BYO Server

BYO Server is the headless, local stdio MCP server for Firmware-CLI's board-debug substrate. Any compatible MCP client can use its ordinary tools. The optional R11 harness is a separate Codex-specific benchmark; it is not the definition of normal BYO use.

The server owns the safety boundary. Clients request operations, while server.py, the guardrails, and the board-facing services validate arguments, enforce flash/recover policy, record sessions, and block repeated unsafe mutation patterns. MCP tool names, schemas, and operation contracts live in the tool docstrings in src/pyocd_debug_mcp/server.py; this project intentionally does not maintain duplicate per-tool sidecar documentation.

Supported deployment

Operational use is checkout-only. Run commands from this BYO-Server/ directory. Board profiles, firmware, pinned-pack metadata, bootstrap scripts, R11 cases, and benchmark workspaces are checkout-owned resources and are not bundled into the wheel. The wheel is built and fresh-installed only to verify metadata, console entrypoints, and importability; an installed wheel is not a supported board-control or benchmark deployment.

Python 3.12 is the team pin in .python-version; package metadata retains the runtime's Python 3.10 minimum. Windows and macOS have bounded setup scripts. Linux is not currently covered by a host setup script.

Related MCP server: dbgprobe-mcp-server

Start here

1. Read init.md for host prerequisites and initial setup.

2. Follow stage0_setup.md for board-scoped readiness and Stage 0/1 validation.

3. Register the stdio server with an MCP client. A generic command shape is:

   {
     "mcpServers": {
       "pyocd-debug": {
         "command": "uv",
         "args": [
           "run",
           "--project",
           "<absolute-path-to-BYO-Server>",
           "--locked",
           "pyocd-debug-mcp"
         ]
       }
     }
   }

   Use the client's normal configuration mechanism and replace the placeholder with this checkout's absolute path. The server uses stdio; stdout belongs to MCP framing.

The retained public console scripts are:

• pyocd-debug-mcp: start the stdio MCP server. It has no conventional --help mode; its contract is the MCP initialize/list-tools surface.

• pyocd-pack-repair --help: inspect or repair selected CMSIS-Pack index descriptors.

• pyocd-zephyr-build --help: provision or use a Zephyr build environment.

Board bootstrap, Stage 0, Stage 1, and R11 remain checkout commands rather than new public entrypoints:

uv run --locked python host_bootstrap.py --help
uv run --locked python stage0_check.py --help
uv run --locked python -m tests.harness.stage1_smoke --help
uv run --locked python -m tests.harness.r11_benchmark --help

Product boundary

Included here are the local MCP server, adapters, guardrails, shared board-facing services, board and firmware data, pack/bootstrap support, and the R10/R11 test and benchmark closure. The turnkey brain, UX, provider-memory runtime, Codex app-server services, R12 harness, skills/playbooks bundles, Rich, and prompt_toolkit are excluded.

The ordinary server is model-agnostic. R11 launches codex exec, requires Codex registration/provider access plus live hardware, enforces its own frozen prompt/result/scoring contract, and writes benchmark artifacts under runs/. Passing R11 demonstrates that benchmark path only; it is not universal proof for every MCP client.

Current state and limits

• Sessions use a process-local InMemorySessionStore plus durable JSONL and summary files under runs/. There is no Redis implementation in this copy.

• A server restart loses the in-memory session index even though prior run files remain on disk.

• Explicit disconnect and normal service paths close owned pyOCD/serial handles, but full descendant process-tree and interrupted-run cleanup proof remains open. A timeout must not be interpreted as proof that every child or hardware-adjacent resource was cleaned up.

• The official proof pair is nrf52833dk plus nucleo_l476rg. nrf52840dk is retained alternate Nordic evidence and does not substitute for exact nrf52833dk or official-pair proof.

• This extraction ran non-hardware checks only. Fresh standalone hardware, provider, MCP Inspector, and cross-host proof remain pending; see docs/verification.md.

Distribution and licensing

No authoritative project-root LICENSE or NOTICE file was available to copy. This project does not invent one and pyproject.toml makes no license claim. Publishing or redistributing the standalone artifact is blocked on a human decision identifying the authoritative license and required notices.

More detail

• Architecture and boundaries

• Verification status and handoff

• Extraction provenance

Verified

The S1-S4 extraction, ordinary MCP contract parity, standalone resource roots, R11 corpus isolation, and the BYO-only packaging/documentation contract have non-hardware evidence recorded in the extraction artifacts.

Pending verification

Complete clean-room integration (S6), independent review, fresh Windows/macOS, official-board hardware, live Codex/R11, MCP Inspector, cleanup, layout/drift, and authoritative licensing decisions remain pending.