feat(codegen): add Claude Agent SDK code generator

[bug-ops]

Summary

• Add new claude_agent module in mcp-codegen for generating Claude Agent SDK compatible TypeScript
• Implement JSON Schema to Zod type mapping with format hints (.email(), .url(), etc.)
• Add --generator claude-agent CLI flag for selecting output format
• Create Handlebars templates for tool.ts, server.ts, and index.ts

Features

New Generator Module

• claude_agent/generator.rs - Main generator for Claude Agent SDK format
• claude_agent/types.rs - Context types for Handlebars templates
• claude_agent/zod.rs - JSON Schema → Zod type conversion with modifiers

CLI Integration

# Generate Claude Agent SDK format
mcp-execution-cli generate --from-config github --generator claude-agent

Generated Structure

~/.claude/agent-sdk/{server-id}/
├── index.ts         # Entry point with exports
├── server.ts        # createSdkMcpServer() definition
└── tools/
    └── {tool}.ts    # Individual tools with Zod schemas

Example Generated Tool

import { tool } from "@anthropic-ai/claude-agent-sdk";
import { z } from "zod";

export const createIssue = tool(
  "create_issue",
  "Creates a new issue",
  {
    repo: z.string().describe("Repository"),
    title: z.string().describe("Issue title"),
    body: z.string().optional()
  },
  async (args) => {
    return { content: [{ type: "text", text: JSON.stringify(args) }] };
  }
);

Test plan

• All 475 existing tests pass
• New unit tests for ClaudeAgentGenerator
• New unit tests for Zod type conversion
• Clippy passes without warnings
• Documentation updated (README, ADR-012)

Related

• ADR: docs/adr/012-claude-agent-sdk-generator.md
• Claude Agent SDK Documentation
• Custom Tools Documentation

Closes #29

[codecov-commenter]

Codecov Report

❌ Patch coverage is 94.54191% with 56 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
crates/mcp-codegen/src/claude_agent/zod.rs	84.83%	42 Missing ⚠️
crates/mcp-codegen/src/template_engine.rs	97.76%	9 Missing ⚠️
crates/mcp-codegen/src/claude_agent/generator.rs	98.06%	5 Missing ⚠️

@@            Coverage Diff             @@
##           master      #29      +/-   ##
==========================================
+ Coverage   93.79%   94.08%   +0.28%     
==========================================
  Files          14       17       +3     
  Lines        2723     3735    +1012     
==========================================
+ Hits         2554     3514     +960     
- Misses        169      221      +52     

Flag	Coverage Δ
unittests	94.08% <94.54%> (+0.28%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
crates/mcp-codegen/src/claude_agent/types.rs	100.00% <100.00%> (ø)
crates/mcp-codegen/src/common/typescript.rs	97.04% <100.00%> (+0.09%)	⬆️
crates/mcp-codegen/src/claude_agent/generator.rs	98.06% <98.06%> (ø)
crates/mcp-codegen/src/template_engine.rs	96.24% <97.76%> (+11.01%)	⬆️
crates/mcp-codegen/src/claude_agent/zod.rs	84.83% <84.83%> (ø)

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