diff --git a/app/(admin)/settings/agent-workflow/agent-workflow-settings-client.tsx b/app/(admin)/settings/agent-workflow/agent-workflow-settings-client.tsx
index 45c7d8b66..fd907f28b 100644
--- a/app/(admin)/settings/agent-workflow/agent-workflow-settings-client.tsx
+++ b/app/(admin)/settings/agent-workflow/agent-workflow-settings-client.tsx
@@ -1974,7 +1974,32 @@ export function AgentWorkflowSettingsClient({
       });
 
       if (!response.ok) {
-        throw new Error("保存失败");
+        let message = "保存失败";
+
+        try {
+          const payload = await response.json();
+          if (Array.isArray(payload?.details) && payload.details.length > 0) {
+            const firstIssue = payload.details[0] as {
+              message?: string;
+              path?: Array<string | number>;
+            };
+            const pathText =
+              Array.isArray(firstIssue.path) && firstIssue.path.length > 0
+                ? firstIssue.path
+                    .filter((segment) => segment !== undefined && segment !== null && segment !== "")
+                    .join(" / ")
+                : "";
+            const reasonText = String(firstIssue.message || "").trim();
+
+            message = [payload?.error, pathText, reasonText].filter(Boolean).join("：");
+          } else if (typeof payload?.error === "string" && payload.error.trim()) {
+            message = payload.error.trim();
+          }
+        } catch {
+          // Ignore JSON parsing issues and keep the generic message.
+        }
+
+        throw new Error(message);
       }
 
       toast.success("智能体工作流配置已保存");
diff --git a/app/api/site-settings/route.ts b/app/api/site-settings/route.ts
index 121d6638d..75aad7178 100644
--- a/app/api/site-settings/route.ts
+++ b/app/api/site-settings/route.ts
@@ -631,6 +631,8 @@ export async function GET() {
   }
 }
 
+const AGENT_WORKFLOW_INPUT_OPTIONS_MAX_ITEMS = 5000;
+
 const updateSchema = z.object({
   siteName: z.string().min(1).max(128).optional(),
   siteLogo: z.string().nullable().optional(),
@@ -728,8 +730,14 @@ const updateSchema = z.object({
     .object({
       inputOptions: z
         .object({
-          brands: z.array(z.string().trim().min(1).max(64)).max(300).optional(),
-          stores: z.array(z.string().trim().min(1).max(64)).max(300).optional(),
+          brands: z
+            .array(z.string().trim().min(1).max(64))
+            .max(AGENT_WORKFLOW_INPUT_OPTIONS_MAX_ITEMS)
+            .optional(),
+          stores: z
+            .array(z.string().trim().min(1).max(64))
+            .max(AGENT_WORKFLOW_INPUT_OPTIONS_MAX_ITEMS)
+            .optional(),
           categoryLabels: z
             .object({
               thirdCategory: z.string().trim().min(1).max(24).optional(),
@@ -737,22 +745,37 @@ const updateSchema = z.object({
               fifthCategory: z.string().trim().min(1).max(24).optional(),
             })
             .optional(),
-          thirdCategories: z.array(z.string().trim().min(1).max(64)).max(300).optional(),
-          fourthCategories: z.array(z.string().trim().min(1).max(64)).max(300).optional(),
-          fifthCategories: z.array(z.string().trim().min(1).max(64)).max(300).optional(),
-          priceBands: z.array(z.string().trim().min(1).max(64)).max(300).optional(),
+          thirdCategories: z
+            .array(z.string().trim().min(1).max(64))
+            .max(AGENT_WORKFLOW_INPUT_OPTIONS_MAX_ITEMS)
+            .optional(),
+          fourthCategories: z
+            .array(z.string().trim().min(1).max(64))
+            .max(AGENT_WORKFLOW_INPUT_OPTIONS_MAX_ITEMS)
+            .optional(),
+          fifthCategories: z
+            .array(z.string().trim().min(1).max(64))
+            .max(AGENT_WORKFLOW_INPUT_OPTIONS_MAX_ITEMS)
+            .optional(),
+          priceBands: z
+            .array(z.string().trim().min(1).max(64))
+            .max(AGENT_WORKFLOW_INPUT_OPTIONS_MAX_ITEMS)
+            .optional(),
           brandStoreEntries: z
             .array(
               z.object({
                 brandName: z.string().trim().min(1).max(64),
-                stores: z.array(z.string().trim().min(1).max(64)).max(300).optional(),
+                stores: z
+                  .array(z.string().trim().min(1).max(64))
+                  .max(AGENT_WORKFLOW_INPUT_OPTIONS_MAX_ITEMS)
+                  .optional(),
                 storeEntries: z
                   .array(
                     z.object({
                       storeName: z.string().trim().min(1).max(64),
                       thirdCategories: z
                         .array(z.string().trim().min(1).max(64))
-                        .max(300)
+                        .max(AGENT_WORKFLOW_INPUT_OPTIONS_MAX_ITEMS)
                         .optional(),
                       thirdCategoryEntries: z
                         .array(
@@ -760,7 +783,7 @@ const updateSchema = z.object({
                             categoryName: z.string().trim().min(1).max(64),
                             fourthCategories: z
                               .array(z.string().trim().min(1).max(64))
-                              .max(300)
+                              .max(AGENT_WORKFLOW_INPUT_OPTIONS_MAX_ITEMS)
                               .optional(),
                             fourthCategoryEntries: z
                               .array(
@@ -768,27 +791,27 @@ const updateSchema = z.object({
                                   categoryName: z.string().trim().min(1).max(64),
                                   fifthCategories: z
                                     .array(z.string().trim().min(1).max(64))
-                                    .max(300)
+                                    .max(AGENT_WORKFLOW_INPUT_OPTIONS_MAX_ITEMS)
                                     .optional(),
                                   sortOrder: z.number().min(0).max(999).optional(),
                                 })
                               )
-                              .max(300)
+                              .max(AGENT_WORKFLOW_INPUT_OPTIONS_MAX_ITEMS)
                               .optional(),
                             sortOrder: z.number().min(0).max(999).optional(),
                           })
                         )
-                        .max(300)
+                        .max(AGENT_WORKFLOW_INPUT_OPTIONS_MAX_ITEMS)
                         .optional(),
                       sortOrder: z.number().min(0).max(999).optional(),
                     })
                   )
-                  .max(300)
+                  .max(AGENT_WORKFLOW_INPUT_OPTIONS_MAX_ITEMS)
                   .optional(),
                 sortOrder: z.number().min(0).max(999).optional(),
               })
             )
-            .max(300)
+            .max(AGENT_WORKFLOW_INPUT_OPTIONS_MAX_ITEMS)
             .optional(),
         })
         .optional(),