feat: Add LLM integration layer for semantic code analysis

[Copilot]

Pull Request

Description

Implements optional LLM integration for semantic code analysis beyond AST syntax comparison. Enables behavioral change detection, code execution simulation, and intelligent documentation synchronization for DocuMCP Orchestrator (ADR-009, ADR-010).

Architecture:

• LLM Client (src/utils/llm-client.ts): Multi-provider abstraction (DeepSeek, OpenAI, Anthropic, Ollama) with rate limiting, timeout handling, and graceful degradation
• Semantic Analyzer (src/utils/semantic-analyzer.ts): Three-mode analysis (LLM/AST/Hybrid) with automatic fallback and confidence-based selection
• Complete isolation: Zero impact on existing functionality, works fully offline without LLM

Usage:

import { SemanticAnalyzer } from './utils/semantic-analyzer.js';

const analyzer = new SemanticAnalyzer();
await analyzer.initialize();

// Detects behavioral changes, not just signature changes
const analysis = await analyzer.analyzeSemanticImpact(
  'function multiply(a, b) { return a * b; }',
  'function multiply(a, b) { return a + b; }'  // Bug!
);

console.log(analysis.hasBehavioralChange);     // true
console.log(analysis.breakingForExamples);     // true
console.log(analysis.analysisMode);            // 'llm' | 'ast' | 'hybrid'
console.log(analysis.confidence);              // 0.0-1.0

// Validate documentation examples without execution
const validation = await analyzer.validateExamples(
  ['const result = multiply(6, 7);  // Should return 42'],
  implementation
);

Configuration (optional):

export DOCUMCP_LLM_API_KEY="sk-..."
export DOCUMCP_LLM_PROVIDER="deepseek"  # default
export DOCUMCP_LLM_MODEL="deepseek-chat"

Type of Change

• New feature (non-breaking change which adds functionality)
• Documentation update

Testing

• Tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes (48 new tests, 1554 total passing)
• Test coverage maintains or improves upon 80% threshold (85-97% on new modules)

Code Quality

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• My changes generate no new warnings
• I have run npm run validate:rules and all checks pass

Documentation

• I have made corresponding changes to the documentation
  • Complete how-to guide: docs/how-to/llm-integration.md
  • Provider configuration for all supported LLMs
  • Usage patterns, best practices, troubleshooting
  • README updated with feature highlights

Security

• I have run npm run security:check and there are no new vulnerabilities
• My changes do not introduce security risks
  • API keys configurable via environment only
  • No keys in code or version control
  • Graceful fallback ensures offline operation
  • Code never sent to LLM unless explicitly configured

ADR Impact

• This change affects existing ADRs (list which ones)
  • ADR-009: Content Accuracy Validation Framework (enables LLM-powered validation)
  • ADR-010: MCP Resource Pattern Redesign (no resource storage, stateless operation)
• This change requires a new ADR
• No ADR impact

Checklist

• I have read the CONTRIBUTING guidelines
• I have linked this PR to relevant issues
• I have updated the TODO.md if this completes tasks

Warning

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I tried to connect to the following addresses, but was blocked by firewall rules:

• example.com
  • Triggering command: /usr/local/bin/node /usr/local/bin/node /home/REDACTED/work/documcp/documcp/node_modules/jest-worker/build/workers/processChild.js (dns block)
  • Triggering command: /usr/local/bin/node /usr/local/bin/node /home/REDACTED/work/documcp/documcp/node_modules/jest-worker/build/workers/processChild.js k/documcp/documc9bbac2319fde065e4b9004787f53c0631b993eb8:tests/utils/llm-client.test.ts git bin/�� --port 4000 node /usr/bin/git semantic-analyzenode 1.11.1 19.6/src git log ll serve --port 3000 --format=%cI k/documcp/node_modules/.bin/sh 19.6/deps/uv/incsh with comprehens-c 19.6/deps/zlib sh (dns block)
• https://api.github.com/test
  • Triggering command: /usr/local/bin/node /usr/local/bin/node /home/REDACTED/work/documcp/documcp/node_modules/jest-worker/build/workers/processChild.js (http block)
  • Triggering command: /usr/local/bin/node /usr/local/bin/node /home/REDACTED/work/documcp/documcp/node_modules/jest-worker/build/workers/processChild.js k/documcp/documc9bbac2319fde065e4b9004787f53c0631b993eb8:tests/utils/llm-client.test.ts git bin/�� --port 4000 node /usr/bin/git semantic-analyzenode 1.11.1 19.6/src git log ll serve --port 3000 --format=%cI k/documcp/node_modules/.bin/sh 19.6/deps/uv/incsh with comprehens-c 19.6/deps/zlib sh (http block)
• httpstat.us
  • Triggering command: /usr/local/bin/node /usr/local/bin/node /home/REDACTED/work/documcp/documcp/node_modules/jest-worker/build/workers/processChild.js (dns block)
  • Triggering command: /usr/local/bin/node /usr/local/bin/node /home/REDACTED/work/documcp/documcp/node_modules/jest-worker/build/workers/processChild.js k/documcp/documc9bbac2319fde065e4b9004787f53c0631b993eb8:tests/utils/llm-client.test.ts git bin/�� --port 4000 node /usr/bin/git semantic-analyzenode 1.11.1 19.6/src git log ll serve --port 3000 --format=%cI k/documcp/node_modules/.bin/sh 19.6/deps/uv/incsh with comprehens-c 19.6/deps/zlib sh (dns block)
• invalid-domain-that-does-not-exist-12345.com
  • Triggering command: /usr/local/bin/node /usr/local/bin/node /home/REDACTED/work/documcp/documcp/node_modules/jest-worker/build/workers/processChild.js (dns block)
  • Triggering command: /usr/local/bin/node /usr/local/bin/node /home/REDACTED/work/documcp/documcp/node_modules/jest-worker/build/workers/processChild.js k/documcp/documc9bbac2319fde065e4b9004787f53c0631b993eb8:tests/utils/llm-client.test.ts git bin/�� --port 4000 node /usr/bin/git semantic-analyzenode 1.11.1 19.6/src git log ll serve --port 3000 --format=%cI k/documcp/node_modules/.bin/sh 19.6/deps/uv/incsh with comprehens-c 19.6/deps/zlib sh (dns block)
• invalid-url-12345.test
  • Triggering command: /usr/local/bin/node /usr/local/bin/node /home/REDACTED/work/documcp/documcp/node_modules/jest-worker/build/workers/processChild.js (dns block)
  • Triggering command: /usr/local/bin/node /usr/local/bin/node /home/REDACTED/work/documcp/documcp/node_modules/jest-worker/build/workers/processChild.js k/documcp/documc9bbac2319fde065e4b9004787f53c0631b993eb8:tests/utils/llm-client.test.ts git bin/�� --port 4000 node /usr/bin/git semantic-analyzenode 1.11.1 19.6/src git log ll serve --port 3000 --format=%cI k/documcp/node_modules/.bin/sh 19.6/deps/uv/incsh with comprehens-c 19.6/deps/zlib sh (dns block)
• this-domain-definitely-does-not-exist-12345.com
  • Triggering command: /usr/local/bin/node /usr/local/bin/node /home/REDACTED/work/documcp/documcp/node_modules/jest-worker/build/workers/processChild.js (dns block)
  • Triggering command: /usr/local/bin/node /usr/local/bin/node /home/REDACTED/work/documcp/documcp/node_modules/jest-worker/build/workers/processChild.js k/documcp/documc9bbac2319fde065e4b9004787f53c0631b993eb8:tests/utils/llm-client.test.ts git bin/�� --port 4000 node /usr/bin/git semantic-analyzenode 1.11.1 19.6/src git log ll serve --port 3000 --format=%cI k/documcp/node_modules/.bin/sh 19.6/deps/uv/incsh with comprehens-c 19.6/deps/zlib sh (dns block)
• this-domain-should-not-exist-12345.com
  • Triggering command: /usr/local/bin/node /usr/local/bin/node /home/REDACTED/work/documcp/documcp/node_modules/jest-worker/build/workers/processChild.js (dns block)
  • Triggering command: /usr/local/bin/node /usr/local/bin/node /home/REDACTED/work/documcp/documcp/node_modules/jest-worker/build/workers/processChild.js k/documcp/documc9bbac2319fde065e4b9004787f53c0631b993eb8:tests/utils/llm-client.test.ts git bin/�� --port 4000 node /usr/bin/git semantic-analyzenode 1.11.1 19.6/src git log ll serve --port 3000 --format=%cI k/documcp/node_modules/.bin/sh 19.6/deps/uv/incsh with comprehens-c 19.6/deps/zlib sh (dns block)
• www.google.com
  • Triggering command: /usr/local/bin/node /usr/local/bin/node /home/REDACTED/work/documcp/documcp/node_modules/jest-worker/build/workers/processChild.js (dns block)
  • Triggering command: /usr/local/bin/node /usr/local/bin/node /home/REDACTED/work/documcp/documcp/node_modules/jest-worker/build/workers/processChild.js k/documcp/documc9bbac2319fde065e4b9004787f53c0631b993eb8:tests/utils/llm-client.test.ts git bin/�� --port 4000 node /usr/bin/git semantic-analyzenode 1.11.1 19.6/src git log ll serve --port 3000 --format=%cI k/documcp/node_modules/.bin/sh 19.6/deps/uv/incsh with comprehens-c 19.6/deps/zlib sh (dns block)

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Original prompt

---

This section details on the original issue you should resolve

<issue_title>feat: Add LLM integration layer for semantic code analysis</issue_title>
<issue_description>## Summary
Add an LLM integration layer to enable semantic analysis of code changes beyond AST-based syntax comparison.

Motivation

The DocuMCP Orchestrator (ADR-009, ADR-010) requires semantic understanding of code changes to:

• Detect behavioral changes within the same function signature
• Simulate code execution paths without running code
• Generate intelligent documentation update suggestions

Proposed Solution

1. Create src/utils/llm-client.ts

export interface LLMConfig {
  provider: 'deepseek' | 'openai' | 'anthropic' | 'ollama';
  apiKey?: string;
  baseUrl?: string;
  model: string;
  maxTokens?: number;
}

export interface LLMClient {
  complete(prompt: string): Promise<string>;
  analyzeCodeChange(before: string, after: string): Promise<SemanticAnalysis>;
  simulateExecution(example: string, implementation: string): Promise<SimulationResult>;
}

2. Create src/utils/semantic-analyzer.ts

export interface SemanticAnalysis {
  hasBehavioralChange: boolean;
  breakingForExamples: boolean;
  changeDescription: string;
  affectedDocSections: string[];
  confidence: number;
}

export class SemanticAnalyzer {
  async analyzeSemanticImpact(
    codeBefore: string,
    codeAfter: string,
    functionName: string
  ): Promise<SemanticAnalysis>;
}

Acceptance Criteria

• LLM client supports multiple providers (DeepSeek default)
• Configuration via environment variables
• Fallback to AST-only mode if LLM unavailable
• Rate limiting and error handling
• Unit tests with mocked LLM responses

Related

• Orchestrator ADR-009: Documentation Sync Agent
• Orchestrator ADR-010: LLM-Validated Documentation Examples
• Orchestrator Repo: https://github.com/tosin2013/documcp-orchestrator

Labels

enhancement, priority-high, orchestrator-integration</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes feat: Add LLM integration layer for semantic code analysis #71

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