The mesh says what it applied, and the replay has an address it may use

The pipeline was observable from a merge to an artifact and went dark where it touched a machine: a
node's report is control traffic only the control plane reads, so nothing said which version a
machine runs, or that it refused to (novox/hq ADR 0134). The control plane now states both under the
seat it holds — a role's events belong to the role and keep their address when the holder is
replaced — and only when the report is news, because a machine reconciles every minute and a fact per
report would be a fact per minute per machine.

Whether a report is news is the store's answer: it holds the previous one, so the listener returns it
and the server states the fact. That also gives the catch-up replay a subject the controller may
publish: it was published as a module's event from a module called "control-plane", which does not
exist, so the controller's own account refused it and every catalogue that asked what it missed was
answered with nothing.

internal/link/events.go

@@ -49,6 +49,39 @@ func eventID() (string, error) {
 	return hex.EncodeToString(raw), nil
 }
 
+// MeshControllerSeat is the role the control plane holds, and therefore where its own facts live: a
+// role's events belong to the role, not to whichever container is holding it today (novox/hq ADR 0121,
+// ADR 0129). It is what makes them addressable while the control plane itself is being replaced.
+const MeshControllerSeat = "mesh-controller"
+
+// The facts the mesh states about its own work (novox/hq ADR 0134).
+const (
+	// KeyApplied: a machine now runs what it was sent.
+	KeyApplied = "applied"
+	// KeyRefused: a machine did not take what it was sent, and why.
+	KeyRefused = "refused"
+	// KeyBuiltBefore: a build the mesh already held, for a catalogue that asked what it missed. Not
+	// `built` — that is the build machine's, said as it happens, and a replay is neither.
+	KeyBuiltBefore = "built-before"
+)
+
+// Applied is what a machine now runs, as the mesh states it.
+type Applied struct {
+	Node     string `json:"node"`
+	Declared string `json:"declared,omitempty"`
+	// Resources is how many the machine applied, not which: the list is the machine's own account
+	// of itself and belongs in the records, not in a fact every listener has to read past.
+	Resources int `json:"resources"`
+}
+
+// Refused is a machine that would not take what it was sent.
+type Refused struct {
+	Node     string            `json:"node"`
+	Declared string            `json:"declared,omitempty"`
+	Refused  string            `json:"refused,omitempty"`
+	Failed   map[string]string `json:"failed,omitempty"`
+}
+
 // KeyModuleBuilt is what the builder announces when it has built something. The catalogue places
 // it in the module graph; nothing else need care.
 const KeyModuleBuilt = "module.builder.built"