feat(mtproto): add domain-fronting and essential mtg options

Expose mtg's [domain-fronting] section (ip/port/proxy-protocol) plus
proxy-protocol-listener, prefer-ip, and debug on MTProto inbounds. Each
key is written to the generated mtg-<id>.toml only when set, so mtg's own
defaults apply otherwise. The instance fingerprint now covers these
fields, so editing an option restarts the sidecar.

Since MTProto is mtg-served (not Xray), sniffing does not apply: hide the
Sniffing tab and the Advanced sniffing sub-editor, drop it from the
Advanced "All" JSON view, and emit empty sniffing in the wire payload,
all gated by a new canEnableSniffing predicate.

frontend/src/pages/inbounds/form/InboundFormModal.tsx

@@ -23,6 +23,7 @@ import { createDefaultInboundSettings } from '@/lib/xray/inbound-defaults';
 import { composeInboundTag, isAutoInboundTag, type InboundTagInput } from '@/lib/xray/inbound-tag';
 import {
   canEnableReality,
+  canEnableSniffing,
   canEnableStream,
   canEnableTls,
   isSS2022,
@@ -160,6 +161,7 @@ export default function InboundFormModal({
   const network = Form.useWatch(['streamSettings', 'network'], form) ?? '';
   const security = Form.useWatch(['streamSettings', 'security'], form) ?? 'none';
   const streamEnabled = canEnableStream({ protocol });
+  const sniffingSupported = canEnableSniffing({ protocol });
 
   const wPort = Form.useWatch('port', form);
   const wListen = (Form.useWatch('listen', form) ?? '') as string;
@@ -776,7 +778,7 @@ export default function InboundFormModal({
                   <div className="advanced-editor-meta">
                     {t('pages.inbounds.advanced.allHelp')}
                   </div>
-                  <AdvancedAllEditor form={form} streamEnabled={streamEnabled} />
+                  <AdvancedAllEditor form={form} streamEnabled={streamEnabled} sniffingEnabled={sniffingSupported} />
                 </>
               ),
             },
@@ -820,25 +822,27 @@ export default function InboundFormModal({
                 ),
               }]
               : []),
-            {
-              key: 'sniffing',
-              label: t('pages.inbounds.advanced.sniffing'),
-              children: (
-                <>
-                  <div className="advanced-editor-meta">
-                    {t('pages.inbounds.advanced.sniffingHelp')}{' '}
-                    <code>{'{ sniffing: { ... } }'}</code>.
-                  </div>
-                  <AdvancedSliceEditor
-                    form={form}
-                    path="sniffing"
-                    wrapKey="sniffing"
-                    minHeight="240px"
-                    maxHeight="420px"
-                  />
-                </>
-              ),
-            },
+            ...(sniffingSupported
+              ? [{
+                key: 'sniffing',
+                label: t('pages.inbounds.advanced.sniffing'),
+                children: (
+                  <>
+                    <div className="advanced-editor-meta">
+                      {t('pages.inbounds.advanced.sniffingHelp')}{' '}
+                      <code>{'{ sniffing: { ... } }'}</code>.
+                    </div>
+                    <AdvancedSliceEditor
+                      form={form}
+                      path="sniffing"
+                      wrapKey="sniffing"
+                      minHeight="240px"
+                      maxHeight="420px"
+                    />
+                  </>
+                ),
+              }]
+              : []),
           ]}
         />
       </div>
@@ -896,7 +900,9 @@ export default function InboundFormModal({
                 { key: 'security', label: t('pages.inbounds.securityTab'), children: securityTab, forceRender: true },
               ]
               : []),
-            { key: 'sniffing', label: t('pages.inbounds.sniffingTab'), children: sniffingTab, forceRender: true },
+            ...(sniffingSupported
+              ? [{ key: 'sniffing', label: t('pages.inbounds.sniffingTab'), children: sniffingTab, forceRender: true }]
+              : []),
             { key: 'advanced', label: t('pages.xray.advancedTemplate'), children: advancedTab, forceRender: true },
           ]} />
         </Form>

frontend/src/pages/inbounds/form/advanced-editors.tsx

@@ -92,9 +92,11 @@ export function AdvancedSliceEditor({
 export function AdvancedAllEditor({
   form,
   streamEnabled,
+  sniffingEnabled,
 }: {
   form: FormInstance<InboundFormValues>;
   streamEnabled: boolean;
+  sniffingEnabled: boolean;
 }) {
   // preserve: true — default useWatch returns only registered fields, so
   // sub-trees we never bound (settings.clients/fallbacks, sniffing
@@ -127,8 +129,10 @@ export function AdvancedAllEditor({
       protocol: wProtocol ?? '',
       tag: wTag ?? '',
       settings: settingsView,
-      sniffing: normalizeSniffing(wSniffing as Parameters<typeof normalizeSniffing>[0]),
     };
+    if (sniffingEnabled) {
+      out.sniffing = normalizeSniffing(wSniffing as Parameters<typeof normalizeSniffing>[0]);
+    }
     if (streamView) out.streamSettings = streamView;
     return JSON.stringify(out, null, 2);
   };
@@ -146,7 +150,7 @@ export function AdvancedAllEditor({
     setText(formStr);
     lastEmitRef.current = formStr;
     // eslint-disable-next-line react-hooks/exhaustive-deps
-  }, [wListen, wPort, wProtocol, wTag, wSettings, wSniffing, wStream, streamEnabled]);
+  }, [wListen, wPort, wProtocol, wTag, wSettings, wSniffing, wStream, streamEnabled, sniffingEnabled]);
 
   return (
     <JsonEditor
@@ -171,7 +175,7 @@ export function AdvancedAllEditor({
         if (parsed.settings && typeof parsed.settings === 'object') {
           form.setFieldValue('settings', parsed.settings);
         }
-        if (parsed.sniffing && typeof parsed.sniffing === 'object') {
+        if (sniffingEnabled && parsed.sniffing && typeof parsed.sniffing === 'object') {
           form.setFieldValue('sniffing', parsed.sniffing);
         }
         if (streamEnabled && parsed.streamSettings && typeof parsed.streamSettings === 'object') {

frontend/src/pages/inbounds/form/protocols/mtproto.tsx

@@ -1,5 +1,5 @@
 import { useTranslation } from 'react-i18next';
-import { Alert, Button, Form, Input, Space } from 'antd';
+import { Button, Form, Input, InputNumber, Select, Space, Switch } from 'antd';
 import { ReloadOutlined } from '@ant-design/icons';
 
 import { generateMtprotoSecret, mtprotoSecretForDomain } from '@/lib/xray/inbound-defaults';
@@ -32,8 +32,44 @@ export default function MtprotoFields() {
           />
         </Space.Compact>
       </Form.Item>
-      <Form.Item wrapperCol={{ span: 24 }}>
-        <Alert type="info" showIcon message={t('pages.inbounds.form.mtprotoHint')} />
+      <Form.Item
+        name={['settings', 'domainFronting', 'ip']}
+        label={t('pages.inbounds.form.mtgDomainFrontingIp')}
+        tooltip={t('pages.inbounds.form.mtgDomainFrontingHint')}
+      >
+        <Input placeholder="127.0.0.1" />
+      </Form.Item>
+      <Form.Item name={['settings', 'domainFronting', 'port']} label={t('pages.inbounds.form.mtgDomainFrontingPort')}>
+        <InputNumber min={0} max={65535} placeholder="443" style={{ width: '100%' }} />
+      </Form.Item>
+      <Form.Item
+        name={['settings', 'domainFronting', 'proxyProtocol']}
+        label={t('pages.inbounds.form.mtgDomainFrontingProxyProtocol')}
+        valuePropName="checked"
+      >
+        <Switch />
+      </Form.Item>
+      <Form.Item
+        name={['settings', 'proxyProtocolListener']}
+        label={t('pages.inbounds.form.mtgProxyProtocolListener')}
+        valuePropName="checked"
+      >
+        <Switch />
+      </Form.Item>
+      <Form.Item name={['settings', 'preferIp']} label={t('pages.inbounds.form.mtgPreferIp')}>
+        <Select
+          allowClear
+          placeholder="prefer-ipv6"
+          options={[
+            { value: 'prefer-ipv6', label: 'prefer-ipv6' },
+            { value: 'prefer-ipv4', label: 'prefer-ipv4' },
+            { value: 'only-ipv6', label: 'only-ipv6' },
+            { value: 'only-ipv4', label: 'only-ipv4' },
+          ]}
+        />
+      </Form.Item>
+      <Form.Item name={['settings', 'debug']} label={t('pages.inbounds.form.mtgDebug')} valuePropName="checked">
+        <Switch />
       </Form.Item>
     </>
   );

frontend/src/pages/inbounds/info/InboundInfoModal.tsx

@@ -640,6 +640,47 @@ export default function InboundInfoModal({
               </Tooltip>
             </dd>
           </div>
+          {(() => {
+            const s = inbound.settings;
+            const df = s.domainFronting as { ip?: string; port?: number; proxyProtocol?: boolean } | undefined;
+            const frontingTarget = df && (df.ip || df.port)
+              ? `${df.ip ?? ''}${df.port ? `:${df.port}` : ''}`
+              : '';
+            return (
+              <>
+                {frontingTarget && (
+                  <div className="info-row">
+                    <dt>{t('pages.inbounds.form.mtgDomainFrontingIp')}</dt>
+                    <dd><Tag color="blue" className="value-tag">{frontingTarget}</Tag></dd>
+                  </div>
+                )}
+                {df?.proxyProtocol && (
+                  <div className="info-row">
+                    <dt>{t('pages.inbounds.form.mtgDomainFrontingProxyProtocol')}</dt>
+                    <dd><Tag color="green" className="value-tag">{t('enabled')}</Tag></dd>
+                  </div>
+                )}
+                {Boolean(s.proxyProtocolListener) && (
+                  <div className="info-row">
+                    <dt>{t('pages.inbounds.form.mtgProxyProtocolListener')}</dt>
+                    <dd><Tag color="green" className="value-tag">{t('enabled')}</Tag></dd>
+                  </div>
+                )}
+                {Boolean(s.preferIp) && (
+                  <div className="info-row">
+                    <dt>{t('pages.inbounds.form.mtgPreferIp')}</dt>
+                    <dd><Tag color="blue" className="value-tag">{s.preferIp as string}</Tag></dd>
+                  </div>
+                )}
+                {Boolean(s.debug) && (
+                  <div className="info-row">
+                    <dt>{t('pages.inbounds.form.mtgDebug')}</dt>
+                    <dd><Tag color="green" className="value-tag">{t('enabled')}</Tag></dd>
+                  </div>
+                )}
+              </>
+            );
+          })()}
           {links.length > 0 && (
             <div className="info-row">
               <dt>{t('pages.inbounds.copyLink')}</dt>