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 # mesh-contracts
 
-The mesh's seat contracts (novox/hq ADR 0608 §5, ADR 0613, ADR 0620; design 26 *A seat's definition*): one
-language-neutral definition per seat, and the Go and TypeScript types generated from it.
+The mesh's seat contracts (novox/hq ADR 0608 §5, ADR 0613, ADR 0620, ADR 0625, ADR 0627; design 26 *A seat's
+definition*): one language-neutral definition per seat, the Go and TypeScript code generated from it, and the client
+of a seat whose callers share logic over it. This repository holds contracts only and no seat: a seat's holder
+implements its contract, and no holder's code lives here.
 
-Every file under `go/` and `ts/` is written by the generators of the Go and the Node build modules, never by hand.
-This repository holds contracts only and no seat: a seat's holder implements its contract.
+## Where a seat's code goes
+
+- **The definition**, written by hand: `seats/<seat>/seat.json`, its fixtures in `seats/<seat>/fixtures/`, and the
+  parts several seats include whole in `parts/` (the four registry seats' verbs and events are `parts/registry.json`).
+  mesh-sdk's `seatdef` is the one reader of the format; the indexer and the generators use it.
+- **The seat set**, generated: `go/seats` (module `git.novox.be/novox/mesh-contracts/go`), every seat's name, scope,
+  verbs and provision at the seat list's grain (ADR 0625 §2). mesh-sdk's `catalogue` is its only importer in mesh-sdk.
+  A change of it rebuilds every importer of the seat set.
+- **A seat defined whole**, generated: `go/seats/<seat without hyphens>`, a Go module of its own importing nothing,
+  holding the seat's verbs, events and subjects, its message types and a test of its fixtures (ADR 0625 §1). A module
+  imports only the seats it uses, so a change of one seat rebuilds only its users. The TypeScript side is `ts/src/`.
+- **A seat's client**, written by hand: `go/clients/<seat without hyphens>client`, a Go module of its own, only where
+  two or more callers share logic over the seat (ADR 0625 §4, ADR 0627 §1): operator-channel's (checking an ask,
+  its digest, a warrant's, and an asking module's keeping of its asks) and the four registry seats' (publishing a file
+  in parts). A client imports its own seat's contract and mesh-sdk's runtime, never another seat's client, and names
+  no module's subject or tool.
+- **Not here**: the value layouts of seats not yet defined whole (they stay in mesh-sdk until their domain moves,
+  ADR 0625 §9), and a role only one module could ever play (that module's own tools and events, ADR 0625 §8).
+
+## How it is checked
+
+Every file under `go/` and `ts/` outside `go/clients/` is written by the generator (seatgen, the source of the Go and
+Node build modules' generate step) and compared on every build: a hand-written file there fails, named (ADR 0625 §5).
+`seatgen -check` also runs the client check (each client is for a seat defined whole, a module of its own, importing
+only its seat's contract and mesh-sdk) and checks `module.json`'s Go package artifacts against the tree.