diff --git a/README.md b/README.md
index e18e6209..83c3b5fb 100644
--- a/README.md
+++ b/README.md
@@ -18,9 +18,9 @@ Be kind. Be clear. Assume good intent. Keep feedback constructive.
 - 👤 **Creator:** [Gilles Romer](https://romerg.de/)
 - ✉️ **Contact:** [info@romerg.de](mailto:info@romerg.de)
 
-![Version](https://img.shields.io/badge/version-v1.27.3-e3000b?style=flat-square) ![Dark Theme](https://img.shields.io/badge/theme-dark-1a1a2e?style=flat-square) ![TCGdex](https://img.shields.io/badge/card%20data-TCGdex-e3000b?style=flat-square) ![Docker](https://img.shields.io/badge/deploy-Docker-2496ed?style=flat-square) ![FastAPI](https://img.shields.io/badge/backend-FastAPI-009688?style=flat-square) ![React](https://img.shields.io/badge/frontend-React%2018-61dafb?style=flat-square) [![Ko-fi](https://img.shields.io/badge/support-Ko--fi-ff5e5b?style=flat-square&logo=ko-fi&logoColor=white)](https://ko-fi.com/gillesromer)
+![Version](https://img.shields.io/badge/version-v1.27.4-e3000b?style=flat-square) ![Dark Theme](https://img.shields.io/badge/theme-dark-1a1a2e?style=flat-square) ![TCGdex](https://img.shields.io/badge/card%20data-TCGdex-e3000b?style=flat-square) ![Docker](https://img.shields.io/badge/deploy-Docker-2496ed?style=flat-square) ![FastAPI](https://img.shields.io/badge/backend-FastAPI-009688?style=flat-square) ![React](https://img.shields.io/badge/frontend-React%2018-61dafb?style=flat-square) [![Ko-fi](https://img.shields.io/badge/support-Ko--fi-ff5e5b?style=flat-square&logo=ko-fi&logoColor=white)](https://ko-fi.com/gillesromer)
 
-**Current version:** `v1.27.3` · Releases are tracked on the [GitHub Releases page](https://github.com/Git-Romer/pokecollector/releases).
+**Current version:** `v1.27.4` · Releases are tracked on the [GitHub Releases page](https://github.com/Git-Romer/pokecollector/releases).
 
 ![WebApp Preview](preview-homescreen.png)
 
diff --git a/VERSION b/VERSION
index 3bae5204..d6201580 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-1.27.3
+1.27.4
diff --git a/frontend/package-lock.json b/frontend/package-lock.json
index 08fc5f53..ae58e99d 100644
--- a/frontend/package-lock.json
+++ b/frontend/package-lock.json
@@ -1,12 +1,12 @@
 {
   "name": "pokemon-tcg-collection",
-  "version": "1.27.3",
+  "version": "1.27.4",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "pokemon-tcg-collection",
-      "version": "1.27.3",
+      "version": "1.27.4",
       "dependencies": {
         "@tanstack/react-query": "^5.18.0",
         "axios": "^1.18.0",
diff --git a/frontend/package.json b/frontend/package.json
index b9406ece..80720a41 100644
--- a/frontend/package.json
+++ b/frontend/package.json
@@ -1,7 +1,7 @@
 {
   "name": "pokemon-tcg-collection",
   "private": true,
-  "version": "1.27.3",
+  "version": "1.27.4",
   "type": "module",
   "scripts": {
     "dev": "vite",
diff --git a/frontend/src/components/PokedexGenerationFilter.jsx b/frontend/src/components/PokedexGenerationFilter.jsx
new file mode 100644
index 00000000..2db66654
--- /dev/null
+++ b/frontend/src/components/PokedexGenerationFilter.jsx
@@ -0,0 +1,76 @@
+import clsx from 'clsx'
+
+export const POKEDEX_GENERATIONS = [
+  { id: 1, region: 'Kanto', range: '#001–151' },
+  { id: 2, region: 'Johto', range: '#152–251' },
+  { id: 3, region: 'Hoenn', range: '#252–386' },
+  { id: 4, region: 'Sinnoh', range: '#387–493' },
+  { id: 5, region: 'Unova', range: '#494–649' },
+  { id: 6, region: 'Kalos', range: '#650–721' },
+  { id: 7, region: 'Alola', range: '#722–809' },
+  { id: 8, region: 'Galar', range: '#810–905' },
+  { id: 9, region: 'Paldea', range: '#906–1025' },
+]
+
+export default function PokedexGenerationFilter({ generation, onSelectGeneration, t }) {
+  const label = t('pokedex.generationFilter')
+
+  return (
+    <>
+      <label className="block sm:hidden">
+        <span className="sr-only">{label}</span>
+        <select
+          value={generation ?? ''}
+          onChange={(event) => {
+            const value = event.target.value
+            onSelectGeneration(value ? Number(value) : null)
+          }}
+          className="select w-full"
+        >
+          <option value="">{t('pokedex.national')}</option>
+          {POKEDEX_GENERATIONS.map((item) => (
+            <option key={item.id} value={item.id}>
+              Gen {item.id} · {item.region} · {item.range}
+            </option>
+          ))}
+        </select>
+      </label>
+
+      <div
+        className="-mx-1 hidden gap-2 overflow-x-auto px-1 pb-1 sm:flex"
+        role="group"
+        aria-label={label}
+      >
+        <button
+          type="button"
+          onClick={() => onSelectGeneration(null)}
+          aria-pressed={!generation}
+          className={clsx(
+            'shrink-0 whitespace-nowrap rounded-full border px-3 py-1.5 text-xs font-bold',
+            !generation
+              ? 'border-brand-red bg-brand-red/20 text-brand-red'
+              : 'border-border text-text-secondary'
+          )}
+        >
+          {t('pokedex.national')}
+        </button>
+        {POKEDEX_GENERATIONS.map((item) => (
+          <button
+            type="button"
+            key={item.id}
+            onClick={() => onSelectGeneration(item.id)}
+            aria-pressed={generation === item.id}
+            className={clsx(
+              'shrink-0 whitespace-nowrap rounded-full border px-3 py-1.5 text-xs font-bold',
+              generation === item.id
+                ? 'border-brand-red bg-brand-red/20 text-brand-red'
+                : 'border-border text-text-secondary'
+            )}
+          >
+            Gen {item.id} · {item.region}
+          </button>
+        ))}
+      </div>
+    </>
+  )
+}
diff --git a/frontend/src/components/PokedexGenerationFilter.test.js b/frontend/src/components/PokedexGenerationFilter.test.js
new file mode 100644
index 00000000..d223ed6e
--- /dev/null
+++ b/frontend/src/components/PokedexGenerationFilter.test.js
@@ -0,0 +1,53 @@
+import { createElement } from 'react'
+import { renderToStaticMarkup } from 'react-dom/server'
+import { describe, expect, it, vi } from 'vitest'
+import PokedexGenerationFilter from './PokedexGenerationFilter'
+
+const translations = {
+  'pokedex.generationFilter': 'Pokédex region',
+  'pokedex.national': 'National',
+}
+const t = key => translations[key] || key
+
+describe('PokedexGenerationFilter', () => {
+  it('renders a labelled mobile select and a non-shrinking desktop control', () => {
+    const markup = renderToStaticMarkup(createElement(PokedexGenerationFilter, {
+      generation: 3,
+      onSelectGeneration: vi.fn(),
+      t,
+    }))
+
+    expect(markup).toContain('<label class="block sm:hidden">')
+    expect(markup).toContain('<span class="sr-only">Pokédex region</span>')
+    expect(markup).toContain('<select class="select w-full">')
+    expect((markup.match(/aria-label="Pokédex region"/g) || [])).toHaveLength(1)
+    expect(markup).toContain('class="-mx-1 hidden gap-2 overflow-x-auto px-1 pb-1 sm:flex"')
+    expect(markup).toContain('role="group"')
+    expect(markup).toContain('aria-label="Pokédex region"')
+    expect(markup).toContain('shrink-0 whitespace-nowrap')
+  })
+
+  it('exposes all generations and the selected desktop state', () => {
+    const markup = renderToStaticMarkup(createElement(PokedexGenerationFilter, {
+      generation: 2,
+      onSelectGeneration: vi.fn(),
+      t,
+    }))
+
+    expect((markup.match(/<option/g) || [])).toHaveLength(10)
+    expect(markup).toContain('<option value="2" selected="">Gen 2 · Johto · #152–251</option>')
+    expect(markup).toContain('aria-pressed="true"')
+    expect(markup).toContain('Gen 2 · Johto')
+  })
+
+  it('selects National consistently when no generation is active', () => {
+    const markup = renderToStaticMarkup(createElement(PokedexGenerationFilter, {
+      generation: null,
+      onSelectGeneration: vi.fn(),
+      t,
+    }))
+
+    expect(markup).toContain('<option value="" selected="">National</option>')
+    expect(markup).toContain('<button type="button" aria-pressed="true"')
+  })
+})
diff --git a/frontend/src/i18n/de.js b/frontend/src/i18n/de.js
index 3280c946..557e170b 100644
--- a/frontend/src/i18n/de.js
+++ b/frontend/src/i18n/de.js
@@ -26,6 +26,7 @@ const de = {
     subtitle: 'Eine beliebige passende Karte vervollständigt das Pokémon.',
     searchPlaceholder: 'Name oder Pokédex-Nummer',
     national: 'National',
+    generationFilter: 'Pokédex-Region',
     generation: 'Gen {generation}',
     all: 'Alle',
     owned: 'Vorhanden',
diff --git a/frontend/src/i18n/en.js b/frontend/src/i18n/en.js
index 3f600e0e..5839d6ec 100644
--- a/frontend/src/i18n/en.js
+++ b/frontend/src/i18n/en.js
@@ -26,6 +26,7 @@ const en = {
     subtitle: 'Own any matching card to complete a species.',
     searchPlaceholder: 'Name or Pokédex number',
     national: 'National',
+    generationFilter: 'Pokédex region',
     generation: 'Gen {generation}',
     all: 'All',
     owned: 'Owned',
diff --git a/frontend/src/pages/Pokedex.jsx b/frontend/src/pages/Pokedex.jsx
index 45e32099..314a775d 100644
--- a/frontend/src/pages/Pokedex.jsx
+++ b/frontend/src/pages/Pokedex.jsx
@@ -1,4 +1,4 @@
-import { useMemo, useState } from 'react'
+import { useEffect, useMemo, useState } from 'react'
 import { useQuery } from '@tanstack/react-query'
 import { useLocation, useNavigate, useSearchParams } from 'react-router-dom'
 import { Check, Search } from 'lucide-react'
@@ -6,20 +6,13 @@ import clsx from 'clsx'
 import { getPokedex } from '../api/client'
 import { useSettings } from '../contexts/SettingsContext'
 import PokeBallLoader from '../components/PokeBallLoader'
+import PokedexGenerationFilter, { POKEDEX_GENERATIONS } from '../components/PokedexGenerationFilter'
 import { getSavedListScrollPosition, isSavedPositionForLocation, useListScrollRestoration } from '../hooks/useListScrollRestoration'
-import { getPokedexGeneration } from '../utils/pokedexUrlState'
-
-const GENERATIONS = [
-  { id: 1, region: 'Kanto', range: '#001–151' },
-  { id: 2, region: 'Johto', range: '#152–251' },
-  { id: 3, region: 'Hoenn', range: '#252–386' },
-  { id: 4, region: 'Sinnoh', range: '#387–493' },
-  { id: 5, region: 'Unova', range: '#494–649' },
-  { id: 6, region: 'Kalos', range: '#650–721' },
-  { id: 7, region: 'Alola', range: '#722–809' },
-  { id: 8, region: 'Galar', range: '#810–905' },
-  { id: 9, region: 'Paldea', range: '#906–1025' },
-]
+import {
+  getPokedexGeneration,
+  normalizePokedexSearchParams,
+  setPokedexGeneration,
+} from '../utils/pokedexUrlState'
 
 function SpeciesImage({ entry, name }) {
   const handleError = (event) => {
@@ -104,6 +97,13 @@ export default function Pokedex() {
   // Keep the URL as the source of truth so browser Back/Forward updates both
   // the active filter and the query without requiring the page to remount.
   const generation = getPokedexGeneration(searchParams)
+  const searchParamsKey = searchParams.toString()
+  useEffect(() => {
+    const normalized = normalizePokedexSearchParams(new URLSearchParams(searchParamsKey))
+    if (normalized.toString() !== searchParamsKey) {
+      setSearchParams(normalized, { replace: true })
+    }
+  }, [searchParamsKey, setSearchParams])
   // The list remounts after Back. Restore non-URL filters before its query runs
   // so the saved Pokémon anchor is present when scroll restoration occurs.
   const savedPosition = getSavedListScrollPosition('pokedex')
@@ -138,7 +138,7 @@ export default function Pokedex() {
   })
   const grouped = useMemo(() => {
     if (generation || search.trim()) return [{ generation, entries }]
-    return GENERATIONS.map((item) => ({
+    return POKEDEX_GENERATIONS.map((item) => ({
       generation: item.id,
       entries: entries.filter((entry) => entry.generation === item.id),
     })).filter((group) => group.entries.length)
@@ -146,10 +146,9 @@ export default function Pokedex() {
 
   const summary = data?.summary || { total: 0, owned: 0, missing: 0 }
   const progress = summary.total ? Math.round((summary.owned / summary.total) * 100) : 0
-  const scope = generation ? GENERATIONS.find((item) => item.id === generation) : null
+  const scope = generation ? POKEDEX_GENERATIONS.find((item) => item.id === generation) : null
   const selectGeneration = (value) => {
-    if (value) setSearchParams({ generation: String(value) })
-    else setSearchParams({})
+    setSearchParams(setPokedexGeneration(searchParams, value))
   }
 
   return (
@@ -187,25 +186,11 @@ export default function Pokedex() {
           />
         </label>
 
-        <div className="-mx-1 flex gap-2 overflow-x-auto px-1 pb-1">
-          <button
-            type="button"
-            onClick={() => selectGeneration(null)}
-            className={clsx('whitespace-nowrap rounded-full border px-3 py-1.5 text-xs font-bold', !generation ? 'border-brand-red bg-brand-red/20 text-brand-red' : 'border-border text-text-secondary')}
-          >
-            {t('pokedex.national')}
-          </button>
-          {GENERATIONS.map((item) => (
-            <button
-              type="button"
-              key={item.id}
-              onClick={() => selectGeneration(item.id)}
-              className={clsx('whitespace-nowrap rounded-full border px-3 py-1.5 text-xs font-bold', generation === item.id ? 'border-brand-red bg-brand-red/20 text-brand-red' : 'border-border text-text-secondary')}
-            >
-              Gen {item.id} · {item.region}
-            </button>
-          ))}
-        </div>
+        <PokedexGenerationFilter
+          generation={generation}
+          onSelectGeneration={selectGeneration}
+          t={t}
+        />
 
         <div className="flex gap-2" role="group" aria-label="Ownership filter">
           {['all', 'owned', 'missing'].map((value) => (
@@ -226,7 +211,7 @@ export default function Pokedex() {
       {!isLoading && !isError && entries.length === 0 && <p className="py-12 text-center text-text-muted">{t('common.noResults')}</p>}
 
       {!isLoading && grouped.map((group) => {
-        const info = GENERATIONS.find((item) => item.id === group.generation)
+        const info = POKEDEX_GENERATIONS.find((item) => item.id === group.generation)
         return (
           <section key={group.generation || 'results'} className="space-y-3">
             {!generation && !search.trim() && info && (
diff --git a/frontend/src/utils/pokedexUrlState.js b/frontend/src/utils/pokedexUrlState.js
index 53c17524..26555d43 100644
--- a/frontend/src/utils/pokedexUrlState.js
+++ b/frontend/src/utils/pokedexUrlState.js
@@ -4,3 +4,25 @@ export const getPokedexGeneration = (searchParams) => {
     ? requestedGeneration
     : null
 }
+
+export const normalizePokedexSearchParams = (searchParams) => {
+  const normalized = new URLSearchParams(searchParams)
+  const requestedGenerations = normalized.getAll('generation')
+  if (!requestedGenerations.length) return normalized
+
+  const generation = getPokedexGeneration(normalized)
+  if (generation) normalized.set('generation', String(generation))
+  else normalized.delete('generation')
+
+  return normalized
+}
+
+export const setPokedexGeneration = (searchParams, generation) => {
+  const updated = new URLSearchParams(searchParams)
+  if (Number.isInteger(generation) && generation >= 1 && generation <= 9) {
+    updated.set('generation', String(generation))
+  } else {
+    updated.delete('generation')
+  }
+  return updated
+}
diff --git a/frontend/src/utils/pokedexUrlState.test.js b/frontend/src/utils/pokedexUrlState.test.js
index cd36d874..eaeb401e 100644
--- a/frontend/src/utils/pokedexUrlState.test.js
+++ b/frontend/src/utils/pokedexUrlState.test.js
@@ -1,5 +1,9 @@
 import { describe, expect, it } from 'vitest'
-import { getPokedexGeneration } from './pokedexUrlState'
+import {
+  getPokedexGeneration,
+  normalizePokedexSearchParams,
+  setPokedexGeneration,
+} from './pokedexUrlState'
 
 describe('Pokédex URL state', () => {
   it('follows generation changes from browser history', () => {
@@ -17,4 +21,25 @@ describe('Pokédex URL state', () => {
     expect(getPokedexGeneration(new URLSearchParams('generation=10'))).toBeNull()
     expect(getPokedexGeneration(new URLSearchParams('generation=2x'))).toBeNull()
   })
+
+  it('normalizes malformed and duplicate generation parameters without removing unrelated state', () => {
+    expect(normalizePokedexSearchParams(
+      new URLSearchParams('generation=invalid&status=owned')
+    ).toString()).toBe('status=owned')
+    expect(normalizePokedexSearchParams(
+      new URLSearchParams('generation=02&generation=3&status=owned')
+    ).toString()).toBe('generation=2&status=owned')
+  })
+
+  it('writes valid generation changes and preserves unrelated search parameters', () => {
+    const initial = new URLSearchParams('status=owned&search=pika')
+
+    const johto = setPokedexGeneration(initial, 2)
+    expect(johto.toString()).toBe('status=owned&search=pika&generation=2')
+    expect(getPokedexGeneration(johto)).toBe(2)
+
+    const national = setPokedexGeneration(johto, null)
+    expect(national.toString()).toBe('status=owned&search=pika')
+    expect(getPokedexGeneration(national)).toBeNull()
+  })
 })