diff --git a/frontend/src/components/AccountAiSettings.tsx b/frontend/src/components/AccountAiSettings.tsx
index 00fa9e5..53dfd36 100644
--- a/frontend/src/components/AccountAiSettings.tsx
+++ b/frontend/src/components/AccountAiSettings.tsx
@@ -42,10 +42,17 @@ function parseConfigured(raw: Record<string, unknown> | undefined): Record<Provi
 }
 
 function pickModel(models: string[], current: string | undefined, fallback: string): string {
-  if (current && models.includes(current)) return current
+  const trimmed = current?.trim()
+  if (trimmed) return trimmed
   return models[0] ?? fallback
 }
 
+function mergeModelOptions(models: string[], current: string | undefined): string[] {
+  const trimmed = current?.trim()
+  if (!trimmed || models.includes(trimmed)) return models
+  return [trimmed, ...models]
+}
+
 export function AccountAiSettings({ accountId, compact }: AccountAiSettingsProps) {
   const [settings, setSettings] = useState<ThreadsAccountAiSettingsData | null>(null)
   const [keyInputs, setKeyInputs] = useState<ProviderApiKeys>({})
@@ -87,14 +94,11 @@ export function AccountAiSettings({ accountId, compact }: AccountAiSettingsProps
             const mainProvider = normalizeSupportedProvider(prev.provider)
             const researchProv = normalizeSupportedProvider(prev.research_provider ?? mainProvider)
             let next = prev
-            if (providerId === mainProvider && !models.includes(prev.model)) {
+            if (providerId === mainProvider && !prev.model?.trim()) {
               next = { ...next, model: models[0] }
             }
-            if (providerId === researchProv) {
-              const currentResearch = prev.research_model ?? ''
-              if (!currentResearch || !models.includes(currentResearch)) {
-                next = { ...next, research_model: models[0] }
-              }
+            if (providerId === researchProv && !prev.research_model?.trim()) {
+              next = { ...next, research_model: models[0] }
             }
             return next
           })
@@ -175,6 +179,8 @@ export function AccountAiSettings({ accountId, compact }: AccountAiSettingsProps
 
   const primaryModels = getModelsForProvider(provider)
   const researchModels = getModelsForProvider(researchProvider)
+  const primaryModelOptions = mergeModelOptions(primaryModels, settings?.model)
+  const researchModelOptions = mergeModelOptions(researchModels, settings?.research_model)
   const primaryModelsMeta = modelsMeta[provider]
   const researchModelsMeta = modelsMeta[researchProvider]
   const currentProviderConfigured = configured[provider]
@@ -288,18 +294,18 @@ export function AccountAiSettings({ accountId, compact }: AccountAiSettingsProps
               }
             >
               <Select
-                value={primaryModels.includes(settings.model) ? settings.model : ''}
-                disabled={primaryModelsMeta?.loading || primaryModels.length === 0}
+                value={settings.model?.trim() ?? ''}
+                disabled={primaryModelsMeta?.loading || primaryModelOptions.length === 0}
                 onChange={(e) =>
                   setSettings((prev) => (prev ? { ...prev, model: e.target.value } : prev))
                 }
               >
-                {primaryModels.length === 0 ? (
+                {primaryModelOptions.length === 0 ? (
                   <option value="">
                     {primaryModelsMeta?.loading ? '載入中…' : '尚無可用模型'}
                   </option>
                 ) : (
-                  primaryModels.map((model) => (
+                  primaryModelOptions.map((model) => (
                     <option key={model} value={model}>
                       {model}
                     </option>
@@ -349,24 +355,20 @@ export function AccountAiSettings({ accountId, compact }: AccountAiSettingsProps
               }
             >
               <Select
-                value={
-                  settings.research_model && researchModels.includes(settings.research_model)
-                    ? settings.research_model
-                    : ''
-                }
-                disabled={researchModelsMeta?.loading || researchModels.length === 0}
+                value={settings.research_model?.trim() ?? ''}
+                disabled={researchModelsMeta?.loading || researchModelOptions.length === 0}
                 onChange={(e) =>
                   setSettings((prev) =>
                     prev ? { ...prev, research_model: e.target.value } : prev,
                   )
                 }
               >
-                {researchModels.length === 0 ? (
+                {researchModelOptions.length === 0 ? (
                   <option value="">
                     {researchModelsMeta?.loading ? '載入中…' : '尚無可用模型'}
                   </option>
                 ) : (
-                  researchModels.map((model) => (
+                  researchModelOptions.map((model) => (
                     <option key={model} value={model}>
                       {model}
                     </option>
diff --git a/frontend/src/lib/aiCredentials.ts b/frontend/src/lib/aiCredentials.ts
index 28fa018..1dfc784 100644
--- a/frontend/src/lib/aiCredentials.ts
+++ b/frontend/src/lib/aiCredentials.ts
@@ -82,9 +82,10 @@ export function resolveProviderApiToken(
   return value
 }
 
-function normalizeModel(provider: ProviderId, model: string | undefined, fallback: string): string {
-  const models = modelsForProvider(provider)
-  if (model && models.includes(model)) return model
+function normalizeModel(_provider: ProviderId, model: string | undefined, fallback: string): string {
+  const trimmed = model?.trim()
+  if (trimmed) return trimmed
+  const models = modelsForProvider(_provider)
   return models[0] ?? fallback
 }