Semcheck: The AI-Powered Solution for Perfect Code-Documentation Sync

Why Do Your Code and Documentation Always Drift Apart?

Every developer faces these frustrating scenarios:

  1. Updating function logic but forgetting to adjust documentation
  2. New team members causing errors by following outdated API docs
  3. Discovering implementation-design mismatches during code reviews
  4. Perpetual “update documentation” tasks in technical debt logs

Specification drift lies at the heart of these problems. Traditional manual checks are time-consuming and error-prone. Enter Semcheck – an AI-powered tool that automates specification compliance, making code-documentation synchronization reliable and effortless.

What Exactly Is Semcheck?

Semcheck is a lightweight CLI tool built with Go that uses Large Language Models (LLMs) to automatically verify alignment between code implementations and specification documents. Its core value proposition:

✅ Real-time change detection – Triggers checks when specs or code change
✅ Multi-model support – Works with OpenAI/Anthropic/local LLMs
✅ Seamless integration – Fits perfectly into Git pre-commit hooks and CI/CD pipelines
✅ Precision targeting – Pinpoints exact locations of spec-implementation mismatches

Like the famous Office meme: “Corporate needs you to find the difference between these pictures – Semcheck declares: They’re identical!”

How It Works: The Technical Breakdown

Three-Layer Architecture

graph TD
    A[Config File] --> B(File Processor)
    C[Code/Docs] --> B
    B --> D[AI Comparison Engine]
    D --> E[Validation Report]

  1. Configuration Layer (semcheck.yaml)
    Defines rules linking implementation files with specifications:

    rules:
  - name: "geoJSON-validator"
    files:
      include: "src/geojson/*.ts"  # Implementation files
      exclude: "*_test.ts"
    specs:
      - path: "https://www.rfc-editor.org/rfc/rfc7946.txt"  # Online spec

  2. Intelligent Matching Engine
    Automatically categorizes files into:

    • Specification files (Spec)
    • Implementation files (Impl)
    • Ignored files (via .gitignore)

  3. AI-Powered Comparison Core
    Performs contextual analysis:

    func ValidateCompliance(specContent, implContent string) (bool, string) {
    prompt := fmt.Sprintf("Compare specification: %s\nWith implementation: %s", 
                         specContent, implContent)
    return aiClient.Process(prompt)
}

Getting Started in 5 Minutes

Installation Guide

# Install Go 1.24+ environment
brew install go

# Install Semcheck
go install github.com/rejot-dev/semcheck@latest

Initial Configuration

semcheck -init  # Generates semcheck.yaml

Sample Configuration

version: "1.0"
provider: anthropic
model: claude-3-opus
api_key: ${ANTHROPIC_API_KEY}  # Reads from environment variables

rules:
  - name: config-validation
    files:
      include: "internal/config/*.go"
    specs:
      - path: "docs/config-spec.md"

Execution Commands

# Validate all rules
semcheck

# Check specific files only
semcheck src/utils.go

# Pre-commit validation (recommended!)
semcheck --pre-commit

Real-World Implementation Scenarios

Scenario 1: API Interface Modifications

When updating OpenAPI documentation:

 paths:
   /user:
     get:
-      summary: Retrieve all users
+      summary: Query active users

Semcheck automatically flags corresponding controller code requiring updates.

Scenario 2: RFC Standard Compliance

Ensure code meets latest RFC standards:

specs:
  - path: "https://www.rfc-editor.org/rfc/rfc9110.txt"  # HTTP/1.1 spec

Scenario 3: Team Collaboration Safeguard

Automated PR checks via GitHub Actions:

jobs:
  semcheck-validation:
    steps:
      - uses: rejot-dev/semcheck@main
        with:
          config-file: semcheck.yaml
        env:
          ANTHROPIC_API_KEY: ${{ secrets.API_KEY }}

Technical Advantages Explained

Comparison with Traditional Methods

Validation Method Accuracy Speed Maintenance Cost
Manual Review Medium Low High
Unit Tests High Medium High
Semcheck High High Low

Intelligent Processing Capabilities

  1. Context Filtering – Automatically ignores test files (*_test.go) and comments
  2. Precision Targeting – Identifies discrepancies at function level
  3. Batch Processing – Concurrent rule validation for maximum efficiency

Developer Best Practices

Optimal Configuration

# Performance tuning tips
timeout: 45  # Timeout in seconds
fail_on_issues: true  # Halt pipeline on errors

# Custom validation instructions
prompt: |  
  Validate only implemented features, ignore TODO markers

Debugging Techniques

# Enable debug mode
SEMCHECK_DEBUG=1 semcheck

# Self-validation example
semcheck specs/semcheck.md  # Validate its own specification

Performance Optimization

  • Limit to ≤5 files per rule (reduces AI context load)
  • Use local LLMs (Ollama) to eliminate network latency
  • Leverage --pre-commit for staged files only

Frequently Asked Questions

Q: Does this expose proprietary code?

No. Semcheck supports local models (Ollama) for sensitive codebases. Cloud APIs receive only relevant snippets.

Q: How to handle large codebases?

Implement modular rules:

rules:
  - name: authentication-module
    files: pkg/auth/*.go
    specs: docs/auth-spec.md
    
  - name: payment-module
    files: pkg/payment/*.go
    specs: docs/payment-spec.md

Q: What about false positives?

Calibrate using custom prompts:

prompt: |
  Note: Our implementation uses snake_case convention,
  camelCase in RFC docs is not an error

Future Development Roadmap

Upcoming features per development plan:

journey
    title Semcheck Evolution Timeline
    section 2024 Q3
      Local LLM optimization --> Rule grouping
    section 2024 Q4
      Issue traceability --> Enhanced GitHub Actions

Start Using Semcheck Today!

Three-step implementation:

  1. Install: go install github.com/rejot-dev/semcheck@latest
  2. Configure: semcheck -init
  3. Add pre-commit hook:

    # .git/hooks/pre-commit
#!/bin/sh
semcheck --pre-commit || exit 1

Technical debt accumulates silently, but specification drift can be stopped automatically. Make Semcheck your codebase’s specification guardian.