diff --git a/app/Http/Controllers/Admin/PageVisitController.php b/app/Http/Controllers/Admin/PageVisitController.php
index 715984c..b9bc49b 100644
--- a/app/Http/Controllers/Admin/PageVisitController.php
+++ b/app/Http/Controllers/Admin/PageVisitController.php
@@ -114,8 +114,9 @@ class PageVisitController extends Controller
             $q->where('channel_id', 'like', '%'.$channelId.'%');
         }
 
-        if ($request->query->has('chain') && $request->query('chain') !== '') {
-            $q->where('chain', (int) $request->query('chain'));
+        $chain = $this->parseChainFilter($request->query('chain'));
+        if ($chain !== null) {
+            $q->where('chain', $chain);
         }
 
         $os = trim((string) $request->query('os', ''));
@@ -149,6 +150,26 @@ class PageVisitController extends Controller
         return $q;
     }
 
+    /** Empty / missing / all = no chain filter. */
+    private function parseChainFilter(mixed $raw): ?int
+    {
+        if ($raw === null) {
+            return null;
+        }
+        $value = is_string($raw) ? strtolower(trim($raw)) : $raw;
+        if ($value === '' || $value === 'all' || $value === []) {
+            return null;
+        }
+        if ($value === 0 || $value === '0' || $value === 'coruna') {
+            return PageVisit::CHAIN_CORUNA;
+        }
+        if ($value === 1 || $value === '1' || $value === 'darksword' || $value === 'ds') {
+            return PageVisit::CHAIN_DARKSWORD;
+        }
+
+        return null;
+    }
+
     /**
      * @return array{0: Carbon, 1: Carbon}
      */
diff --git a/resources/views/admin/visits/index.blade.php b/resources/views/admin/visits/index.blade.php
index 15e5f42..639d3dd 100644
--- a/resources/views/admin/visits/index.blade.php
+++ b/resources/views/admin/visits/index.blade.php
@@ -23,9 +23,9 @@
         <label class="layui-form-label">利用链</label>
         <div class="layui-input-block">
           <select name="chain">
-            <option value="">全部</option>
-            <option value="0">Coruna</option>
-            <option value="1">DarkSword</option>
+            <option value="all" selected>全部</option>
+            <option value="coruna">Coruna</option>
+            <option value="darksword">DarkSword</option>
           </select>
         </div>
       </div>
@@ -144,7 +144,11 @@ layui.use(['table', 'form', 'layer'], function () {
   });
 
   form.on('submit(LAY-visit-search)', function (data) {
-    where = data.field;
+    var field = data.field || {};
+    if (!field.chain || field.chain === 'all') {
+      delete field.chain;
+    }
+    where = field;
     table.reload('LAY-visit-list', { where: where, page: { curr: 1 } });
     return false;
   });
diff --git a/tests/Feature/PageVisitTest.php b/tests/Feature/PageVisitTest.php
index 3c24a0e..914e366 100644
--- a/tests/Feature/PageVisitTest.php
+++ b/tests/Feature/PageVisitTest.php
@@ -281,6 +281,48 @@ class PageVisitTest extends TestCase
             ->assertJsonPath('data.0.client_uid', '50624FE26CC4A0DF689EAEA117557C3E');
     }
 
+    #[Test]
+    public function visits_data_does_not_filter_chain_until_explicitly_chosen(): void
+    {
+        PageVisit::query()->create([
+            'channel_id' => self::CHANNEL,
+            'client_uid' => 'aaaaaaaaaaaaaaaa',
+            'chain' => PageVisit::CHAIN_CORUNA,
+            'os' => 'iOS',
+            'created_at' => now(),
+        ]);
+        PageVisit::query()->create([
+            'channel_id' => self::CHANNEL,
+            'client_uid' => '50624FE26CC4A0DF689EAEA117557C3E',
+            'chain' => PageVisit::CHAIN_DARKSWORD,
+            'os' => 'iOS',
+            'created_at' => now(),
+        ]);
+
+        $admin = Admin::query()->create(['username' => 'admin', 'password' => 'admin123']);
+        $this->actingAs($admin, 'admin');
+
+        foreach (['', 'all'] as $chain) {
+            $this->getJson(route('admin.visits.data', ['range' => 'today', 'chain' => $chain]))
+                ->assertOk()
+                ->assertJsonPath('count', 2);
+        }
+
+        $this->getJson(route('admin.visits.data', ['range' => 'today']))
+            ->assertOk()
+            ->assertJsonPath('count', 2);
+
+        $this->getJson(route('admin.visits.data', ['range' => 'today', 'chain' => 'coruna']))
+            ->assertOk()
+            ->assertJsonPath('count', 1)
+            ->assertJsonPath('data.0.chain', 0);
+
+        $this->getJson(route('admin.visits.data', ['range' => 'today', 'chain' => 'darksword']))
+            ->assertOk()
+            ->assertJsonPath('count', 1)
+            ->assertJsonPath('data.0.chain', 1);
+    }
+
     #[Test]
     public function visits_logs_returns_ds_stages(): void
     {