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The work order's group-3 question answered: an ordinary module the mesh assigns to the machine a person sits at, holding a minted credential, calling tools under a manifest grant (invokes), serving MCP on loopback. Design 34; pointers in 33, 25 and 0095; module check designed into 12 (issue 148); README stops claiming an indexing nothing provides (issue 006).
95 lines
6.9 KiB
Markdown
95 lines
6.9 KiB
Markdown
# Glossary — the words this repository uses, and the ones it stopped using
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One name per thing. This page is the authority; where an older record says something else, that
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record is being superseded, not this page. It exists because the terms kept drifting in
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conversation — control plane / controller / master / hub for one thing, substrate / foundation for
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another — and a mesh you cannot name precisely is a mesh two people describe differently.
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## The mesh and its machines
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- **node** — a machine in the mesh. There are 0..n of them, and each runs the host agent. A node is
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just a machine that has joined; being one implies nothing about what it runs.
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- **control-node** — the one node that also holds the `mesh-controller` seat. There is exactly one
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per mesh. "control-node" is not a separate kind of machine — it is a node that additionally runs
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the controller (and, today, the foundation). Lose it and the other nodes keep running what they
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were last told; they simply cannot be told anything new.
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- ~~master / slave~~, ~~hub / peer~~ — not used. The relationship is *controller and nodes*, and no
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node is subordinate: a node applies declarations on its own and survives the control-node dying.
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## What runs the mesh
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- **controller** — the component that decides what each node should be, holds the mesh's records,
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and tells nodes over the broker. Replaces **"control plane"** (borrowed from networking's
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control-plane/data-plane, and opaque here).
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- **mesh-controller** — the module that runs the controller. It **claims** the `mesh-controller`
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seat at mesh scope, which is what makes it singular. Replaces the module name **`mesh-control`**.
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(The git repository has been renamed `mesh-control` -> `mesh-controller` on the forge; the module,
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container and image it produces are `mesh-controller`.)
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- **foundation** — the store and the broker, raised at genesis before any module system exists.
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Replaces **"substrate"** (a biology metaphor that landed for no one). The foundation is not a
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third thing beside the store and broker — it *is* those two, named together.
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- **store** — the one postgres server. It holds the controller's own context databases
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(`inventory`, `identity`, `licences` — a context owns its store, [ADR 0008](../02-DECISIONS/0008-a-context-owns-its-store.md))
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and every module's own database. One server, many databases — never one shared "mesh database".
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- **bus** — the mesh's own nervous system: NATS, one per mesh, carrying every link the mesh has —
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control, declarations, builds, events, tool calls
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([ADR 0106](../02-DECISIONS/0106-the-bus-is-nats.md)). A module reaches it by requiring
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`mesh-bus` ([ADR 0128](../02-DECISIONS/0128-the-mesh-bus-is-required-not-ambient.md)); one that
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does not require it has no account on it. Held by the `mesh-broker` seat, which is named after
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the *role* rather than the server, so the server can change without the seat doing so.
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- **the deprecated broker** — the lavinmq module. It was the mesh's bus and is not any more. It
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keeps running as an **ordinary provider** of the `amqp` provision, for modules that need a
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message broker of their own the way something needs a database
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([ADR 0127](../02-DECISIONS/0127-amqp-is-a-provision-not-the-bus.md) (superseded by [ADR 0131](../02-DECISIONS/0131-everything-on-the-mesh-speaks-to-the-broker-seat.md))) — no seat, not foundation,
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never raised at genesis, and a mesh that never installs it is complete.
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Say *the deprecated broker*, not "the compatibility broker" (it serves the mesh's own modules,
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not only the predecessor's) and not "the AMQP broker" (naming it after a protocol invites
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describing the bus by contrast with it, which is backwards: the bus is the mesh's nervous
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system and this is a module).
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## What the mesh stores and serves
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- **package** — what code resolves when it is **compiled**: an npm/cargo/pypi dependency, by
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**version**. Served by the **package-registry** (gitea). Only a builder talks to it.
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- **artifact** — what the mesh delivers to a machine to **install and run**: an OCI image, by
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**digest**. Served by the **artifact-store** (distribution). Every node pulls from it.
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- These are two protocols, not one store being weak — see [ADR 0075](../02-DECISIONS/0075-two-stores-and-which-provides-what.md).
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## How modules relate to the mesh
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- **seat** — a named role at a scope (node / site / mesh), held by a module assignment, from a
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**closed set** the mesh defines: a claim naming a seat outside the set is refused. A seat may
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**deliver a provision**, and its holder is then the mesh's answer for it when several modules
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provide it ([ADR 0126](../02-DECISIONS/0126-a-module-declares-its-own-seats.md) (superseding [ADR 0110](../02-DECISIONS/0110-a-seat-is-a-module-assignment-from-a-closed-set.md))).
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The set, with who holds each seat, is the overview of what a mesh has
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([26 — The seats](../03-DESIGN/01-to-be/26-the-seats.md)). A seat has a **capacity**: a
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capacity-1 seat is exclusive (one holder); a higher-capacity seat is a **bench** (several holders
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coexist).
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- **claim** — a module taking a spot on a seat. `claims: [{name, scope}]` in a manifest. A
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mesh-scoped exclusive claim is how the mesh says "there is one of me". A foundation seat is
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named after the server it guards: the `mesh-controller`, `postgres` and `lavinmq` modules claim
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the `mesh-controller`, `mesh-store` and `mesh-broker` seats ([ADR 0079](../02-DECISIONS/0079-the-foundation-seats-are-named-after-their-servers.md)).
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- **provision** — a service one module `provides` and others `require`; the mesh resolves a provider
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and wires the two with an endpoint and a credential. A provision is a service you offer, a seat
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is a role you occupy, and the two meet where a seat delivers a provision: occupying the seat is
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what makes a module *the* provider of it.
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## The surfaces
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- **console** — the module (`mesh-console`) that puts the mesh's tools in front of whoever is on a
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machine: an MCP endpoint on the machine's loopback for an agent, the same endpoint for a person. It
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is assigned like any module, holds a credential the mesh minted, and calls tools under a grant its
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manifest declares (`invokes`). Loopback is the authority boundary: whoever is on the machine owns the
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mesh there ([ADR 0152](../02-DECISIONS/0152-the-operators-surface-is-a-module-the-console.md)).
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Not "the tool bridge", "the brain" or "the MCP server" — those name the predecessor's program or a
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protocol, and the console is a module.
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- **invokes** — the manifest word for the tools a module calls, `<module>.<tool>` each or `*` for
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every one. A grant on the publish side and nothing else; a module that declares none calls nothing.
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## How this page is kept
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A new name for an existing thing lands here first, in the same change that introduces it in code. A
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record under `02-DECISIONS/` keeps whatever word it was written with — those are immutable — so a
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term retired here may still appear there, and the mapping above is how to read it.
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