ADRs 0138 and 0139: an assignment binds an endpoint and says how far it reaches, and a network is forwarded because a module declared it

Both follow from the same rule the mesh is built on — a node's configuration is
composed from the modules assigned to it. Reach was settled separately by the
filter, the proxy's names and the certificate authority, so "this must not be
public" could not be written; it becomes one value on the assignment that all
three read. And the forward chain consulted two constants plus a typed list
although modules already declare their networks; it now forwards what they
declared, with the host rendering the addresses it allocated.

02-DECISIONS/0138-an-assignment-binds-an-endpoint-and-says-how-far-it-reaches.md

@@ -0,0 +1,154 @@
+---
+topic: what runs on it
+status: accepted
+date: 2026-09-28
+deciders: jochen
+reconstructed: false
+extends: 02-DECISIONS/0045-a-machine-firewall-is-the-sum-of-what-it-listens-on.md
+---
+
+# 138. An assignment binds an endpoint and says how far it reaches
+
+## Context
+
+[ADR 0045](0045-a-machine-firewall-is-the-sum-of-what-it-listens-on.md) settled that a machine's
+packet filter is derived from what its modules declare they listen on, and that the `from` of a
+listen "is the whole of public-versus-internal". That was true of the packet filter, and it turned
+out to be true of nothing else.
+
+Reachability is now settled three times, in three places, by three mechanisms that cannot disagree
+out loud ([issue 140](../04-ISSUES/140-an-endpoints-reach-is-not-declared/00-report.md)):
+
+- **The filter** reads a listen's source, and a per-node setting may override it. That setting has
+  exactly one caller in the control plane — the function that builds the node's rules.
+- **The names** come from a route contribution, which names a label and a port and says nothing
+  about reach. The reverse proxy composes a **public** name and an **internal** name for every route
+  it is given, because it can.
+- **The certificate authority** follows from which names exist. Measured on the control-node: an
+  identity provider carries a public certificate valid 90 days and an internal one valid 24 hours and
+  renewed daily. No assignment asked for either.
+
+So *this endpoint must not be public* cannot be written. It is therefore enforced by nothing, while a
+public certificate for that very name is obtained automatically — the fault
+[how-we-build.md](../00-META/how-we-build.md) names, an unenforced rule being indistinguishable from
+a wrong one, with the additional cost that the wrong thing is done eagerly.
+
+And a port that is not routed cannot be spoken about at all beyond the filter. The forge serves git
+over ssh; that endpoint has no name, no certificate and no way to be called public except a key only
+the filter reads.
+
+**Two per-node settings already exist and are half of this.** One gives a module's declared port a
+machine port. One overrides a declared port's source. They key on port numbers, so nothing ties a
+port to the route that serves it: a route contribution names a port too, and the two are equal only
+by coincidence.
+
+**Where this belongs is already decided.** [ADR 0046](0046-a-module-configuration-is-its-assignments-not-its-manifest.md)
+says a module's configuration is its assignments. Whether the forge answers git-over-ssh from the
+public internet is a fact about one installation and one machine, not a property of the software —
+and [ADR 0112](0112-a-module-definition-names-no-node-mesh-or-path.md) already refuses an
+installation's decisions in a definition.
+
+## Considered Options
+
+1. **Leave reach in the manifest, as `from` today.** Rejected: it is an installation's decision
+   written into the definition, and it cannot differ between two machines running the same module —
+   which is exactly the case the forge presents.
+2. **Extend the existing source override to the names and the certificate, without naming
+   endpoints.** Rejected: it keys on a port number. A module's route contribution names a port as
+   well, and nothing says the two are the same thing, so one statement cannot be made to reach all
+   three mechanisms. Naming the endpoint is what makes that possible.
+3. **Derive reach from whether the node has a public domain recorded.** Rejected: that is a property
+   of the machine, and two endpoints on one machine differ — a database and a web front end on the
+   same host.
+4. **A fourth reach for "public name, internal authority"** — a name that resolves publicly and must
+   not appear in a public issuance log, obtained by DNS-01. Deferred, not rejected: it is a real case
+   and it is a question about which challenge an authority uses, not about how far an endpoint
+   reaches. Left to the certificate work as an open question.
+5. **Make the manifest silent on reach and require every assignment to state it.** Rejected for the
+   transition: every endpoint reachable today would close until an assignment named it, which is a
+   flag day across the whole catalogue.
+
+## Decision
+
+**A module declares named endpoints.** An endpoint is one port the module serves, with a name the
+module chooses, its protocol, and what it is for. A route contribution **names the endpoint it
+routes** rather than repeating a port number. The manifest says what the module serves and what it
+would serve it to by default; it does not say what this installation does with it.
+
+**An assignment binds each endpoint and says how far it reaches.** Per node: the machine port the
+endpoint is published on, and its **reach** — one of `internal`, `public` or `both`. An assignment
+that states nothing keeps the manifest's default, so no machine changes until an assignment says so.
+
+**Reach means all three mechanisms at once, and is the only thing that decides them.**
+
+- `internal` — the filter opens the machine port to the private network; the proxy serves the
+  internal name and not the public one; the certificate comes from the mesh's own authority.
+- `public` — the filter opens it to anywhere; the proxy serves the public name; the certificate
+  comes from the public authority.
+- `both` — both names, each from its own authority, and the filter opens to anywhere.
+
+**An endpoint that is not routed is reached but never named.** An endpoint with no route contribution
+yields filter rules and nothing else: no name is composed and no certificate is requested. Git over
+ssh is that case, and it is the case the model could not express.
+
+**The authority stops being chosen by which names happen to exist.** The proxy composes the names the
+assignments asked for, and asks each name's own authority for it. A name nobody asked for is not
+composed, so it is not certified.
+
+**The two existing settings are this, completed.** The per-node port mapping becomes the endpoint's
+binding. The per-node source override becomes its reach, widened from the filter alone to the names
+and the certificate as well.
+
+## Consequences
+
+- **A manifest gains endpoint names, and a route contribution names an endpoint instead of a port.**
+  Every routed module's manifest changes. The word ships one release before any manifest uses it, and
+  reaches the build machine and the control plane first.
+- **One derived value is read by three things** — the filter's rules, the proxy's contributions, the
+  certificate request — so they can no longer disagree, and a disagreement becomes a refusal at the
+  assignment rather than a surprise on a machine.
+- **A name that must not be public becomes writable, and therefore checkable.** It also gives
+  [issue 129](../04-ISSUES/129-nothing-makes-a-machine-trust-the-meshs-authority/00-report.md) a
+  declared answer to read: which endpoints are internal is what says whose root must be installed
+  where.
+- **[Issue 139](../04-ISSUES/139-an-internal-route-name-resolves-to-the-consumers-node/00-report.md)
+  becomes answerable**: the endpoint's assignment names the machine that serves it, which is the fact
+  the internal name should be composed from.
+- **Reach becomes reportable.** The mesh can say, per endpoint, where it is reachable from and which
+  authority holds its certificate — neither of which `status` can say today.
+- **This narrows [ADR 0045](0045-a-machine-firewall-is-the-sum-of-what-it-listens-on.md).** Its
+  decision stands: the firewall is derived and host-applied, not a provider. What no longer holds is
+  that a listen's `from` is the whole of public-versus-internal; it is the filter's share of a
+  statement that also governs names and certificates.
+- **What got harder:** every endpoint needs a name, including a module that serves exactly one port
+  and had no reason to name it. And an installation that wants a module public must now say so on the
+  assignment rather than inheriting it from the definition, which is more to say and the reason it is
+  right.
+
+## How it is checked
+
+- **One module, two endpoints, different reach.** A module declaring an internal endpoint and a
+  public one renders a filter opening one to the private network and one to anywhere, asserted per
+  chain body so a rule in the wrong chain cannot pass.
+- **The names follow the reach.** The same module's routed endpoint composes the internal name only
+  when internal, the public name only when public, and both when both — and a certificate is
+  requested from the matching authority for each name composed and for no other. This fails against
+  the previous behaviour, where both names and both certificates are always composed, which is how
+  it is written.
+- **An unrouted endpoint is filtered and never named.** Asserted for an endpoint with reach and no
+  route contribution: rules rendered, no contribution, no certificate request.
+- **An assignment naming an endpoint the module does not declare is refused where it is said**, as is
+  a reach that is not one of the three — before it reaches a machine, because a ruleset that does not
+  load is a machine filtering nothing.
+- **An assignment that states nothing renders byte-identically to today**, so every machine already
+  converged is untouched until its assignment says otherwise.
+
+## References
+
+- [ADR 0045](0045-a-machine-firewall-is-the-sum-of-what-it-listens-on.md) — narrowed here
+- [ADR 0046](0046-a-module-configuration-is-its-assignments-not-its-manifest.md) — where reach belongs
+- [ADR 0066](0066-public-routing-is-name-agnostic.md) — the public name this composes
+- [ADR 0112](0112-a-module-definition-names-no-node-mesh-or-path.md) — why reach is not a definition's
+- [issue 140](../04-ISSUES/140-an-endpoints-reach-is-not-declared/00-report.md) — the measurement
+- [issue 139](../04-ISSUES/139-an-internal-route-name-resolves-to-the-consumers-node/00-report.md),
+  [issue 129](../04-ISSUES/129-nothing-makes-a-machine-trust-the-meshs-authority/00-report.md)

02-DECISIONS/0139-a-network-is-forwarded-because-a-module-declared-it.md

@@ -0,0 +1,136 @@
+---
+topic: what runs on it
+status: accepted
+date: 2026-09-28
+deciders: jochen
+reconstructed: false
+extends: 02-DECISIONS/0137-a-machine-says-which-networks-it-routes.md
+---
+
+# 139. A network is forwarded because a module declared it
+
+## Context
+
+[ADR 0137](0137-a-machine-says-which-networks-it-routes.md), decided the same week, gave a machine a
+way to say which networks it routes for its guests. It was written because the derived filter's
+forward chain allowed two ranges named as constants in the control plane's source — the container
+runtime's bridge pool, and part of the pool its compose files are given — with a comment admitting
+the gap: *a machine whose runtime is configured with something else needs this to say so, which is a
+thing the mesh cannot derive.*
+
+**It can be derived, and from the right place.** Measured on the last machine still to be converged
+([issue 141](../04-ISSUES/141-the-forward-chain-does-not-follow-the-modules/00-report.md)): twenty-one
+container networks, nine inside the runtime's bridge pool, twelve in the other private range, and six
+of those outside the constant's lower bound — so the flip would have cut their guests off exactly as
+it did on the workstation that produced 0137.
+
+Naming a range to cover the six is what 0137 provides for, and it is the wrong instrument. Of those
+six networks, **four are networks the mesh's own modules declare**, present as network resources in
+the node's plan and created by the host because a module asked for them. **Two are the predecessor's
+leftovers** — compose networks of services the mesh does not run. Any range wide enough to keep the
+four forwards the two as well: a firewall widened by hand to protect networks that should not exist.
+
+The mesh already knows which of the twenty-one are its own, because it made them.
+
+**And the node's configuration is meant to follow the modules assigned to it.** That is the mesh's
+founding shape — the machine runs modules, and its files, its filter and its accounts are composed
+from what runs there ([ADR 0005](0005-the-node-host.md),
+[ADR 0010](0010-delivery.md),
+[ADR 0045](0045-a-machine-firewall-is-the-sum-of-what-it-listens-on.md)). The forward chain is the
+one derived thing that consults a constant and a list a person types.
+
+## Considered Options
+
+1. **Keep 0137 as it stands** — two constants plus a named list. Rejected: the list is written in
+   addresses, and addresses are what the runtime allocates, so the only entry safe enough to keep a
+   machine working is wider than the truth. It cannot distinguish a network the mesh made from one
+   left behind, which is the distinction that decides whether forwarding it is correct.
+2. **Derive it from what the machine reports.** Still rejected, on 0137's own grounds: a test bed
+   creates its bridge between one declaration and the next, and a filter that follows whatever
+   appeared on a machine is a firewall that widens itself. **This decision is not that** — see below.
+3. **Have the control plane allocate each module network's range from a pool it owns,** so it can
+   render the address itself. Rejected: more machinery for no gain. The runtime already allocates and
+   the host already knows, and taking allocation over means the mesh owning an address space it has no
+   other reason to own.
+4. **Have each module declare its network's range.** Rejected by
+   [ADR 0112](0112-a-module-definition-names-no-node-mesh-or-path.md): a definition names no address,
+   and the same definition runs on machines whose runtimes have allocated differently.
+
+## Decision
+
+**A network is forwarded because a module declared it.** Per node, the forward chain forwards the
+networks of the modules assigned there, and by default nothing else. A module unassigned stops being
+forwarded at the next reconcile.
+
+**The host resolves a declared network to its addresses.** A network resource carries a name; the
+runtime allocates the subnet when the network is created. So the control plane declares *forward the
+networks these modules asked for* and the host — which made them, and already resolves a container by
+its name — renders the addresses. [ADR 0005](0005-the-node-host.md) holds: the host applies, it does
+not decide.
+
+**Deriving from the declaration is not deriving from the machine.** Both of 0137's objections fall
+away. The set is known before the network exists, because a module declared it, so a network created
+between two declarations is already in the one that asked for it. And it cannot widen itself: a
+network nobody declared is never forwarded, however it appeared on the machine.
+
+**The runtime's own default bridge is forwarded, from what the runtime reports.** Containers that name
+no module network attach to it, and it belongs to the runtime rather than to any module — so the host
+renders it from what the runtime says, not from a range named in the control plane. The constants go.
+
+**What a machine says is for guests no module declares.** A test bed is not a module and its range is
+not a module's; that is the case 0137's mechanism is for, and it keeps it — added to the derived set,
+never replacing it, as 0137 decided. Narrowed to that, it is named for it.
+
+**Their guests keep address and name service**, per declared network, unchanged from
+[ADR 0137](0137-a-machine-says-which-networks-it-routes.md): the input chain admits that network's own
+DHCP and DNS and nothing else.
+
+## Consequences
+
+- **The two constants are removed**, and with them the class of fault that a machine's guests depend
+  on a range that describes some other machine.
+- **This is a behaviour change, not a refactor.** On the machine measured, the derived set and the
+  constant do not cover the same ground — that is the whole reason for the record. A machine whose
+  module networks happen to fall inside the old ranges renders the same rules.
+- **A range that exists only to keep a leftover alive becomes visible as such**, because it will not
+  be in the derived set and has to be said out loud to survive.
+- **`node networks` narrows** to guests no module declares, and the preview says which of a machine's
+  networks are the mesh's and which are not, so the difference is readable before a flip rather than
+  after.
+- **A module's declaration gains nothing.** It already declares its network; what changes is that the
+  filter reads it.
+- **What got harder:** the host renders part of the forward chain from what it created, so the
+  control plane no longer holds the whole rule set as text. The rule the mesh states is the set of
+  networks; the addresses are the machine's.
+
+## How it is checked
+
+- **Only declared networks are forwarded.** A node with two modules that declare networks renders
+  forward rules for exactly those two, and none for a third network present on the machine that no
+  module declared. This fails against the previous behaviour, which forwards by range and cannot tell
+  them apart, and that is how it is written.
+- **Unassigning a module removes its network's rule** at the next reconcile, asserted on the rendered
+  chain rather than on the intent.
+- **Guests of a declared network keep address and name service**, asserted per chain body so a line in
+  the wrong chain cannot pass — carried from 0137.
+- **The runtime's own default bridge comes from the runtime**, asserted by rendering for a runtime
+  whose default bridge is somewhere other than the range the constant named.
+- **A machine that names a range for guests no module declares still gets it**, added to the derived
+  set and not replacing it.
+- **Each family is matched in its own syntax**, carried from 0137: one set holding both is a syntax
+  error, and a ruleset that does not load is a machine filtering nothing while its unit reports a
+  fault.
+
+## References
+
+- [ADR 0137](0137-a-machine-says-which-networks-it-routes.md) — narrowed here; its mechanism keeps the
+  case it is right for
+- [ADR 0005](0005-the-node-host.md) — the host applies; the addresses are the machine's
+- [ADR 0045](0045-a-machine-firewall-is-the-sum-of-what-it-listens-on.md) — the filter is derived from
+  what runs there
+- [ADR 0112](0112-a-module-definition-names-no-node-mesh-or-path.md) — why a module does not name its
+  range
+- [issue 141](../04-ISSUES/141-the-forward-chain-does-not-follow-the-modules/00-report.md) — the
+  measurement
+- [issue 137](../04-ISSUES/137-converging-a-machine-cut-off-its-own-guests/00-report.md) — the
+  breakage that produced 0137

02-DECISIONS/README.md

@@ -218,6 +218,8 @@ python3 00-META/checks/index.py            fail if stale
 - **0135** — [A module version prepares its state before it runs](0135-a-module-version-prepares-its-state-before-it-runs.md)
 - **0136** — [A step gates its module, not the machine](0136-a-step-gates-its-module-not-the-machine.md)
 - **0137** — [A machine says which networks it routes](0137-a-machine-says-which-networks-it-routes.md)
+- **0138** — [An assignment binds an endpoint and says how far it reaches](0138-an-assignment-binds-an-endpoint-and-says-how-far-it-reaches.md)
+- **0139** — [A network is forwarded because a module declared it](0139-a-network-is-forwarded-because-a-module-declared-it.md)
 
 ### How it is built
 

03-DESIGN/01-to-be/08-connectivity.md

@@ -7,8 +7,10 @@ code:
   - mesh-controller internal/identity/authority.go
   - mesh-host internal/identity/serving.go
   - mesh-host internal/apply (the service that reflects a rule set)
-updated: 2026-09-27
+updated: 2026-09-28
 decisions:
+  - 02-DECISIONS/0138-an-assignment-binds-an-endpoint-and-says-how-far-it-reaches.md
+  - 02-DECISIONS/0139-a-network-is-forwarded-because-a-module-declared-it.md
   - 02-DECISIONS/0104-a-provision-may-be-answered-by-an-adapter-to-the-predecessor.md
   - 02-DECISIONS/0106-the-bus-is-nats.md
   - 02-DECISIONS/0105-the-mesh-adopts-the-predecessors-tunnel-in-place.md
@@ -625,6 +627,42 @@ the found firewall reloads and reachable from a container on the node, that a ma
 enrols through the openings before and after a reload and a reboot, and that after the flip the
 declared port is open and the undeclared one closed.
 
+### The networks it forwards are the ones its modules declared
+
+*2026-09-28, preparing the control-node's convergence —
+[issue 141](../../04-ISSUES/141-the-forward-chain-does-not-follow-the-modules/00-report.md), settled by
+[ADR 0139](../../02-DECISIONS/0139-a-network-is-forwarded-because-a-module-declared-it.md).*
+
+The forward chain denies by default, so a machine's own guests have to be allowed back in. Until now
+that was two ranges named in the control plane and, since
+[ADR 0137](../../02-DECISIONS/0137-a-machine-says-which-networks-it-routes.md), a list a machine could
+add to. On the machine measured here, six of its container networks fell outside those ranges — and
+four of the six were networks the mesh's own modules had declared and the host had created, while two
+were the predecessor's leftovers. A range wide enough to keep the four keeps the two: a filter widened
+by hand to protect what should not be there.
+
+**A network is forwarded because a module declared it.** The forward chain forwards the networks of the
+modules assigned to that node and, by default, nothing else; a module unassigned stops being forwarded
+at the next reconcile. The control plane says which networks, by name, and the host — which created
+them — renders their addresses, because the runtime allocates the subnet and the host is what knows it.
+That keeps §4's shape and this document's: the mesh decides, the host applies.
+
+**This is derivation from the declaration, not from the machine.** 0137 rejected reading the machine,
+for two reasons that do not apply here: a network created between two declarations is already named in
+the one that asked for it, and a network nobody declared is never forwarded however it appeared. What
+0137's mechanism keeps is the case it was right for — guests no module declares, a test bed's range —
+added to the derived set and never replacing it.
+
+The runtime's own default bridge, which a container attaches to when it names no module network, is the
+runtime's and not a module's, so the host renders it from what the runtime reports. With that, no range
+is named in the control plane at all.
+
+*How it is checked:* a node with two modules declaring networks renders rules for exactly those two and
+none for a third present on the machine that nothing declared — which fails against forwarding by
+range, and is how it was written; unassigning one removes its rule at the next reconcile; the default
+bridge is asserted for a runtime whose bridge is somewhere other than the old constant named; and the
+guests of a declared network keep address and name service, per chain body.
+
 ## 5 — Certificates
 
 **Two authorities, kept separate on purpose.**
@@ -710,6 +748,60 @@ that verifies against the internal root and nothing else — which cannot succee
 first reached the name to certify it*
 ([ADR 0066](../../02-DECISIONS/0066-public-routing-is-name-agnostic.md)).
 
+## 6 — One statement behind exposure, filtering and certificates
+
+*2026-09-28, preparing the control-node's convergence —
+[issue 140](../../04-ISSUES/140-an-endpoints-reach-is-not-declared/00-report.md), settled by
+[ADR 0138](../../02-DECISIONS/0138-an-assignment-binds-an-endpoint-and-says-how-far-it-reaches.md).*
+
+The three sections above each decide, independently, how far a service reaches. §3 composes a name
+from a label and the node's domain. §4 opens a port to the source a listen named. §5 certifies the
+names that exist, from whichever authority the proxy holds. Each is coherent on its own, and together
+they mean **reachability is never stated anywhere** — it is the sum of three derivations, and a sum is
+not something anyone can review or refuse.
+
+What that costs, measured: an identity provider holding a public certificate valid 90 days and an
+internal one valid 24 hours, neither asked for by any assignment, because both names existed and a
+proxy certifies what it serves. And an endpoint that is not routed — git over ssh — which can be
+spoken about only in the filter's vocabulary, so *this must be reachable from outside* is a setting
+exactly one mechanism reads.
+
+**An endpoint is the thing that was missing.** A module declares named endpoints: one port it serves,
+what it is for, and what it would serve that to absent any instruction. A route contribution names an
+endpoint rather than repeating a port number. An assignment — which is where a module's configuration
+lives ([ADR 0046](../../02-DECISIONS/0046-a-module-configuration-is-its-assignments-not-its-manifest.md))
+— then binds each endpoint to a machine port and says how far it reaches.
+
+One value, three readers:
+
+| reach | the filter opens | the proxy serves | the certificate comes from |
+|---|---|---|---|
+| `internal` | the machine port, to the private network | the internal name | the mesh's own authority |
+| `public` | the machine port, to anywhere | the public name | the public authority |
+| `both` | the machine port, to anywhere | both names | each name's own authority |
+
+**An endpoint that is not routed is reached and never named.** No route contribution means no name is
+composed and no certificate requested, while the filter still acts on it. That is the case the model
+could not express at all, and it is the ordinary case for anything that is not HTTP.
+
+**Nothing moves until an assignment says so.** An endpoint whose assignment is silent keeps the
+default its manifest states, so every machine already converged renders exactly as it does today —
+the same property §4 needed when a machine gained a way to say which networks it routes.
+
+This is what the certificate questions were waiting for. Which authority signs a name, whether a name
+may appear in a public issuance log, and what must be trusted where are all answerable once an
+endpoint says whether it is internal — and unanswerable while the proxy decides by composing every
+name it can. It is also the fact
+[issue 139](../../04-ISSUES/139-an-internal-route-name-resolves-to-the-consumers-node/00-report.md)
+needs: an internal name should be composed from the machine serving the endpoint, which is the
+assignment that bound it.
+
+**How it is checked** is stated with the decision: one module with two endpoints of differing reach
+asserted per chain body; the names and the certificate requests following the reach and failing
+against today's behaviour, where both are always composed; an unrouted endpoint filtered and never
+named; an assignment naming an endpoint the module does not declare refused where it is said; and a
+silent assignment rendering byte-identically to today.
+
 ## What this removes
 
 The list is worth having in one place, because it is most of the argument:

04-ISSUES/140-an-endpoints-reach-is-not-declared/00-report.md

@@ -0,0 +1,79 @@
+---
+status: located
+opened: 2026-09-28
+located-in:
+  - mesh-controller internal/catalogue/manifest.go
+  - mesh-controller internal/catalogue/filtering.go
+  - mesh-controller internal/catalogue/declaration.go
+  - mesh-controller examples/route-proxy
+  - mesh-catalog (every routed module manifest)
+fixed-by:
+amended-design: 03-DESIGN/01-to-be/08-connectivity.md
+---
+
+# 140 — An endpoint's reach is not declared, so three mechanisms each decide it separately
+
+## What was observed
+
+Preparing to converge the mesh's control-node — the last machine still running the firewall it
+had before the mesh — the question came up for one module: the forge serves git over ssh, and that
+port must stay reachable from outside the private network. Where is that said?
+
+The manifest declares the port with a source of `mesh`, so the derived filter would close it to
+everything but the private network. Looking for the place an assignment says otherwise, there are
+two per-node settings keys: one that gives a module's declared port a machine port, and one that
+overrides a declared port's source. The second has exactly one caller — the function that builds
+the node's filter rules. Nothing else in the control plane reads it.
+
+A module's routed endpoint is declared somewhere else entirely: a route contribution naming a label
+and a port. It says nothing about reach. The proxy composes a **public** name and an **internal**
+name for every route it is given, and obtains a certificate for each from a different authority.
+Measured on that machine the same day: an identity provider's public name signed by the public
+authority for 90 days, its internal name signed by the mesh's own intermediate for 24 hours and
+renewed daily. Both names exist, and both certificates, because the proxy makes every name it can.
+No assignment asked for either.
+
+So the forge's ssh endpoint has a firewall source and nothing else — no name, no certificate, and no
+way to say it should be public other than a key the filter alone reads. And the forge's web endpoint
+has two names and two certificates that nobody requested.
+
+## Why it matters beyond this instance
+
+**Reach is stated twice, in two vocabularies, in two places that cannot disagree out loud.** A port
+may be exposed to anywhere while the module contributes no public route; a public route may be served
+for a module whose own listen is private. Nothing reconciles the pair or refuses it. Each mechanism
+is separately defensible and the combination is unstated.
+
+**The vocabulary belongs to the filter, not to reachability.** *Public, internal, or both* cannot be
+expressed. A source of `anywhere` is one rule on one chain; it says nothing about which names should
+exist or which authority should sign them. So "this endpoint must not be public" has no way to be
+written, and is therefore enforced by nothing — while a public certificate for that very name is
+obtained automatically.
+
+**An endpoint is not a thing in the model.** A module has ports, and separately it has routes.
+Nothing binds a port to a name to a certificate, which is why three mechanisms each decide reach on
+their own and none of them is wrong. This is
+[ADR 0045](../../02-DECISIONS/0045-a-machine-firewall-is-the-sum-of-what-it-listens-on.md)'s fault
+one level up: that record closed "a declaration that reads as a restriction and restricts nothing"
+for the packet filter. Here the declaration is absent altogether and the mechanisms guess.
+
+**It blocks the certificate work.** The open question recorded for certificates — a name that must
+not be public needs either DNS-01 or the internal authority only — cannot be answered while no
+assignment states whether a name should be public. Neither can expiry reporting, revocation, or what
+happens to a name when a machine leaves: all of them need to know which names were *meant*.
+
+## Open questions
+
+- Should an assignment name each of a module's endpoints, bind it to a node-level port, and state
+  whether it is reachable publicly, internally or both — with the filter, the proxy's names and the
+  certificate authority all derived from that one statement?
+- What is an endpoint that is neither routed nor certified? Git over ssh is public reach with no name
+  and no certificate; the model has to hold that without inventing one.
+- Are the two existing settings keys the same statement, half-built? If so, is this a new declaration
+  or the completion of theirs?
+- Does an internal-only endpoint get a certificate at all, and from which authority — and does that
+  settle [issue 129](../129-nothing-makes-a-machine-trust-the-meshs-authority/00-report.md), where nothing
+  installs the mesh's own root?
+- Does declaring reach per assignment also settle
+  [issue 139](../139-an-internal-route-name-resolves-to-the-consumers-node/00-report.md), where an
+  internal name resolves to the consumer's machine instead of the one serving the endpoint?

04-ISSUES/141-the-forward-chain-does-not-follow-the-modules/00-report.md

@@ -0,0 +1,76 @@
+---
+status: located
+opened: 2026-09-28
+located-in:
+  - mesh-controller internal/catalogue/filtering.go
+  - mesh-host internal/apply
+fixed-by:
+amended-design: 03-DESIGN/01-to-be/08-connectivity.md
+---
+
+# 141 — The forward chain does not follow the modules, though the modules declare their networks
+
+## What was observed
+
+[ADR 0137](../../02-DECISIONS/0137-a-machine-says-which-networks-it-routes.md), decided the same
+week, gave a machine a way to say which networks it routes for its guests, because the derived
+filter's forward chain had until then allowed two ranges named as constants in the control plane's
+own source — the container runtime's default bridge pool, and half of the pool its compose files
+are given.
+
+Checking the last machine still to be converged, the same fault was found to be live there, and the
+declaration needed to work around it turned out to be wrong in kind.
+
+That machine hosts twenty-one container networks. Nine fall inside the runtime's bridge pool and
+are forwarded. Twelve sit in the other private range, and **six of those fall below the lower bound
+of the constant**, so the flip would have cut their guests off exactly as it did on the workstation
+that produced 0137.
+
+Naming a range to cover the six was the obvious move, and is what 0137 provides for. But of those
+six networks, **four are networks the mesh's own modules declare** — they appear as network
+resources in the node's plan, created by the host because a module asked for them — and **two are
+leftovers of the predecessor**, compose networks of services the mesh does not run. A range wide
+enough to keep the four would have forwarded the two as well: a firewall widened by hand to protect
+networks that should not exist.
+
+The mesh already knows which of the twenty-one are its own. It made them.
+
+## Why it matters beyond this instance
+
+**The node's configuration is supposed to follow the modules assigned to it.** That is the mesh's
+founding shape — the machine runs modules, and its files, its filter and its accounts are composed
+from what runs there. The forward chain is the one derived thing that does not: it consults two
+constants and, since 0137, a list a person types. A module added tomorrow brings a network the filter
+will not forward; a module deprecated leaves a range in the list that outlives it.
+
+**A typed range cannot distinguish the mesh's networks from what was left behind.** It is stated in
+addresses, and addresses are what the runtime allocates, so the only honest declaration is one wide
+enough to include whatever else the runtime has handed out. The derivation is narrower than anything
+a person can safely write, because it names networks rather than ranges.
+
+**0137 rejected deriving this, and was right about what it rejected.** It considered deriving the
+list from *what the machine reports* and refused, on two grounds: a test bed creates its bridge
+between one declaration and the next, and a filter that follows whatever appeared on the machine is a
+firewall that widens itself. Deriving from the **declaration** is neither. The set is known before
+the network exists, because a module declared it; and it cannot widen itself, because only a network
+some module asked for is ever forwarded. What remains genuinely for a machine to say is guests no
+module declares — a test bed's pool — which is a much smaller residue than the list as it stands.
+
+**The gap is invisible in the one place that should show it.** The converge preview lists what
+*listens*, and routing is not a listener. It says in one line what the machine routes, and a reader
+has to know the runtime's allocations to tell whether that line is sufficient. On the machine
+measured here it read as though nothing needed saying.
+
+## Open questions
+
+- Should the forward chain be derived from the network resources the node's modules declare, with the
+  host resolving each declared network to its address the way it already resolves a container by name?
+  The controller cannot render the address itself: a module's network resource carries a name, and the
+  runtime allocates the subnet at creation.
+- What remains of `node networks` once that exists — only guests no module declares, such as a test
+  bed's pool? And should it then be named for that, rather than for all routing?
+- The runtime's own default bridge, which containers attach to when no module network is named, is
+  not a module's network. Is it derived from the machine, declared by the module that owns the
+  runtime, or left as the one constant?
+- Should the preview say which of a machine's networks are the mesh's and which are not, so a range
+  that exists to protect a leftover is visible as such?