v0.335.0: no app stop for a tier the agent will refuse because its host is busy (host_busy pre-check, R-921)

controller/internal/agentapi/r921_inflight_test.go

@@ -73,3 +73,35 @@ func TestBackupJobsInFlight_StatusErrorIsReturned(t *testing.T) {
 		t.Fatal("a failed status read was swallowed — the caller could not tell it from 'nothing in flight'")
 	}
 }
+
+// R-921 part 2: HostBusy reads the agent's real wire shape (untargeted GET /backup/status, `host_busy`); an agent
+// without the field is „not known" — never „free".
+func TestHostBusy_ReadsTheAgentsGate(t *testing.T) {
+	for _, tc := range []struct {
+		name, body  string
+		busy, known bool
+		what        string
+	}{
+		{"held", `{"ok":true,"data":{"vmid":9201,"phase":"idle","host_busy":{"busy":true,"what":"os-pve-step"}}}`, true, true, "os-pve-step"},
+		{"free", `{"ok":true,"data":{"vmid":9201,"phase":"idle","host_busy":{"busy":false}}}`, false, true, ""},
+		{"older agent", `{"ok":true,"data":{"vmid":9201,"phase":"idle"}}`, false, false, ""},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			mux := http.NewServeMux()
+			mux.HandleFunc("GET /backup/status", func(w http.ResponseWriter, r *http.Request) {
+				if r.URL.RawQuery != "" {
+					http.Error(w, "want the untargeted status", http.StatusBadRequest)
+					return
+				}
+				_, _ = w.Write([]byte(tc.body))
+			})
+			s := httptest.NewTLSServer(mux)
+			defer s.Close()
+			c := clientFor(t, s, strings.TrimPrefix(s.URL, "https://"))
+			busy, what, known, err := c.HostBusy(context.Background())
+			if err != nil || busy != tc.busy || known != tc.known || what != tc.what {
+				t.Fatalf("HostBusy = %v %q known=%v err=%v, want %v %q known=%v", busy, what, known, err, tc.busy, tc.what, tc.known)
+			}
+		})
+	}
+}