fix: address PR review feedback for config UI controls

- Fix subturn_max_depth_hint: clarify that 0 uses default (3), not disable
- Fix subturn_default_timeout_hint: clarify that 0 uses system default (5 min)
- Add fatal log level option to i18n translations (en + zh)
- Extract select .find() lookups to component-level variables
- Add validation: routing enabled requires non-empty light_model
- Only parse filterMinLength when filter_sensitive_data is enabled

web/frontend/src/components/config/config-page.tsx

@@ -213,6 +213,9 @@ export function ConfigPage() {
         )
 
         // Routing fields
+        if (form.routingEnabled && !form.routingLightModel.trim()) {
+          throw new Error("Light Model is required when Smart Routing is enabled.")
+        }
         const routingThreshold = form.routingEnabled
           ? parseFloatField(form.routingThreshold, "Routing threshold", {
               min: 0,
@@ -230,11 +233,12 @@ export function ConfigPage() {
         const maxMediaSize = form.maxMediaSize.trim()
           ? parseIntField(form.maxMediaSize, "Max media size", { min: 0 })
           : undefined
-        const filterMinLength = parseIntField(
-          form.filterMinLength,
-          "Filter min length",
-          { min: 0 },
-        )
+        const filterMinLength =
+          form.filterSensitiveData && form.filterMinLength.trim()
+            ? parseIntField(form.filterMinLength, "Filter min length", {
+                min: 0,
+              })
+            : undefined
 
         const execConfigPatch: Record<string, unknown> = {
           enabled: form.execEnabled,
@@ -287,7 +291,7 @@ export function ConfigPage() {
               routing: form.routingEnabled
                 ? {
                     enabled: true,
-                    light_model: form.routingLightModel,
+                    light_model: form.routingLightModel.trim() || undefined,
                     threshold: routingThreshold,
                   }
                 : { enabled: false },

web/frontend/src/components/config/config-sections.tsx

@@ -72,6 +72,9 @@ export function AgentDefaultsSection({
   onFieldChange,
 }: AgentDefaultsSectionProps) {
   const { t } = useTranslation()
+  const selectedSteeringModeOption = STEERING_MODE_OPTIONS.find(
+    (o) => o.value === form.steeringMode,
+  )
 
   return (
     <ConfigSectionCard title={t("pages.config.sections.agent")}>
@@ -210,12 +213,6 @@ export function AgentDefaultsSection({
         hint={t("pages.config.steering_mode_hint")}
         layout="setting-row"
       >
-        {(() => {
-          const selectedSteeringModeOption = STEERING_MODE_OPTIONS.find(
-            (o) => o.value === form.steeringMode,
-          )
-
-          return (
         <Select
           value={form.steeringMode}
           onValueChange={(value) => onFieldChange("steeringMode", value)}
@@ -238,8 +235,6 @@ export function AgentDefaultsSection({
             ))}
           </SelectContent>
         </Select>
-          )
-        })()}
       </Field>
 
       <Field
@@ -618,6 +613,9 @@ interface RuntimeSectionProps {
 
 export function RuntimeSection({ form, onFieldChange }: RuntimeSectionProps) {
   const { t } = useTranslation()
+  const selectedLogLevelOption = LOG_LEVEL_OPTIONS.find(
+    (o) => o.value === form.gatewayLogLevel,
+  )
   const selectedDmScopeOption = DM_SCOPE_OPTIONS.find(
     (scope) => scope.value === form.dmScope,
   )
@@ -704,14 +702,12 @@ export function RuntimeSection({ form, onFieldChange }: RuntimeSectionProps) {
         >
           <SelectTrigger className="w-full">
             <SelectValue>
-              {(() => {
-                const selected = LOG_LEVEL_OPTIONS.find(
-                  (o) => o.value === form.gatewayLogLevel,
+              {selectedLogLevelOption
+                ? t(
+                    selectedLogLevelOption.labelKey,
+                    selectedLogLevelOption.labelDefault,
                   )
-                return selected
-                  ? t(selected.labelKey, selected.labelDefault)
-                  : form.gatewayLogLevel
-              })()}
+                : form.gatewayLogLevel}
             </SelectValue>
           </SelectTrigger>
           <SelectContent>

web/frontend/src/i18n/locales/en.json

@@ -513,11 +513,11 @@
       "max_media_size_hint": "Maximum upload file size in bytes. Leave empty for the default (20 MB).",
       "subturn_description": "Configure sub-turn spawning for background tasks and parallel agent work.",
       "subturn_max_depth": "Max Depth",
-      "subturn_max_depth_hint": "Maximum nesting depth for spawned sub-turns. Set to 0 to disable spawning.",
+      "subturn_max_depth_hint": "Maximum nesting depth for spawned sub-turns. Values \u2264 0 use the default (3).",
       "subturn_max_concurrent": "Max Concurrent",
       "subturn_max_concurrent_hint": "Maximum number of sub-turns that can run in parallel.",
       "subturn_default_timeout": "Default Timeout (minutes)",
-      "subturn_default_timeout_hint": "Default timeout in minutes for spawned sub-turns. Set to 0 for no timeout.",
+      "subturn_default_timeout_hint": "Default timeout in minutes for spawned sub-turns. Leave empty or set to 0 to use the system default (5 minutes).",
       "subturn_token_budget": "Token Budget",
       "subturn_token_budget_hint": "Default token budget for each sub-turn. Set to 0 for unlimited.",
       "subturn_concurrency_timeout": "Concurrency Timeout (seconds)",
@@ -541,6 +541,7 @@
       "log_level_info": "Info",
       "log_level_warn": "Warn",
       "log_level_error": "Error",
+      "log_level_fatal": "Fatal",
       "sections": {
         "agent": "Agent",
         "runtime": "Runtime",

web/frontend/src/i18n/locales/zh.json

@@ -513,11 +513,11 @@
       "max_media_size_hint": "上传文件的最大字节数。留空使用默认值（20 MB）。",
       "subturn_description": "配置子轮次的后台任务派生与并行工作。",
       "subturn_max_depth": "最大深度",
-      "subturn_max_depth_hint": "派生子轮次的最大嵌套深度。设为 0 禁用派生。",
+      "subturn_max_depth_hint": "派生子轮次的最大嵌套深度。设为 0 或留空将使用默认值（3）。",
       "subturn_max_concurrent": "最大并发数",
       "subturn_max_concurrent_hint": "可同时运行的子轮次最大数量。",
       "subturn_default_timeout": "默认超时（分钟）",
-      "subturn_default_timeout_hint": "派生子轮次的默认超时时间（分钟）。设为 0 表示无超时。",
+      "subturn_default_timeout_hint": "派生子轮次的默认超时时间（分钟）。留空或设为 0 使用系统默认值（5 分钟）。",
       "subturn_token_budget": "Token 预算",
       "subturn_token_budget_hint": "每个子轮次的默认 Token 预算。设为 0 表示不限制。",
       "subturn_concurrency_timeout": "并发超时（秒）",
@@ -541,6 +541,7 @@
       "log_level_info": "信息",
       "log_level_warn": "警告",
       "log_level_error": "错误",
+      "log_level_fatal": "致命",
       "sections": {
         "agent": "智能体",
         "runtime": "运行时",