fix: memoize telegram WSL2 autoSelectFamily decision

src/telegram/network-config.test.ts

@@ -1,5 +1,8 @@
 import { afterEach, describe, expect, it, vi } from "vitest";
-import { resolveTelegramAutoSelectFamilyDecision } from "./network-config.js";
+import {
+  resetTelegramNetworkConfigStateForTests,
+  resolveTelegramAutoSelectFamilyDecision,
+} from "./network-config.js";
 
 // Mock isWSL2Sync at the top level
 vi.mock("../infra/wsl.js", () => ({
@@ -11,6 +14,7 @@ import { isWSL2Sync } from "../infra/wsl.js";
 describe("resolveTelegramAutoSelectFamilyDecision", () => {
   afterEach(() => {
     vi.restoreAllMocks();
+    resetTelegramNetworkConfigStateForTests();
   });
 
   it("prefers env enable over env disable", () => {
@@ -115,5 +119,13 @@ describe("resolveTelegramAutoSelectFamilyDecision", () => {
       const decision = resolveTelegramAutoSelectFamilyDecision({ env: {}, nodeMajor: 22 });
       expect(decision).toEqual({ value: true, source: "default-node22" });
     });
+
+    it("memoizes WSL2 detection across repeated defaults", () => {
+      vi.mocked(isWSL2Sync).mockReset();
+      vi.mocked(isWSL2Sync).mockReturnValue(false);
+      resolveTelegramAutoSelectFamilyDecision({ env: {}, nodeMajor: 22 });
+      resolveTelegramAutoSelectFamilyDecision({ env: {}, nodeMajor: 22 });
+      expect(isWSL2Sync).toHaveBeenCalledTimes(1);
+    });
   });
 });

src/telegram/network-config.ts

@@ -12,6 +12,16 @@ export type TelegramAutoSelectFamilyDecision = {
   source?: string;
 };
 
+let wsl2SyncCache: boolean | undefined;
+
+function isWSL2SyncCached(): boolean {
+  if (typeof wsl2SyncCache === "boolean") {
+    return wsl2SyncCache;
+  }
+  wsl2SyncCache = isWSL2Sync();
+  return wsl2SyncCache;
+}
+
 export function resolveTelegramAutoSelectFamilyDecision(params?: {
   network?: TelegramNetworkConfig;
   env?: NodeJS.ProcessEnv;
@@ -33,7 +43,7 @@ export function resolveTelegramAutoSelectFamilyDecision(params?: {
     return { value: params.network.autoSelectFamily, source: "config" };
   }
   // WSL2 has unstable IPv6 connectivity; disable autoSelectFamily to use IPv4 directly
-  if (isWSL2Sync()) {
+  if (isWSL2SyncCached()) {
     return { value: false, source: "default-wsl2" };
   }
   if (Number.isFinite(nodeMajor) && nodeMajor >= 22) {
@@ -41,3 +51,7 @@ export function resolveTelegramAutoSelectFamilyDecision(params?: {
   }
   return { value: null };
 }
+
+export function resetTelegramNetworkConfigStateForTests(): void {
+  wsl2SyncCache = undefined;
+}