fix(oauth): harden browser launch handling

packages/ai/test/github-copilot-oauth.test.ts

@@ -84,6 +84,97 @@ describe("GitHub Copilot OAuth device flow", () => {
 		await loginPromise;
 	});
 
+	it("rejects a non-http(s) verification_uri before it reaches onDeviceCode", async () => {
+		// A malicious enterprise OAuth server could return a verification_uri that
+		// the browser launcher would otherwise hand to the OS. Ensure such values
+		// are rejected at the deserialization boundary.
+		const fetchMock = vi.fn(async (input: unknown): Promise<Response> => {
+			const url = getUrl(input);
+			if (url.endsWith("/login/device/code")) {
+				return jsonResponse({
+					device_code: "device-code",
+					user_code: "ABCD-EFGH",
+					verification_uri: "$(id>/tmp/pwned)",
+					interval: 1,
+					expires_in: 900,
+				});
+			}
+			throw new Error(`Unexpected fetch URL: ${url}`);
+		});
+
+		vi.stubGlobal("fetch", fetchMock);
+
+		const onDeviceCode = vi.fn();
+		await expect(
+			loginGitHubCopilot({
+				onDeviceCode,
+				onPrompt: async () => "",
+			}),
+		).rejects.toThrow(/Untrusted verification_uri/);
+		expect(onDeviceCode).not.toHaveBeenCalled();
+	});
+
+	it("normalizes verification_uri before it reaches onDeviceCode", async () => {
+		vi.useFakeTimers();
+		vi.setSystemTime(new Date("2026-03-09T00:00:00Z"));
+
+		const rawVerificationUri = "https://github.com/login/\x1b]8;;evil";
+		const normalizedVerificationUri = new URL(rawVerificationUri).href;
+		expect(normalizedVerificationUri).not.toBe(rawVerificationUri);
+
+		const fetchMock = vi.fn(async (input: unknown): Promise<Response> => {
+			const url = getUrl(input);
+
+			if (url.endsWith("/login/device/code")) {
+				return jsonResponse({
+					device_code: "device-code",
+					user_code: "ABCD-EFGH",
+					verification_uri: rawVerificationUri,
+					interval: 1,
+					expires_in: 900,
+				});
+			}
+
+			if (url.endsWith("/login/oauth/access_token")) {
+				return jsonResponse({ access_token: "ghu_refresh_token" });
+			}
+
+			if (url.includes("/copilot_internal/v2/token")) {
+				return jsonResponse({
+					token: "tid=test;exp=9999999999;proxy-ep=proxy.individual.githubcopilot.com;",
+					expires_at: 9999999999,
+				});
+			}
+
+			if (url.includes("/models/") && url.endsWith("/policy")) {
+				return new Response("", { status: 200 });
+			}
+
+			throw new Error(`Unexpected fetch URL: ${url}`);
+		});
+
+		vi.stubGlobal("fetch", fetchMock);
+
+		const onDeviceCode = vi.fn();
+		const loginPromise = loginGitHubCopilot({
+			onDeviceCode,
+			onPrompt: async () => "",
+		});
+
+		await vi.advanceTimersByTimeAsync(0);
+
+		expect(onDeviceCode).toHaveBeenCalledWith({
+			userCode: "ABCD-EFGH",
+			verificationUri: normalizedVerificationUri,
+			intervalSeconds: 1,
+			expiresInSeconds: 900,
+		});
+		expect(onDeviceCode).not.toHaveBeenCalledWith(expect.objectContaining({ verificationUri: rawVerificationUri }));
+
+		await vi.advanceTimersByTimeAsync(1000);
+		await loginPromise;
+	});
+
 	it("polls immediately and increases the interval after slow_down", async () => {
 		vi.useFakeTimers();
 		const startTime = new Date("2026-03-09T00:00:00Z");