Merge pull request 'ADR 0138: reach asks for names on a routed endpoint' (#178) from decision/0138-insight-reach-and-the-proxy into main

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

@@ -99,6 +99,31 @@ composed, so it is not certified.
 binding. The per-node source override becomes its reach, widened from the filter alone to the names
 and the certificate as well.
 
+## Progressive insight — 2026-09-29, from building it
+
+**Reach does not mean the same thing to the filter for an endpoint the proxy serves.** The decision
+above says `internal` means "the filter opens the machine port to the private network" and `public`
+means "the filter opens it to anywhere". For a routed endpoint the second half is wrong, and
+[ADR 0045](0045-a-machine-firewall-is-the-sum-of-what-it-listens-on.md) already said so before this
+record was written: *a public service is exposed through the proxy, not by opening its own port* — it
+listens `from: mesh`, only the proxy reaches it, and it is exposed by name.
+
+Found by trying to express one real module, not by review. Its routed name must be public, because
+browsers post to it; its machine-side port must not be, because that port serves the dashboard in
+cleartext. Under one value driving both, saying "public" would have reopened a port an operator had
+just closed. Measured the same evening: that module's routed name answered from the internet over TLS
+while its machine-side port was refused from the same place. The port is not the path.
+
+So the reach of a **routed** endpoint asks for names, and its port keeps what the manifest said. The
+reach of an **unrouted** endpoint — git over ssh, a mail port, the bus — governs the port, because
+there is no name and the port is the only way in. That is the same split this record already draws in
+*an endpoint that is not routed is reached but never named*; what it got wrong was carrying the filter
+across it.
+
+This corrects a fact, not the decision: one statement per endpoint, three things derived from it and
+none of them deciding on its own, all stand. The table in the decision should be read with the filter
+column applying to an unrouted endpoint.
+
 ## Consequences
 
 - **A manifest gains endpoint names, and a route contribution names an endpoint instead of a port.**