The controller follows the subject it decodes

The decoder named the forge's merge subject as the fourth thing followed and the
list was three long: every message that fell through to that switch panicked the
control plane (2026-09-28). The entry was written and lost between two attempts
at the same edit. A test now walks the list; the composed grants and the genesis
template carry the subject.

internal/broker/streams.go

@@ -175,6 +175,9 @@ var ControllerFollows = []string{
 	// message on the control branch. Same three audiences, one publish: whoever asked, this, and the
 	// catalogue.
 	seatEventSubject("mesh-build-machine", "built"),
+	// The forge's merges: what moved a source, so the mesh builds what that source produces
+	// without anybody telling it (novox/hq 04-ISSUES/131). Appended, because the index is a name.
+	moduleEventSubject("gitea", "pull.merged"),
 }
 
 // moduleEventSubject is where one module's event lands. The same derivation PermissionsFor uses, so