fix(inspector): drain discovery requests after sibling failure (#9598)

fix(inspector): drain failed discovery requests

src/inspector/V8InspectorEndpoint.test.ts

@@ -3,6 +3,7 @@ import { createServer } from "node:http";
 import { expect, it } from "vitest";
 
 import { V8InspectorProvider } from "./V8InspectorProvider.js";
+import { awaitAcknowledgement } from "../../tests/fixtures/lifecycleAcknowledgement.js";
 import { startFakeV8Inspector } from "../../tests/fixtures/inspector/fakeV8Inspector.js";
 import { projectAnalysisError } from "../domain/analysisErrorProjection.js";
 
@@ -149,3 +150,97 @@ it("keeps connectable siblings when a target omits its direct socket", async ()
     await new Promise<void>((resolve) => server.close(() => resolve()));
   }
 });
+
+it.each(["/json/version", "/json/list"])(
+  "closes the other discovery request when %s fails",
+  async (failedPath) => {
+    let failedResponse: import("node:http").ServerResponse | undefined;
+    let held = false;
+    let heldClosed!: () => void;
+    const closed = new Promise<void>((resolve) => {
+      heldClosed = resolve;
+    });
+    const server = createServer((request, response) => {
+      if (request.url === failedPath) {
+        failedResponse = response;
+      } else {
+        held = true;
+        request.on("close", heldClosed);
+      }
+      if (held) failedResponse?.writeHead(500).end();
+    });
+    await new Promise<void>((resolve) =>
+      server.listen(0, "127.0.0.1", resolve),
+    );
+    const address = server.address();
+    if (address === null || typeof address === "string")
+      throw new Error("no address");
+    const provider = new V8InspectorProvider();
+    try {
+      const result = await provider.listTargets({
+        inspector_endpoint: `http://127.0.0.1:${address.port}`,
+      });
+      if (result.ok) throw new Error("expected discovery failure");
+      expect(projectAnalysisError(result.error).code).toBe("unreadable_output");
+      await awaitAcknowledgement(
+        closed,
+        new Promise<never>(() => undefined),
+        "pending discovery socket close",
+      );
+    } finally {
+      server.closeAllConnections();
+      await new Promise<void>((resolve, reject) =>
+        server.close((error) => (error ? reject(error) : resolve())),
+      );
+      await provider.close();
+    }
+  },
+);
+
+it("closes both discovery requests and retains caller cancellation", async () => {
+  let arrived = 0;
+  let released = 0;
+  let acknowledgeStarted!: () => void;
+  let acknowledgeClosed!: () => void;
+  const started = new Promise<void>((resolve) => {
+    acknowledgeStarted = resolve;
+  });
+  const closed = new Promise<void>((resolve) => {
+    acknowledgeClosed = resolve;
+  });
+  const server = createServer((request) => {
+    request.on("close", () => {
+      if (++released === 2) acknowledgeClosed();
+    });
+    if (++arrived === 2) acknowledgeStarted();
+  });
+  await new Promise<void>((resolve) => server.listen(0, "127.0.0.1", resolve));
+  const address = server.address();
+  if (address === null || typeof address === "string")
+    throw new Error("no address");
+  const provider = new V8InspectorProvider();
+  const controller = new AbortController();
+  const reason = new Error("caller stopped observation");
+  const operation = provider.listTargets(
+    { inspector_endpoint: `http://127.0.0.1:${address.port}` },
+    { signal: controller.signal },
+  );
+  try {
+    await awaitAcknowledgement(started, operation, "both discovery requests");
+    controller.abort(reason);
+    const result = await operation;
+    if (result.ok) throw new Error("expected cancellation");
+    expect(result.error.cause).toBe(reason);
+    await awaitAcknowledgement(
+      closed,
+      new Promise<never>(() => undefined),
+      "cancelled discovery sockets",
+    );
+  } finally {
+    server.closeAllConnections();
+    await new Promise<void>((resolve, reject) =>
+      server.close((error) => (error ? reject(error) : resolve())),
+    );
+    await provider.close();
+  }
+});

src/inspector/V8InspectorEndpoint.ts

@@ -39,10 +39,24 @@ export const discoverV8Inspector = async (
   operation: BrowserObservationOperation,
   signal?: AbortSignal,
 ): Promise<V8InspectorDiscovery> => {
-  const [versionInput, targetsInput] = await Promise.all([
-    readCdpJson(new URL("/json/version", endpoint), operation, signal),
-    readCdpJson(new URL("/json/list", endpoint), operation, signal),
-  ]);
+  const controller = new AbortController();
+  const discoverySignal =
+    signal === undefined
+      ? controller.signal
+      : AbortSignal.any([signal, controller.signal]);
+  const reads = [
+    readCdpJson(new URL("/json/version", endpoint), operation, discoverySignal),
+    readCdpJson(new URL("/json/list", endpoint), operation, discoverySignal),
+  ] as const;
+  let versionInput: unknown;
+  let targetsInput: unknown;
+  try {
+    [versionInput, targetsInput] = await Promise.all(reads);
+  } catch (cause: unknown) {
+    controller.abort(cause);
+    await Promise.allSettled(reads);
+    throw cause;
+  }
   const version = parseCdpEndpointValue(versionSchema, versionInput, operation);
   const { targets, limitations, ambiguousTargetIds } = parseCdpDiscoveryTargets(
     targetsInput,