feat: auto generate config file on first run

Author: qduc

README.md

@@ -107,6 +107,17 @@ export CODE_RAG_CHUNK_SIZE="2048"
 export CODE_RAG_ADDITIONAL_IGNORE_PATTERNS="*.tmp,*.bak,logs/"
 ```
 
+
+### Configuration Files
+
+Code-RAG looks for configuration in the following order (first found wins):
+
+1. `CODE_RAG_CONFIG_FILE` environment variable
+2. `code-rag.config` in the current directory (project-specific)
+3. `~/.config/code-rag/config` (user-global)
+   - **Auto-created with default values** if it doesn't exist.
+4. Shell environment variables (highest priority - these override files)
+
 Full configuration options in [docs/IMPLEMENTATION.md](docs/IMPLEMENTATION.md#configuration-system).
 
 ## How It Works

src/config/config.py

@@ -5,15 +5,65 @@
 
 from dotenv import load_dotenv
 
-env_path = Path(__file__).resolve().parent.parent.parent / ".env"
-load_dotenv(env_path)
+DEFAULT_CONFIG = """# Configuration for code-rag
+# This file is automatically generated. Modify as needed.
+
+# Embedding model to use for generating vector embeddings
+# Options:
+# - nomic-ai/CodeRankEmbed (Recommended for code)
+# - text-embedding-3-small (Requires OPENAI_API_KEY)
+CODE_RAG_EMBEDDING_MODEL=nomic-ai/CodeRankEmbed
+
+# Database type: 'chroma' or 'qdrant'
+CODE_RAG_DATABASE_TYPE=chroma
+
+# Database path (optional, defaults to OS-specific cache directory)
+# Windows: %LOCALAPPDATA%\\code-rag
+# macOS: ~/Library/Caches/code-rag
+# Linux: ~/.cache/code-rag
+# CODE_RAG_DATABASE_PATH=
+
+# Chunk size in characters for splitting files
+CODE_RAG_CHUNK_SIZE=1024
+
+# Batch size for processing documents
+CODE_RAG_BATCH_SIZE=32
+
+# Whether to include file headers in chunks (true/false)
+CODE_RAG_INCLUDE_FILE_HEADER=true
+
+# Whether to exclude test files from indexing (true/false)
+CODE_RAG_EXCLUDE_TESTS=false
+
+# Additional ignore patterns (comma-separated list)
+# Examples: *.log,*.tmp,custom_ignore_dir/
+CODE_RAG_ADDITIONAL_IGNORE_PATTERNS=
+
+# Whether reranking is enabled (true/false)
+CODE_RAG_RERANKER_ENABLED=false
+
+# Reranker model to use
+CODE_RAG_RERANKER_MODEL=mixedbread-ai/mxbai-rerank-xsmall-v1
+
+# Type of reranking to perform
+CODE_RAG_RERANKER_MULTIPLIER=2
+
+# Security / Verification
+CODE_RAG_VERIFY_CHANGES_WITH_HASH=true
+
+# Shared Embedding Server
+# Enables reusing the model across multiple calls to save memory
+CODE_RAG_SHARED_SERVER=true
+CODE_RAG_SHARED_SERVER_PORT=8199
+"""
 
 
 class Config:
     """Configuration handler for the code-rag application."""
 
     def __init__(self):
         """Initialize configuration from environment variables or defaults."""
+        self._load_config_files()
         self.embedding_model = os.getenv(
             "CODE_RAG_EMBEDDING_MODEL", "nomic-ai/CodeRankEmbed"
         )
@@ -80,6 +130,60 @@ def __init__(self):
         ).lower() in ("true", "1", "yes")
         self.shared_server_port = self._get_int_env("CODE_RAG_SHARED_SERVER_PORT", 8199)
 
+    def _load_config_files(self) -> None:
+        """
+        Load configuration from config files in precedence order.
+
+        1. Custom config file (CODE_RAG_CONFIG_FILE)
+        2. Current directory (code-rag.config)
+        3. User config (~/.config/code-rag/config) - Auto-created if missing
+        """
+        paths_to_check = []
+
+        # 1. Direct path via env var (highest file priority)
+        if custom_path := os.getenv("CODE_RAG_CONFIG_FILE"):
+            paths_to_check.append(Path(custom_path).expanduser())
+
+        # 2. Local directory project config
+        paths_to_check.append(Path.cwd() / "code-rag.config")
+
+        # 3. User configuration (XDG-style)
+        # We prefer ~/.config/code-rag/config
+        user_config_dir = Path.home() / ".config" / "code-rag"
+        user_config_file = user_config_dir / "config"
+
+        # Auto-create if it doesn't exist and we aren't testing
+        if not user_config_file.exists():
+            try:
+                user_config_dir.mkdir(parents=True, exist_ok=True)
+                user_config_file.write_text(DEFAULT_CONFIG, encoding="utf-8")
+                # Only print via stderr to avoid corrupting MCP stdout if this happens during tool use
+                # But Config might be initialized during module import, so be careful.
+                # Safe to write, maybe skip print or print to stderr.
+            except Exception:
+                # working in a read-only fs or permission error, skip creation
+                pass
+
+        paths_to_check.append(user_config_file)
+
+        # 4. Package source fallback (for dev envs, keeping .env here as it's gitignored)
+        paths_to_check.append(Path(__file__).resolve().parent.parent.parent / ".env")
+
+        # Load found files. override=False means:
+        # - Shell vars > File vars
+        # - We want specific files to override general ones?
+        # load_dotenv defaults to override=False (don't overwrite system env).
+        # But for file-vs-file, we want the first ones we check (files) to take precedence?
+        # Actually load_dotenv adds to os.environ but doesn't overwrite if exists.
+        # So we should load High Priority files FIRST.
+        # Order above was: Custom -> Local -> User -> Package.
+        # This is correct for load_dotenv(override=False).
+        # The first file loaded sets the var. Subsequent files won't overwrite it.
+
+        for path in paths_to_check:
+            if path.is_file():
+                load_dotenv(path)
+
     @staticmethod
     def _get_default_database_path() -> str:
         """Get the default database path in the user's cache directory."""