diffchunk

peteretelej/diffchunk

3.4

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The diffchunk MCP server is designed to efficiently navigate and analyze large diff files, optimizing the process by focusing on relevant changes and reducing unnecessary token usage.

diffchunk

MCP server that enables LLMs to navigate large diff files efficiently. Instead of reading entire diffs sequentially, LLMs can jump directly to relevant changes using pattern-based navigation.

Problem

Large diffs exceed LLM context limits and waste tokens on irrelevant changes. A 50k+ line diff can't be processed directly and manual splitting loses file relationships.

Solution

MCP server with 4 navigation tools:

  • load_diff - Parse diff file with custom settings (optional)
  • list_chunks - Show chunk overview with file mappings (auto-loads)
  • get_chunk - Retrieve specific chunk content (auto-loads)
  • find_chunks_for_files - Locate chunks by file patterns (auto-loads)

Setup

Prerequisite: Install uv (an extremely fast Python package manager) which provides the uvx command.

Add to your MCP client configuration:

{
  "mcpServers": {
    "diffchunk": {
      "command": "uvx",
      "args": ["--from", "diffchunk", "diffchunk-mcp"]
    }
  }
}

Usage

Basic Workflow

# Generate diff file
git diff main..feature-branch > /tmp/changes.diff
# LLM analyzes using diffchunk tools
Use diffchunk to analyze the diff at /tmp/changes.diff and find any bugs.

Tracking Analysis Progress

For large diffs requiring systematic analysis, LLMs can maintain tracking documents to resume work:

# Initial analysis with tracking
Use diffchunk to analyze /tmp/large-feature.diff. Create a tracking document 
to monitor progress through all chunks, then provide final summary.

# LLM maintains internal tracking:
# - Chunk 1/15: API endpoints - ANALYZED
# - Chunk 2/15: Database models - ANALYZED  
# - Chunk 3/15: Tests - IN PROGRESS
# - Chunks 4-15: PENDING

# Clean up tracking before final results

The tracking document concept allows LLMs to:

  • Resume analysis where they left off
  • Ensure comprehensive coverage of large diffs
  • Maintain context across multiple chunks
  • Provide complete analysis results

Tool Usage Patterns

Overview first:

list_chunks("/tmp/changes.diff")
# → 5 chunks across 12 files, 3,847 total lines

Target specific files:

find_chunks_for_files("/tmp/changes.diff", "*.py")
# → [1, 3, 5] - Python file chunks

get_chunk("/tmp/changes.diff", 1)
# → Content of first Python chunk

Systematic analysis:

# Process each chunk in sequence
get_chunk("/tmp/changes.diff", 1)
get_chunk("/tmp/changes.diff", 2)
# ... continue through all chunks

Configuration

Path Requirements

  • Absolute paths only: /home/user/project/changes.diff
  • Cross-platform: Windows (C:\path) and Unix (/path)
  • Home expansion: ~/project/changes.diff

Auto-Loading Defaults

Tools auto-load with optimized settings:

  • max_chunk_lines: 1000
  • skip_trivial: true (whitespace-only)
  • skip_generated: true (lock files, build artifacts)

Custom Settings

Use load_diff for non-default behavior:

load_diff(
    "/tmp/large.diff",
    max_chunk_lines=2000,
    include_patterns="*.py,*.js",
    exclude_patterns="*test*"
)

Supported Formats

  • Git diff output (git diff, git show)
  • Unified diff format (diff -u)
  • Multiple files in single diff
  • Binary file change indicators

Performance

  • Efficiently handles 100k+ line diffs
  • Memory efficient streaming
  • Auto-reload on file changes

Documentation

  • - Architecture and implementation details
  • - Development setup and workflows

License