Merge pull request 'Issues 140 and 141: an endpoint's reach, and a forward chain that does not follow the modules' (#169) from issue/140-endpoint-reach-and-141-forward-chain into main

Found preparing the control-node's convergence. Reach is settled independently by
the filter, the proxy's names and the certificate authority, so "this must not be
public" cannot be written and a public certificate is obtained regardless. And the
forward chain allows two hardcoded ranges plus a typed list, though the mesh
already knows which networks exist because its own modules declared them — a range
wide enough to keep four of them would have forwarded two predecessor leftovers too.

02-DECISIONS/0137-a-machine-says-which-networks-it-routes.md

@@ -0,0 +1,116 @@
+---
+topic: what runs on it
+status: accepted
+date: 2026-09-28
+deciders: jochen
+extends: 02-DECISIONS/0100-a-node-in-use-is-adopted-before-it-is-converged.md
+reconstructed: false
+---
+
+# 137. A machine says which networks it routes
+
+## Context
+
+The filter the mesh derives denies forwarding by default, because without a forward chain it says
+nothing about a container's published port
+([ADR 0100](0100-a-node-in-use-is-adopted-before-it-is-converged.md), [issue 047](../04-ISSUES/047-the-firewall-does-not-cover-published-container-ports/00-report.md)).
+To keep a machine's own containers working it then allows two ranges: the container runtime's
+default bridge pool, and the pool its compose files are given. Those two are named in the
+controller's code, with a comment saying what the gap is:
+
+> A machine whose runtime is configured with something else needs this to say so — which is a thing
+> the mesh cannot derive and a reason this list is named here rather than computed.
+
+**There was no way to say so.** The list was a constant. A machine whose guests live anywhere else
+was filtered by a rule that looked deliberate and was a guess.
+
+**Measured, on the day a workstation was converged.** Flipping it cut egress for five of its
+container networks at once, and for every network its test beds create — the beds allocate a fresh
+range per run, from a pool neither default covers. Nothing reported a fault. The containers could
+not reach anything, the machine went on reporting that it had applied what it was told, and the
+converge preview had said nothing about it either, because the preview lists what *listens* and
+routing is not a listener.
+
+**And two questions, not one.** A guest also asks its host for an address and for names. Both arrive
+at the input chain, where nothing declared them, so denying by default left the guests of a routed
+network with no address and no resolution — which is not a closed port but a network that does not
+function, asked for by this machine's own guest.
+
+**Why the machine cannot simply be read.** A test bed creates its bridge while it runs, between one
+declaration and the next, so a filter derived from what the machine last reported would be correct
+only for the networks that already existed when it was composed. A declared range covers the ones
+that do not exist yet.
+
+## Decision
+
+**A machine says which networks it routes for what it hosts, and the filter forwards them.** A
+node-level fact, beside the node's public domain
+([ADR 0066](0066-public-routing-is-name-agnostic.md)) and for the same reason: the
+machine routes them, and the module that loads the filter holds a seat and may be replaced.
+
+**Added to the runtime's defaults, never replacing them.** A machine that names one range has not
+stopped hosting whatever was already on the runtime's own pools, and replacing would trade one
+silent breakage for another.
+
+**Their guests keep address and name service.** For a network that was named, the input chain admits
+that network's own DHCP and DNS, and nothing else: everything else a guest might want from its host
+is a port somebody declares, like every other port on this machine.
+
+**Said in CIDR form and checked when it is said.** An entry that does not parse is a line nftables
+refuses, and a refused ruleset is a machine filtering nothing while its unit reports a fault — so
+the refusal happens where a person can read it, not on the machine.
+
+**A machine that says nothing is filtered exactly as before.** Every machine already converged is
+untouched by this.
+
+## Options considered
+
+1. **Leave it constant and edit the code per installation.** Rejected: the value is a property of
+   one machine, the code is the whole mesh's, and the two ranges as they stand describe a machine
+   whose runtime was left at its defaults. It is also how this got here.
+2. **Derive it from what the machine reports.** Rejected as insufficient, not as wrong: it cannot
+   cover a network created between two declarations, which is precisely the case that was broken. It
+   would also make the filter follow whatever appeared on the machine, which is a firewall that
+   widens itself.
+3. **A per-node setting on the module that loads the filter.** Rejected: the machine routes the
+   networks. The filter module holds a node-scoped seat and is meant to be replaceable, and a
+   replacement must not lose the machine's own truth.
+4. **Replace the defaults with what is said.** Rejected: see the decision. The first machine to name
+   its bed range would lose its containers.
+5. **Admit all input from a routed network, not only address and name service.** Rejected: that is
+   every port on the machine open to anything it hosts, which is the derivation abandoned.
+
+## Consequences
+
+**The converge preview says what a machine routes**, including when it routes nothing but the
+defaults, with the command that changes it. The preview's own sentence about traffic it cannot
+preview stays, because a tunnel and the found firewall's NAT are still not previewable.
+
+**A machine whose guests are already broken by an earlier flip is fixed by saying its networks and
+pushing**, with no flip to undo.
+
+**The list is one more thing that can be wrong and stale.** A range removed from the machine and
+left here keeps forwarding for a network that no longer exists, which admits nothing, because there
+is no guest on it to admit. That is the safe direction of being out of date.
+
+## How this is checked
+
+- **What a machine says it routes is forwarded, and its guests keep address and name service.** A
+  test renders a ruleset for a machine that names one range and asserts both chains, per chain body
+  so a line in the wrong chain cannot pass it. It fails against the previous behaviour, which is how
+  it was written.
+- **The runtime's own defaults survive naming a range.** Asserted in the same test.
+- **A machine that names nothing renders byte-identically to one that names nil**, so every machine
+  already behind this filter is untouched.
+- **Each family is matched in its own syntax.** A test with one v4 and one v6 network asserts
+  `ip saddr` and `ip6 saddr`, because one set holding both is a syntax error and a ruleset that does
+  not load is a machine filtering nothing.
+- **An entry that is not a network is refused where it is said**, by the parse in the setter.
+
+## References
+
+- [ADR 0100](0100-a-node-in-use-is-adopted-before-it-is-converged.md) — the derived filter this completes
+- [ADR 0066](0066-public-routing-is-name-agnostic.md) — the precedent for a node-level fact
+- [issue 047](../04-ISSUES/047-the-firewall-does-not-cover-published-container-ports/00-report.md) — why there is a forward chain at all
+- [issue 137](../04-ISSUES/137-converging-a-machine-cut-off-its-own-guests/00-report.md) — the measurement that produced this
+- mesh-controller `internal/catalogue/filtering.go` — the constant whose own comment named this gap

02-DECISIONS/README.md

@@ -217,6 +217,7 @@ python3 00-META/checks/index.py            fail if stale
 - **0133** — [A module owns its migrations, and the mesh owns when they run](0133-a-module-owns-its-migrations-and-the-mesh-owns-when-they-run.md)  *(superseded)*
 - **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)
 
 ### How it is built
 

04-ISSUES/136-a-module-may-name-a-program-the-machine-does-not-have/00-report.md

@@ -0,0 +1,92 @@
+---
+status: resolved
+opened: 2026-09-28
+located-in: [mesh-catalog modules/fail2ban]
+fixed-by: mesh-catalog — the intrusion-prevention module bans through an action it ships itself, already in use on every machine, instead of naming a firewall front-end two of them do not have. The instance is closed; the class in "What is still true" is not.
+amended-design:
+---
+
+# 136 — A module may name a program the machine does not have, and everything reports success
+
+## What was observed
+
+Two machines were given the intrusion-prevention module on 2026-09-28. Both refused to start it:
+
+```
+ERROR Failed during configuration: Have not found any log file for 'recidive' jail.
+ERROR Async configuration of server failed
+fail2ban.service: Main process exited, code=exited, status=255/EXCEPTION
+```
+
+The jail that bans whoever keeps coming back reads the service's *own* log, and the service checks
+every jail's log file while it configures itself — before it has created that log. The module
+declared the jail and shipped the rotation for that log, and never declared the log. On the two
+machines where it had run for years the file was simply there, so nothing had ever noticed.
+
+That failure was loud. Fixing it uncovered a second one in the same module that is not.
+
+The module's defaults named `ufw` as the way to ban an address. Two of these four machines have no
+`ufw` — they filter with nftables — and nothing checks that until an address is banned. Asked to ban
+a documentation address on such a machine, the service accepted the instruction, counted it, ran the
+command, and wrote this to a log nobody reads:
+
+```
+ERROR   ... -- stderr: '/bin/sh: line 5: ufw: command not found'
+ERROR   ... -- returned 127
+ERROR   Failed to execute ban jail 'sshd' action 'ufw' ... Error banning 192.0.2.99
+```
+
+No rule existed afterwards. Throughout, the unit was `active`, the module was applied, and the
+machine's report said so. **A machine had been added to the mesh's intrusion prevention, reported as
+protected, and was banning nobody.**
+
+## Why it matters beyond this instance
+
+**The two faults are the same mistake with opposite symptoms.** Both are the module assuming
+something about the machine — a file that happens to exist, a program that happens to be installed.
+One stopped the service, which anybody notices. The other left it running and empty, which nobody
+does. A mesh that only catches the loud one is a mesh whose coverage is unknown.
+
+**"The unit is running" was taken for "the module is doing its job".** That is the only health a
+service resource has. It is the right answer for most modules and it is silent for any module whose
+work happens later, on an event — a ban, a renewal, a backup, a notification. The report cannot
+distinguish "protecting this machine" from "installed and inert".
+
+**And it is exactly the naming rule, one level down.**
+[ADR 0112](../../02-DECISIONS/0112-a-module-definition-names-no-node-mesh-or-path.md) says a
+definition names no node, no mesh and no host path, because the same definition has to raise a
+different mesh. `ufw` is not a node name, but it is the same class of assumption: a value the module
+cannot know, true on some machines and false on others, written as though it were a constant. The
+module already knew how to do better a few lines away — the mesh's own address range is named there
+as something the machine fills in.
+
+## What was done
+
+The module declares the log its own jail reads, created once and never touched again, since what
+grows in it is the service's and the rotation the module already ships is what keeps it small. And
+it bans through the action it ships itself, which every machine here can run, which was already in
+use by the other jail on all four, and which covers a container's published port as well as the
+host's own.
+
+All four machines now run it, with both jails, and a ban lands on each — verified by banning and
+unbanning a documentation address on every one.
+
+## What is still true
+
+**Nothing would have caught either fault before it shipped.** The control plane reads a manifest, not
+a machine; `ufw` and `/var/log/…` are strings in a file it has no way to evaluate. The host could in
+principle be asked whether a declared program exists, but no resource says "this file names a command
+that must be there", so there is nothing to check.
+
+**Two machines' bans from before this are stale rules in the old front-end**, which the service no
+longer knows about and will never lift. They reject two addresses for ever. Harmless, and a reminder
+that changing how a module enforces something leaves what it already enforced behind.
+
+## Open questions
+
+- What does a service resource's health mean for a module whose work is event-driven? A unit being
+  active is the weakest claim available, and four of this mesh's modules are of that kind.
+- Should a declaration be able to say that a resource depends on a program, so the machine can refuse
+  what it cannot carry out rather than reporting success?
+- Where should the packet filter a module bans through come from — the module's own choice, as now,
+  or the seat that owns the machine's filtering?

04-ISSUES/137-converging-a-machine-cut-off-its-own-guests/00-report.md

@@ -0,0 +1,74 @@
+---
+status: resolved
+opened: 2026-09-28
+located-in: [mesh-controller internal/catalogue]
+fixed-by: mesh-controller — a machine says which networks it routes and the derived filter forwards them, their guests keeping address and name service ([ADR 0137](../../02-DECISIONS/0137-a-machine-says-which-networks-it-routes.md)).
+amended-design:
+---
+
+# 137 — Converging a machine cut off its own guests, and nothing said so
+
+## What was observed
+
+A workstation was flipped from adopted to converged, so the mesh's derived filter replaced what was
+there. The flip reported success, the machine reported that it had applied its declaration, and every
+surface of the mesh read green.
+
+A container on one of that machine's networks could no longer reach anything:
+
+```
+192.168.64.2/20
+OUTBOUND BLOCKED
+```
+
+Five of the machine's container networks were affected, and every network its test beds create. The
+reason is in the filter's forward chain, which denies by default and then allows two ranges:
+
+```
+ip saddr 172.16.0.0/12 accept   # the container runtime's bridge networks
+ip saddr 192.168.128.0/17 accept # the networks its compose files are given
+```
+
+Those two are constants in the controller. The machine's guests were allocated from neither: its
+compose networks from other parts of `192.168/16`, and each test bed a fresh `10.x/24`. So the rules
+were correct for a machine whose runtime was left at its defaults, and a guess on this one.
+
+Two further things were closed by the same flip, and for the same reason nobody saw them: a guest asks
+its host for an address over DHCP and for names over DNS, both of which arrive at the input chain,
+where no module had declared them.
+
+## Why it matters beyond this instance
+
+**The preview could not have warned.** It lists what the machine reported as *listening*, and says so
+honestly: it ends with a line that traffic the machine routes is "not previewed". What it did not say
+is that routing was about to be denied by default, or which ranges would survive. An operator reading
+a 350-line preview approves what it shows.
+
+**It is the second time today that a constant stood in for something the mesh cannot know.** The
+intrusion-prevention module named a firewall front-end two machines do not have
+([issue 136](../136-a-module-may-name-a-program-the-machine-does-not-have/00-report.md)), and the
+filter names the address ranges one runtime happens to use. Both were true where they were written and
+silently false elsewhere.
+
+**And the code already knew.** The comment above those two lines says a machine configured otherwise
+"needs this to say so — which is a thing the mesh cannot derive and a reason this list is named here
+rather than computed". The gap was documented at the point where it was introduced, and the way to say
+it was never built. A comment naming a missing mechanism is a rule that is not enforced.
+
+## What was done
+
+A machine says which networks it routes; the filter forwards them and admits their guests' address and
+name service. Added to the runtime's defaults rather than replacing them, so a machine that names one
+range keeps the others. Node-level, because the machine routes them and the module that loads the
+filter may be replaced. The converge preview now says what a machine routes, and what it will keep
+forwarding if it says nothing.
+
+## What is still true
+
+**The flip is still the moment a machine's unmanaged services close.** That is what converging means
+and the preview names each one. This issue is not about the ports that were meant to close; it is about
+the ones nothing could name.
+
+**Egress is still not previewed per network.** The preview says which ranges will be forwarded, not
+which of the machine's guests sit inside them. Deriving that would need the machine to report its
+bridges, and a bed's bridge does not exist until the bed runs.

04-ISSUES/138-two-modules-claim-one-seat-and-are-not-interchangeable/00-report.md

@@ -0,0 +1,56 @@
+---
+status: open
+opened: 2026-09-28
+located-in: [mesh-controller internal/catalogue, mesh-catalog]
+fixed-by:
+amended-design:
+---
+
+# 138 — Two modules claim one seat and are not interchangeable, and nothing says so
+
+## What was observed
+
+Three modules claim the node-scoped uplink seat: one for each network manager a machine here might
+run. [ADR 0117](../../02-DECISIONS/0117-a-machines-uplink-is-a-seat.md) gives each of them the same
+job — ask the manager the machine already runs to leave the resolver file alone and to leave the mesh's
+interface alone — and deliberately keeps the machine's own links out of the mesh's hands.
+
+A seat means one holder and an interchangeable holder. These are interchangeable in what they *ask*
+and not in what they *do*:
+
+- None installs, enables, starts or stops the manager. That is on purpose: stopping it takes every
+  link down, including the mesh's own way in.
+- None carries an address, a route or a wireless credential, for the same reason.
+- **Nothing checks that the module holding the seat names the manager the machine is actually
+  running.** Assigning the systemd-networkd holder to a machine running NetworkManager writes a file
+  for a daemon that is inactive and disabled, the seat reports held, and the two things the seat
+  exists to arrange are arranged for nobody. NetworkManager goes back to rewriting the resolver file
+  on every lease, which is the failure the module's own comment describes.
+
+The machine reports which service manager and which units are active, so the fact needed to catch this
+is already in the report the mesh holds.
+
+## Why it matters beyond this instance
+
+**A seat is the mesh's promise that a role is filled.** If the holder can be a module for software
+that is not running, the seat says a role is filled while nothing fills it — and the surface that
+would tell an operator says "held".
+
+**It is the same shape as two faults found the same day.** A module named a firewall front-end the
+machine does not have ([issue 136](../136-a-module-may-name-a-program-the-machine-does-not-have/00-report.md)),
+and the filter named address ranges one runtime happens to use
+([issue 137](../137-converging-a-machine-cut-off-its-own-guests/00-report.md)). Each is a claim about
+the machine that nothing on the machine checks.
+
+**And it decides whether the seat is worth having.** Either the holder must match what the machine
+runs, which is a condition the mesh can check from the report it already has, or the holders must be
+able to switch the manager, which ADR 0117 refuses for a reason that has not changed.
+
+## Open questions
+
+- Should a seat's conditions of holding include a capability the machine reports, so a holder naming
+  absent or inactive software is refused rather than recorded?
+- Is "the uplink" one seat at all, if its holders are three dialects of the same two requests? The
+  alternative is one module that speaks whichever dialect the machine needs, chosen from the report.
+- What should happen on a machine that switches manager afterwards? The seat would then be held by the
+  wrong module, and the machine is the only place that knows.

04-ISSUES/139-an-internal-route-name-resolves-to-the-consumers-node/00-report.md

@@ -0,0 +1,51 @@
+---
+status: open
+opened: 2026-09-28
+located-in: [mesh-controller internal/catalogue]
+fixed-by:
+amended-design:
+---
+
+# 139 — An internal route name resolves to the consumer's node, not the one that serves it
+
+## What was observed
+
+A module that requires a route is given two names: a public one composed under the serving node's
+domain, and an internal one composed under the consumer's own machine — `<label>.<node>.internal`.
+
+The two are published differently:
+
+- The **public** name is written into every machine's hosts file at the address of the node whose
+  proxy answers it. The mesh computes that deliberately, so any container resolving a routed name
+  reaches the proxy.
+- The **internal** name is resolved by the machine's own resolver, which answers every name under
+  `<node>.internal` with that node's address — the consumer's, because the name was composed from it.
+
+Where the proxy runs beside the consumer these are the same machine, which is every case on this mesh
+today, and both names work. Measured on 2026-09-28: the internal name of a service on the control node
+answers with a certificate from the mesh's internal authority, and the public name with one from the
+public authority.
+
+Where the proxy is on another machine they disagree. The internal name sends the client to a machine
+that runs no proxy and has nothing listening on the port, while the public name sends it to the one
+that does.
+
+## Why it matters beyond this instance
+
+**It is latent exactly where the mesh is heading.** `route` is provided mesh-wide precisely so a
+module can be routed by a proxy on another machine. The first module assigned that way gets an
+internal name that does not work, and the public one that does — with no error anywhere, because both
+names resolve.
+
+**A per-machine name is what an operator will reach for.** `<service>.<machine>.internal` reads like a
+promise that the service on that machine is reachable there, and the wildcard makes every such name
+resolve whether or not anything answers.
+
+## Open questions
+
+- Should the internal name be composed under the serving node, like the public one, or should it stay
+  the consumer's and be published at the serving node's address like the public name is?
+- Is a per-node route holder the real answer — a proxy on every machine that serves its own names —
+  and if so, is `route` still one mesh-wide provision or a node-scoped seat with a mesh-wide fallback?
+- What certifies the name in either case? The certificate is obtained by whoever terminates TLS, and
+  that is the question above in another form.

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

@@ -0,0 +1,74 @@
+---
+status: open
+opened: 2026-09-28
+located-in: []
+fixed-by:
+amended-design:
+---
+
+# 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 +1,74 @@
+---
+status: open
+opened: 2026-09-28
+located-in: []
+fixed-by:
+amended-design:
+---
+
+# 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?