Describe the mesh MCP server as it runs and mark its design implemented (issue 1008) #400
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---
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layer: as-is
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status: implemented
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code: [mesh-catalog modules/mesh-console, mesh-tools src/mesh.ts, mesh-tools src/http.ts, mesh-tools src/runtime.ts, mesh-controller internal/broker, mesh-controller cmd/mesh-controller/check.go, mesh-controller cmd/mesh-controller/seatverbs.go]
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updated: 2026-10-10
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code: [mesh-tools, mesh-host, mesh-controller]
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updated: 2026-10-17
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decisions:
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- "ADR 0152"
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- "ADR 0095"
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- "ADR 0037"
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- "ADR 0175"
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- "ADR 0195"
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- "ADR 0197"
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- "ADR 0367"
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- "ADR 0154"
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---
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# The mesh MCP server, as it runs
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**The mesh's tools reach a person through a module the mesh assigned to their machine.** Since
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2026-09-30 a workstation that is a node can be assigned `mesh-console`; the mesh mints a bus account
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`<node>.mesh-console`, seals its credential to the machine, and the container binds
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`127.0.0.1:<port>` with the port the mesh assigned for the manifest's declared one. An agent on the
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machine is pointed at `http://127.0.0.1:<port>/mcp` and sees the mesh's tools; a person uses the same
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endpoint. Nothing on the machine holds a credential a person had to carry.
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**The `mesh-console` container no longer exists.** Read 2026-10-17 from `mesh-tools` (package
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`node-tools`), `mesh-host` and `mesh-controller` on their forges' main, and from the live mesh
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through `mesh_overview`, `mesh_machine`, `mesh_runtimes` and `mesh_describe`. Checked: the
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catalogue (`mesh-catalog`) carries no module named `mesh-console` any more — the name survives only
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in the glossary's retired-words list and in a test fixture — and none of the four nodes answers a
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module of that name.
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## What it is now
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**The tool runner is one of the mesh's core components**, named `node-tools` beside
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`mesh-controller`, `mesh-host` (the node-engine) and `nats` (the bus) — the mesh's own repositories'
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check treats the four the same way, as the core whose health the mesh itself defines rather than a
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module's own. `mesh-host` and `mesh-controller` supervise, compose and account for it as a core
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process rather than as an ordinary assignment (`ComponentNodeTools`/`BusNodeTools` in both, the
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witness and lease code that restarts and rolls it back, the account named `<node>.node-tools` on
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the bus).
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**It still carries a manifest, `node-tools/module.json` in `mesh-tools`,** and that manifest is
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where its grants live: `invokes` names `*`, so its account may call every tool on the mesh;
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`waits` names the five event families `mesh_wait` may subscribe to (the knowledge base's reviews,
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mesh-delivery's transitions, the forge's status, the controller's checked event, and the operator
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channel's decision for the agent module) — the bus refuses a subscription outside this list
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(ADR 0367 §2); and it
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`provides` one provision, the MCP endpoint, at node scope, and `listens` on the port it serves from,
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opened only to the machine itself. Its code lives under `node-tools/` in the `mesh-tools`
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repository (`internal/console`, `internal/announce`, `internal/bus`).
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**One runtime per node, run by the node-engine as a sibling process, never a container**
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(ADR 0175). It holds the node's one bus credential and may call every tool on the mesh; its account
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publishes nothing else. It binds `127.0.0.1:<port>` and refuses to bind anything else, said before
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binding rather than after (`node-tools/internal/console/http.go`, citing ADR 0152): whoever is on
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the machine owns the mesh there, and nobody else may reach this port. An agent or a person on the
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node is pointed at `http://127.0.0.1:<port>/mcp` once; the `serverInfo.name` the handshake answers
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is `mesh`.
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## What it answers
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`initialize`, `tools/list`, `tools/call`, over HTTP, one JSON body per request, no session and no event
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stream. `tools/list` is what the running modules answered: every tool runner built on or after that day
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serves a `tools` verb for its module, and the mesh MCP server asks the catalogue for the roster and each module
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for its tools. A module that did not answer is named in the list's `_meta.notAnswering`. On the day it
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shipped that was 36 of 51 modules — those that serve no tools at all, and those whose rebuilt runtime the
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mesh records rather than rolls out — and 62 tools from the rest.
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`initialize`, `notifications/initialized`, `ping`, `tools/list`, `tools/call`, over HTTP, one JSON
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body per request, no session and no event stream (`node-tools/internal/console/mcp.go`).
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`tools/call` reaches any tool by `<module>.<tool>`, listed or not. The mesh MCP server's grant is `*`, so what it
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may call is every tool on the mesh; its account may publish nothing else and subscribes nothing.
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**It announces seven tools, not five** (ADR 0195, extended by ADR 0367): `mesh_overview`,
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`mesh_machine`, `mesh_search`, `mesh_describe`, `mesh_call`, `mesh_runtimes` and `mesh_wait`. The
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handshake's `instructions` text names all seven and the four address forms. `mesh_overview` is
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where the mesh-wide count of modules and tools is read live — a number copied into this document
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would drift; asked on 2026-10-17 it answered 103 modules and 645 tools across the whole mesh, with
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two module instances (`route-proxy` on two of the nodes) named as not answering rather than silently
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absent.
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No call is refused for want of a person's approval: a tool runner serves every call it is issued, whoever made
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it, and cannot tell an agent from the operator (ADR 0259 §6, issue 340). An act waits for the operator's warrant
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only where its module asks first, in its own code: the agent module's instruction proposals, and the
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controller's settings proposals and the actions it offers on a condition.
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**Addresses, exactly as the handshake states them:** `<seat>.<verb>` for a seat held once for the
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mesh (`mesh-controller.status`); `<node>/<seat>.<verb>` for a seat every machine holds
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(`<node>/node-packet-filter.rules`); `<node>/<module>.<tool>` for a module assigned to one machine;
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and `<module>.<tool>` also for a module whose instances are interchangeable. A tool not listed can
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still be called by address — listing is discovery, calling is the grant — and a module that is not
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interchangeable is refused with the machines it runs on rather than guessed at.
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**What exists is what announced itself** (ADR 0197). Every node's tool runner answers the NATS services
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protocol's `$SRV.PING`, `$SRV.INFO` and `$SRV.STATS`, one service per process, naming in each
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endpoint's metadata which module, seat, scope and machine serves it. `mesh_overview` and
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`mesh_machine` gather one request's answers: at least 750ms so a runtime that only just answered
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`$SRV.PING` is still waited for, up to 5s for one that said it is there but has not yet sent its
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full announcement — a fixed shorter window lost the largest runtime's listing once a live
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measurement found how slow its round trip over the bus could be. An announcement unchanged since
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last asked (by its digest) is not re-fetched, which is why `mesh_runtimes` can show a runtime
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answering in under 100ms for hundreds of kilobytes of discovery.
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## mesh_wait
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**The seventh tool, added by ADR 0367**, lets a session wait on the bus for an event instead of
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polling: a call names one or more granted event families and an optional filter, and either answers
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the first match or says it timed out. The tool runner's own bus account hears only the families its
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manifest's `waits` list names; an event it hears is never taken as the state — a session reads the
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state from the verb that owns it once woken. It is meant to be called in a loop from a background
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command, not inline, because one call blocks until it answers or times out.
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## The mesh's own verbs
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*Since 2026-09-30 evening (ADR 0154).*
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The mesh MCP server asks the `mesh-controller` seat's `tools` verb beside the modules and lists every role's
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tools as `<seat>.<verb>` — `mesh-controller.status`, `mesh-controller.push` and the other ten. A call
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to `<prefix>.<name>` reaches the seat when the prefix is a seat declaring that verb, and the module
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otherwise; `seat:<seat>.<verb>` says so outright. When the controller does not answer, the list
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names `mesh-controller (seat)` as not answering and carries the modules' tools regardless. The
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`mesh-controller` *module* is always named as not answering: it serves no module tools, only its seat's.
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**These already answer directly, not as a stated future.** Beside every assigned module's tools,
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the tool runner asks the `mesh-controller` seat for its own verbs the same way (ADR 0154): measured
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live, the mesh-controller runtime is one instance, mesh-wide, and it answers 63 verbs for that one
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seat (`status`, `push`, `assign`, `build`, `artifacts` and the rest), and the `mesh-controller`
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*module* answers none of its own — it serves no module tools, only its seat's, exactly as design 33
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described while it was still only designed. The 56-to-93 seat-verb counts each node's tool runner
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answers (below) are a different thing: the tool runner serves the verbs of whichever node-scoped
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seats are held on that node (`node-backup`, `node-build-agent`, `node-service-manager` among them),
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on behalf of the modules holding them, not the mesh-controller seat's — that one is served by the
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mesh-controller runtime itself, a separate process, and the tool runner only asks it and relays what
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it answers.
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## Around it
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## Where it runs
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- **`invokes`** in a manifest is the grant. It is composed into the bus's user list exactly as a
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person's account is; the mesh MCP server is the only module that declares it.
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- **`module check <file|dir>…`** on the controller's binary judges a manifest with no mesh: the strict
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parse, every per-manifest problem, and the rules between the manifests given. It prints what it cannot
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judge without a store rather than refusing. The mesh MCP server's own manifest was the first thing checked
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with it, and the whole catalogue passes.
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- **The person's client remains.** `operator issue` and `mesh tools|call|mcp` with a credential file
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still work, for a machine that is not a node and for a mesh not yet able to assign anything.
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`mesh tools --console <url>` goes through a running mesh MCP server with no credential; it is covered by the
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runtime repository's tests and was not exercised on the live mesh.
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**Every node, not a per-operator assignment.** Measured live: all four of the mesh's machines
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answer a `node-tools` runtime, each with its own module and tool count (between 294 and 312 tools,
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56 to 93 seat verbs, in this reading). This is a fact that shipped past the design it came from: the
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to-be document still describes it as assigned to "whichever machines an operator sits at"; what
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actually runs is the opposite — every node the mesh holds carries one, because it is core
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infrastructure the mesh itself depends on (discovery, the controller's own verbs, every module's
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tools), not a convenience assigned to a workstation. There is accordingly no assign or unassign verb
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for it: removing it from a node is not an operation the controller or the catalogue exposes.
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## What shipped bent
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## What this repository's prior text got wrong
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- A module registered by hand from the catalogue with `--source <url> --path modules/<m>` records a URL,
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not a place on the git seat: `--self` takes the forge path form (`<owner>/<repository>`), which the
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operator did not pass. The rebuild-on-merge matched the URL anyway.
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- Modules whose upgrade policy is *record* — the forge among them — answered `tools` only once
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something pushed their rebuilt runtime; until then they are listed as not answering while still
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callable. That is the policy doing what it says, not a fault of the mesh MCP server.
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The document this replaces described `mesh-console` as a catalogue module served by a container and
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assigned only to workstations. That module and its container are gone; the manifest is not — it
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moved to `node-tools/module.json`, still declares `invokes: ["*"]`, and gained `waits` and the
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`mcp-endpoint` provision, described above. What also moved is which language builds it: the
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manifest's `build.artifacts` names a Go binary built from `cmd/node-tools`, and that is what a node
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runs. The repository still carries the earlier TypeScript sources (`node-tools/src/mesh.ts`,
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`http.ts`, `runtime.ts`, `announce.ts`, `broker-nats.ts`, `client.ts`, `launch.ts`, `main.ts`,
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`mcp.ts`) on main, but the manifest does not build from them. The quirks the prior text recorded
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from the `mesh-console` era (a module registered by hand recording its source as a URL; a
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*record*-policy module staying listed as not-answering until its rebuilt runtime is pushed) are not
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re-checked here: they were about the `mesh-console` container's registration path, which no longer
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exists.
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## How it is checked
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- `mesh_overview` and `mesh_machine <node>`: the live tool and seat-verb counts, and which modules
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are named not-answering.
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- `mesh_runtimes`: which runtimes answered discovery, how long they took, how large their
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announcement was, and whether it was shortened to fit the bus — read this when an address is said
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to be missing or on another machine.
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- `mesh_describe <address>` for one tool's schema; a call through `mesh_call` reaches the module or
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seat over the bus and the answer is its own, unshaped.
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- The code: `mesh-tools` (`node-tools/internal/console`, `internal/announce`, `internal/bus`),
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`mesh-host` and `mesh-controller`'s core-component handling of `node-tools` (witness, lease,
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bus-user naming). Their unit tests hold the loopback-only refusal, the seven-tool handshake, the
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discovery gather window and `mesh_wait`'s event-then-read-state rule.
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- `knowledge-base.get` with `kind: decision` and number 152, 175, 195, 197, 367 or 154.
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@@ -1,11 +1,13 @@
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---
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layer: to-be
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status: designed
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code: [mesh-catalog, mesh-tools, mesh-controller]
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updated: 2026-10-03
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status: implemented
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code: [mesh-tools, mesh-host, mesh-controller]
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updated: 2026-10-17
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decisions:
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- "ADR 0197"
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- "ADR 0195"
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- "ADR 0175"
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- "ADR 0367"
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- "ADR 0160"
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- "ADR 0159"
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- "ADR 0152"
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@@ -163,11 +165,16 @@ matched it by URL.
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## What this does not settle
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- Narrowing a mesh MCP server's grant per assignment. ADR 0046 makes it a setting; nothing reads one yet.
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- The mesh's own verbs on the bus. Design 33's third family; this document only says where they appear
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once they exist.
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- A person's identity behind the mesh MCP server. The mesh sees the mesh MCP server's account; design 15 keeps the
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question open.
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- **The mesh's own verbs on the bus.** Design 33's third family: these now answer directly, through
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the `mesh-controller` seat, under ADR 0154 — settled, not open. [As-is 13](../00-as-is/13-the-console.md)
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records it live.
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- **Narrowing the tool runner's grant per assignment.** ADR 0046 makes it a setting; nothing reads
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one yet. Owned by [design 58](58-agent-work-as-the-meshs-own.md) milestone 6 (issue 883): an
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identity asked for each assignment is one of that milestone's parts.
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- **A person's identity behind the mesh MCP server.** The mesh still sees only the tool runner's own
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account, never the caller's; design 15 raised the question and leaves it open. Owned by the same
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milestone (design 58 milestone 6, issue 883): its outcome is that every person, agent and module
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becomes an identity with a role, and a call carries which one made it.
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## References
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