Tool Concurrency Limits

Todo2026-11-03Jean Mertz

tracking-rfd: 129type: tracking

Tracking ticket for RFD 129.

Implementation plan

• Add tool-level concurrency limits: Adds concurrency to ToolConfig with its accessor, validation (one limit per key), and tests, plus Host scheduling in ToolCoordinator::release and the step handler. fan_out.concurrency stays for now. Coordinator tests cover order and limit within a key, parallel keys, questions keeping the slot, failures releasing the next call, cancellation of parked calls, fan-out operations counting against the tool's key, and restart order.
• Remove fan_out.concurrency: Removes concurrency from FanOutConfig and FanOut, strips the server Gate down to the stop check, and adds the on_error = "stop" validation (config error with an unbounded limit). Updates the tests and schema snapshot that use it and closes ticket 0ya5qnf. Depends on phase 1.
• Declare concurrency in jp-rfd tools: Declares concurrency = { key = "rfd" } on the writing tools (draft, promote, rename, renumber, abandon, extend, require, supersede) in the shipped definitions and in .jp/mcp/tools/rfd/. Depends on phase 1.