Browser-based OAuth flow using Anthropic's hosted callback.
Users authorize on claude.ai, paste the code back, and tokens
are encrypted and stored in D1. Includes auto-refresh, Bearer
auth via custom fetch wrapper, and mcp_ tool name prefixing
required by the OAuth endpoint.
Also fixes provider-config save bug that required encryption
key unconditionally — now only checks when API key is present.
Extract agent-core as shared package with agentic loop,
tool definitions, and MCP integration. Compass tools
wrapped as MCP server using low-level Server API. Client
manager connects multiple MCP servers (in-memory, stdio,
HTTP) with unified tool routing. External MCP server
configs stored in DB with CRUD actions. Both Workers and
Bun runtimes use the new MCP client manager.
