ADR 0144: anything on a machine may call anything on it, superseding 0143

Everything should be able to call what runs on the same machine, another machine's
service exposed to the private network, and another machine's service exposed
publicly. Three cases; the filter had two.

The first was expressed as the machines' own addresses on the private network. A
caller on the machine carries such an address; a caller in one of its containers
carries a bridge address and matched nothing — measured, same destination and same
machine: src 10.10.0.1 against src 172.17.0.8. The second case worked by accident,
because the tunnel rewrites a caller's address to the sending machine's. Two of
three working is why it read as correct.

0143 answered the wrong question. It proposed verifying each grant from the
consumer's own network position and went to length about which position, because
whether a caller sat in a container changed the answer — and that difference was the
bug. Observing a configuration error is not its remedy. Superseded, and nothing
replaces it; whether the mesh should check a grant is still open in issue 145 and
must stand on its own.

And a module is not a container: 61 of 72 happen to use one, 11 do not, and a rule
reasoning about containers describes most of the mesh rather than the mesh.

02-DECISIONS/0143-a-consumer-verifies-the-grant-it-is-given.md

@@ -0,0 +1,135 @@
+---
+topic: what runs on it
+status: superseded
+date: 2026-09-29
+deciders: jochen
+reconstructed: false
+extends: 02-DECISIONS/0010-delivery.md
+superseded-by: 02-DECISIONS/0144-anything-on-a-machine-may-call-anything-on-it.md
+---
+
+# 143. A consumer verifies the grant it is given
+
+## Context
+
+A **grant** is what the mesh writes on a consumer's machine so it can reach a provider. The real one
+the forge receives for its database, as it arrives:
+
+```
+provision  postgres-database
+at         <the provider's machine, by name>
+port       the machine port the provider is published on
+as         the role the provider created for this consumer
+```
+
+with the credential sealed in a separate file. Four facts and a password, and they are the whole
+mechanism by which anything in the mesh reaches anything else.
+
+**The mesh asserts that claim and never finds out whether it is true.**
+[Issue 145](../04-ISSUES/145-a-machine-reads-healthy-while-its-modules-cannot-reach-each-other/00-report.md):
+converging a machine dropped the path from a container to a port on its own machine, and for eleven
+hours the mesh answered *all doing what they were told, all heard from, every module current with its
+source* while a web application logged, six thousand times:
+
+```
+connection to server at "<the machine>" (10.10.0.1), port 6852 failed: timeout expired
+```
+
+Every check the mesh makes passed, because every check it makes is about the relationship between the
+mesh and a machine: the declaration was applied, the digest matched, every container named was running.
+None of them asks whether a consumer can reach what it requires — though the mesh composed the grant
+and therefore knows the consumer, the machine, the address, the port and the credential.
+
+**And where the check runs decides whether it catches anything.** The rule in force admitted the
+machines' own addresses on the private network. A dial from the *machine* to its own address carries
+exactly such a source address, so a check run by the host on its own behalf would have matched that rule
+and passed — while every container on the machine was refused. This is inference from the rule that was
+loaded, not a measurement: the fault was found and fixed before anyone thought to dial from the host.
+It is enough to decide the question, because a check whose position differs from the consumer's is
+testing something nobody asked about.
+
+## Considered Options
+
+1. **The control plane dials each provision.** Rejected, and it is the tempting one because the control
+   plane holds every fact. It sits on the provider's machine for most provisions here and reaches the
+   address by a path no consumer uses; in the measured outage it would have passed throughout.
+2. **The host dials on the consumer's behalf, from the machine.** Rejected for the reason above: the
+   machine's network position is not the consumer's, and the one outage this exists to catch is exactly
+   a difference between them.
+3. **Ask the module.** Rejected: a module is arbitrary software that the mesh does not write. Some could
+   report on their provisions and most cannot, and a check that covers the modules that opted in tells
+   nobody anything about the rest.
+4. **Read the module's logs.** Rejected: the failure was in a log the whole time, and reading a module's
+   logs makes the mesh depend on the wording of software it does not control.
+5. **The consumer verifies it, from its own network position.** Adopted.
+
+## Decision
+
+**A consumer verifies each grant it is given, from its own network position.** After a reconcile has
+applied a grant, the machine opens a connection to the address and port that grant names, from inside
+the consumer's own network namespace — the same position the consumer's software dials from, which is
+the only position that answers the question the grant asks.
+
+**It is a connection, not a conversation.** Whether the port accepts a connection is what a grant
+claims; whether the credential is right, the role exists or the schema is current is the provider's to
+answer and the consumer's to discover. A check that spoke each provision's protocol would be a second
+implementation of every provision, and would fail for reasons that are not the mesh's.
+
+**One failure is not news.** A provider restarting is ordinary, and so is a consumer between containers.
+A grant is reported unreachable only after it has failed on **consecutive** reconciles, and the count is
+what the machine reports rather than the last attempt — so a reader can tell "it was briefly away" from
+"it has never worked".
+
+**A grant that cannot be checked is said to be unchecked, never assumed good.** A consumer that is not
+running has no network position to dial from; that is not a broken grant and must not read as one. It is
+also not a verified grant, and the two are different sentences.
+
+**What it costs to be wrong is the constraint on all of it.** A check that reports a working provision
+broken trains a reader to ignore the report, which is worse than having none — the fault this
+repository keeps finding, one level up. So the threshold is consecutive failures, the check is the
+cheapest thing that answers the question, and an unknown is reported as unknown.
+
+**The mesh says it where it says everything else.** A machine's report carries its unreachable grants,
+and `status` names them beside what is out of date — so "every module current with its source" stops
+being the whole of what the mesh will tell you about a machine whose modules cannot reach each other.
+
+## Consequences
+
+- **The mesh can be wrong out loud.** It has been able to assert a grant and not check it; now a grant
+  that does not work is a thing the mesh says, and the eleven hours of issue 145 become minutes.
+- **The host gains the ability to act from a container's network position**, which it has not needed
+  before. That is a real capability and the only one this needs.
+- **A machine reports something that is not about the declaration.** Everything it reports today is
+  what it applied and what it holds; this is the first thing it says about whether what it applied
+  works.
+- **A provision with no port is not checked**, because there is nothing to dial. Several are files and
+  secrets, and saying "checked" about those would be the appearance of verification that this record
+  exists to remove.
+- **What got harder:** a reconcile does more than apply. Every grant adds a connection attempt on a
+  cadence, which is cheap individually and worth naming: a machine with many consumers dials once per
+  grant per reconcile.
+
+## How it is checked
+
+- **The outage is caught.** A bed drops the path from a consumer's network position to a provider's
+  port while leaving the machine's own path to it open — the exact shape of issue 145 — and the grant
+  reads unreachable. This fails against the previous behaviour, where nothing reported anything, and
+  against a check run from the machine, which passes while the consumer cannot reach it.
+- **A restarting provider is not an outage.** One failed reconcile reports nothing; the count rises and
+  falls, and the grant reads reachable again without anybody acting.
+- **A consumer that is not running reads unchecked, not broken**, asserted separately from the
+  unreachable case because they are different sentences.
+- **A provision with no port is not claimed to be checked.**
+- **The report carries the count, not the last attempt**, so "briefly away" and "never worked" are
+  distinguishable by a reader who sees only the report.
+- **`status` names an unreachable grant**, asserted on the output, since a check nothing surfaces is
+  the same as no check.
+
+## References
+
+- [ADR 0010](0010-delivery.md) — the declaration is owned resources; a grant is one of them
+- [ADR 0009](0009-modules-and-the-graph.md) — what a provision and a consumer are
+- [issue 145](../04-ISSUES/145-a-machine-reads-healthy-while-its-modules-cannot-reach-each-other/00-report.md)
+  — the eleven hours
+- [issue 136](../04-ISSUES/136-a-module-may-name-a-program-the-machine-does-not-have/00-report.md) — the
+  same distance between a declaration and a machine, one level down

02-DECISIONS/0144-anything-on-a-machine-may-call-anything-on-it.md

@@ -0,0 +1,121 @@
+---
+topic: what runs on it
+status: accepted
+date: 2026-09-29
+deciders: jochen
+reconstructed: false
+extends: 02-DECISIONS/0045-a-machine-firewall-is-the-sum-of-what-it-listens-on.md
+supersedes: 02-DECISIONS/0143-a-consumer-verifies-the-grant-it-is-given.md
+---
+
+# 144. Anything on a machine may call anything on it, and that is the whole of "local"
+
+## Context
+
+Everything in the mesh should be able to call:
+
+- what runs on the same machine;
+- another machine's service over the private network, if that service is exposed there;
+- another machine's service over the public network, if it is exposed there.
+
+Three cases. The filter had two of them.
+
+**The first was broken and the break was invisible.** A service exposed to the private network rendered
+as the machines' own addresses on it. A caller on the machine carries such an address; a caller inside
+one of that machine's containers carries a bridge address and matched nothing. Measured:
+
+```
+the machine:   local 10.10.0.1 dev lo   src 10.10.0.1
+a container:   10.10.0.1 via 172.17.0.1 dev eth0  src 172.17.0.8
+```
+
+Same destination, same machine, two source addresses. The rule named the first and silently refused the
+second, so a module reaching its database on its own machine's name timed out for eleven hours
+([issue 145](../04-ISSUES/145-a-machine-reads-healthy-while-its-modules-cannot-reach-each-other/00-report.md)).
+
+**The second case works, and by accident.** A caller on another machine reaches the private network over
+the tunnel, and arrives carrying that machine's own address — so the rule matches. It would not have
+matched the caller's own address either; the tunnel rewrites it. That two of three cases worked is why
+this looked correct.
+
+**[ADR 0143](0143-a-consumer-verifies-the-grant-it-is-given.md) answered the wrong question.** Written
+hours earlier, it proposed that a consumer verify each grant it is given by opening a connection from
+its own network position — and it went to some length about *which* position, because whether a caller
+sat in a container changed the answer. That difference was the bug. A verification mechanism would have
+reported this outage sooner and would not have prevented it, and the machinery it needed existed only
+because the rule was wrong. The remedy for a configuration error is the correct configuration.
+
+**And a module is not a container.** A module is software that delivers one or more services, and it may
+do that as a container, an installed package with a unit, a binary, or files something else reads. Of 72
+modules in the catalogue, 61 happen to use a container and 11 do not — among them the resolver, the ssh
+daemon and the intrusion-prevention module. A rule that reasons about containers describes most of the
+mesh and not the mesh.
+
+## Considered Options
+
+1. **A line per service admitting the machine's own callers.** Rejected: it is what was written first,
+   and it only ever covers the services somebody remembered to think about. It also states, service by
+   service, a thing that is true of the machine.
+2. **Verify each grant from the consumer's position** ([ADR 0143](0143-a-consumer-verifies-the-grant-it-is-given.md)).
+   Rejected as a remedy: it observes the fault rather than removing it, and the question it agonised over
+   — which network position — exists only while the fault does.
+3. **Enumerate the addresses a machine's callers may have.** Rejected for the reason no address is named
+   anywhere in this filter any more ([ADR 0140](0140-the-filter-constrains-what-arrives-from-outside.md)):
+   a range describes one machine and goes stale in silence.
+4. **Local is not filtered, stated once.** Adopted.
+
+## Decision
+
+**Anything on a machine may call anything on that machine, and the filter says so once.** Not per
+service, not per port, and not by naming who the callers are: traffic that did not arrive from outside
+the machine and did not arrive over the private network is the machine's own, and is admitted. It is
+asked by the link the traffic arrived on, because that is a fact about the machine rather than a list
+that describes one.
+
+**Local is not a boundary this mesh draws.** Whether a caller is a container, a unit, or the operator's
+shell changes nothing, because the thing being decided is "is this the same machine" and the answer does
+not depend on the form the caller takes.
+
+**The other two cases are unchanged and are now legible beside it.** A service exposed to the private
+network admits the machines on it; a service exposed publicly admits anything. Three cases, three lines,
+and a reader can see all three at once.
+
+**[ADR 0143](0143-a-consumer-verifies-the-grant-it-is-given.md) is superseded and nothing replaces it.**
+Whether the mesh should check that a grant works is a real question — it reported this machine healthy
+for eleven hours — but it is a question about what the mesh can say, not about what it should do, and it
+must stand on its own rather than as the remedy for a rule that was wrong. It is not built.
+
+## Consequences
+
+- **The three things everything should be able to call are three lines**, and the first is one line
+  rather than one per service, so a service added tomorrow is reachable locally without anybody
+  remembering to say so.
+- **A form of module stops mattering to the filter.** The 11 modules that are not containers were never
+  affected by this bug and were never the reason it was hard to see; they are the reason the rule should
+  never have mentioned containers.
+- **The mesh still cannot say when a grant stops working.** That is the live gap, recorded in issue 145
+  and no longer pretending to have an answer.
+- **What got harder:** nothing. This removes a line per service and replaces it with one.
+
+## How it is checked
+
+- **A caller on the machine reaches a service on it, in the input chain**, asserted on that chain's own
+  body — because the forward chain carries the same line in the same words, and an assertion on the
+  whole rendered file passed with the input chain's copy deleted. That is what
+  [ADR 0137](0137-a-machine-says-which-networks-it-routes.md)'s tests already say to do.
+- **It is one rule, not one per service.** Asserted by rendering two services of different reach and
+  refusing a per-port local line.
+- **The three reaches render as three lines**, asserted together, so the whole of what the filter says
+  about who may call what is one test.
+- **The measured case:** from a container on the machine, a service exposed to the private network on
+  that machine answers. This is the outage, and it fails against the rule this replaces.
+
+## References
+
+- [ADR 0045](0045-a-machine-firewall-is-the-sum-of-what-it-listens-on.md) — the filter is the sum
+  of what its modules listen on
+- [ADR 0140](0140-the-filter-constrains-what-arrives-from-outside.md) — why no address is named
+- [ADR 0138](0138-an-assignment-binds-an-endpoint-and-says-how-far-it-reaches.md) — internal and public,
+  the other two cases
+- [ADR 0143](0143-a-consumer-verifies-the-grant-it-is-given.md) — superseded here
+- [issue 145](../04-ISSUES/145-a-machine-reads-healthy-while-its-modules-cannot-reach-each-other/00-report.md)

02-DECISIONS/README.md

@@ -223,6 +223,8 @@ python3 00-META/checks/index.py            fail if stale
 - **0139** — [A network is forwarded because a module declared it](0139-a-network-is-forwarded-because-a-module-declared-it.md)  *(superseded)*
 - **0140** — [The filter constrains what arrives from outside, and says nothing about a machine's own guests](0140-the-filter-constrains-what-arrives-from-outside.md)
 - **0141** — [The host delivers its own successor, and versions live side by side](0141-the-host-delivers-its-own-successor.md)
+- **0143** — [A consumer verifies the grant it is given](0143-a-consumer-verifies-the-grant-it-is-given.md)  *(superseded)*
+- **0144** — [Anything on a machine may call anything on it, and that is the whole of "local"](0144-anything-on-a-machine-may-call-anything-on-it.md)
 
 ### How it is built
 

03-DESIGN/01-to-be/10-delivery.md

@@ -5,7 +5,7 @@ code:
   - mesh-controller internal/builder
   - mesh-controller cmd/mesh-controller (build, build --behind, push, status)
   - mesh-controller internal/inventory/builds.go
-updated: 2026-09-21
+updated: 2026-09-29
 decisions:
   - 02-DECISIONS/0090-a-failure-that-repeats-is-said-to-be-stuck.md
   - 02-DECISIONS/0082-the-registry-is-reached-by-name-and-trusted-by-the-overlay.md
@@ -226,3 +226,34 @@ when the current failure began and how many reports in a row have said it — th
 id, whatever the words; three make the machine stuck, and `status` says so beside the failure. The host keeps trying — stuck is what the mesh
 knows, not what the machine is told. *How it is checked:* an inventory test counts three identical
 reports, a different one, and a clean apply; the status test asserts the word appears.
+
+## Everything may call what is exposed to it, and local is not a boundary
+
+*2026-09-29, from an outage that ran eleven hours —
+[issue 145](../../04-ISSUES/145-a-machine-reads-healthy-while-its-modules-cannot-reach-each-other/00-report.md),
+settled by [ADR 0144](../../02-DECISIONS/0144-anything-on-a-machine-may-call-anything-on-it.md).*
+
+A grant is four facts and a credential: the provision, the machine, the port, and who the consumer is
+when it connects. It is the whole mechanism by which anything in the mesh reaches anything else, and it
+rests on three things being callable — what runs on the same machine, another machine's service over the
+private network where it is exposed there, and another machine's service over the public network where it
+is exposed there.
+
+The filter had two of those. A service exposed to the private network admitted the machines' own addresses
+on it; a caller on the machine carries such an address, and a caller inside one of that machine's
+containers carries a bridge address and matched nothing. Measured, same destination and same machine:
+`src 10.10.0.1` from the machine, `src 172.17.0.8` from a container on it. So a module reaching its
+database on its own machine's name timed out for eleven hours while the mesh called the machine healthy.
+
+The second case worked by accident: a caller on another machine arrives over the tunnel carrying that
+machine's address, which the rule matched. Two of three working is why this read as correct.
+
+**So local is not a boundary this mesh draws, and the filter says so once.** Traffic that did not arrive
+from outside the machine and did not arrive over the private network is the machine's own, and is
+admitted — for every service there, not per service. Whether the caller is a container, a unit or a shell
+decides nothing, because the question is "is this the same machine".
+
+A verification mechanism was drafted for this and withdrawn. It would have reported the outage sooner and
+would not have prevented it, and the part of it that was hard — deciding which network position to check
+from — existed only because the rule was wrong. Whether the mesh should check that a grant works is still
+open, in issue 145; it is not the remedy for a configuration error.

04-ISSUES/145-a-machine-reads-healthy-while-its-modules-cannot-reach-each-other/00-report.md

@@ -5,7 +5,7 @@ located-in:
   - mesh-controller internal/catalogue/filtering.go (fixed for this instance)
   - mesh-controller (what status reports, and what it does not ask)
 fixed-by:
-amended-design:
+amended-design: 03-DESIGN/01-to-be/10-delivery.md
 ---
 
 # 145 — A machine reads healthy while its modules cannot reach each other
@@ -72,6 +72,28 @@ distance between a declaration and the machine, and in both cases the report was
 **And the eleven hours are the measurement, not the bug.** The filter fault was one line and is fixed.
 What is not fixed is that nothing in the mesh would have told anybody.
 
+## What was decided
+
+*2026-09-29, the same day, in two steps and the first was wrong.*
+
+The first answer was [ADR 0143](../../02-DECISIONS/0143-a-consumer-verifies-the-grant-it-is-given.md):
+the consumer verifies each grant from its own network position, because whether a caller sat in a
+container changed whether it could reach the provider. **That difference was the fault**, and the record
+is superseded. A verification mechanism would have reported this sooner and would not have prevented it,
+and the part of it that was difficult — deciding which network position to check from — existed only
+while the rule was wrong.
+
+The remedy is [ADR 0144](../../02-DECISIONS/0144-anything-on-a-machine-may-call-anything-on-it.md):
+anything on a machine may call anything on it, said once rather than per service, and asked by the link
+traffic arrives on rather than the address it carries. Everything should be able to call what runs on the
+same machine, another machine's service exposed to the private network, and another machine's service
+exposed publicly. The filter had the second and third and expressed the first as a list of addresses that
+no container could match.
+
+**The question this issue is actually about is still open.** Nothing in the mesh would have said a grant
+had stopped working, and nothing does now. That is not answered by a configuration fix, and it should not
+be answered by a mechanism adopted as a remedy for one.
+
 ## Open questions
 
 - Should a grant be checked? The mesh knows the consumer, the provider, the address and the port, so a