ci: add per-file handle-leak diagnostic to inprocess Node legs

Runs the inprocess transport legs with --no-file-parallelism plus a setup
file that logs active-resource deltas per test file, so cumulative native
handle growth can be attributed to the leaking file. Diagnostic only; gated
by VITEST_LEAK_BY_FILE and scoped to the inprocess matrix legs.

Author: SteveSandersonMS

.github/workflows/nodejs-sdk-tests.yml

@@ -80,8 +80,14 @@ jobs:
         if: matrix.transport == 'inprocess'
         run: |
           echo "COPILOT_SDK_DEFAULT_CONNECTION=inprocess" >> "$GITHUB_ENV"
+          echo "VITEST_LEAK_BY_FILE=1" >> "$GITHUB_ENV"
 
       - name: Run Node.js SDK tests
         env:
           COPILOT_HMAC_KEY: ${{ secrets.COPILOT_DEVELOPER_CLI_INTEGRATION_HMAC_KEY }}
-        run: npm test
+        run: |
+          if [ "${{ matrix.transport }}" = "inprocess" ]; then
+            npm test -- --no-file-parallelism --reporter=default --reporter=hanging-process
+          else
+            npm test
+          fi

nodejs/test/diagnostics/leakByFile.ts

@@ -0,0 +1,47 @@
+import { afterAll, beforeAll } from "vitest";
+
+// Diagnostic (opt-in via VITEST_LEAK_BY_FILE=1): with --no-file-parallelism all
+// files share one worker, so logging the active-resource counts before/after each
+// file attributes cumulative native-handle growth to the file that caused it.
+
+function countByType(): Record<string, number> {
+    const info = (process as unknown as { getActiveResourcesInfo?: () => string[] }).getActiveResourcesInfo?.() ?? [];
+    const counts: Record<string, number> = {};
+    for (const t of info) counts[t] = (counts[t] ?? 0) + 1;
+    return counts;
+}
+
+function total(counts: Record<string, number>): number {
+    return Object.values(counts).reduce((a, b) => a + b, 0);
+}
+
+const testFile = (() => {
+    try {
+        // eslint-disable-next-line @typescript-eslint/no-explicit-any
+        const fp = (globalThis as any).__vitest_worker__?.filepath as string | undefined;
+        return fp ? fp.replace(/\\/g, "/").split("/").slice(-2).join("/") : "<unknown>";
+    } catch {
+        return "<unknown>";
+    }
+})();
+
+let before: Record<string, number> = {};
+
+beforeAll(() => {
+    before = countByType();
+});
+
+afterAll(() => {
+    const after = countByType();
+    const delta = total(after) - total(before);
+    const typeDeltas: string[] = [];
+    const keys = new Set([...Object.keys(before), ...Object.keys(after)]);
+    for (const k of keys) {
+        const d = (after[k] ?? 0) - (before[k] ?? 0);
+        if (d !== 0) typeDeltas.push(`${k}:${d > 0 ? "+" : ""}${d}`);
+    }
+    // eslint-disable-next-line no-console
+    console.log(
+        `[LEAKDIAG] ${testFile} deltaTotal=${delta} nowTotal=${total(after)} ${typeDeltas.join(" ")}`
+    );
+});

nodejs/vitest.config.ts

@@ -9,6 +9,8 @@ export default defineConfig({
         teardownTimeout: 10000,
         isolate: true, // Run each test file in isolation
         pool: "forks", // Use process forking for better isolation
+        setupFiles:
+            process.env.VITEST_LEAK_BY_FILE === "1" ? ["./test/diagnostics/leakByFile.ts"] : [],
         // Exclude our ad-hoc test files that aren't vitest-based
         exclude: [
             "**/node_modules/**",