fix(tools): preserve dashboard identity fields in patch mode (#722)

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: sd2k

tools/dashboard.go

@@ -94,6 +94,10 @@ func updateDashboardWithPatches(ctx context.Context, args UpdateDashboardParams)
 		return nil, fmt.Errorf("dashboard is not a JSON object")
 	}
 
+	// Preserve the numeric ID before patching so it survives any
+	// accidental mutation by patch operations.
+	origID := dashboardMap["id"]
+
 	// Apply each patch operation
 	for i, op := range args.Operations {
 		switch op.Op {
@@ -110,6 +114,16 @@ func updateDashboardWithPatches(ctx context.Context, args UpdateDashboardParams)
 		}
 	}
 
+	// Restore identity fields so the Grafana API updates the existing
+	// dashboard in place instead of creating a clone with a new UID.
+	// The UID is always taken from the request args (the value used to
+	// fetch the dashboard) to guarantee consistency even when the
+	// dashboard body returned by the API did not include it.
+	dashboardMap["uid"] = args.UID
+	if origID != nil {
+		dashboardMap["id"] = origID
+	}
+
 	// Use the folder UID from the existing dashboard if not provided
 	folderUID := args.FolderUID
 	if folderUID == "" && dashboard.Meta != nil {

tools/dashboard_test.go

@@ -335,6 +335,64 @@ func TestDashboardTools(t *testing.T) {
 		assert.Equal(t, newTitle, dashboardMap["title"])
 	})
 
+	t.Run("update dashboard - patch preserves UID", func(t *testing.T) {
+		ctx := newTestContext()
+
+		// Get our test dashboard
+		dashboard := getExistingTestDashboard(t, ctx, newTestDashboardName)
+		originalUID := dashboard.UID
+
+		// Fetch the full dashboard to get the numeric ID
+		fullDashboard, err := getDashboardByUID(ctx, GetDashboardByUIDParams{UID: originalUID})
+		require.NoError(t, err)
+		origMap, ok := fullDashboard.Dashboard.(map[string]interface{})
+		require.True(t, ok)
+		originalID := origMap["id"]
+
+		// Patch via uid + operations
+		patchedTitle := "Patch UID Preservation Test"
+		result, err := updateDashboard(ctx, UpdateDashboardParams{
+			UID: originalUID,
+			Operations: []PatchOperation{
+				{
+					Op:    "replace",
+					Path:  "$.title",
+					Value: patchedTitle,
+				},
+			},
+			Message: "Testing UID preservation",
+		})
+		require.NoError(t, err)
+		require.NotNil(t, result)
+
+		// The response UID must match the original — not a newly generated UUID.
+		require.NotNil(t, result.UID, "response UID should not be nil")
+		assert.Equal(t, originalUID, *result.UID,
+			"patch response UID should match the original dashboard UID, not a new one")
+
+		// Fetch the dashboard by the original UID and verify:
+		// 1. The title was actually changed (patch applied to the right dashboard)
+		// 2. The numeric ID is unchanged (same dashboard, not a clone)
+		updatedDashboard, err := getDashboardByUID(ctx, GetDashboardByUIDParams{UID: originalUID})
+		require.NoError(t, err)
+
+		updatedMap, ok := updatedDashboard.Dashboard.(map[string]interface{})
+		require.True(t, ok)
+		assert.Equal(t, patchedTitle, updatedMap["title"],
+			"title should be updated on the original dashboard")
+		assert.Equal(t, originalID, updatedMap["id"],
+			"numeric ID should be unchanged — dashboard should be updated in place, not cloned")
+
+		// Restore the original title so subsequent tests can find the dashboard
+		_, err = updateDashboard(ctx, UpdateDashboardParams{
+			UID: originalUID,
+			Operations: []PatchOperation{
+				{Op: "replace", Path: "$.title", Value: newTestDashboardName},
+			},
+		})
+		require.NoError(t, err)
+	})
+
 	t.Run("update dashboard - patch add description", func(t *testing.T) {
 		ctx := newTestContext()