don't write no-ops as new URL history items

CHANGELOG.md

@@ -21,6 +21,8 @@ and this project adheres to
 
 ### Fixed
 
+- Fix issue where back button must be pressed 3 times to go back once from the
+  Workflow canvas [#4812](https://github.com/OpenFn/lightning/issues/4812)
 - Fix `purge_deleted` Oban job crashing when a soft-deleted project has
   associated OAuth clients. The `project_oauth_clients` join rows are now
   cleaned up alongside the other project-scoped deletes in

assets/js/react/lib/use-url-state.ts

@@ -102,6 +102,10 @@ class URLStore {
     const newURL = new URL(window.location.pathname, window.location.origin);
     newURL.search = newParams.toString();
     newURL.hash = window.location.hash;
+    // Skip no-op writes so mount-time normalization doesn't stack
+    // duplicate browser history entries (a no-op pushState never notifies
+    // subscribers anyway, due to the guard in updateParams).
+    if (newURL.href === window.location.href) return;
     history.pushState({}, '', newURL);
   };
 

assets/test/react/lib/use-url-state.test.ts

@@ -11,7 +11,7 @@
  */
 
 import { renderHook, act } from '@testing-library/react';
-import { describe, test, expect, beforeEach } from 'vitest';
+import { describe, test, expect, beforeEach, afterEach, vi } from 'vitest';
 
 import { useURLState } from '../../../js/react/lib/use-url-state';
 
@@ -201,6 +201,41 @@ describe('useURLState', () => {
     });
   });
 
+  describe('updateSearchParams - no-op writes', () => {
+    afterEach(() => {
+      vi.restoreAllMocks();
+    });
+
+    test('does not push a history entry when params are unchanged', () => {
+      history.replaceState({}, '', '/workflow?panel=run&job=abc');
+
+      const { result } = renderHook(() => useURLState());
+      const pushSpy = vi.spyOn(history, 'pushState');
+
+      act(() => {
+        // Same values that are already in the URL -> a no-op
+        result.current.updateSearchParams({ panel: 'run', job: 'abc' });
+      });
+
+      expect(pushSpy).not.toHaveBeenCalled();
+      expect(window.location.search).toBe('?panel=run&job=abc');
+    });
+
+    test('still pushes a history entry when a param actually changes', () => {
+      history.replaceState({}, '', '/workflow?panel=run');
+
+      const { result } = renderHook(() => useURLState());
+      const pushSpy = vi.spyOn(history, 'pushState');
+
+      act(() => {
+        result.current.updateSearchParams({ panel: 'inspector' });
+      });
+
+      expect(pushSpy).toHaveBeenCalledTimes(1);
+      expect(result.current.params.panel).toBe('inspector');
+    });
+  });
+
   describe('replaceSearchParams', () => {
     test('replaces all params with new ones (clears unspecified params)', () => {
       history.replaceState({}, '', '/workflow?panel=run&job=abc&step=5');