feat(core): add claude provider using @anthropic-ai/claude-agent-sdk

[christso]

Summary

Replace the current claude-code provider (subprocess scraper) with a new claude provider using the official @anthropic-ai/claude-agent-sdk. This follows the same pattern as the copilot provider (PR #211) which replaced the subprocess-based copilot-cli with the typed SDK.

Motivation

The current claude-code provider spawns the Claude CLI as a subprocess and scrapes stdout. The Agent SDK provides:

• Structured messages via AsyncGenerator<SDKMessage> - typed SDKAssistantMessage, SDKResultMessage
• Token usage & cost from SDKResultMessage.usage, modelUsage, total_cost_usd
• Duration from SDKResultMessage.duration_ms
• Tool call tracking via assistant message content blocks or PostToolUse hooks
• Permission control via permissionMode: 'bypassPermissions' (no interactive prompts)
• Model selection via options.model
• Budget control via options.maxBudgetUsd and options.maxTurns
• Abort support via options.abortController

SDK API Overview

import { query } from '@anthropic-ai/claude-agent-sdk';

const q = query({
  prompt: 'What is 2+2?',
  options: {
    model: 'claude-sonnet-4-5-20250929',
    permissionMode: 'bypassPermissions',
    allowDangerouslySkipPermissions: true,
    cwd: '/path/to/workspace',
    systemPrompt: 'custom system prompt',
    maxTurns: 50,
    maxBudgetUsd: 1.0,
    abortController: new AbortController(),
  }
});

for await (const message of q) {
  if (message.type === 'assistant') {
    // message.message contains APIAssistantMessage with content blocks
  }
  if (message.type === 'result') {
    // message.result - final text
    // message.usage - { input_tokens, output_tokens, cache_* }
    // message.modelUsage - per-model breakdown with costUSD
    // message.total_cost_usd - total cost
    // message.duration_ms - total duration
    // message.num_turns - number of turns
  }
}

Implementation Plan

Follow the same pattern as the copilot provider (see PR #211):

Files to modify

1. types.ts - Rename claude-code → claude in ProviderKind, add claude-code as alias
2. targets.ts - Update resolved config and target resolution
3. index.ts - Wire new provider, remove old
4. targets-validator.ts - Update settings validation

Files to create

1. claude.ts - New provider using @anthropic-ai/claude-agent-sdk
   • Lazy-load SDK (same pattern as copilot provider)
   • Use query() with permissionMode: 'bypassPermissions'
   • Map SDKAssistantMessage content blocks → ToolCall[] and OutputMessage[]
   • Extract usage, total_cost_usd, duration_ms from SDKResultMessage
2. claude-log-tracker.ts - Log tracker (rename from claude-code variant)
3. claude.test.ts - Unit tests with mocked SDK

Files to delete

1. claude-code.ts - Old subprocess provider
2. claude-code-log-tracker.ts - Old log tracker
3. claude-code.test.ts - Old tests (if exists)

Dependencies

• Add @anthropic-ai/claude-agent-sdk to packages/core/package.json and apps/cli/package.json
• Add to CLI's tsup.config.ts external list

Key Design Decisions

• Naming: claude (canonical), claude-code (alias for backward compat)
• Permissions: Use bypassPermissions + allowDangerouslySkipPermissions for unattended eval
• Tool calls: Extract from SDKAssistantMessage.message.content blocks (type tool_use / tool_result)
• Streaming: Iterate the async generator, collect all messages, extract result at end

References

• TypeScript Agent SDK docs
• PR feat(core): add copilot-sdk provider #211 - copilot provider implementation (pattern to follow)