- Add reasoning_plan built-in tool: decomposes goals into ordered steps
with dependency edges; persists to task backend when available, falls
back to in-context plan otherwise.
- Add PlanBackend/PlanBackendSetter interfaces and PlanStep type to
pkg/tools; add GetServer to Dispatcher.
- Add dispatchPlanBackend in pkg/agent: routes task_create calls through
the dispatcher to any registered task MCP server.
- BuildAgentEnv auto-wires the task backend to the reasoning server after
connecting MCP servers; re-wires on every /agent switch.
- Add ListServers() to Core interface: groups all registered tools by
server, returns formatted text.
- Add /mcp command to handleCommand(); update /help.
- Add doc/PLANNING.md and update ARCHITECTURE.md.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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