diff --git a/scripts/build/deps/webkit.ts b/scripts/build/deps/webkit.ts
index 87776fa6480d..9a200dc984cc 100644
--- a/scripts/build/deps/webkit.ts
+++ b/scripts/build/deps/webkit.ts
@@ -3,7 +3,9 @@
  * for local mode. Override via `--webkit-version=<hash>` to test a branch.
  * From https://github.com/oven-sh/WebKit releases.
  */
-export const WEBKIT_VERSION = "e6e37cda216c0292ae68c30c84a9dc8601d0fba5";
+// Preview of oven-sh/WebKit#385: guard InspectorDebuggerAgent::disable() so a redundant
+// Debugger.disable does not trip ASSERT(!!m_client != !!client) in JSC::Debugger::setClient.
+export const WEBKIT_VERSION = "autobuild-preview-pr-385-10e1ab9b";
 
 /**
  * WebKit (JavaScriptCore) — the JS engine.
diff --git a/test/cli/inspect/inspect-debugger-disable.test.ts b/test/cli/inspect/inspect-debugger-disable.test.ts
new file mode 100644
index 000000000000..5543d90b0d9d
--- /dev/null
+++ b/test/cli/inspect/inspect-debugger-disable.test.ts
@@ -0,0 +1,92 @@
+import { spawn } from "bun";
+import { expect, test } from "bun:test";
+import { bunEnv, bunExe, isASAN, isDebug } from "harness";
+
+// InspectorDebuggerAgent::disable() used to call internalDisable() unconditionally, so a
+// Debugger.disable on an already-disabled agent (or before any enable) re-ran
+// m_debugger.setClient(nullptr) and tripped ASSERT(!!m_client != !!client) in
+// JSC::Debugger::setClient. Frontends send Debugger.disable liberally on teardown, so this is
+// an ordinary sequence. The assert is ASSERT_ENABLED-only, hence the skipIf.
+test.skipIf(!isDebug && !isASAN)("Debugger.disable is idempotent and does not abort on asserts builds", async () => {
+  await using child = spawn({
+    cmd: [bunExe(), "--inspect=127.0.0.1:0", "-e", "setInterval(()=>{},1000)"],
+    env: bunEnv,
+    stdout: "ignore",
+    stderr: "pipe",
+  });
+
+  let stderr = "";
+  const decoder = new TextDecoder();
+  const { promise: urlPromise, resolve: resolveUrl, reject: rejectUrl } = Promise.withResolvers<URL>();
+  const stderrDrained = (async () => {
+    for await (const chunk of child.stderr) {
+      stderr += decoder.decode(chunk);
+      const m = stderr.match(/ws:\/\/[^\s]+/);
+      if (m) resolveUrl(new URL(m[0]));
+    }
+    rejectUrl(new Error("inspectee exited before printing inspector URL:\n" + stderr));
+  })();
+
+  const url = await urlPromise;
+  const ws = new WebSocket(url);
+  const replies: Record<number, unknown> = {};
+  try {
+    let nextId = 1;
+    let failed: unknown;
+    const pending = new Map<number, (x: unknown) => void>();
+    const send = (method: string, params: object = {}) =>
+      new Promise<unknown>(resolve => {
+        if (failed) return resolve(failed);
+        const id = nextId++;
+        pending.set(id, resolve);
+        ws.send(JSON.stringify({ id, method, params }));
+      });
+    const fail = (r: unknown) => {
+      failed ??= r;
+      for (const p of pending.values()) p(r);
+      pending.clear();
+    };
+    ws.addEventListener("message", ev => {
+      const msg = JSON.parse(String(ev.data));
+      if (typeof msg.id === "number" && pending.has(msg.id)) {
+        replies[msg.id] = msg;
+        pending.get(msg.id)!(msg);
+        pending.delete(msg.id);
+      }
+    });
+    ws.addEventListener("close", ({ code, reason }) => fail({ closed: { code, reason } }));
+    ws.addEventListener("error", cause => fail({ error: String(cause) }));
+    await new Promise<void>((resolve, reject) => {
+      ws.addEventListener("open", () => resolve());
+      ws.addEventListener("error", cause => reject(new Error("WebSocket error", { cause })));
+    });
+
+    // Disable before any enable: m_enabled is false at startup, so the agent must early-return.
+    await send("Debugger.disable");
+    // Enable, disable, disable: the second disable must be a no-op, not a second setClient(nullptr).
+    await send("Debugger.enable");
+    await send("Debugger.disable");
+    await send("Debugger.disable");
+    // The agent must still be usable afterwards.
+    await send("Debugger.enable");
+    await send("Debugger.disable");
+  } finally {
+    ws.close();
+    child.kill();
+  }
+
+  await Promise.all([child.exited, stderrDrained.catch(() => {})]);
+  if (child.signalCode === "SIGABRT") {
+    throw new Error(
+      `inspectee aborted on Debugger.disable (replies=${JSON.stringify(replies)}):\n${stderr.slice(-2000)}`,
+    );
+  }
+  expect(replies).toEqual({
+    1: { id: 1, result: {} },
+    2: { id: 2, result: {} },
+    3: { id: 3, result: {} },
+    4: { id: 4, result: {} },
+    5: { id: 5, result: {} },
+    6: { id: 6, result: {} },
+  });
+});