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.
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---
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status: open
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status: resolved
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opened: 2026-09-23
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located-in: []
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fixed-by:
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amended-design:
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located-in: [mesh-controller internal/inventory, mesh-controller internal/artifacts, mesh-host internal/apply, mesh-catalog modules/distribution]
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fixed-by: 02-DECISIONS/0189-the-store-keeps-what-the-records-name.md
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amended-design: 03-DESIGN/01-to-be/18-building-a-module.md
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---
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# 108 — The registry has no garbage collection, and two doors make it harder to add
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@@ -75,3 +75,32 @@ real thing services need, and the mesh cannot express one.
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images by digest and moves by version — is retention "the digests no recorded build names"?
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- Who owns the routine when the store and its public door are two modules — the store, since the
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volume is its?
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## Answered, 2026-10-02 — [ADR 0189](../../02-DECISIONS/0189-the-store-keeps-what-the-records-name.md)
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The three open questions, answered:
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- **A maintenance step, or a backend that does not need its writers stopped?** The step. A
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scheduled container may name `while-stopped` — resource ids of **its own module's** containers,
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which the host stops before the run and starts again after it whatever the step did. A storage
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backend the mesh does not run would be a bigger thing to own than the mechanism it avoids, and
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the mechanism is wanted anyway: a service that cannot have work done underneath it is a real
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shape and the mesh could not express it at all.
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- **Is retention "the digests no recorded build names"?** Nearly. An artifact stays because a
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definition the mesh holds names it (no age limit), or because it belongs to one of the five most
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recent successful builds of its module. Last-N-tags was the predecessor's rule for a registry
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that knew nothing else; this mesh knows what each digest is for.
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- **Who owns the routine now the second door is gone?** Both halves, each where it can be. The
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**mesh** decides what may go — only it holds the records — and asks the store to drop it. The
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**store** reclaims the bytes, because only it can stop its own server. Neither half can be done
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by the other.
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And the sharpened point — enabling deletion on a door with no accounts — dissolved on inspection:
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**that door already accepts a push**, so a writer who can reach it can already replace any tag.
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Delete takes nothing a push did not have. What it does not do is undo ADR 0082's bargain, which
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putting an authenticated door in front of deletion would have.
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The second registry process is not built, as the 2026-09-26 note says, so the shared blob cache
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and the deletion-cached-by-the-other-door problem never arise. Plain `garbage-collect` is enough:
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what the mesh keeps is still a manifest in the store, so `--delete-untagged` — the flag that would
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delete images machines are running — is not needed at all.
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+67
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---
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status: open
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opened: 2026-10-02
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located-in: [mesh-catalog modules/dnsmasq, mesh-controller cmd/mesh-controller]
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fixed-by:
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amended-design:
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---
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# 202 — A module whose required setting nobody set is left out of the machine, and the resolver is the module it happened to
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## What was observed
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Running the controller's own test suite against the catalogue beside it, 2026-10-02.
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`TestTheResolverIsToldEveryMachineOnTheNetworkAndToldAgainWhenOneLeaves` fails with *"the resolver
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was not handed the machines"*. Composing the same machine by hand and listing what it receives
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shows why: **dnsmasq contributes nothing at all.** Four resources are composed for that node, all
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of them the overlay's. The resolver's package, its configuration, its service and the fact that
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carries every machine's name are simply not there.
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The cause is one line added to `dnsmasq`'s configuration earlier the same day: the addresses it
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listens on beside the machine's own became an operator setting,
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`listen-address=${setting:listen-addresses}`, with no default. A `${setting:…}` nothing sets is
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refused, a module that cannot be composed is **left out** rather than failing the whole machine
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([ADR 0163](../../02-DECISIONS/0163-taking-a-module-over-is-a-comparison.md)), and so a node
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assigned the resolver is handed a declaration with no resolver in it.
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The failing test is the symptom that surfaced it. The test is not what is wrong.
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**Proven rather than inferred.** Composing the same machine a second time with
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`listen-addresses` set to `127.0.0.1` and nothing else changed, every one of dnsmasq's eight
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resources appears — `needs-broker`, `mesh-state`, `package`, `config`, `runtime-dns`, `runtime`,
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`service` and `fact-node-zones`. The only difference between a machine with a resolver and a
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machine without one is whether somebody set a value that did not exist yesterday.
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## Why it matters beyond this instance
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**Leaving a module out is right, and being quiet about it is not.** The rule exists so one
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module's broken setting cannot stop a machine converging — a good rule. But the outcome here is a
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machine that applies cleanly, reports current, and is missing its DNS resolver. Every name on that
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machine then resolves through whatever was there before, or not at all, and nothing in the mesh
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says the resolver was dropped. That is the shape
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[issue 152](../152-a-nodes-plan-failure-silently-drops-its-routed-names/00-report.md) records for
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routed names, here for a whole module.
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**And a setting with no default is a definition that cannot be assigned.** Every other
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`${setting:…}` in the catalogue names something that is genuinely particular to one installation —
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a public domain, an issuer. "Which addresses besides my own do I answer on" has an obvious correct
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default for every machine that is not a LAN gateway: none beside loopback. A definition that
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refuses to compose until somebody sets a value most machines do not need is a definition that
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breaks the next node to be assigned it, and genesis with it.
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## What this does not claim
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Whether the live machines are affected was not checked — those four have had the setting set, or
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their resolvers would already be gone. The claim is about a machine assigned the resolver *from
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now on*, and about the silence.
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## Open questions
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- Should the declaration say which modules it left out, where a person or the console can see it?
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`left_out` already travels to the host ([ADR 0163](../../02-DECISIONS/0163-taking-a-module-over-is-a-comparison.md));
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what is missing is anything that reads it back and says so.
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- Should a `${setting:…}` be allowed a default in the definition — making "unset" mean "the
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default" rather than "refuse" — or is a setting with a default no longer the operator's value?
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- Is leaving a module out ever right for a module a node is **assigned**, as opposed to one it
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merely pulls in? An assignment is somebody saying *this machine runs this*; silently not running
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it is the one answer nobody asked for.
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