feat(capability): add release scoped shadow bindings

cmd/commit-runtime/main.go

@@ -73,15 +73,18 @@ func main() {
 	if err != nil {
 		log.Fatal(err)
 	}
-	notificationSecret, err := readCommitSecretFile("NOTIFICATION_WRITE_TOKEN_FILE")
+	candidateContext, err := candidateReleaseContextFromRuntime()
 	if err != nil {
 		log.Fatal(err)
 	}
-	notificationSecretRef := os.Getenv("NOTIFICATION_WRITE_SECRET_REF")
-	if notificationSecretRef == "" {
-		log.Fatal("NOTIFICATION_WRITE_SECRET_REF is required")
+	notificationSecretRef, notificationSecret, err := notificationCredentialsFromRuntime(candidateContext != nil)
+	if err != nil {
+		log.Fatal(err)
 	}
-	dispatcher := operationDispatcher{continuityExecutor: continuityExecutor, continuityReconciler: continuityExecutor, bindings: creatorCore, secretRef: notificationSecretRef, secret: notificationSecret, client: creatorHTTPClient}
+	if candidateContext != nil {
+		creatorCore.serviceCredential = delegatedControlPlaneCredential
+	}
+	dispatcher := operationDispatcher{continuityExecutor: continuityExecutor, continuityReconciler: continuityExecutor, bindings: creatorCore, secretRef: notificationSecretRef, secret: notificationSecret, client: creatorHTTPClient, candidateContext: candidateContext}
 	mux := http.NewServeMux()
 	mux.Handle("/healthz", health.Handler{Runtime: "commit-runtime", SemanticGeneration: 1, ArchitectureGeneration: 1})
 	readinessClient := &http.Client{Timeout: 2 * time.Second}
@@ -162,6 +165,24 @@ func main() {
 	}
 }
 
+// notificationCredentialsFromRuntime keeps candidate shadow execution
+// physically separate from the production notification credential mount.
+func notificationCredentialsFromRuntime(candidate bool) (string, string, error) {
+	fileName, refName := "NOTIFICATION_WRITE_TOKEN_FILE", "NOTIFICATION_WRITE_SECRET_REF"
+	if candidate {
+		fileName, refName = "CANDIDATE_NOTIFICATION_WRITE_TOKEN_FILE", "CANDIDATE_NOTIFICATION_WRITE_SECRET_REF"
+	}
+	secret, err := readCommitSecretFile(fileName)
+	if err != nil {
+		return "", "", err
+	}
+	ref := os.Getenv(refName)
+	if ref == "" {
+		return "", "", fmt.Errorf("%s is required", refName)
+	}
+	return ref, secret, nil
+}
+
 func readCommitSecretFile(name string) (string, error) {
 	path := os.Getenv(name)
 	if path == "" {