diff --git a/packages/cli/src/browser/downloadStall.process.test.ts b/packages/cli/src/browser/downloadStall.process.test.ts
index 6f0af07b11..20cf3d525c 100644
--- a/packages/cli/src/browser/downloadStall.process.test.ts
+++ b/packages/cli/src/browser/downloadStall.process.test.ts
@@ -40,15 +40,14 @@ async function runFixture(onConnection: (socket: Socket) => void) {
   });
   let stderr = "";
   child.stderr.on("data", (chunk) => (stderr += chunk));
-  const startedAt = Date.now();
   const code = await new Promise<number | null>((resolve) => {
-    const giveUp = setTimeout(() => resolve(null), 20_000);
+    const giveUp = setTimeout(() => resolve(null), 110_000);
     child.once("exit", (exitCode) => {
       clearTimeout(giveUp);
       resolve(exitCode);
     });
   });
-  return { code, stderr, port, home, elapsedMs: Date.now() - startedAt };
+  return { code, stderr, port, home };
 }
 
 it("exits with code 1 when the download host accepts the connection and never answers", async () => {
@@ -58,21 +57,4 @@ it("exits with code 1 when the download host accepts the connection and never an
   expect(run.stderr).toContain(`The Chrome download from 127.0.0.1:${run.port} stalled`);
   expect(run.stderr).toContain("Retrying (2/2)");
   expect(existsSync(join(run.home, ".cache", "hyperframes", ".chrome.install.lock"))).toBe(false);
-}, 30_000);
-
-it("does not call a download that keeps sending bytes a stall", async () => {
-  const run = await runFixture((socket) => {
-    socket.once("data", () => {
-      socket.write("HTTP/1.1 200 OK\r\ncontent-length: 100000\r\n\r\n");
-      const trickle = setInterval(() => socket.write("x"), 80);
-      setTimeout(() => {
-        clearInterval(trickle);
-        socket.destroy();
-      }, 1_200);
-    });
-  });
-
-  expect(run.code).toBe(1);
-  expect(run.stderr).not.toContain("no data for");
-  expect(run.elapsedMs).toBeGreaterThan(1_000);
-}, 30_000);
+}, 120_000);
diff --git a/packages/cli/src/browser/installInChild.test.ts b/packages/cli/src/browser/installInChild.test.ts
new file mode 100644
index 0000000000..0c1798ec85
--- /dev/null
+++ b/packages/cli/src/browser/installInChild.test.ts
@@ -0,0 +1,60 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
+import { installProgressLine } from "./installProtocol.js";
+
+const worker = vi.hoisted(() => ({
+  options: undefined as { signal: AbortSignal; onStdout: (chunk: string) => void } | undefined,
+  finish: undefined as ((paths: string) => void) | undefined,
+}));
+
+vi.mock("../utils/cancellableProcess.js", () => ({
+  runRenderSetupWorker: (_mode: string, _input: unknown, options: typeof worker.options) => {
+    worker.options = options;
+    return new Promise<string>((resolve, reject) => {
+      worker.finish = resolve;
+      options!.signal.addEventListener("abort", () => reject(options!.signal.reason));
+    });
+  },
+}));
+
+const { BrowserDownloadStalledError, installInChild } = await import("./installInChild.js");
+
+const STALL_MS = 200;
+const input = {
+  browser: "chrome-headless-shell",
+  buildId: "1",
+  cacheDir: "/x",
+  unpack: false,
+} as const;
+
+beforeEach(() => vi.useFakeTimers());
+afterEach(() => vi.useRealTimers());
+
+describe("installInChild stall watchdog", () => {
+  it("does not call a download that keeps reporting progress a stall", async () => {
+    const result = installInChild(input as never, {
+      stallMs: STALL_MS,
+      host: "h",
+      onLog: () => {},
+    });
+    for (let downloaded = 1; downloaded <= 100; downloaded++) {
+      await vi.advanceTimersByTimeAsync(STALL_MS - 1);
+      worker.options!.onStdout(installProgressLine(downloaded, 1000));
+    }
+    expect(worker.options!.signal.aborted).toBe(false);
+    worker.finish!("done");
+    await expect(result).resolves.toBe("done");
+  });
+
+  it("aborts with the host and window once no progress arrives for the stall window", async () => {
+    const result = installInChild(input as never, {
+      stallMs: STALL_MS,
+      host: "h",
+      onLog: () => {},
+    });
+    const rejected = expect(result).rejects.toThrow(BrowserDownloadStalledError);
+    worker.options!.onStdout(installProgressLine(1, 100));
+    await vi.advanceTimersByTimeAsync(STALL_MS);
+    await rejected;
+    await expect(result).rejects.toThrow("The Chrome download from h stalled: no data for 0.2s.");
+  });
+});
diff --git a/packages/studio-server/src/history/projectHistory.test.ts b/packages/studio-server/src/history/projectHistory.test.ts
index e6199dffe9..d1c9f90431 100644
--- a/packages/studio-server/src/history/projectHistory.test.ts
+++ b/packages/studio-server/src/history/projectHistory.test.ts
@@ -36,6 +36,7 @@ import { openBlobStore } from "./blobStore";
 // A test can hold a media copy, and run work after its blob is stored but before history records it.
 const mediaCopy = vi.hoisted(() => ({
   held: null as Promise<void> | null,
+  entered: null as (() => void) | null,
   stored: null as (() => Promise<unknown>) | null,
   copies: [] as string[],
   fails: null as ((copy: number) => boolean) | null,
@@ -50,6 +51,7 @@ vi.mock("./blobStore", async (importOriginal) => {
         ...store,
         put: async (path: string) => {
           if (path.endsWith(".bin")) {
+            mediaCopy.entered?.();
             await mediaCopy.held;
             mediaCopy.copies.push(basename(path));
             if (mediaCopy.fails?.(mediaCopy.copies.length)) throw new Error("The disk is full.");
@@ -70,7 +72,7 @@ const cleanup: Array<() => unknown> = [];
 
 afterEach(async () => {
   for (const step of cleanup.splice(0).reverse()) await step();
-  Object.assign(mediaCopy, { held: null, stored: null, copies: [], fails: null });
+  Object.assign(mediaCopy, { held: null, entered: null, stored: null, copies: [], fails: null });
 });
 
 const inside = (dir: string, path: string) => readFileSync(join(dir, path), "utf-8");
@@ -366,11 +368,13 @@ describe("openProjectHistory", () => {
   it("never copies the media of a folder that replaced the project", async () => {
     let release = () => {};
     mediaCopy.held = new Promise<void>((resolve) => (release = resolve));
+    const firstCopyRunning = new Promise<void>((resolve) => (mediaCopy.entered = resolve));
     const media = {
       "a.bin": Buffer.alloc(2 * 1024 ** 2, 1),
       "b.bin": Buffer.alloc(2 * 1024 ** 2, 2),
     };
     const { history, write, projectDir } = await project({ "index.html": "A", ...media });
+    await firstCopyRunning;
     renameSync(projectDir, `${projectDir}-moved`);
     cleanup.push(() => rmSync(`${projectDir}-moved`, { recursive: true, force: true }));
     mkdirSync(projectDir);