Include local backend target in checkpoint identity

internal/framework/llm/promptkit_client_test.go

@@ -312,6 +312,83 @@ func TestPromptKitClientCheckpointFingerprintTracksProfileSource(t *testing.T) {
 	}
 }
 
+func TestPromptKitClientCheckpointFingerprintTracksLocalBackendTarget(t *testing.T) {
+	const (
+		firstEndpoint  = "http://localhost:8000/v1"
+		secondEndpoint = "https://inference.example.test/v1"
+	)
+	fingerprintsFor := func(endpoint string, concurrencyLimit int) []CheckpointFingerprint {
+		t.Helper()
+		client, err := NewPromptKitClient(PromptKitClientConfig{
+			Assets: newTestPromptKitAssets(t),
+			LocalBackend: &PromptKitLocalBackendConfig{
+				Endpoint:         endpoint,
+				ConcurrencyLimit: concurrencyLimit,
+			},
+		})
+		if err != nil {
+			t.Fatal(err)
+		}
+		values, err := client.LLMCheckpointFingerprints()
+		if err != nil {
+			t.Fatal(err)
+		}
+		return values
+	}
+
+	baseline := fingerprintsFor(firstEndpoint, 0)
+	if len(baseline) != 2 ||
+		baseline[0].Name != promptKitProfileFingerprintName ||
+		baseline[1].Name != promptKitLocalBackendFingerprintName {
+		t.Fatalf("checkpoint fingerprints = %#v, want profile source then local backend target", baseline)
+	}
+	endpointChanged := fingerprintsFor(secondEndpoint, 0)
+	if baseline[0] != endpointChanged[0] || baseline[1] == endpointChanged[1] {
+		t.Fatalf("endpoint fingerprints = %#v and %#v, want only local target to change", baseline, endpointChanged)
+	}
+	concurrencyChanged := fingerprintsFor(firstEndpoint, 4)
+	if !reflect.DeepEqual(baseline, concurrencyChanged) {
+		t.Fatalf("concurrency fingerprints = %#v, want %#v", concurrencyChanged, baseline)
+	}
+	for _, values := range [][]CheckpointFingerprint{baseline, endpointChanged} {
+		for _, fingerprint := range values {
+			if strings.Contains(fingerprint.Value, firstEndpoint) ||
+				strings.Contains(fingerprint.Value, secondEndpoint) {
+				t.Fatalf("checkpoint fingerprint exposes endpoint: %#v", fingerprint)
+			}
+		}
+	}
+
+	localBackend := &PromptKitLocalBackendConfig{
+		Endpoint:         " " + firstEndpoint + " ",
+		ConcurrencyLimit: 0,
+	}
+	client, err := NewPromptKitClient(PromptKitClientConfig{
+		Assets:       newTestPromptKitAssets(t),
+		LocalBackend: localBackend,
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	localBackend.Endpoint = secondEndpoint
+	copy, err := client.LLMCheckpointFingerprints()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !reflect.DeepEqual(copy, baseline) {
+		t.Fatalf("fingerprints after input mutation = %#v, want retained target %#v", copy, baseline)
+	}
+	copy[0].Value = "mutated-profile"
+	copy[1].Value = "mutated-target"
+	fresh, err := client.LLMCheckpointFingerprints()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !reflect.DeepEqual(fresh, baseline) {
+		t.Fatalf("fingerprints after returned-slice mutation = %#v, want %#v", fresh, baseline)
+	}
+}
+
 func TestPromptKitClientUsesPromptDefaultProfileWhenRequestProfileEmpty(t *testing.T) {
 	fake := &fakePromptKitLLM{content: `{"ok":true}`}
 	client := newTestPromptKitClient(t, fake)