these too

frontend/src/hooks/useTravelTime.test.ts

@@ -0,0 +1,68 @@
+import { act, renderHook } from '@testing-library/react';
+import { describe, expect, it } from 'vitest';
+
+import { travelFieldKey, useTravelTime, type TravelTimeEntry } from './useTravelTime';
+
+describe('useTravelTime', () => {
+  it('creates backend field keys from mode and destination slug', () => {
+    expect(
+      travelFieldKey({
+        mode: 'transit',
+        slug: 'kings-cross',
+        label: 'Kings Cross',
+        timeRange: [0, 45],
+        useBest: true,
+      })
+    ).toBe('tt_transit_kings-cross');
+  });
+
+  it('adds, updates, toggles, and removes travel-time entries', () => {
+    const { result } = renderHook(() => useTravelTime());
+
+    act(() => result.current.handleAddEntry('transit'));
+    expect(result.current.entries).toEqual([
+      { mode: 'transit', slug: '', label: '', timeRange: null, useBest: false },
+    ]);
+    expect(result.current.activeEntries).toEqual([]);
+
+    act(() => result.current.handleSetDestination(0, 'bank', 'Bank'));
+    expect(result.current.entries[0]).toMatchObject({
+      slug: 'bank',
+      label: 'Bank',
+      timeRange: [0, 120],
+    });
+    expect(result.current.activeEntries).toHaveLength(1);
+
+    act(() => result.current.handleTimeRangeChange(0, [10, 35]));
+    expect(result.current.entries[0].timeRange).toEqual([10, 35]);
+
+    act(() => result.current.handleToggleBest(0));
+    expect(result.current.entries[0].useBest).toBe(true);
+
+    act(() => result.current.handleRemoveEntry(0));
+    expect(result.current.entries).toEqual([]);
+  });
+
+  it('replaces entries wholesale for AI-generated filters', () => {
+    const initial: TravelTimeEntry = {
+      mode: 'walking',
+      slug: 'old',
+      label: 'Old',
+      timeRange: [0, 20],
+      useBest: false,
+    };
+    const replacement: TravelTimeEntry = {
+      mode: 'car',
+      slug: 'new',
+      label: 'New',
+      timeRange: [5, 30],
+      useBest: false,
+    };
+    const { result } = renderHook(() => useTravelTime({ entries: [initial] }));
+
+    act(() => result.current.handleSetEntries([replacement]));
+
+    expect(result.current.entries).toEqual([replacement]);
+    expect(result.current.activeEntries).toEqual([replacement]);
+  });
+});