Complete Environment Variable Reference for Configuring code-review-graph

The complete environment variable reference for code-review-graph is defined in code_review_graph/constants.py and documented in docs/USAGE.md, covering storage paths, embedding providers, parser settings, and resource limits.

The code-review-graph ecosystem is designed to be configured entirely through environment variables, allowing you to customize data storage, embedding providers, and processing behavior without modifying source code. All configuration options use the CRG_ prefix and are read at startup via os.getenv with sensible defaults defined in the constants module. This article provides a comprehensive reference for every available variable based on the source code implementation in the tirth8205/code-review-graph repository.

Central Configuration in constants.py

How Environment Variables Are Loaded

According to the tirth8205/code-review-graph source code, the canonical definitions for all configuration variables live in code_review_graph/constants.py. Each variable name is declared alongside its default fallback value. When a variable is unset or empty, the implementation normalizes the string and applies the default (for example, CRG_DATA_DIR defaults to <repo>/.code-review-graph when unspecified).

Repository and Storage Variables

Control where the tool stores its graph database and registry files:

• CRG_HOME: Overrides the location of the central registry directory.
• CRG_DATA_DIR: Specifies the path for the graph database files; defaults to a .code-review-graph subdirectory within the repository.
• CRG_REPO_ROOT: Forces a custom Git root path when the autodetection logic needs to be overridden.

Parser Control and Parallelism

Configure how the codebase parser executes and utilizes system resources:

• CRG_SERIAL_PARSE: Set to 1 to force serial parsing instead of parallel execution (useful for debugging).
• CRG_PARSE_EXECUTOR: Chooses the execution backend, accepting either process or thread.
• CRG_PARSE_WORKERS: Sets the number of parallel workers for parsing operations.

Embedding Provider Configuration

The code_review_graph/embeddings.py module selects embedding providers based on the following variables. Cloud providers emit a warning unless explicitly acknowledged.

Local Models:

• CRG_EMBEDDING_MODEL: Specifies a local sentence-transformer model name (e.g., sentence-transformers/all-MiniLM-L6-v2).

OpenAI-Compatible Endpoints:

• CRG_OPENAI_BASE_URL: The API endpoint URL (e.g., https://api.openai.com/v1).
• CRG_OPENAI_API_KEY: Authentication key for the API.
• CRG_OPENAI_MODEL: Model identifier (e.g., text-embedding-3-small).
• CRG_OPENAI_DIMENSION: Vector dimensionality (e.g., 1536).
• CRG_OPENAI_BATCH_SIZE: Number of embeddings to request per batch.

Voyage AI Specific:

• CRG_VOYAGE_MODEL: Model name for Voyage embeddings.
• CRG_VOYAGE_BASE_URL: Custom base URL for Voyage API.
• CRG_VOYAGE_OUTPUT_DIMENSION: Desired output dimension for Voyage embeddings.

Cloud Provider Safety:

• CRG_ACCEPT_CLOUD_EMBEDDINGS: Set to 1 to silence warnings when using cloud-based embedding providers like OpenAI, Gemini, or MiniMax.

Tool Filtering and Execution Limits

Control which MCP tools are exposed and their runtime constraints:

• CRG_TOOLS: Comma-separated list limiting which tools are loaded (e.g., query_graph_tool).
• CRG_TOOL_TIMEOUT: Hard timeout in seconds for each tool call invocation.

Change Analysis and Git Settings

Configure analysis depth and Git interaction parameters:

• CRG_MAX_CHANGED_FUNCS: Caps the number of functions examined in large diffs.
• CRG_MAX_TRANSITIVE_FRONTIER: Limits the size of the transitive frontier for change analysis.
• CRG_GIT_TIMEOUT: Timeout in seconds for Git commands to prevent hanging operations.
• CRG_RECURSE_SUBMODULES: Boolean flag to enable or disable traversal of Git submodules.

Reproducibility and Safety Settings

Ensure deterministic results and control security policies:

• CRG_LEIDEN_SEED: Seed value for deterministic Leiden community detection, ensuring reproducible graphs across different machines as detailed in docs/REPRODUCING.md.
• CRG_ALLOW_REMOTE_CODE: Permit HuggingFace models that require trust_remote_code=True.

Testing and Debug Variables

Internal variables for development and testing scenarios:

• CRG_TEST_IMPACT_FLOAT: Overrides the impact-float value used in test suites.

Configuration Examples

Configure a local embedding model with cloud provider acceptance:

export CRG_EMBEDDING_MODEL="sentence-transformers/all-MiniLM-L6-v2"
export CRG_ACCEPT_CLOUD_EMBEDDINGS=1
crg build

Use OpenAI's embedding endpoint with custom dimensions:

export CRG_OPENAI_BASE_URL="https://api.openai.com/v1"
export CRG_OPENAI_API_KEY="sk-xxxx"
export CRG_OPENAI_MODEL="text-embedding-3-small"
export CRG_OPENAI_DIMENSION=1536
crg serve

Force serial parsing with limited workers and custom tool timeout:

export CRG_SERIAL_PARSE=1
export CRG_PARSE_WORKERS=2
export CRG_TOOL_TIMEOUT=30
crg serve --tools query_graph_tool

Override default storage locations:

export CRG_DATA_DIR="/tmp/crg-data"
export CRG_HOME="/tmp/crg-registry"
crg update

Summary

• The definitive environment variable reference lives in code_review_graph/constants.py with documentation in docs/USAGE.md.
• All variables use the CRG_ prefix and are read via os.getenv with empty-string normalization.
• Storage variables (CRG_HOME, CRG_DATA_DIR) control where data persists.
• Embedding variables support local sentence-transformers, OpenAI-compatible APIs, and Voyage AI, with CRG_ACCEPT_CLOUD_EMBEDDINGS=1 required to bypass warnings.
• Parser variables (CRG_SERIAL_PARSE, CRG_PARSE_WORKERS) tune parallel processing behavior.
• Safety variables (CRG_ALLOW_REMOTE_CODE, CRG_LEIDEN_SEED) manage security and reproducibility.

Frequently Asked Questions

Where are the environment variables defined in the codebase?

All environment variable names and their default values are centrally defined in code_review_graph/constants.py. The implementation reads these using Python's os.getenv function and normalizes empty strings to ensure robust fallback behavior when variables are unset.

What is the default data directory if CRG_DATA_DIR is not set?

When CRG_DATA_DIR is not configured, the code falls back to a .code-review-graph subdirectory within the repository root. This default is hardcoded in constants.py and ensures the tool works out-of-the-box without manual configuration.

How do I enable cloud embedding providers without security warnings?

Set CRG_ACCEPT_CLOUD_EMBEDDINGS=1 before invoking any crg command. This variable silences the egress warning that appears when using OpenAI, Gemini, MiniMax, or Voyage endpoints, confirming that you accept the transmission of code snippets to external APIs.

Can I force serial parsing instead of parallel processing?

Yes. Export CRG_SERIAL_PARSE=1 to disable parallel parsing and use a single thread. This is particularly useful for debugging parsing issues or when running in resource-constrained environments. You can also fine-tune parallelism using CRG_PARSE_EXECUTOR (choosing between process or thread) and CRG_PARSE_WORKERS to set the exact worker count.

{
  "mcpServers": {
    "instagit": {
      "command": "npx",
      "args": ["-y", "instagit@latest"]
    }
  }
}