime configuration.

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Fields

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api_key
str
required
Gemini API key for authentication. Must be set via environment variable or .env file.
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model
str
required
Gemini model identifier (e.g., "gemini-2.0-flash-exp"). Falls back to DEFAULT_MODEL if not specified.
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output
str
required
Output file path for generated documentation. Defaults to "README.md".

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Example

from docugen.utils.config_manager import RuntimeConfig

config = RuntimeConfig(
    api_key="your-api-key",
    model="gemini-2.0-flash-exp",
    output="docs/README.md"
)

print(config.api_key)  # "your-api-key"
print(config.model)    # "gemini-2.0-flash-exp"

# Config is immutable
# config.model = "other"  # Raises FrozenInstanceError

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load_runtime_config()

def load_runtime_config(
    cli_model: str | None,
    cli_output: str | None,
    config_path: Path | None = None
) -> RuntimeConfig
Load and merge configuration from all available sources.

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Parameters

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cli_model
str | None
required
Model name from CLI argument (--model). Takes highest precedence if provided.
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cli_output
str | None
required
Output path from CLI argument (--output). Takes highest precedence if provided.
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config_path
Path | None
default:"None"
Explicit path to TOML config file. If provided, only this file is checked (skips automatic discovery).

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Returns

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return
RuntimeConfig
Fully resolved configuration with all settings merged according to precedence rules.

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Configuration Precedence

Settings are loaded in order from lowest to highest priority:
  1. Default values - Hardcoded fallbacks (DEFAULT_MODEL, "README.md")
  2. TOML config files - Searched in order:
    • ~/.docugen.toml
    • ~/.config/docugen/config.toml
    • ./.docugen.toml (current directory)
    • $DOCUGEN_CONFIG environment variable path
    • Explicit config_path parameter
  3. Environment variables & .env files - For API key only:
    • .env in project root
    • .env in current directory
    • $DOCUGEN_DOTENV environment variable path
    • $GEMINI_API_KEY environment variable
  4. CLI arguments - Highest priority (overrides all other sources)

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Example

from pathlib import Path
from docugen.utils.config_manager import load_runtime_config

# Load with CLI overrides
config = load_runtime_config(
    cli_model="gemini-2.0-flash-thinking-exp",
    cli_output="OUTPUT.md",
    config_path=Path("custom-config.toml")
)

print(config.model)   # "gemini-2.0-flash-thinking-exp" (from CLI)
print(config.output)  # "OUTPUT.md" (from CLI)
print(config.api_key) # Loaded from env or .env file

# Load with defaults and config file discovery
config = load_runtime_config(
    cli_model=None,
    cli_output=None
)
# Uses values from discovered config files or defaults

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TOML Configuration Format

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Basic Format

model = "gemini-2.0-flash-exp"
output = "docs/README.md"

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Nested Format (with [docugen] section)

[docugen]
model = "gemini-2.0-flash-thinking-exp"
output = "documentation.md"
Both formats are supported. The nested format allows other tools to share the same config file. Settings in the [docugen] section override top-level settings.

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Environment Variables

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API Key Resolution

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GEMINI_API_KEY
string
Gemini API key. Checked in environment first, then in .env files.

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Configuration Paths

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DOCUGEN_CONFIG
string
Path to custom TOML config file. Overrides automatic discovery.
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DOCUGEN_DOTENV
string
Path to custom .env file. If not set, searches current directory and project root.

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Example .env File

# .env
GEMINI_API_KEY=your-api-key-here

# With export prefix (also supported)
export GEMINI_API_KEY="your-api-key-here"

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Configuration Discovery

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TOML Config Search Order

  1. config_path parameter (if provided) - stops searching if found
  2. $DOCUGEN_CONFIG environment variable
  3. ./.docugen.toml (current directory)
  4. ~/.config/docugen/config.toml
  5. ~/.docugen.toml (home directory)
All existing files are loaded and merged, with later files overriding earlier ones.

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.env File Search Order

  1. $DOCUGEN_DOTENV environment variable
  2. ./.env (current directory)
  3. <project-root>/.env
First file with GEMINI_API_KEY is used; searching stops after first match.

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