Merge pull request 'Issue 145: a machine reads healthy while its modules cannot reach each other' (#179) from issue/145-healthy-while-broken into main

04-ISSUES/144-the-predecessors-rules-outlive-the-firewall-it-was-found-as/00-report.md

@@ -57,6 +57,20 @@ enrolment path the design guarantees.
 **The safe direction is not the same as the correct one.** Being more closed than intended broke nothing
 visible, which is exactly why it went unnoticed for as long as the mesh has been on this machine.
 
+## What it cost, measured later the same day
+
+*2026-09-29.* The predecessor's chain was removed, and something it had been carrying went with it. It
+admitted the private ranges wholesale, which is how a container on the machine reached a port declared
+for the private network — the mesh's own filter admits the machines' overlay addresses, and a container
+comes from a bridge. Every module that reached another by the machine's own name had been relying on the
+predecessor's rule without anybody knowing.
+
+That is [issue 145](../145-a-machine-reads-healthy-while-its-modules-cannot-reach-each-other/00-report.md),
+and it ran for eleven hours while the mesh reported the machine healthy. The filter is fixed. What this
+adds to the account here is that "the machine is more closed than the mesh believes" was not the
+harmless direction after all — it was harmless for everything reached from outside, and an outage for
+everything reached from within.
+
 ## Open questions
 
 - Should the host report every place the machine filters from, rather than one kind — the front-end,

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

@@ -0,0 +1,89 @@
+---
+status: located
+opened: 2026-09-29
+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:
+---
+
+# 145 — A machine reads healthy while its modules cannot reach each other
+
+## What was observed
+
+Converging the control-node closed every path by which a module on that machine reached another module
+by the machine's own name. It ran for **eleven hours**. Throughout, the mesh answered:
+
+```
+4 machine(s), all doing what they were told, all heard from,
+running what the mesh would send them, and every module current with its source
+```
+
+What was actually happening, from one affected module's own log:
+
+```
+Doctrine\DBAL\Exception: Failed to connect to the database:
+SQLSTATE[08006] connection to server at "novox.internal" (10.10.0.1), port 6852 failed: timeout expired
+```
+
+6,154 of them, beginning at the minute of the flip. The web application accepted TCP connections and
+never answered an HTTP request; a client waited 35 seconds and gave up. Confirmed from a throwaway
+container on the machine: neither the store nor the forge was reachable on the machine's own address.
+
+The cause is [issue 144](../144-the-predecessors-rules-outlive-the-firewall-it-was-found-as/00-report.md)'s
+sibling and is fixed: a port declared reachable from the private network admitted the machines' own
+overlay addresses, and a container on the machine comes from a bridge address, matching none of them.
+What this issue is about is the eleven hours.
+
+**Nothing the mesh reports would have shown it.** Every check the mesh makes passed, because every
+check the mesh makes is about the relationship between the mesh and a machine:
+
+- the machine applied what it was sent, and said so;
+- its declaration digest matches what the mesh would send;
+- every module's source commit matches what the mesh holds;
+- every container the declaration names is running.
+
+None of those asks whether a module can reach what it requires. The mesh knows precisely who requires
+what — it composes the grants — and never checks that the grant works.
+
+**Nor would an operator's usual look.** The ports were probed from outside and behaved correctly; the
+routed services answered; a container's egress to the internet worked. Those are the paths a person
+checks after changing a firewall, and all three were fine. The broken path was module-to-module over
+the machine's own name, which nothing routine exercises.
+
+## Why it matters beyond this instance
+
+**A mesh that composes a dependency and never tests it can only report on itself.** Every provision the
+mesh grants is a claim that a consumer can reach a provider. The mesh asserts that claim, delivers
+credentials for it, and has no mechanism that ever finds out. "Every module current with its source"
+is a statement about bytes, not about whether anything works.
+
+**The failure was silent in the direction that hides longest.** A service that will not start is
+noticed. A service that starts, accepts connections and then cannot reach its database serves errors
+under a healthy-looking process, and the machine's own report says the container is running — which it
+is.
+
+**It is the same shape as [issue 136](../136-a-module-may-name-a-program-the-machine-does-not-have/00-report.md),
+one level up.** There, a module named a program the machine lacked and everything reported success.
+Here, the mesh granted a provision the filter refused and everything reported success. Both are the
+distance between a declaration and the machine, and in both cases the report was about the declaration.
+
+**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.
+
+## Open questions
+
+- Should a grant be checked? The mesh knows the consumer, the provider, the address and the port, so a
+  reachability check is expressible — but from where: the consumer's machine, as part of a reconcile,
+  or the provider's?
+- What would it cost to be wrong in the other direction? A check that reports a provision broken while
+  it works is worse than none, because it trains a reader to ignore the report. A provider restarting is
+  ordinary; a consumer between containers is ordinary.
+- What should `status` say about a machine whose modules cannot reach each other? It currently has one
+  vocabulary for "heard from and current", and that sentence was true the whole time.
+- Is there a cheaper signal than a probe? The affected module was logging the failure 6,154 times. The
+  mesh reads no module's logs and arguably should not — but something a module could *say* about its
+  own provisions would have surfaced this in minutes.
+- Does the same blindness apply to the other direction — a provider that lost a consumer's grant and
+  is refusing it? Nothing checks that either.