Repatch is an autonomous, test-driven engineering agent designed to handle the entire bug-fixing lifecycle with zero human intervention. Unlike standard LLM assistants, Repatch is grounded by an Inviolable Loop of empirical verification, ensuring that every patch is not just generated, but proven correct in a sandboxed environment.

Repatch operates on a strict state machine that mandates reproduction before implementation.

• Reproduction-First: The agent is physically unable to modify source code until it has authored a test case that fails against the current HEAD.
• Surgical Execution: High-precision edit_file operations minimize diff noise.
• Verification Guarantee: Every submission includes raw logs of the reproduction failure and the subsequent verification success.

To eliminate the "hallucinated paths" common in autonomous agents, Repatch builds a Semantic Index of the repository upon initialization. This "Map of Truth" ensures the agent's internal monologue is always grounded in the actual file system structure.

Repatch generates PR descriptions based exclusively on the Actual Git Diff, not the initial plan.

• Diff-Grounding: The agent analyzes the final code changes post-execution to write factual engineering narratives.
• Plan Divergence Tracking: If the implementation diverged from the plan (e.g., "Simplified approach to fix critical import error"), it is explicitly noted.

Leveraging Nixpacks and Docker, Repatch automatically detects the project's runtime (Node, Python, Go, etc.) and spawns an ephemeral, OCI-compliant container for isolated test execution and linting.

graph TD
    A[Issue Report] --> B[UNDERSTAND: Structural Analysis]
    B --> C[EXPLORE: Semantic Path Mapping]
    C --> D[REPRODUCE: Authors Failing Test]
    D --> E[PLAN: Surgical Patch Design]
    E --> F[EXECUTE: Intent-Based Code Modification]
    F --> G[VERIFY: Multi-Stage Validation]
    G --> H[SUBMIT: Diff-Grounded PR Creation]
    G -- Fails --> E

• Orchestration: Decoupled Step Pattern (Strategy Pattern) for robust state transitions.
• Inference Layer: Provider-agnostic wrapper supporting OpenAI, Anthropic, and Gemini.
• Fuzzy Matching: Custom sliding-window algorithm for surgical code edits that resist minor whitespace/indentation shifts.
• Persistence Middleware: Checkpoint-based state management for long-running autonomous tasks.

• Node.js 20+
• Docker Desktop (Daemon must be running)
• GH_TOKEN (Exported in your environment for PR submission)

git clone https://github.com/Sagar-024/Repatch.git
cd Repatch
npm install
npm run build

Run the agent against any public repository or local path:

# Example: Fix a logic error in a local repo
npm run dev -- autofix /path/to/repo -i "Calculator returns false for 1+1"

This project is licensed under the MIT License - see the LICENSE file for details.