diff --git a/web/src/app/home/components/models-dialog/ModelsDialog.tsx b/web/src/app/home/components/models-dialog/ModelsDialog.tsx
index be9d3367..d1c3e47e 100644
--- a/web/src/app/home/components/models-dialog/ModelsDialog.tsx
+++ b/web/src/app/home/components/models-dialog/ModelsDialog.tsx
@@ -29,15 +29,36 @@ interface ModelsDialogProps {
   onOpenChange: (open: boolean) => void;
 }
 
+type ExtraArgValue = string | number | boolean | Record<string, unknown>;
+
 function convertExtraArgsToObject(
   args: ExtraArg[],
-): Record<string, string | number | boolean> {
-  const obj: Record<string, string | number | boolean> = {};
+): Record<string, ExtraArgValue> {
+  const obj: Record<string, ExtraArgValue> = {};
   args.forEach((arg) => {
-    if (arg.key.trim()) {
-      if (arg.type === 'number') obj[arg.key] = Number(arg.value);
-      else if (arg.type === 'boolean') obj[arg.key] = arg.value === 'true';
-      else obj[arg.key] = arg.value;
+    if (!arg.key.trim()) return;
+    if (arg.type === 'number') {
+      obj[arg.key] = Number(arg.value);
+    } else if (arg.type === 'boolean') {
+      obj[arg.key] = arg.value === 'true';
+    } else if (arg.type === 'object') {
+      const raw = arg.value.trim() || '{}';
+      let parsed: unknown;
+      try {
+        parsed = JSON.parse(raw);
+      } catch {
+        throw new Error(`Invalid JSON for extra parameter "${arg.key}"`);
+      }
+      if (
+        parsed === null ||
+        typeof parsed !== 'object' ||
+        Array.isArray(parsed)
+      ) {
+        throw new Error(`Extra parameter "${arg.key}" must be a JSON object`);
+      }
+      obj[arg.key] = parsed as Record<string, unknown>;
+    } else {
+      obj[arg.key] = arg.value;
     }
   });
   return obj;
diff --git a/web/src/app/home/components/models-dialog/components/AddModelPopover.tsx b/web/src/app/home/components/models-dialog/components/AddModelPopover.tsx
index b4e3913c..c9dab2cd 100644
--- a/web/src/app/home/components/models-dialog/components/AddModelPopover.tsx
+++ b/web/src/app/home/components/models-dialog/components/AddModelPopover.tsx
@@ -258,11 +258,16 @@ export default function AddModelPopover({
         </Button>
       </PopoverTrigger>
       <PopoverContent
-        className="w-[min(24rem,calc(100vw-2rem))] max-h-[calc(100vh-8rem)] overflow-y-auto"
+        className="w-[min(24rem,calc(100vw-2rem))] max-h-[70vh] overflow-y-auto overscroll-none focus:outline-none focus-visible:outline-none focus-visible:ring-0"
+        style={{
+          maxHeight: 'min(70vh, var(--radix-popover-content-available-height))',
+        }}
         align="end"
         side="left"
         sideOffset={8}
         collisionPadding={16}
+        onWheel={(e) => e.stopPropagation()}
+        onTouchMove={(e) => e.stopPropagation()}
         onClick={(e) => e.stopPropagation()}
       >
         <Tabs value={tab} onValueChange={(v) => setTab(v as ModelType)}>
@@ -437,7 +442,7 @@ export default function AddModelPopover({
               </div>
 
               <div
-                className="h-64 overflow-y-auto overscroll-contain rounded-md border"
+                className="h-64 overflow-y-auto overscroll-none rounded-md border"
                 onWheel={(e) => e.stopPropagation()}
               >
                 <div className="p-3 space-y-2">
diff --git a/web/src/app/home/components/models-dialog/components/ExtraArgsEditor.tsx b/web/src/app/home/components/models-dialog/components/ExtraArgsEditor.tsx
index 72a10c1f..86dc8e46 100644
--- a/web/src/app/home/components/models-dialog/components/ExtraArgsEditor.tsx
+++ b/web/src/app/home/components/models-dialog/components/ExtraArgsEditor.tsx
@@ -1,6 +1,7 @@
 import { Plus, X, HelpCircle } from 'lucide-react';
 import { Button } from '@/components/ui/button';
 import { Input } from '@/components/ui/input';
+import { Textarea } from '@/components/ui/textarea';
 import { Label } from '@/components/ui/label';
 import {
   Select,
@@ -47,9 +48,30 @@ export default function ExtraArgsEditor({
   ) => {
     const newArgs = [...args];
     newArgs[index] = { ...newArgs[index], [field]: value };
+    // When switching to object type, seed an empty JSON object so the textarea
+    // doesn't start with an unparseable empty string.
+    if (
+      field === 'type' &&
+      value === 'object' &&
+      !newArgs[index].value.trim()
+    ) {
+      newArgs[index].value = '{}';
+    }
     onChange(newArgs);
   };
 
+  const isInvalidJson = (raw: string) => {
+    if (!raw.trim()) return false;
+    try {
+      const parsed = JSON.parse(raw);
+      return (
+        parsed === null || typeof parsed !== 'object' || Array.isArray(parsed)
+      );
+    } catch {
+      return true;
+    }
+  };
+
   return (
     <div className="space-y-2">
       <div className="flex items-center justify-between">
@@ -90,49 +112,79 @@ export default function ExtraArgsEditor({
       {args.length === 0 ? (
         <p className="text-sm text-muted-foreground">{t('common.none')}</p>
       ) : (
-        args.map((arg, index) => (
-          <div key={index} className="flex gap-2 items-center">
-            <Input
-              placeholder={t('models.keyName')}
-              value={arg.key}
-              className="flex-1"
-              disabled={disabled}
-              onChange={(e) => handleUpdate(index, 'key', e.target.value)}
-            />
-            <Select
-              value={arg.type}
-              disabled={disabled}
-              onValueChange={(value) => handleUpdate(index, 'type', value)}
-            >
-              <SelectTrigger className="w-24">
-                <SelectValue />
-              </SelectTrigger>
-              <SelectContent>
-                <SelectItem value="string">{t('models.string')}</SelectItem>
-                <SelectItem value="number">{t('models.number')}</SelectItem>
-                <SelectItem value="boolean">{t('models.boolean')}</SelectItem>
-              </SelectContent>
-            </Select>
-            <Input
-              placeholder={t('models.value')}
-              value={arg.value}
-              className="flex-1"
-              disabled={disabled}
-              onChange={(e) => handleUpdate(index, 'value', e.target.value)}
-            />
-            {!disabled && (
-              <Button
-                type="button"
-                variant="ghost"
-                size="icon"
-                className="h-8 w-8 flex-shrink-0"
-                onClick={() => handleRemove(index)}
-              >
-                <X className="h-4 w-4" />
-              </Button>
-            )}
-          </div>
-        ))
+        args.map((arg, index) => {
+          const isObject = arg.type === 'object';
+          const jsonError = isObject && isInvalidJson(arg.value);
+          return (
+            <div key={index} className="space-y-1">
+              <div className="flex gap-2 items-start">
+                <Input
+                  placeholder={t('models.keyName')}
+                  value={arg.key}
+                  className={isObject ? 'flex-[2]' : 'flex-1'}
+                  disabled={disabled}
+                  onChange={(e) => handleUpdate(index, 'key', e.target.value)}
+                />
+                <Select
+                  value={arg.type}
+                  disabled={disabled}
+                  onValueChange={(value) => handleUpdate(index, 'type', value)}
+                >
+                  <SelectTrigger className="w-24">
+                    <SelectValue />
+                  </SelectTrigger>
+                  <SelectContent>
+                    <SelectItem value="string">{t('models.string')}</SelectItem>
+                    <SelectItem value="number">{t('models.number')}</SelectItem>
+                    <SelectItem value="boolean">
+                      {t('models.boolean')}
+                    </SelectItem>
+                    <SelectItem value="object">{t('models.object')}</SelectItem>
+                  </SelectContent>
+                </Select>
+                {!isObject && (
+                  <Input
+                    placeholder={t('models.value')}
+                    value={arg.value}
+                    className="flex-1"
+                    disabled={disabled}
+                    onChange={(e) =>
+                      handleUpdate(index, 'value', e.target.value)
+                    }
+                  />
+                )}
+                {!disabled && (
+                  <Button
+                    type="button"
+                    variant="ghost"
+                    size="icon"
+                    className="h-8 w-8 flex-shrink-0"
+                    onClick={() => handleRemove(index)}
+                  >
+                    <X className="h-4 w-4" />
+                  </Button>
+                )}
+              </div>
+              {isObject && (
+                <Textarea
+                  placeholder={t('models.objectJsonPlaceholder')}
+                  value={arg.value}
+                  className={`w-full font-mono text-xs min-h-[96px] resize-y ${
+                    jsonError ? 'border-destructive' : ''
+                  }`}
+                  disabled={disabled}
+                  spellCheck={false}
+                  onChange={(e) => handleUpdate(index, 'value', e.target.value)}
+                />
+              )}
+              {jsonError && (
+                <p className="text-xs text-destructive pl-1">
+                  {t('models.invalidJsonObject')}
+                </p>
+              )}
+            </div>
+          );
+        })
       )}
     </div>
   );
diff --git a/web/src/app/home/components/models-dialog/components/ModelItem.tsx b/web/src/app/home/components/models-dialog/components/ModelItem.tsx
index 88a37ed2..8c35bdd8 100644
--- a/web/src/app/home/components/models-dialog/components/ModelItem.tsx
+++ b/web/src/app/home/components/models-dialog/components/ModelItem.tsx
@@ -46,10 +46,25 @@ interface ModelItemProps {
 function convertExtraArgsToArray(extraArgs?: object): ExtraArg[] {
   if (!extraArgs) return [];
   return Object.entries(extraArgs).map(([key, value]) => {
-    let type: 'string' | 'number' | 'boolean' = 'string';
-    if (typeof value === 'number') type = 'number';
-    else if (typeof value === 'boolean') type = 'boolean';
-    return { key, type, value: String(value) };
+    let type: ExtraArg['type'] = 'string';
+    let stringValue: string;
+    if (typeof value === 'number') {
+      type = 'number';
+      stringValue = String(value);
+    } else if (typeof value === 'boolean') {
+      type = 'boolean';
+      stringValue = String(value);
+    } else if (
+      value !== null &&
+      typeof value === 'object' &&
+      !Array.isArray(value)
+    ) {
+      type = 'object';
+      stringValue = JSON.stringify(value, null, 2);
+    } else {
+      stringValue = String(value);
+    }
+    return { key, type, value: stringValue };
   });
 }
 
@@ -209,7 +224,16 @@ export default function ModelItem({
           )}
         </div>
       </PopoverTrigger>
-      <PopoverContent className="w-80" align="start">
+      <PopoverContent
+        className="w-80 max-h-[70vh] overflow-y-auto overscroll-none focus:outline-none focus-visible:outline-none focus-visible:ring-0"
+        align="start"
+        collisionPadding={16}
+        style={{
+          maxHeight: 'min(70vh, var(--radix-popover-content-available-height))',
+        }}
+        onWheel={(e) => e.stopPropagation()}
+        onTouchMove={(e) => e.stopPropagation()}
+      >
         <div className="space-y-3">
           <div className="space-y-2">
             <Label>{t('models.modelName')}</Label>
diff --git a/web/src/app/home/components/models-dialog/types.ts b/web/src/app/home/components/models-dialog/types.ts
index 271f5462..1fa6d784 100644
--- a/web/src/app/home/components/models-dialog/types.ts
+++ b/web/src/app/home/components/models-dialog/types.ts
@@ -9,7 +9,8 @@ import {
 
 export type ExtraArg = {
   key: string;
-  type: 'string' | 'number' | 'boolean';
+  type: 'string' | 'number' | 'boolean' | 'object';
+  // For 'object' type, value holds a JSON string that will be parsed on save.
   value: string;
 };
 
diff --git a/web/src/i18n/locales/en-US.ts b/web/src/i18n/locales/en-US.ts
index b82ba13b..082f8d8f 100644
--- a/web/src/i18n/locales/en-US.ts
+++ b/web/src/i18n/locales/en-US.ts
@@ -200,6 +200,9 @@ const enUS = {
     string: 'String',
     number: 'Number',
     boolean: 'Boolean',
+    object: 'Object',
+    objectJsonPlaceholder: '{ "type": "disabled" }',
+    invalidJsonObject: 'Value must be a valid JSON object',
     selectModelProvider: 'Select Model Provider',
     modelProviderDescription:
       'Please fill in the model name provided by the provider',
diff --git a/web/src/i18n/locales/es-ES.ts b/web/src/i18n/locales/es-ES.ts
index bece13a5..39c45b72 100644
--- a/web/src/i18n/locales/es-ES.ts
+++ b/web/src/i18n/locales/es-ES.ts
@@ -205,6 +205,9 @@ const esES = {
     string: 'Cadena',
     number: 'Número',
     boolean: 'Booleano',
+    object: 'Objeto',
+    objectJsonPlaceholder: '{ "type": "disabled" }',
+    invalidJsonObject: 'El valor debe ser un objeto JSON válido',
     selectModelProvider: 'Seleccionar proveedor del modelo',
     modelProviderDescription:
       'Por favor, introduce el nombre del modelo proporcionado por el proveedor',
diff --git a/web/src/i18n/locales/ja-JP.ts b/web/src/i18n/locales/ja-JP.ts
index 4bebb1f0..54c9e5d5 100644
--- a/web/src/i18n/locales/ja-JP.ts
+++ b/web/src/i18n/locales/ja-JP.ts
@@ -203,6 +203,9 @@
     string: '文字列',
     number: '数値',
     boolean: 'ブール値',
+    object: 'オブジェクト',
+    objectJsonPlaceholder: '{ "type": "disabled" }',
+    invalidJsonObject: '値は有効なJSONオブジェクトである必要があります',
     selectModelProvider: 'モデルプロバイダーを選択',
     modelProviderDescription: 'プロバイダーが提供するモデル名をご入力ください',
     modelManufacturer: 'モデルメーカー',
diff --git a/web/src/i18n/locales/ru-RU.ts b/web/src/i18n/locales/ru-RU.ts
index 21421d73..e8e34b29 100644
--- a/web/src/i18n/locales/ru-RU.ts
+++ b/web/src/i18n/locales/ru-RU.ts
@@ -202,6 +202,9 @@ const ruRU = {
     string: 'Строка',
     number: 'Число',
     boolean: 'Логический',
+    object: 'Объект',
+    objectJsonPlaceholder: '{ "type": "disabled" }',
+    invalidJsonObject: 'Значение должно быть допустимым объектом JSON',
     selectModelProvider: 'Выберите провайдера модели',
     modelProviderDescription:
       'Пожалуйста, введите название модели, предоставленное провайдером',
diff --git a/web/src/i18n/locales/th-TH.ts b/web/src/i18n/locales/th-TH.ts
index ad631957..ff1c3799 100644
--- a/web/src/i18n/locales/th-TH.ts
+++ b/web/src/i18n/locales/th-TH.ts
@@ -198,6 +198,9 @@ const thTH = {
     string: 'สตริง',
     number: 'ตัวเลข',
     boolean: 'บูลีน',
+    object: 'อ็อบเจกต์',
+    objectJsonPlaceholder: '{ "type": "disabled" }',
+    invalidJsonObject: 'ค่าต้องเป็นอ็อบเจกต์ JSON ที่ถูกต้อง',
     selectModelProvider: 'เลือกผู้ให้บริการโมเดล',
     modelProviderDescription: 'กรุณากรอกชื่อโมเดลที่ผู้ให้บริการจัดเตรียมไว้',
     modelManufacturer: 'ผู้ผลิตโมเดล',
diff --git a/web/src/i18n/locales/vi-VN.ts b/web/src/i18n/locales/vi-VN.ts
index 559d88a4..601ddb55 100644
--- a/web/src/i18n/locales/vi-VN.ts
+++ b/web/src/i18n/locales/vi-VN.ts
@@ -202,6 +202,9 @@ const viVN = {
     string: 'Chuỗi',
     number: 'Số',
     boolean: 'Boolean',
+    object: 'Đối tượng',
+    objectJsonPlaceholder: '{ "type": "disabled" }',
+    invalidJsonObject: 'Giá trị phải là một đối tượng JSON hợp lệ',
     selectModelProvider: 'Chọn nhà cung cấp mô hình',
     modelProviderDescription:
       'Vui lòng điền tên mô hình do nhà cung cấp cung cấp',
diff --git a/web/src/i18n/locales/zh-Hans.ts b/web/src/i18n/locales/zh-Hans.ts
index 688dfe89..93b673ed 100644
--- a/web/src/i18n/locales/zh-Hans.ts
+++ b/web/src/i18n/locales/zh-Hans.ts
@@ -192,6 +192,9 @@ const zhHans = {
     string: '字符串',
     number: '数字',
     boolean: '布尔值',
+    object: '对象',
+    objectJsonPlaceholder: '{ "type": "disabled" }',
+    invalidJsonObject: '值必须是有效的 JSON 对象',
     selectModelProvider: '选择模型供应商',
     modelProviderDescription: '请填写供应商向您提供的模型名称',
     modelManufacturer: '模型厂商',
diff --git a/web/src/i18n/locales/zh-Hant.ts b/web/src/i18n/locales/zh-Hant.ts
index d7736799..fd56f406 100644
--- a/web/src/i18n/locales/zh-Hant.ts
+++ b/web/src/i18n/locales/zh-Hant.ts
@@ -192,6 +192,9 @@ const zhHant = {
     string: '字串',
     number: '數字',
     boolean: '布林值',
+    object: '物件',
+    objectJsonPlaceholder: '{ "type": "disabled" }',
+    invalidJsonObject: '值必須是有效的 JSON 物件',
     selectModelProvider: '選擇模型供應商',
     modelProviderDescription: '請填寫供應商向您提供的模型名稱',
     modelManufacturer: '模型廠商',