fix(outbound): parse xmux from imported share links (#5353)

The inbound link generator bundles xmux and downloadSettings as nested
objects inside the `extra=` JSON blob, but the outbound link parser only
pulled scalar fields and headers from it, silently dropping xmux on
import. Extract the nested objects too so they round-trip into the
outbound XMUX sub-form.

frontend/src/lib/xray/outbound-link-parser.ts

@@ -9,8 +9,9 @@ import { Base64 } from '@/utils';
 // fields the common vmess:// / vless:// links carry as query params.
 // XHTTP advanced fields (xPaddingBytes, scMaxEachPostBytes,
 // scMinPostsIntervalMs, uplinkChunkSize, noGRPCHeader) round-trip when
-// present in either the JSON or URL params. xmux, reality shortIds,
-// padding obfs key/header/placement, hysteria udphop are still left
+// present in either the JSON or URL params. xmux and downloadSettings
+// round-trip through the `extra` JSON blob. reality shortIds, padding
+// obfs key/header/placement, hysteria udphop are still left
 // to the user to fill in after import — the legacy Outbound.fromLink
 // was ~250 lines of dense edge-case handling we don't need to
 // replicate verbatim for the common phone-to-panel workflow.
@@ -33,6 +34,10 @@ const XHTTP_NUMBER_KEYS = [
 const XHTTP_BOOL_KEYS = [
   'xPaddingObfsMode', 'noSSEHeader', 'noGRPCHeader',
 ] as const;
+// Nested objects the inbound link bundles into the `extra` JSON blob
+// (and vmess JSON carries inline). The outbound form adapter expands
+// xmux into the XMUX sub-form (enableXmux) on load.
+const XHTTP_OBJECT_KEYS = ['xmux', 'downloadSettings'] as const;
 
 function asBool(s: string | null): boolean | undefined {
   if (s === null) return undefined;
@@ -88,6 +93,10 @@ function applyXhttpStringFromJson(xhttp: Raw, json: Record<string, unknown>): vo
   for (const k of XHTTP_BOOL_KEYS) {
     if (typeof json[k] === 'boolean') xhttp[k] = json[k];
   }
+  for (const k of XHTTP_OBJECT_KEYS) {
+    const v = json[k];
+    if (v && typeof v === 'object' && !Array.isArray(v)) xhttp[k] = v;
+  }
 }
 
 function buildStream(network: string, security: string): Raw {

frontend/src/test/outbound-link-parser.test.ts

@@ -392,6 +392,23 @@ describe('parseVlessLink — extra / fm / x_padding_bytes (B20)', () => {
     expect(xhttp.xPaddingBytes).toBe('900-9000');
   });
 
+  it('extracts the nested xmux object from the extra JSON blob', () => {
+    // The inbound link bundles xmux into `extra` as a nested object
+    // (sub/service.go). It must survive import so the outbound form's
+    // XMUX sub-form populates rather than silently dropping it (#5353).
+    const extra = encodeURIComponent(JSON.stringify({
+      xmux: { maxConcurrency: '8-16', hMaxRequestTimes: '700-1000' },
+    }));
+    const link = 'vless://u@h:1?type=xhttp&security=none&path=%2F&host=&mode=auto'
+      + '&extra=' + extra + '#t';
+    const parsed = parseVlessLink(link);
+    const xhttp = (parsed!.streamSettings as Record<string, unknown>).xhttpSettings as Record<string, unknown>;
+    const xmux = xhttp.xmux as Record<string, unknown>;
+    expect(xmux).toBeDefined();
+    expect(xmux.maxConcurrency).toBe('8-16');
+    expect(xmux.hMaxRequestTimes).toBe('700-1000');
+  });
+
   it('ignores malformed extra JSON without breaking the rest of the link', () => {
     const link = 'vless://u@h:1?type=xhttp&security=none&path=%2F&host=&mode=auto'
       + '&extra=not-json&fp=chrome#t';