diff --git a/packages/browser-runtime/src/automation/cdp-commander.test.ts b/packages/browser-runtime/src/automation/cdp-commander.test.ts
new file mode 100644
index 00000000..96e4af38
--- /dev/null
+++ b/packages/browser-runtime/src/automation/cdp-commander.test.ts
@@ -0,0 +1,49 @@
+import { beforeEach, describe, expect, it, vi } from "vitest";
+import { CdpCommander, rejectPendingCommands } from "./cdp-commander";
+
+describe("CdpCommander", () => {
+  let commandCallback: ((result?: unknown) => void) | undefined;
+
+  beforeEach(() => {
+    vi.useFakeTimers();
+    commandCallback = undefined;
+    global.chrome = {
+      debugger: {
+        sendCommand: vi.fn((_target, _command, _params, callback) => {
+          commandCallback = callback as (result?: unknown) => void;
+        }),
+      },
+      runtime: { lastError: undefined },
+    } as unknown as typeof chrome;
+  });
+
+  it("rejects a pending CDP command when its signal is aborted", async () => {
+    const controller = new AbortController();
+    const pending = new CdpCommander(1, controller.signal).sendCommand(
+      "Accessibility.getFullAXTree",
+      {},
+    );
+    controller.abort(new Error("cancel CDP"));
+
+    await expect(pending).rejects.toThrow("cancel CDP");
+    expect(() => commandCallback?.({ nodes: [] })).not.toThrow();
+  });
+
+  it("rejects commands when debugger cleanup starts", async () => {
+    const pending = new CdpCommander(2).sendCommand("DOM.enable", {});
+    rejectPendingCommands(2, "Debugger detaching");
+
+    await expect(pending).rejects.toThrow(
+      "CDP command 'DOM.enable' aborted: Debugger detaching",
+    );
+  });
+
+  it("cleans up a command after its own timeout", async () => {
+    const pending = new CdpCommander(3).sendCommand("DOM.getDocument", {}, 50);
+    const assertion = expect(pending).rejects.toThrow("timed out after 50ms");
+    await vi.advanceTimersByTimeAsync(50);
+    await assertion;
+
+    expect(() => rejectPendingCommands(3, "late cleanup")).not.toThrow();
+  });
+});
diff --git a/packages/browser-runtime/src/automation/cdp-commander.ts b/packages/browser-runtime/src/automation/cdp-commander.ts
index b5d3d678..d05da88f 100644
--- a/packages/browser-runtime/src/automation/cdp-commander.ts
+++ b/packages/browser-runtime/src/automation/cdp-commander.ts
@@ -8,37 +8,58 @@ const DEFAULT_CDP_TIMEOUT = 10000;
 
 const pendingCommands = new Map<
   number,
-  Set<{ reject: (error: Error) => void; command: string }>
+  Set<{ abort: (error: Error) => void; command: string }>
 >();
 
 export function rejectPendingCommands(tabId: number, reason: string): void {
   const pending = pendingCommands.get(tabId);
   if (pending) {
-    for (const { reject, command } of pending) {
-      reject(new Error(`CDP command '${command}' aborted: ${reason}`));
+    for (const { abort, command } of [...pending]) {
+      abort(new Error(`CDP command '${command}' aborted: ${reason}`));
     }
-    pending.clear();
     pendingCommands.delete(tabId);
   }
 }
 
 export class CdpCommander {
-  constructor(readonly tabId: number) {}
+  constructor(
+    readonly tabId: number,
+    private readonly signal?: AbortSignal,
+  ) {}
 
   async sendCommand<T = unknown>(
     command: string,
     params: Record<string, unknown>,
     timeout: number = DEFAULT_CDP_TIMEOUT,
+    signal: AbortSignal | undefined = this.signal,
   ): Promise<T> {
     return new Promise((resolve, reject) => {
-      const pendingEntry = { reject, command };
-
-      const timeoutId = setTimeout(() => {
+      let settled = false;
+      let timeoutId: ReturnType<typeof setTimeout>;
+      const cleanup = () => {
+        clearTimeout(timeoutId);
+        signal?.removeEventListener("abort", handleAbort);
         const pending = pendingCommands.get(this.tabId);
-        if (pending) {
-          pending.delete(pendingEntry);
-        }
-        reject(
+        pending?.delete(pendingEntry);
+        if (pending?.size === 0) pendingCommands.delete(this.tabId);
+      };
+      const rejectCommand = (error: Error) => {
+        if (settled) return;
+        settled = true;
+        cleanup();
+        reject(error);
+      };
+      const handleAbort = () => {
+        rejectCommand(
+          signal?.reason instanceof Error
+            ? signal.reason
+            : new Error(`CDP command '${command}' aborted`),
+        );
+      };
+      const pendingEntry = { abort: rejectCommand, command };
+
+      timeoutId = setTimeout(() => {
+        rejectCommand(
           new Error(`CDP command '${command}' timed out after ${timeout}ms`),
         );
       }, timeout);
@@ -47,23 +68,25 @@ export class CdpCommander {
         pendingCommands.set(this.tabId, new Set());
       }
       pendingCommands.get(this.tabId)!.add(pendingEntry);
+      signal?.addEventListener("abort", handleAbort, { once: true });
+      if (signal?.aborted) {
+        handleAbort();
+        return;
+      }
 
       chrome.debugger.sendCommand(
         { tabId: this.tabId },
         command,
         params,
         (result) => {
-          clearTimeout(timeoutId);
-
-          const pending = pendingCommands.get(this.tabId);
-          if (pending) {
-            pending.delete(pendingEntry);
-          }
-
-          if (chrome.runtime.lastError) {
+          const lastError = chrome.runtime.lastError;
+          if (settled) return;
+          settled = true;
+          cleanup();
+          if (lastError) {
             reject(
               new Error(
-                `Failed to send CDP command '${command}': ${chrome.runtime.lastError.message}`,
+                `Failed to send CDP command '${command}': ${lastError.message}`,
               ),
             );
           } else {