Issue 191: an internal name is served to the private network only

The first fix served the dropped route to anyone who sent its name. Record
why in the issue, as a progressive insight on ADR 0138, and in the to-be
connectivity design.

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

@@ -7,7 +7,7 @@ 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: 2026-09-30
+updated: 2026-10-02
 decisions:
   - 02-DECISIONS/0148-the-meshs-names-are-resolved-not-copied-into-containers.md
   - 02-DECISIONS/0151-a-routes-internal-name-is-composed-under-the-node-that-serves-it.md
@@ -842,6 +842,15 @@ One value, three readers:
 | `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 |
 
+*2026-10-02.* **The proxy serves an internal name to the private network only**
+([ADR 0138](../../02-DECISIONS/0138-an-assignment-binds-an-endpoint-and-says-how-far-it-reaches.md),
+its insight of this date). It answers public and internal names on the same listeners, so the name a
+request carries is the request's own claim, not where the request came from. An internal name is
+served to the mesh's range, to the machine itself and to its own container networks; to anyone else
+it is answered as a name never routed, in the handshake as well as the request. Without this, an
+endpoint with reach `internal` would be public under a name that is easy to guess
+([issue 191](../../04-ISSUES/191-a-route-with-only-an-internal-name-is-dropped/00-report.md)).
+
 **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.