feat: implement inbound XMUX form fields (#5211)

* feat: implement inbound XMUX form fields

* fix: replace any cast to satisfy eslint

* test: update xhttp form snapshot for XMUX

* fix(inbound): persist xmux on save so the XMUX form actually round-trips

The inbound wire normalizer unconditionally deleted xhttpSettings.xmux,
so the new inbound XMUX form was stripped on save and never reached the
stored config — the subscription extra blob (buildXhttpExtra) could
never see it. Gate the deletion on the enableXmux toggle, mirroring the
outbound adapter, and add regression tests for both on/off cases.

* fix(xmux): enforce xray-core's maxConnections/maxConcurrency exclusivity

xray-core's XmuxConfig rejects a config that sets both maxConnections
and maxConcurrency. The panel pre-fills maxConcurrency ('16-32') whenever
XMUX is enabled, so an explicit maxConnections would always collide and
make xray refuse the config. Mirror core's semantics in the wire
normalizer: when maxConnections is set (>0, an explicit opt-in since it
defaults to 0), drop the leftover default maxConcurrency. Applies to both
inbound and outbound xhttp.

---------

Co-authored-by: Sanaei <ho3ein.sanaei@gmail.com>

frontend/src/lib/xray/inbound-form-adapter.ts

@@ -12,6 +12,9 @@ import type { Sniffing } from '@/schemas/primitives';
 import type { z } from 'zod';
 import { normalizeStreamSettingsForWire } from '@/lib/xray/stream-wire-normalize';
 import { canEnableSniffing } from '@/lib/xray/protocol-capabilities';
+import { XHttpXmuxSchema } from '@/schemas/protocols/stream/xhttp';
+
+const XMUX_DEFAULTS = XHttpXmuxSchema.parse({});
 
 // Plain-data adapter between the panel's stored inbound row shape and
 // the typed InboundFormValues that Form.useForm<T> carries inside
@@ -157,6 +160,16 @@ export function rawInboundToFormValues(row: RawInboundRow): InboundFormValues {
   if (streamSettings) {
     healStreamNetworkKey(streamSettings as unknown as Record<string, unknown>);
     synthesizeTlsCertUseFile(streamSettings as unknown as Record<string, unknown>);
+    const streamRecord = streamSettings as unknown as Record<string, unknown>;
+    const xh = streamRecord.xhttpSettings;
+    if (xh && typeof xh === 'object' && !Array.isArray(xh)) {
+      const xhttp = xh as Record<string, unknown>;
+      const xmux = xhttp.xmux;
+      if (xmux && typeof xmux === 'object' && !Array.isArray(xmux)) {
+        xhttp.enableXmux = true;
+        xhttp.xmux = { ...XMUX_DEFAULTS, ...(xmux as Record<string, unknown>) };
+      }
+    }
   }
   const sniffing = coerceJsonObject(row.sniffing) as unknown as Sniffing;
 

frontend/src/lib/xray/stream-wire-normalize.ts

@@ -41,6 +41,36 @@ function hasMeaningfulHeaders(headers: unknown): boolean {
   return isRecord(headers) && Object.keys(headers).length > 0;
 }
 
+// Upper bound of an xray-core Int32Range value: "16-32" -> 32, "4" -> 4,
+// 4 -> 4, "" / null -> 0. xmux fields are ranges, and xray-core keys its
+// mutual-exclusivity check on the `.To` (upper) side.
+function int32RangeUpper(v: unknown): number {
+  if (typeof v === 'number') return Number.isFinite(v) ? v : 0;
+  if (typeof v !== 'string') return 0;
+  const trimmed = v.trim();
+  if (trimmed === '') return 0;
+  const parts = trimmed.split('-');
+  const n = Number(parts[parts.length - 1]);
+  return Number.isFinite(n) ? n : 0;
+}
+
+// xray-core's XmuxConfig rejects a config that sets BOTH maxConnections
+// and maxConcurrency ("maxConnections cannot be specified together with
+// maxConcurrency"). The panel pre-fills maxConcurrency ("16-32") whenever
+// XMUX is enabled, so any explicit maxConnections would otherwise always
+// collide and make xray refuse the config. maxConnections defaults to 0
+// (off), so a positive value is an explicit opt-in to connection-pool
+// mode — honor it and drop the leftover default maxConcurrency, matching
+// core's "one strategy at a time" semantics.
+function resolveXmuxExclusivity(xmux: Record<string, unknown>): Record<string, unknown> {
+  if (int32RangeUpper(xmux.maxConnections) > 0 && int32RangeUpper(xmux.maxConcurrency) > 0) {
+    const out = { ...xmux };
+    delete out.maxConcurrency;
+    return out;
+  }
+  return xmux;
+}
+
 /** Validates REALITY inbound `target` / `dest` (must include a port). */
 export function validateRealityTarget(target: string): string | undefined {
   const trimmed = target.trim();
@@ -115,15 +145,19 @@ export function normalizeXhttpForWire(
 ): Record<string, unknown> {
   const out: Record<string, unknown> = { ...raw };
   const mode = typeof out.mode === 'string' && out.mode !== '' ? out.mode : 'auto';
-
+  const enableXmux = out.enableXmux === true;
   delete out.enableXmux;
 
   if (side === 'inbound') {
-    delete out.xmux;
+    if (!enableXmux) delete out.xmux;
     delete out.scMinPostsIntervalMs;
     delete out.uplinkChunkSize;
   }
 
+  if (isRecord(out.xmux)) {
+    out.xmux = resolveXmuxExclusivity(out.xmux);
+  }
+
   dropEmptyStrings(out, PLACEMENT_STRING_FIELDS);
   // Empty tuning fields mean "use xray-core's default" — never emit them.
   dropEmptyStrings(out, ['scMaxEachPostBytes', 'scMinPostsIntervalMs', 'scStreamUpServerSecs']);