diff --git a/src/langbot/pkg/api/http/controller/groups/provider/models.py b/src/langbot/pkg/api/http/controller/groups/provider/models.py
index 236000d9f..5d17d7ffc 100644
--- a/src/langbot/pkg/api/http/controller/groups/provider/models.py
+++ b/src/langbot/pkg/api/http/controller/groups/provider/models.py
@@ -1,10 +1,14 @@
 import quart
 
+from langbot.pkg.provider.modelmgr import errors as provider_errors
 from ....authz import Permission, has_permission
 from ....context import RequestContext
 from ... import group
 
 
+MODEL_TEST_ERROR_CODE = 'model_test_failed'
+
+
 @group.group_class('models/llm', '/api/v1/provider/models/llm')
 class LLMModelsRouterGroup(group.RouterGroup):
     async def initialize(self) -> None:
@@ -96,7 +100,14 @@ class LLMModelsRouterGroup(group.RouterGroup):
             permission=Permission.PROVIDER_SECRET_MANAGE,
         )
         async def _(model_uuid: str, request_context: RequestContext) -> str:
-            await self.ap.llm_model_service.test_llm_model(request_context, model_uuid, await quart.request.json)
+            try:
+                await self.ap.llm_model_service.test_llm_model(
+                    request_context,
+                    model_uuid,
+                    await quart.request.json,
+                )
+            except (provider_errors.RequesterError, ValueError) as exc:
+                return self.http_status(400, MODEL_TEST_ERROR_CODE, str(exc))
             return self.success()
 
 
@@ -191,9 +202,14 @@ class EmbeddingModelsRouterGroup(group.RouterGroup):
             permission=Permission.PROVIDER_SECRET_MANAGE,
         )
         async def _(model_uuid: str, request_context: RequestContext) -> str:
-            await self.ap.embedding_models_service.test_embedding_model(
-                request_context, model_uuid, await quart.request.json
-            )
+            try:
+                await self.ap.embedding_models_service.test_embedding_model(
+                    request_context,
+                    model_uuid,
+                    await quart.request.json,
+                )
+            except (provider_errors.RequesterError, ValueError) as exc:
+                return self.http_status(400, MODEL_TEST_ERROR_CODE, str(exc))
             return self.success()
 
 
@@ -288,5 +304,12 @@ class RerankModelsRouterGroup(group.RouterGroup):
             permission=Permission.PROVIDER_SECRET_MANAGE,
         )
         async def _(model_uuid: str, request_context: RequestContext) -> str:
-            await self.ap.rerank_models_service.test_rerank_model(request_context, model_uuid, await quart.request.json)
+            try:
+                await self.ap.rerank_models_service.test_rerank_model(
+                    request_context,
+                    model_uuid,
+                    await quart.request.json,
+                )
+            except (provider_errors.RequesterError, ValueError) as exc:
+                return self.http_status(400, MODEL_TEST_ERROR_CODE, str(exc))
             return self.success()
diff --git a/tests/integration/api/test_providers.py b/tests/integration/api/test_providers.py
index 4aa2e1342..df72d9084 100644
--- a/tests/integration/api/test_providers.py
+++ b/tests/integration/api/test_providers.py
@@ -12,6 +12,7 @@ import pytest
 from unittest.mock import MagicMock, AsyncMock, Mock
 from types import SimpleNamespace
 
+from langbot.pkg.provider.modelmgr.errors import RequesterError
 from tests.factories import FakeApp
 
 
@@ -111,16 +112,19 @@ def fake_provider_app():
     app.llm_model_service.create_llm_model = AsyncMock(return_value={'uuid': 'new-model-uuid'})
     app.llm_model_service.update_llm_model = AsyncMock(return_value={})
     app.llm_model_service.delete_llm_model = AsyncMock()
+    app.llm_model_service.test_llm_model = AsyncMock()
 
     # Embedding model service
     app.embedding_models_service = Mock()
     app.embedding_models_service.get_embedding_models = AsyncMock(return_value=[])
     app.embedding_models_service.create_embedding_model = AsyncMock(return_value={'uuid': 'new-embedding-uuid'})
+    app.embedding_models_service.test_embedding_model = AsyncMock()
 
     # Rerank model service
     app.rerank_models_service = Mock()
     app.rerank_models_service.get_rerank_models = AsyncMock(return_value=[])
     app.rerank_models_service.create_rerank_model = AsyncMock(return_value={'uuid': 'new-rerank-uuid'})
+    app.rerank_models_service.test_rerank_model = AsyncMock()
 
     # Model manager
     app.model_mgr = Mock()
@@ -290,6 +294,43 @@ class TestModelEndpoints:
 
         assert response.status_code == 200
 
+    @pytest.mark.asyncio
+    @pytest.mark.parametrize(
+        ('service_name', 'method_name', 'path'),
+        [
+            ('llm_model_service', 'test_llm_model', '/api/v1/provider/models/llm/_/test'),
+            (
+                'embedding_models_service',
+                'test_embedding_model',
+                '/api/v1/provider/models/embedding/_/test',
+            ),
+            ('rerank_models_service', 'test_rerank_model', '/api/v1/provider/models/rerank/_/test'),
+        ],
+    )
+    async def test_model_test_returns_requester_error_details(
+        self,
+        quart_test_client,
+        fake_provider_app,
+        service_name,
+        method_name,
+        path,
+    ):
+        test_model = getattr(getattr(fake_provider_app, service_name), method_name)
+        test_model.side_effect = RequesterError('API key invalid')
+        try:
+            response = await quart_test_client.post(
+                path,
+                headers={'Authorization': 'Bearer test_token'},
+                json={'name': 'broken-model'},
+            )
+        finally:
+            test_model.side_effect = None
+
+        assert response.status_code == 400
+        data = await response.get_json()
+        assert data['code'] == 'model_test_failed'
+        assert data['msg'] == '模型请求失败: API key invalid'
+
 
 @pytest.mark.usefixtures('mock_circular_import_chain')
 class TestEmbeddingModelEndpoints:
diff --git a/web/src/app/home/agents/components/AgentDebugPanel.tsx b/web/src/app/home/agents/components/AgentDebugPanel.tsx
index 913d7ecc3..2cdbe06c6 100644
--- a/web/src/app/home/agents/components/AgentDebugPanel.tsx
+++ b/web/src/app/home/agents/components/AgentDebugPanel.tsx
@@ -312,48 +312,55 @@ export default function AgentDebugPanel({
                 }
               >
                 {entry.direction === 'error' && <AlertCircle />}
-                <div className="mb-2 flex items-center justify-between gap-2">
-                  <Badge variant="outline">{entry.eventType}</Badge>
-                  <span className="text-xs text-muted-foreground">
-                    {entry.direction === 'output'
-                      ? t('agents.debugAgentOutput')
-                      : entry.direction === 'error'
-                        ? t('common.error')
-                        : t('agents.debugTestInput')}
-                  </span>
-                </div>
-                <pre className="min-w-0 whitespace-pre-wrap break-words font-sans text-sm leading-relaxed">
-                  {entry.text}
-                </pre>
-                {entry.detail && (
-                  <Collapsible className="mt-3">
-                    <CollapsibleTrigger asChild>
-                      <Button type="button" variant="ghost" size="sm">
-                        {t('agents.debugErrorDetails')}
-                        <ChevronDown className="size-3.5" />
-                      </Button>
-                    </CollapsibleTrigger>
-                    <CollapsibleContent>
-                      <pre className="mt-2 max-h-32 overflow-auto whitespace-pre-wrap break-words rounded-md bg-muted p-2 font-mono text-xs text-muted-foreground">
-                        {entry.detail}
-                      </pre>
-                    </CollapsibleContent>
-                  </Collapsible>
-                )}
-                {(entry.errorCode?.endsWith('.config_invalid') ||
-                  entry.errorCode === 'runner_execution_failed' ||
-                  entry.errorCode === 'runner.timeout') &&
-                  onOpenRunnerConfig && (
-                    <Button
-                      type="button"
+                <div className="col-start-2 min-w-0">
+                  <div className="mb-2 flex min-w-0 flex-wrap items-center justify-between gap-2">
+                    <Badge
                       variant="outline"
-                      size="sm"
-                      className="mt-3"
-                      onClick={onOpenRunnerConfig}
+                      className="max-w-full overflow-hidden text-ellipsis"
                     >
-                      {t('agents.debugReviewRunnerConfig')}
-                    </Button>
+                      {entry.eventType}
+                    </Badge>
+                    <span className="shrink-0 text-xs text-muted-foreground">
+                      {entry.direction === 'output'
+                        ? t('agents.debugAgentOutput')
+                        : entry.direction === 'error'
+                          ? t('common.error')
+                          : t('agents.debugTestInput')}
+                    </span>
+                  </div>
+                  <pre className="min-w-0 whitespace-pre-wrap break-words [overflow-wrap:anywhere] font-sans text-sm leading-relaxed">
+                    {entry.text}
+                  </pre>
+                  {entry.detail && (
+                    <Collapsible className="mt-3">
+                      <CollapsibleTrigger asChild>
+                        <Button type="button" variant="ghost" size="sm">
+                          {t('agents.debugErrorDetails')}
+                          <ChevronDown className="size-3.5" />
+                        </Button>
+                      </CollapsibleTrigger>
+                      <CollapsibleContent>
+                        <pre className="mt-2 max-h-32 overflow-auto whitespace-pre-wrap break-words [overflow-wrap:anywhere] rounded-md bg-muted p-2 font-mono text-xs text-muted-foreground">
+                          {entry.detail}
+                        </pre>
+                      </CollapsibleContent>
+                    </Collapsible>
                   )}
+                  {(entry.errorCode?.endsWith('.config_invalid') ||
+                    entry.errorCode === 'runner_execution_failed' ||
+                    entry.errorCode === 'runner.timeout') &&
+                    onOpenRunnerConfig && (
+                      <Button
+                        type="button"
+                        variant="outline"
+                        size="sm"
+                        className="mt-3"
+                        onClick={onOpenRunnerConfig}
+                      >
+                        {t('agents.debugReviewRunnerConfig')}
+                      </Button>
+                    )}
+                </div>
               </Alert>
             ))}
           </div>
diff --git a/web/src/app/home/components/models-dialog/ModelsPanel.tsx b/web/src/app/home/components/models-dialog/ModelsPanel.tsx
index c8d8cfdda..0292ef630 100644
--- a/web/src/app/home/components/models-dialog/ModelsPanel.tsx
+++ b/web/src/app/home/components/models-dialog/ModelsPanel.tsx
@@ -522,8 +522,9 @@ export default function ModelsPanel({
       setTestResult({ success: true, duration });
     } catch (err) {
       console.error('Failed to test model', err);
-      toast.error(t('models.testError') + ': ' + (err as CustomApiError).msg);
-      setTestResult(null);
+      const message = (err as CustomApiError).msg || t('models.testError');
+      toast.error(t('models.testError') + ': ' + message);
+      setTestResult({ success: false, message });
     } finally {
       setIsTesting(false);
     }
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 f12756749..bbf71c6a2 100644
--- a/web/src/app/home/components/models-dialog/components/AddModelPopover.tsx
+++ b/web/src/app/home/components/models-dialog/components/AddModelPopover.tsx
@@ -437,6 +437,14 @@ export default function AddModelPopover({
                       )}
                     </Button>
                   </div>
+                  {testResult?.success === false && (
+                    <p
+                      role="alert"
+                      className="rounded-md border border-destructive/30 bg-destructive/5 p-2 text-xs text-destructive [overflow-wrap:anywhere]"
+                    >
+                      {testResult.message}
+                    </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 12e61da77..fae9be86f 100644
--- a/web/src/app/home/components/models-dialog/components/ModelItem.tsx
+++ b/web/src/app/home/components/models-dialog/components/ModelItem.tsx
@@ -412,6 +412,14 @@ export default function ModelItem({
               )}
             </Button>
           </div>
+          {testResult?.success === false && (
+            <p
+              role="alert"
+              className="rounded-md border border-destructive/30 bg-destructive/5 p-2 text-xs text-destructive [overflow-wrap:anywhere]"
+            >
+              {testResult.message}
+            </p>
+          )}
         </div>
       </PopoverContent>
     </Popover>
diff --git a/web/src/app/home/components/models-dialog/types.ts b/web/src/app/home/components/models-dialog/types.ts
index 8ed008e46..f8f72e0b1 100644
--- a/web/src/app/home/components/models-dialog/types.ts
+++ b/web/src/app/home/components/models-dialog/types.ts
@@ -27,10 +27,9 @@ export interface ProviderModels {
   rerank: RerankModel[];
 }
 
-export interface TestResult {
-  success: boolean;
-  duration: number;
-}
+export type TestResult =
+  | { success: true; duration: number }
+  | { success: false; message: string };
 
 export type SelectedScannedModel = {
   model: ScannedProviderModel;