fix: trim whitespace in search filters to prevent API 400 errors

frontend/common/utils/__tests__/featureFilterParams.test.ts

@@ -8,6 +8,7 @@ import {
   buildApiFilterParams,
   getFiltersFromParams,
   hasActiveFilters,
+  normaliseFilters,
 } from 'common/utils/featureFilterParams'
 import { SortOrder } from 'common/types/requests'
 import { TagStrategy } from 'common/types/responses'
@@ -187,6 +188,24 @@ describe('featureFilterParams', () => {
     })
   })
 
+  describe('normaliseFilters', () => {
+    it.each`
+      field             | input               | expected
+      ${'search'}       | ${'   '}            | ${null}
+      ${'search'}       | ${''}               | ${null}
+      ${'search'}       | ${null}             | ${null}
+      ${'search'}       | ${'  hello  '}      | ${'hello'}
+      ${'value_search'} | ${'   '}            | ${null}
+      ${'value_search'} | ${'  test value  '} | ${'test value'}
+    `(
+      'normalises $field "$input" to $expected',
+      ({ expected, field, input }) => {
+        const result = normaliseFilters({ [field]: input })
+        expect(result[field as keyof typeof result]).toBe(expected)
+      },
+    )
+  })
+
   describe('hasActiveFilters', () => {
     it('returns false for default filters', () => {
       expect(hasActiveFilters(createDefaultFilters())).toBe(false)

frontend/common/utils/featureFilterParams.ts

@@ -67,6 +67,20 @@ function parsePageNumber(value: string | string[] | undefined): number {
   return 1
 }
 
+/** Normalises filter updates by trimming string fields to prevent whitespace-only API requests. */
+export function normaliseFilters(
+  filters: Partial<FilterState>,
+): Partial<FilterState> {
+  const result = { ...filters }
+  if ('search' in result) {
+    result.search = result.search?.trim() || null
+  }
+  if ('value_search' in result) {
+    result.value_search = result.value_search?.trim() || null
+  }
+  return result
+}
+
 /** Check if any filters are currently active. */
 export function hasActiveFilters(filters: FilterState): boolean {
   return !!(

frontend/web/components/pages/features/hooks/useFeatureFilters.ts

@@ -5,7 +5,9 @@ import {
   hasActiveFilters,
   buildUrlParams,
   getFiltersFromParams,
+  normaliseFilters,
 } from 'common/utils/featureFilterParams'
+import { isEqual } from 'lodash'
 import Utils from 'common/utils/utils'
 
 /**
@@ -43,7 +45,12 @@ export function useFeatureFilters(history: History): {
   }, [updateURLParams])
 
   const handleFilterChange = (updates: Partial<FilterState>) => {
-    setFilters((prev) => ({ ...prev, ...updates }))
+    const normalised = normaliseFilters(updates)
+    setFilters((prev) => {
+      const next = { ...prev, ...normalised }
+      if (isEqual(prev, next)) return prev
+      return next
+    })
     setPage(1)
   }