fix: preserve primitive exception messages

apps/extension/src/browser-driver/__tests__/chromium-cdp.test.ts

@@ -852,6 +852,29 @@ describe("ChromiumCdp", () => {
     ]);
   });
 
+  it.each([
+    [{ type: "string", value: "connection token expired" }, "connection token expired"],
+    [{ type: "string", value: "first line\nsecond line" }, "first line"],
+    [{ type: "number", value: 0, description: "0" }, "0"],
+    [{ type: "boolean", value: false }, "false"],
+    [{ type: "object", subtype: "null", value: null }, "null"],
+    [{ type: "undefined" }, "[undefined]"],
+  ])("records the thrown primitive %j in console entries", async (exception, text) => {
+    const { api, onEvent } = fakeApi();
+    const cdp = new ChromiumCdp(api);
+    try {
+      await cdp.ensureAttached(22);
+      onEvent.fire({ tabId: 22 }, "Runtime.exceptionThrown", {
+        exceptionDetails: { text: "Uncaught", exception },
+      });
+      expect(cdp.consoleEntriesSince(22, 0, 50, 1000, false).entries).toMatchObject([
+        { kind: "exception", level: "error", text },
+      ]);
+    } finally {
+      cdp.dispose();
+    }
+  });
+
   it("filters console entries by cursor and caps result size", async () => {
     const { api, onEvent } = fakeApi();
     const cdp = new ChromiumCdp(api);

apps/extension/src/browser-driver/chromium-cdp.ts

@@ -1271,7 +1271,7 @@ export function parseExceptionThrown(params: unknown): ParsedConsoleEntry | null
   const details = (raw.exceptionDetails ?? {}) as Record<string, unknown>;
   const exception = (details.exception ?? {}) as Record<string, unknown>;
   const text =
-    firstLine(typeof exception.description === "string" ? exception.description : undefined) ||
+    firstLine(remoteObjectToText(exception)) ||
     firstLine(typeof details.text === "string" ? details.text : undefined) ||
     "Uncaught (unknown error)";
   return makeConsoleEntry({

apps/extension/src/tools/__tests__/evaluate.test.ts

@@ -221,6 +221,28 @@ describe("handleEvaluate", () => {
     expect(res.error?.column).toBe(8);
   });
 
+  it.each([
+    [{ type: "string", value: "connection token expired" }, "Uncaught connection token expired"],
+    [{ type: "boolean", value: false }, "Uncaught false"],
+    [{ type: "object", subtype: "null", value: null }, "Uncaught null"],
+    [{ type: "number", value: 0, description: "0" }, "0"],
+  ])("preserves a thrown primitive %j ahead of the generic header", async (exception, text) => {
+    const sm = new SessionManager({ agentWindow: fakeAgentWindow([100]) });
+    await sm.start("aa11");
+    const fake = makeFakeCdp({
+      evaluate: () => ({
+        result: exception,
+        exceptionDetails: { text: "Uncaught", lineNumber: 0, columnNumber: 0, exception },
+      }),
+    });
+    const res = await handleEvaluate(
+      sm,
+      { session_id: "aa11", expression: "throw value" },
+      { cdp: fake.cdp, tabsApi: fake.tabsApi },
+    );
+    expect(res).toMatchObject({ ok: false, error: { text, line: 1, column: 0 } });
+  });
+
   it("stringifies unserializableValue (Infinity / NaN / BigInt)", async () => {
     const sm = new SessionManager({ agentWindow: fakeAgentWindow([100]) });
     await sm.start("aa11");

apps/extension/src/tools/evaluate.ts

@@ -75,19 +75,17 @@ function abortedError(signal: AbortSignal | undefined): RpcError | null {
 
 /**
  * Pull a human-readable error text out of CDP's exception payload.
- * Prefers `exception.description` (the full stack) and falls back to
- * `exceptionDetails.text` (the short header). Both are best-effort —
- * Chrome sometimes ships an empty string when the throw value is
- * `null` / `undefined` / a non-Error primitive.
+ * Prefers `exception.description` (the full stack), then a thrown
+ * primitive's value, before falling back to the generic short header.
  */
 function extractErrorText(details: CdpExceptionDetails): string {
   const desc = details.exception?.description?.trim();
   if (desc) return desc;
-  const text = details.text?.trim();
-  if (text) return text;
   if (details.exception?.value !== undefined) {
     return `Uncaught ${String(details.exception.value)}`;
   }
+  const text = details.text?.trim();
+  if (text) return text;
   return "Uncaught (unknown error)";
 }