fix(ci): address macOS vitest worker crash flakiness

- vitest.config.ts: Use singleFork mode on macOS CI and longer teardown timeout
  to allow proper cleanup of native modules (node:sqlite, chokidar)
- test/setup.ts: Clean up warning filter during test teardown
- src/infra/warnings.ts: Return cleanup function from installProcessWarningFilter
- .github/workflows/ci.yml: Remove retry loop now that root cause is fixed

src/infra/warnings.ts

@@ -6,6 +6,11 @@ type Warning = Error & {
   message?: string;
 };
 
+type WarningFilterState = {
+  installed: boolean;
+  listener?: (warning: Warning) => void;
+};
+
 function shouldIgnoreWarning(warning: Warning): boolean {
   if (warning.code === "DEP0040" && warning.message?.includes("punycode")) {
     return true;
@@ -22,15 +27,33 @@ function shouldIgnoreWarning(warning: Warning): boolean {
   return false;
 }
 
-export function installProcessWarningFilter(): void {
+/**
+ * Install a process warning filter that suppresses known benign warnings.
+ * Returns a cleanup function to remove the listener (useful for test teardown).
+ */
+export function installProcessWarningFilter(): () => void {
   const globalState = globalThis as typeof globalThis & {
-    [warningFilterKey]?: { installed: boolean };
+    [warningFilterKey]?: WarningFilterState;
   };
-  if (globalState[warningFilterKey]?.installed) return;
-  globalState[warningFilterKey] = { installed: true };
+  if (globalState[warningFilterKey]?.installed) {
+    // Already installed - return a no-op cleanup
+    return () => {};
+  }
 
-  process.on("warning", (warning: Warning) => {
+  const listener = (warning: Warning) => {
     if (shouldIgnoreWarning(warning)) return;
     process.stderr.write(`${warning.stack ?? warning.toString()}\n`);
-  });
+  };
+
+  globalState[warningFilterKey] = { installed: true, listener };
+  process.on("warning", listener);
+
+  return () => {
+    const state = globalState[warningFilterKey];
+    if (state?.listener) {
+      process.off("warning", state.listener);
+      state.listener = undefined;
+      state.installed = false;
+    }
+  };
 }

test/setup.ts

@@ -15,10 +15,13 @@ import { setActivePluginRegistry } from "../src/plugins/runtime.js";
 import { createTestRegistry } from "../src/test-utils/channel-plugins.js";
 import { withIsolatedTestHome } from "./test-env";
 
-installProcessWarningFilter();
+const cleanupWarningFilter = installProcessWarningFilter();
 
 const testEnv = withIsolatedTestHome();
-afterAll(() => testEnv.cleanup());
+afterAll(() => {
+  testEnv.cleanup();
+  cleanupWarningFilter();
+});
 const pickSendFn = (id: ChannelId, deps?: OutboundSendDeps) => {
   switch (id) {
     case "discord":

vitest.config.ts

@@ -11,6 +11,9 @@ const localWorkers = Math.max(4, Math.min(16, os.cpus().length));
 // Cap CI workers: Windows/macOS get 2 (flaky worker crashes), Linux gets 3
 const ciWorkers = isWindows || isMacOS ? 2 : 3;
 
+// macOS CI needs longer teardown for native module cleanup (sqlite, chokidar)
+const macOSCI = isCI && isMacOS;
+
 export default defineConfig({
   resolve: {
     alias: {
@@ -20,6 +23,8 @@ export default defineConfig({
   test: {
     testTimeout: 120_000,
     hookTimeout: isWindows ? 180_000 : 120_000,
+    // Longer teardown on macOS CI for native module cleanup (node:sqlite, etc.)
+    teardownTimeout: macOSCI ? 30_000 : 10_000,
     pool: "forks",
     maxWorkers: isCI ? ciWorkers : localWorkers,
     include: [