Curated catalog of 20 GNU Radio OOT modules served via two MCP
resources (oot://directory, oot://directory/{name}). Each entry
includes git URL, branch, build deps, and a ready-to-use
install_oot_module() example.
Modules are tagged preinstalled when they ship with the
gnuradio-runtime base Docker image (12 of 20), so agents can
distinguish what's already available from what needs building.
Single MCP tool call builds any GNU Radio OOT module from a git repo
into a reusable Docker image. Generates a Dockerfile from template,
builds via Docker SDK, and tracks results in a persistent JSON registry.
New tools: install_oot_module, list_oot_images, remove_oot_image
Also changes launch_flowgraph default xmlrpc_port from 8080 to 0 (auto)
Flowgraphs generated by GRC on the host often fail in Docker containers
due to three issues:
1. message_debug constructor signature changed between GR 3.10.5 and
3.10.12 — strip the second arg for older runtimes
2. XML-RPC binds to localhost, unreachable from Docker host — rewrite
to 0.0.0.0
3. input('Press Enter to quit:') gets immediate EOF in detached
containers, killing the flowgraph instantly — inject signal.pause()
fallback after EOFError
All patches are applied in a single pass via patch_flowgraph() before
the container launches. The original file is never modified.
Add add_block_path() and get_block_paths() MCP tools for incremental
OOT module loading with BlockPathsModel responses. On startup, auto-scan
/usr/local/share and ~/.local/share for OOT blocks so modules like
gr-lora_sdr are available without manual configuration.
The lru_cache on get_block() caused three cache coherence bugs:
1. Removed blocks remained accessible — set_block_params would
modify a detached block object that no longer exists in the
flowgraph, so save_flowgraph would serialize stale state.
2. Re-created blocks with the same auto-generated name would
return the cached (removed) block instead of the new one.
3. Renamed blocks (via set_block_params id=...) left phantom
cache entries under the old name.
Fix: always look up blocks from the live flowgraph. Block lookup
is a linear scan of typically <20 blocks — no cache needed.
Raises KeyError instead of StopIteration for missing blocks.
GRC's SimpleXMLRPCServer uses register_instance() which doesn't
expose system.listMethods. Wrap the connectivity check in a
try/except so a Fault is treated as "connected" while
ConnectionRefusedError still propagates.
Prevent silent Docker bind failures by checking port availability
before container creation. Supports auto-allocation (port=0) and
patches compiled flowgraphs when the embedded XML-RPC port differs
from the requested port.
