ADR 0189: the store keeps what the records name, and a maintenance step holds its writers still

Issue 108: the artifact store has never collected anything. Fifty-three
repositories on the machine that serves everything else, and the only outcome
of leaving it is a full disk reported as somebody else's failure.

The mesh decides what may go — from its own build records, so it never names
a digest it did not put there — and the store reclaims the bytes in a nightly
window with its server held still. Deletion on the one door takes nothing a
push did not already have.

Designs 18 and 20 amended; issue 108 resolved.

Also issue 202, found running the controller's suite: a module whose required
setting nobody set is left out of the machine in silence, and dnsmasq became
that module this morning.

03-DESIGN/01-to-be/18-building-a-module.md

@@ -5,9 +5,10 @@ code:
   - mesh-controller cmd/mesh-builder
   - mesh-controller internal/builder
   - mesh-catalog modules/builder
-updated: 2026-10-01
+updated: 2026-10-02
 decisions:
   - 02-DECISIONS/0157-a-build-says-what-it-does-on-the-bus-as-it-happens.md
+  - 02-DECISIONS/0189-the-store-keeps-what-the-records-name.md
   - 02-DECISIONS/0150-a-modules-own-code-runs-as-supervised-processes-under-one-account.md
   - 02-DECISIONS/0142-the-mesh-delivers-its-own-components-as-binaries.md
   - 02-DECISIONS/0111-a-build-source-is-on-the-git-seat-or-external.md
@@ -293,6 +294,44 @@ build's lines reach a reader of its subject in order and the stream holds them a
 against a real server); the seat verb with an id reads the log (controller test); and, live, a build
 after the roll-out read line by line through the console.
 
+## The store keeps what the records name
+
+*2026-10-02 — [ADR 0189](../../02-DECISIONS/0189-the-store-keeps-what-the-records-name.md),
+[issue 108](../../04-ISSUES/108-the-registry-has-no-garbage-collection-once-it-has-two-doors/00-report.md).*
+
+Every build pushes another layer set and, until this, nothing ever removed one. The registry's own
+answer — collect what no tag names — is wrong for this mesh: each artifact is pushed under one
+moving tag and machines are pinned by digest, so every build but the newest is untagged and some
+machine may still be running it.
+
+**The mesh decides and the store reclaims.** Deletion is enabled on the store's one door — that
+door already accepts a push, and a writer who can push can replace any tag, so delete takes
+nothing a push did not already have, and ADR 0082's bargain (a store every machine reaches with no
+credential to distribute first) is kept. The mesh then removes what it put there and no longer
+keeps, **naming it from its own build records** rather than enumerating the store: it has never
+put anything there it did not record, so a digest it did not record making is never named, which
+is what keeps the sweep away from the images genesis pushed before any record existed.
+
+An artifact stays for one of two reasons and otherwise goes: a definition the mesh holds names it
+(no age limit — this is the floor), or it belongs to one of the five most recent successful builds
+of its module (somewhere for a wrong release to return to). The sweep runs after a build the mesh
+recorded, which is the moment new bytes landed and the moment the keep set moved; it needs no
+timer. Deleting a manifest frees no bytes, so the store's own collector runs nightly as a
+scheduled step with the server held still — which is what `while-stopped` exists for
+([design 20](20-writing-a-module.md)). Plain collection, not `--delete-untagged`: what the mesh
+keeps is still a manifest and so still referenced, and the dangerous flag is not needed once the
+mesh is the one deciding.
+
+A machine behind by more than five builds of a module, recreating a container, cannot pull what it
+was running. It is already a machine the mesh reports as behind, and the answer is the current
+declaration.
+
+*How it is checked:* the keep set, against records, holds what a manifest names and the five most
+recent builds and nothing else; a reference the mesh never recorded is never in the delete set; an
+image and an archive are asked for at their own endpoints; a store with deletion off names the
+remedy rather than the status code; a store that does not have it is recorded collected rather
+than retried for ever. Live: the store's size before and after the first nightly collection.
+
 ## The builder compiles the languages the mesh is written in
 
 *2026-09-29 —