One tool runtime per node, host-side, is what the runtime was written to be; the catalogue built a
container per module around it instead. This lets `serve` take a list — MESH_TOOL_MODULES as
<module>=<entrypoint> entries — and do for every assigned module what it did for one: read that
module's membership and follow it, serve its tools where the membership says, serve each held
seat's verbs on the seat's subjects. The seats come from the memberships now, so the node's
credential carries no claims; a module's own runtime still reads its credential's, so nothing
built today changes behaviour. A bare path in MESH_TOOL_MODULES stays the one-module form.
A bundle that throws on import is said in the log and in what `tools` answers for its module
(`failed`), which discovery lists with the reason instead of as "not answering"; the other bundles
serve. The filter that dropped every registration under a name but the one module goes; what
stays is that a registration under a seat's name is served only where some served module claims
the seat. A tool runs attributed to its module, so an event it emits lands on the module's
subject and not the runtime's. MESH_OPERATOR_ACCOUNT and MESH_OPERATOR_HOME are read and said;
tools take them from their environment.
Proven against a real bus: three bundles, one broken; five tools and two seat verbs answer on
their subjects; `tools` names the failed bundle; a membership re-issued mid-run re-serves.
A module implementing a seat its credential does not (yet) claim registered tools under the seat's
name; the runtime treated them as the module's own, refused to serve another module's key, and the
whole runtime restarted in a loop — postgres on the control node, 2026-10-01, whose credential predated
the claims. Such a registration is now named in the log and left out; the module's own tools serve.
The one address a runtime derives for itself is mesh.assignment.<node>.<module>. It reads the
membership there with a direct get on the ASSIGNMENTS stream, serves each tool exactly where the
membership says — the plain subject in the module's queue when the mesh issued one, this machine's
beside it — and follows the subject, re-serving when a new membership arrives. A mesh that has issued
nothing yet gets the shape it always derived, and the log says so.
A seat's verbs are the role's, not the software's (ADR 0159): a module implements them with
registerModuleTools("<seat>", …), the runtime serves that on the seat's subjects when the credential
claims the seat, and never lists it among the module's own tools. A module named like its seat
registers once and is both.
The tools answer carries each tool's subjects, and the console and CLI call the subject the listing
gave them instead of composing one.
The runtime serves a tools verb per module with names, descriptions and schemas (design 34 §3), and
refuses a module naming its own tool tools. Discovery asks catalog_modules then each module, naming
what did not answer. One MCP handler over two transports: stdio (mesh mcp) and loopback HTTP (mesh
serve, the mesh-console module, novox/hq ADR 0152); serve refuses any bind but loopback. tools/call
may go through a running console with --console and no credential.
jochen
jschoubben