Review of 0164-0166 and 190: the mesh's own setting words stay settable; changing runtime verbs are not the console's wildcard; migration steps 1-2 are one push; dnsmasq's dns key dates from 09-23

Proposed for the operator's review: settings declared with defaults and cost (0164),
container-runtime as a kernel capability (0165), node-container-runtime seat with the
host creating containers through its holder (0166), and the runtime's file written by
modules that are not its own (190).

02-DECISIONS/0164-a-setting-is-declared-with-its-default-its-meaning-and-what-changing-it-costs.md

@@ -0,0 +1,135 @@
+---
+topic: what runs on it
+status: proposed
+date: 2026-10-01
+deciders: jochen
+reconstructed: false
+extends: 02-DECISIONS/0046-a-module-configuration-is-its-assignments-not-its-manifest.md
+---
+
+# 164. A setting is declared with its default, its meaning and what changing it costs
+
+## Context
+
+The operator asked for one thing for every module, with the container runtime as the first case: **one
+consistent default configuration for every machine, overridable per assignment, and easy to change
+later.** The four machines' runtime configurations were each written by hand and differ — one keeps
+running containers through a daemon restart and one does not, their log rotation differs, and each
+names its resolver and its trusted registries in its own words.
+
+Most of this was already decided.
+[ADR 0046](0046-a-module-configuration-is-its-assignments-not-its-manifest.md) said the definition is
+identity and **defaults**, the assignment's settings are the configuration, *unset is the default*, and
+*an unknown setting is refused*. [ADR 0112](0112-a-module-definition-names-no-node-mesh-or-path.md) made
+a setting an operator requirement whose contract is "a type and, optionally, a default", answered by
+"the assignment's, or the requirement's default, or unresolved". An assignment is a module on a node,
+so the node layer of a module's settings already *is* the per-assignment override, and the mesh-wide
+layer is the one consistent default a person changes once.
+
+What was built is narrower than what was decided, measured in the controller on the day of deciding:
+
+- **Nothing declares which keys are settable.** A mergeable file's content is its defaults, and every
+  key of it — and every key not in it — is accepted. Nothing tells a person, or the console, what can be
+  set, of what type, or what it means.
+- **The refusal of an unknown setting is not there for most modules.** The stray-setting report returns
+  nothing at all for a module with any mergeable file, because such a file "takes any key"
+  ([issue 173](../04-ISSUES/173-a-modules-settings-reach-every-fact-it-contributes/00-report.md) left
+  files that way on purpose). It reports rather than refuses where it does run.
+- **A value in a file that is not JSON can have no default.** `${setting:<key>}`
+  ([ADR 0155](0155-a-definition-names-no-installation-and-how-that-is-checked.md)) is refused when no
+  layer sets it — right for a mail domain, where a default is the very literal 0155 removes, and wrong
+  for a tunable like the resolver's upstreams, which the resolver module therefore carries as literals
+  in its file.
+- **What a change costs is said per file, not per key.** A service names the files it is reloaded or
+  restarted on. The runtime re-reads its trusted registries on a reload and its `dns` key only when it
+  starts; the resolver module declared a reload, so on two machines the key was written, reloaded,
+  and never read, and every container got a public resolver for weeks while everything read as
+  current ([issue 110](../04-ISSUES/110-a-container-on-the-runtimes-own-network-cannot-reach-the-resolver/01-resolution.md)).
+
+## Considered Options
+
+1. **Leave settings implicit; document each module's keys in its README.** Rejected: a key the mesh
+   does not know cannot be refused, typed, listed by the console or costed, and a README is a rule
+   enforced by nothing.
+2. **A second mechanism for tunables beside settings** — defaults in a new block, settings untouched.
+   Rejected: two ways to state one person's value, and design 27 already retires six mechanisms
+   that grew that way.
+3. **Settings declared in the definition, as 0112's operator requirement: a key, a type, a meaning,
+   optionally a default, and what a change costs.** Adopted.
+
+## Decision
+
+**A module declares every setting it takes.** Each declared setting has a name, a type, one sentence
+of meaning, optionally a default, and what a change to it costs. The spelling is design 27's to settle
+with the rest of the requirement form; this record decides the content.
+
+**A setting with a default is a tunable; a setting without one is the operator's.** A tunable resolves
+to its default when no layer sets it — wherever it is read, a mergeable file or `${setting:<key>}` in a
+file of any format. A setting with no default is refused by name when nothing sets it, as 0155 decided;
+0155's refusal is narrowed to exactly that case, not changed for it. Whether a value has a default is a
+fact about the software (a log size does, a mail domain does not), and the definition states it once.
+
+**The layers stay as they are, and every value says where it came from.** The definition's default,
+then the mesh-wide layer, then the node's — later wins, objects merge, lists replace. One consistent
+configuration for every machine is the default plus the mesh-wide layer; one machine that differs says
+so in its own layer and nothing else. Asked for a module's configuration on a machine, the mesh lists
+every declared setting with its effective value and its source: *default*, *mesh*, or *node*.
+
+**Changing later is changing one of three places, and the plan shows its reach before anything moves.**
+A new default ships with the module's next version and reaches every assignment that does not override
+it; a mesh-wide setting reaches every assignment of the module; a node's reaches one. The plan of a
+change names each assignment whose effective value moves.
+
+**A declared setting is the only kind accepted.** Setting a key the module does not declare is refused
+when it is set, naming the declared keys, rather than reported when the machine is planned. The mesh's
+own words — where a port, a directory or an operator's data is placed, how far an endpoint reaches —
+are the mesh's to validate as they are today, and no module declares them. A module
+that declares no settings keeps today's behaviour until it does; a catalogue test lists those modules,
+and the list shrinks to empty before the implicit form is removed — design 27's rule for every retired
+mechanism.
+
+**A setting says what it costs: nothing, a reload, or a restart.** When a file changes, the host
+applies the strongest cost among the settings whose values moved in it, so a key the software reads
+only at start can no longer be written and never read. A setting that reaches a container's environment
+costs that container being recreated, which the host already does when a container's specification
+changes; it needs no declaration. A service's `reload-on` and `restart-on` keep
+naming the files that are not settings — a generated roster, a credential.
+
+**The container runtime is the first module to declare its settings** and the model for the rest:
+its log rotation, keeping containers through a daemon restart, and its resolver are tunables, and
+its trusted registries are what the mesh tells it.
+
+## Consequences
+
+- The console can show a module's settings as a form: what can be set, of what type, its default,
+  and where the current value came from. That is the surface the operator wants for changing a
+  default later.
+- `settings set` can refuse an unknown key, so ADR 0046's rule is enforced where it was only stated.
+- The resolver's upstreams, the runtime's log rotation, and other literals a definition carries
+  because it could not give them a default become declared tunables.
+- **What got harder:** every module that takes settings must list them, and a mergeable file no
+  longer silently accepts a key its author did not foresee. A person who needs one adds it to the
+  definition, which is a new module version, not a setting.
+- Issue 173's open question — a consumer checks nothing against a contract — is unchanged; this record
+  is the operator half of design 27's contract, not the provider half.
+- Not decided here: the spelling (design 27); whether a node's layer may be narrowed to a single key
+  rather than replaced whole, as `settings set` does today.
+
+## How this is checked
+
+| Rule | Checked by |
+|---|---|
+| Every setting a module takes is declared | A parser test refusing a setting declaration without a type or meaning; a catalogue test listing modules with mergeable files or `${setting:}` and no declarations, which must be empty before the implicit form is removed |
+| A tunable resolves to its default; an operator value without one is refused | Resolution tests: an unset tunable in a JSON file and in a text file both take the default; an unset setting with no default is refused naming it (0155's existing test) |
+| An undeclared key is refused when set | A controller test: `settings set` with an undeclared key fails naming the declared keys, and nothing is stored |
+| Every effective value names its source | A test listing a module's configuration on a node with one key from each of default, mesh and node |
+| A change's reach is shown before it moves | A plan test: changing a mesh-wide setting names every assignment whose effective value moves and no other |
+| The strongest cost applies | A host test: a file where a reload-cost key and a restart-cost key both moved restarts; a file where only reload-cost keys moved reloads |
+| Live | The container runtime's module lists its settings with their sources on every machine, and a mesh-wide change to its log rotation reaches all four at the next push |
+
+## References
+
+- [ADR 0046](0046-a-module-configuration-is-its-assignments-not-its-manifest.md), [ADR 0112](0112-a-module-definition-names-no-node-mesh-or-path.md), [ADR 0155](0155-a-definition-names-no-installation-and-how-that-is-checked.md), [ADR 0102](0102-the-mesh-writes-into-a-shared-file-never-over-it.md)
+- [Design 27 — a module requires, the mesh resolves](../03-DESIGN/01-to-be/27-a-module-requires-the-mesh-resolves.md)
+- Issues [110](../04-ISSUES/110-a-container-on-the-runtimes-own-network-cannot-reach-the-resolver/00-report.md), [173](../04-ISSUES/173-a-modules-settings-reach-every-fact-it-contributes/00-report.md)
+- mesh-controller `internal/catalogue/settings.go` (`settle`, `UnusedSettings`), `internal/catalogue/setting_into.go`

02-DECISIONS/0165-container-runtime-is-what-a-machine-can-run-and-a-running-runtime-is-its-holders-health.md

@@ -0,0 +1,105 @@
+---
+topic: what runs on it
+status: proposed
+date: 2026-10-01
+deciders: jochen
+reconstructed: false
+extends: 02-DECISIONS/0161-what-deserves-a-seat.md
+---
+
+# 165. `container-runtime` is what a machine can run; that a runtime is running is its holder's health
+
+## Context
+
+A capability is a requirement a module places on a machine, detected by the host and renewed with
+every report ([ADR 0161](0161-what-deserves-a-seat.md)). The host's `container-runtime` asks the
+daemon for its version: *a running daemon, not an installed client*. It was made that way by
+[issue 007](../04-ISSUES/007-an-installed-package-is-not-a-capability/00-report.md), where an
+installed package was believed to be a working service, and
+[design 05](../03-DESIGN/01-to-be/05-the-node-host.md)'s table says the same: *a runtime is
+running*. The installer's preflight borrows the same detector to wait for the runtime the
+foundation bundle installs, so there is one answer to "is there a runtime here".
+
+The mesh is now to have a module for the runtime itself — its packages, its configuration, its
+service — on every machine ([ADR 0166](0166-the-container-runtime-is-a-node-seat-and-the-host-creates-containers-through-its-holder.md)).
+That module cannot declare `container-runtime` as defined: it would require the very thing it
+installs, the cycle [research 011](../01-RESEARCH/011-the-module-graph/cases.md)'s case 12 names
+("something the mesh installs that then becomes a node capability"). The operator defined the word
+for it: **`container-runtime` means the machine is able, at the kernel level, to install a runtime and
+execute containers** — not that one is installed, and not that one is running.
+
+The host already draws this line once. `seat` is hardware, a display server *could* run here;
+`graphical-session` is state, one *is* running; the detector's own comment says "assignment needs the
+first". A machine without a display has no seat however much software is installed, and a machine
+with one has a seat before anything is.
+
+Fifty-four catalogue modules declare `container-runtime` today, counted on the catalogue's main
+branch on the day of deciding: every module that delivers a container. Each relies on the current
+meaning to keep it off a machine with no running runtime.
+
+## Considered Options
+
+1. **Keep the meaning; let the runtime's module declare nothing.** Rejected: a module that installs
+   the runtime has requirements on the machine — the kernel features without which installing it is
+   pointless — and would state none of them. The cycle stays, only hidden.
+2. **Two capabilities, "can run" and "is running".** Rejected: the second is made true by assigning a
+   module, so it is the module's state, not a fact of the machine; a capability the mesh itself
+   flips by its own assignment is case 12's cycle with an extra name.
+3. **The capability is the kernel's; whether a runtime runs is the runtime module's health, and a
+   module that delivers a container needs the runtime's seat held.** Adopted.
+
+## Decision
+
+**`container-runtime` is detected from what the kernel offers**, as `seat` is: the namespaces a
+container needs, a control-group hierarchy the runtime can manage, and an overlay filesystem the
+running kernel has or can load. Present when all three are; absent naming the missing one. Nothing is
+run and no runtime is asked. The verdict's detail names what was found, not a runtime's version.
+
+**"A runtime is running and answers" is one probe, owned by the host and used twice:** by the
+installer's preflight, which waits for the runtime the foundation installs, and as the runtime
+module's health. It asks the daemon, as issue 007 requires. The preflight stops borrowing the
+capability's detector, and there is still one answer to "is a runtime running here".
+
+**The runtime's module declares `container-runtime`**, with `package-manager`, `service-manager` and
+`privileged`, like any module that manages machine software.
+
+**A module that delivers a container needs the runtime seat held on its machine**, and is refused
+otherwise, naming the seat and the modules that could hold it — the refusal design 27 already lists
+for an unheld seat. That requirement is derived from the container resource and needs no manifest
+field ([ADR 0166](0166-the-container-runtime-is-a-node-seat-and-the-host-creates-containers-through-its-holder.md)).
+The fifty-four existing declarations of the capability stay valid and become redundant; a catalogue
+test lists them, and they retire when the list is empty.
+
+**The order is fixed, not preferred.** The detector changes only once the seat requirement is
+enforced. In between, a machine with the kernel and no running runtime would read as able to run
+every containerised module, which is issue 007 again.
+
+## Consequences
+
+- Design 05's capability table changes its `container-runtime` row from *a runtime is running* to
+  *the kernel can run containers*, and names the runtime module's health as where "running" is now
+  asked.
+- The node listing stops showing the runtime's version beside the capability. The version moves to
+  the runtime module's health and its seat's verbs.
+- A fresh machine with no runtime reads as able to run one, so it can be assigned the runtime's
+  module, which is what makes the mesh able to install the runtime instead of the bootstrap alone.
+- **What got harder:** "is this machine running containers" is no longer one glance at the profile;
+  it is the runtime seat's holder and its health. The node's listing should show both side by side.
+
+## How this is checked
+
+| Rule | Checked by |
+|---|---|
+| The capability is the kernel's | Host detector tests over a fixture `/proc` and `/sys`: all three present → present; each one missing → absent naming it; no runtime binary on the fixture machine changes nothing |
+| One probe asks whether a runtime runs | A host test that the preflight and the runtime module's health call the same probe, and that the probe fails against a stopped daemon with an installed client (issue 007's shape) |
+| A containerised module needs the runtime seat held | A resolution test: a module with a container resource on a machine whose runtime seat is unheld is refused, naming the seat and its candidate holders |
+| The order holds | The host release that changes the detector is gated on the controller release that enforces the seat requirement — stated in both changes' descriptions and checked at review |
+| Live | Every machine's profile shows `container-runtime` present with the kernel's features as its detail; a machine with no runtime installed reads present too |
+
+## References
+
+- [ADR 0161](0161-what-deserves-a-seat.md) — the profile renewed by every report; a capability that names a dialect
+- [ADR 0166](0166-the-container-runtime-is-a-node-seat-and-the-host-creates-containers-through-its-holder.md) — the seat and its holder
+- [Issue 007](../04-ISSUES/007-an-installed-package-is-not-a-capability/00-report.md), [research 011](../01-RESEARCH/011-the-module-graph/cases.md) cases 12–13
+- [Design 05 — the node host](../03-DESIGN/01-to-be/05-the-node-host.md)
+- mesh-host `internal/profile/detectors.go` (the runtime detector), `internal/profile/seat.go` (the hardware/state split), `internal/bootstrap/preflight.go` (the preflight that borrows it)

02-DECISIONS/0166-the-container-runtime-is-a-node-seat-and-the-host-creates-containers-through-its-holder.md

@@ -0,0 +1,161 @@
+---
+topic: what runs on it
+status: proposed
+date: 2026-10-01
+deciders: jochen
+reconstructed: false
+extends: 02-DECISIONS/0161-what-deserves-a-seat.md
+---
+
+# 166. The container runtime is a node seat, and the host creates containers through its holder
+
+## Context
+
+Every container the mesh runs on a machine is created by the host, which looks for a runtime
+(`docker info`, then `podman info`) and drives that runtime's command line itself: run, inspect,
+remove, exec. Research 012 called this "detected rather than declared": the host takes over whatever
+runtime it finds. Nothing in the mesh owns the runtime. Its package came from the foundation bundle
+or was already on the machine. Its configuration file was written by hand, differs on each of the
+four machines, and is also written into by two modules that are not the runtime's
+([issue 190](../04-ISSUES/190-the-runtimes-configuration-is-written-by-modules-that-are-not-the-runtime/00-report.md)).
+Its service is declared by those same two.
+
+The operator set the direction:
+
+- a module for the runtime, on every machine, owning "what is needed to run containers here": its
+  packages, its configuration and its service;
+- that module holds a node seat for the runtime, so a second runtime (podman) can later compete
+  for the seat;
+- the host stops speaking to the runtime directly and uses the seat's holder. The host stays the one
+  that decides, and the holder becomes the one that executes;
+- every container on the machine is in scope, not only the mesh's. A development environment started
+  by hand, or a test database a tool runs, is legitimate. The host already calls these *strays*: 3,
+  8 and 25 on three of the machines on the day of deciding;
+- the runtime's events and verbs are subjects on the bus, and the mesh's own interface is built on
+  them. The third-party interface run until now was removed by hand.
+
+[ADR 0161](0161-what-deserves-a-seat.md)'s test for a seat is whether the mesh's own code finds it by
+name. Here it does: the host would look up the holder on its own machine. A singular role of a module
+held once per machine is a `node-*` seat ([ADR 0121](0121-a-system-seat-is-named-for-its-scope-and-modules-define-their-own.md)),
+in the controller's seed.
+
+The constraint that decides most of this record is a cycle. The bus runs in containers. On the
+broker's machine, the broker's own container is created by the host. A holder's code served from a
+container cannot create the container that runs it. On a first machine, before the controller exists,
+nothing holds anything.
+
+## Considered Options
+
+1. **The host calls the holder's verbs over the bus.** Rejected: with the broker down, no machine can
+   create any container, including the broker's. The mesh would be unable to restart its own
+   transport.
+2. **The holder picks a dialect that the host speaks itself, as with the uplink.** Rejected: the
+   host would still drive the runtime, and the module would drive it too for every other caller.
+   That is two programs speaking to one daemon, and they come to disagree about the same machine
+   (the installer's preflight already exists to avoid this).
+3. **The holder's code runs as a supervised process on the machine and serves the seat's verbs
+   twice: locally to the host, on the bus to everyone else.** Adopted.
+
+## Decision
+
+**`node-container-runtime` is a seat of the mesh's own, node-scoped,** in the controller's seed under
+this record. It delivers no provision; what it carries is its role's protocol: verbs its holder must
+serve ([ADR 0132](0132-a-seat-carries-the-tools-its-holder-must-serve.md)) and events its holder emits
+([ADR 0129](0129-a-seat-carries-the-protocol-of-its-role.md)). The runtime's module, `docker`, claims
+it and is assigned to every machine. A podman module may claim it later; one machine runs one.
+
+**The seat's verbs cover every container on the machine:** list, inspect, logs, stats, start, stop,
+restart, create and remove. A mesh-held container is marked by the host's label and says which
+assignment holds it. **A container the runtime runs can be root on the machine** — privileged, a host
+path mounted, the host's network or process namespace, the runtime's own socket — so a caller other
+than the host may not create one that is any of these; only a declaration the mesh composed may ask
+for them. And the verbs that change anything are granted by name, never by a wildcard: a grant of
+every tool (the console's today) reaches the reading verbs only. Issue 193 is what a verb that trusts
+its caller costs. **Creating or removing a mesh-held container is the host's alone.** Any other
+caller is refused naming the assignment, because the host would undo it at its next apply. Starting,
+stopping or restarting one is allowed, and the answer says the host will restore what its
+declaration says. A container the mesh does not hold is the caller's to do anything with.
+
+**The seat's events are the runtime's own** — a container created, started, stopped, died, removed,
+its health changed. They are emitted on the seat's subjects, so every holder emits the same events and
+no reader depends on which runtime holds the seat. As
+[ADR 0160](0160-the-mesh-issues-an-assignments-subjects-and-a-runtime-serves-what-it-is-issued.md)
+decides, the subjects are issued by the controller, not composed by the module.
+
+**The holder's code is a supervised process, not a container** ([ADR 0150](0150-a-modules-own-code-runs-as-supervised-processes-under-one-account.md)).
+A runtime cannot be run by the thing it runs. The process serves the seat's verbs on the bus to the
+console, to tools and to the mesh's interface. The same verbs are served on a local socket on the
+machine, which only the host may use. **The host creates, inspects and removes its containers
+through that socket and nothing else.** If the holder does not answer, the host creates nothing. It
+says so in its report, naming the seat. It never falls back to the command line.
+
+**A container needs the seat held on its machine.** An assignment that delivers a container on a
+machine whose runtime seat is unheld is refused, naming the seat and its candidates
+([ADR 0165](0165-container-runtime-is-what-a-machine-can-run-and-a-running-runtime-is-its-holders-health.md)).
+Mounting the runtime's socket into a container is granted by the seat, not by the capability. The
+socket's path is the holder's to state, because podman's is not docker's.
+
+**The runtime module owns the runtime's configuration.** Its settings are declared with defaults
+([ADR 0164](0164-a-setting-is-declared-with-its-default-its-meaning-and-what-changing-it-costs.md)):
+the resolver containers use, the registries it trusts, log rotation, and keeping containers through a
+daemon restart. The module is given the resolver's address and the mesh's registry as values; no other
+module writes the runtime's file or declares its service.
+
+**The first machine is bootstrapped with the holder, and adopted afterwards.** The foundation bundle
+already installs the runtime's package and service. It also carries the holder's process, delivered as
+a binary the way the host is ([ADR 0142](0142-the-mesh-delivers-its-own-components-as-binaries.md)).
+When the runtime module is assigned, it adopts what the bundle made, as the store and broker modules
+adopt theirs ([ADR 0078](0078-the-store-and-broker-are-modules.md)).
+
+## Consequences
+
+- **The migration on the running mesh has a fixed order:**
+  1. Each machine's hand-written configuration is read, because the module's defaults replace what
+     differs.
+  2. In one push per machine: the resolver module and the private network stop writing the
+     runtime's file ([issue 190](../04-ISSUES/190-the-runtimes-configuration-is-written-by-modules-that-are-not-the-runtime/00-report.md)),
+     and the runtime module is assigned and adopts the runtime, its file and its service. Split in
+     two, either the controller refuses two modules declaring one path, or a machine is left with
+     nothing setting `dns` and `live-restore`.
+  3. The controller seeds the seat and enforces the container requirement.
+  4. The host releases the version that uses the holder.
+  5. The host's command-line path is removed in the release after every machine's holder answers.
+     Until then, the host reports per machine which path it used.
+- **Every container the host makes depends on the holder's process.** A crash-looping holder stops
+  new containers on its machine. Running containers are unaffected. The host's report names the cause.
+- The process form of a module's own code must serve tools on the live mesh before this ships. Only the
+  showcase declares it, and [issue 117](../04-ISSUES/117-a-modules-own-code-is-a-container-and-a-process/01-diagnosis.md)
+  found the showcase's tools declared in a form nothing runs. The runtime module is the first whose
+  tools cannot fall back to a container.
+- A user interface subscribing to events directly does not exist. Today a reader of events is a module
+  that consumes them. The mesh's container view is a module, or waits for that path.
+- [ADR 0005](0005-the-node-host.md) ("a container runtime is detected, not chosen") and
+  [ADR 0006](0006-the-substrate-and-the-control-plane.md)'s matching line describe the mechanism this replaces: on
+  acceptance, each gets a dated note saying the runtime is now a seat's holder, as the decision
+  records' rule for a moved mechanism requires. Design 05 and design 26 are amended after acceptance.
+- The operator's decision to remove the third-party interface by hand needs no mechanism. No
+  module-retires-module rule is introduced.
+- **What got harder:** the host gains a dependency it did not have, and a first machine's bundle gains
+  a component. The direct path was simpler and is what makes a runtime a black box to the rest of the
+  mesh.
+
+## How this is checked
+
+| Rule | Checked by |
+|---|---|
+| The seat is the mesh's own, node-scoped, with its verbs and events | A catalogue test on the default seats; registration refuses a claimant that does not serve every verb (design 33's existing check) |
+| Creating or removing a mesh-held container is the host's alone | A test of the runtime module's verbs: create or remove of a container carrying the host's label, from any caller but the host's socket, is refused naming the assignment; the same verbs on an unlabelled container succeed |
+| No caller but the host creates a container that is root on the machine | A test of `create` from the bus: privileged, a host path, the host's namespaces and the runtime's socket are each refused; the same request on the host's socket is accepted. A broker test: a grant of every tool does not reach a changing verb |
+| The host uses the holder and never the command line | A host test with a fake holder on the local socket: every container operation goes to it, and with the holder absent the apply creates nothing and reports the seat; after step 5, the host carries no command-line runtime code (checked by build: the package is gone) |
+| A container needs the seat held | A resolution test refusing a containerised assignment on a machine with the seat unheld, naming the seat |
+| Socket mounts are granted by the seat | A catalogue test: a module mounting the runtime's socket on a machine whose holder states a different path is refused |
+| No other module writes the runtime's file | The existing collision check, once the private network's computed resources are inside it ([issue 190](../04-ISSUES/190-the-runtimes-configuration-is-written-by-modules-that-are-not-the-runtime/00-report.md)) |
+| Live | `seats` lists `node-container-runtime` held on every machine; the node listing shows each machine's containers, strays included, from the seat's `list` verb; a container started by hand appears as an event on the bus |
+
+## References
+
+- [ADR 0121](0121-a-system-seat-is-named-for-its-scope-and-modules-define-their-own.md), [ADR 0129](0129-a-seat-carries-the-protocol-of-its-role.md), [ADR 0132](0132-a-seat-carries-the-tools-its-holder-must-serve.md), [ADR 0159](0159-a-tool-call-names-the-machine-and-a-holder-serves-its-seats-verbs.md), [ADR 0160](0160-the-mesh-issues-an-assignments-subjects-and-a-runtime-serves-what-it-is-issued.md), [ADR 0161](0161-what-deserves-a-seat.md)
+- [ADR 0150](0150-a-modules-own-code-runs-as-supervised-processes-under-one-account.md), [ADR 0142](0142-the-mesh-delivers-its-own-components-as-binaries.md), [ADR 0078](0078-the-store-and-broker-are-modules.md), [ADR 0005](0005-the-node-host.md)
+- [ADR 0164](0164-a-setting-is-declared-with-its-default-its-meaning-and-what-changing-it-costs.md), [ADR 0165](0165-container-runtime-is-what-a-machine-can-run-and-a-running-runtime-is-its-holders-health.md), [issue 190](../04-ISSUES/190-the-runtimes-configuration-is-written-by-modules-that-are-not-the-runtime/00-report.md)
+- [Design 26 — the seats](../03-DESIGN/01-to-be/26-the-seats.md), [design 33 — the tools the mesh answers](../03-DESIGN/01-to-be/33-the-tools-the-mesh-answers.md)
+- mesh-host `internal/apply/apply.go` (the runtime lookup and the command line it drives)

02-DECISIONS/README.md

@@ -267,6 +267,9 @@ python3 00-META/checks/index.py            fail if stale
 - **0150** — [A module's own code runs as supervised processes under the module's one account](0150-a-modules-own-code-runs-as-supervised-processes-under-one-account.md)
 - **0152** — [The operator's surface is a module the mesh assigns: the console](0152-the-operators-surface-is-a-module-the-console.md)
 - **0155** — [A definition names no installation: how that is checked, and the three ways a value that did gets out](0155-a-definition-names-no-installation-and-how-that-is-checked.md)
+- **0164** — [A setting is declared with its default, its meaning and what changing it costs](0164-a-setting-is-declared-with-its-default-its-meaning-and-what-changing-it-costs.md)  *(proposed)*
+- **0165** — [`container-runtime` is what a machine can run; that a runtime is running is its holder's health](0165-container-runtime-is-what-a-machine-can-run-and-a-running-runtime-is-its-holders-health.md)  *(proposed)*
+- **0166** — [The container runtime is a node seat, and the host creates containers through its holder](0166-the-container-runtime-is-a-node-seat-and-the-host-creates-containers-through-its-holder.md)  *(proposed)*
 
 ### How it is built
 

04-ISSUES/190-the-runtimes-configuration-is-written-by-modules-that-are-not-the-runtime/00-report.md

@@ -0,0 +1,78 @@
+---
+status: located
+opened: 2026-10-01
+located-in: [mesh-catalog modules/dnsmasq, mesh-controller internal/overlay/generator.go, mesh-controller internal/catalogue/resolve.go (checkResources)]
+fixed-by:
+amended-design:
+---
+
+# 190 — The container runtime's configuration is written by modules that are not the runtime's
+
+## What was observed
+
+The runtime's configuration file and its service are declared by two parties, neither of which is
+the runtime:
+
+- **The resolver module** writes the runtime's `dns` key (the machine's private address) and
+  `live-restore` into the runtime's file, written into rather than over
+  ([ADR 0102](../../02-DECISIONS/0102-the-mesh-writes-into-a-shared-file-never-over-it.md)). It also
+  declares the runtime's service, reloaded when that file changes. The `dns` key has been written
+  since the resolver module was converted from its predecessor on 2026-09-23; `live-restore` and the
+  service were added on 2026-09-30 while fixing
+  [issue 110](../110-a-container-on-the-runtimes-own-network-cannot-reach-the-resolver/00-report.md),
+  where containers silently resolved through a public resolver.
+- **The private network** writes the runtime's `insecure-registries` into the same file, and declares
+  the same service reloaded on it, as [ADR 0082](../../02-DECISIONS/0082-the-registry-is-reached-by-name-and-trusted-by-the-overlay.md)
+  and ADR 0102 decided. The controller generates both resources per machine.
+
+On the three machines that run the resolver module, both declare one path and one unit. Nothing refuses
+it. The collision check compares the resources of catalogue modules. The private network is computed,
+so its resources are produced when a machine's declaration is composed, and the check never sees them.
+
+The machine without the resolver module shows the other half. Its runtime still has the predecessor's
+resolver and `live-restore` off, because the only module that sets them is a DNS server. A machine
+gets a correct container runtime only as a side effect of being given a resolver.
+
+## Why this is here
+
+The operator ruled it a defect, not a design: **a module does not write another software's
+configuration.** The need behind each write is real. Containers must resolve the mesh's names
+([ADR 0148](../../02-DECISIONS/0148-the-meshs-names-are-resolved-not-copied-into-containers.md) step 2).
+A daemon restart must not stop every container. Every machine on the network must trust the mesh's
+registry. But each of these is a fact the runtime must be *given*, and the module that gives it is the
+runtime's own. With three writers, nobody can say what the file should contain. Two of the facts are
+reloaded when one of them needs a restart (issue 110's first fault). And the moment a module for the
+runtime exists, it is refused on every machine with the resolver, or, through the private network's
+path, accepted without anyone noticing a collision.
+
+## What resolves it
+
+[ADR 0166](../../02-DECISIONS/0166-the-container-runtime-is-a-node-seat-and-the-host-creates-containers-through-its-holder.md)
+gives the runtime a module that holds its seat and owns its file and service.
+[ADR 0164](../../02-DECISIONS/0164-a-setting-is-declared-with-its-default-its-meaning-and-what-changing-it-costs.md)
+gives that module declared settings with defaults. The fix, once both are accepted:
+
+1. The resolver module drops its runtime file and runtime service. It knows nothing of the runtime.
+2. The private network stops generating either resource. ADR 0082's decision stands — being on the
+   network is what grants the trust, and no module author is involved — and only *who writes it*
+   moves. The mesh gives the registry to the runtime module as a value. ADR 0082 and ADR 0102 each
+   get a dated note saying where their mechanism now lives.
+3. The runtime module writes `dns`, `live-restore` and `insecure-registries`, each a declared
+   setting with its cost: `dns` costs a restart, which `live-restore` makes harmless.
+4. Steps 1–3 land in one push. A runtime module declaring the file beside a resolver module still
+   declaring it is refused.
+5. The collision check sees a computed module's resources as well, so a second writer cannot come
+   back through generated code.
+
+## Open questions
+
+- **How the resolver's address reaches the runtime.** Either the resolver seat (`node-dns-resolver`)
+  delivers an address its holder serves, or the runtime module reads a machine fact and the seat
+  being held is only a precondition. The first tracks a resolver moving off the private address. The
+  second needs nothing new.
+- **What `dns` defaults to on a machine with no resolver seat held.** Nothing, leaving the runtime's
+  own behaviour, is the honest default. A public resolver hides exactly the failure issue 110 took a
+  day to find.
+- **The adopted machine's predecessor values.** The runtime module adopting a file with a
+  hand-written `dns` and `live-restore: false` replaces both. That is intended, and is the one
+  restart the operator must make on that machine.