feat: 添加浏览器切换所需错误处理，增强步骤 10 的诊断信息

tests/background-auth-chain-guard.test.js

@@ -71,6 +71,7 @@ test('executeStep reuses the active top-level auth chain instead of starting a d
   const api = new Function(`
 const LOG_PREFIX = '[test]';
 const STOP_ERROR_MESSAGE = '流程已被用户停止。';
+const BROWSER_SWITCH_REQUIRED_ERROR_PREFIX = 'BROWSER_SWITCH_REQUIRED::';
 const AUTH_CHAIN_STEP_IDS = new Set([7, 8, 9, 10]);
 let activeTopLevelAuthChainExecution = null;
 let stopRequested = false;
@@ -106,6 +107,10 @@ function isTerminalSecurityBlockedError() {
   return false;
 }
 async function handleCloudflareSecurityBlocked() {}
+function isBrowserSwitchRequiredError() {
+  return false;
+}
+async function handleBrowserSwitchRequired() {}
 function doesStepUseCompletionSignal() {
   return false;
 }
@@ -159,6 +164,95 @@ return {
   assert.ok(events.logs.some(({ message }) => /复用当前授权链/.test(message)));
 });
 
+test('executeStep stops flow when browser-switch-required error is raised', async () => {
+  const api = new Function(`
+const LOG_PREFIX = '[test]';
+const STOP_ERROR_MESSAGE = '流程已被用户停止。';
+const BROWSER_SWITCH_REQUIRED_ERROR_PREFIX = 'BROWSER_SWITCH_REQUIRED::';
+const AUTH_CHAIN_STEP_IDS = new Set([7, 8, 9, 10]);
+let activeTopLevelAuthChainExecution = null;
+let stopRequested = false;
+const events = {
+  logs: [],
+  statusCalls: [],
+  stopRequests: [],
+  appendRecords: [],
+};
+
+async function addLog(message, level = 'info') {
+  events.logs.push({ message, level });
+}
+async function setStepStatus(step, status) {
+  events.statusCalls.push({ step, status });
+}
+async function humanStepDelay() {}
+async function getState() {
+  return {
+    flowStartTime: null,
+    stepStatuses: {},
+  };
+}
+function getErrorMessage(error) {
+  return error?.message || String(error || '');
+}
+async function appendManualAccountRunRecordIfNeeded(status, _state, reason) {
+  events.appendRecords.push({ status, reason });
+}
+function isTerminalSecurityBlockedError() {
+  return false;
+}
+async function handleCloudflareSecurityBlocked() {}
+async function requestStop(options = {}) {
+  events.stopRequests.push(options);
+}
+function doesStepUseCompletionSignal() {
+  return false;
+}
+function isRetryableContentScriptTransportError() {
+  return false;
+}
+const stepRegistry = {
+  async executeStep() {
+    throw new Error('BROWSER_SWITCH_REQUIRED::请更换浏览器进行注册登录。');
+  },
+};
+
+${extractFunction('isStopError')}
+${extractFunction('throwIfStopped')}
+${extractFunction('isAuthChainStep')}
+${extractFunction('acquireTopLevelAuthChainExecution')}
+${extractFunction('isBrowserSwitchRequiredError')}
+${extractFunction('getBrowserSwitchRequiredMessage')}
+${extractFunction('handleBrowserSwitchRequired')}
+${extractFunction('executeStep')}
+
+return {
+  executeStep,
+  snapshot() {
+    return events;
+  },
+};
+`)();
+
+  await assert.rejects(
+    () => api.executeStep(10),
+    /流程已被用户停止。/
+  );
+
+  const events = api.snapshot();
+  assert.deepStrictEqual(events.stopRequests, [
+    { logMessage: '请更换浏览器进行注册登录。' },
+  ]);
+  assert.deepStrictEqual(events.statusCalls, [
+    { step: 10, status: 'running' },
+  ]);
+  assert.equal(
+    events.logs.some(({ message }) => /步骤 10 失败/.test(message)),
+    false,
+    'browser-switch-required error should stop the flow before generic failed logging'
+  );
+});
+
 test('oauth timeout budget ignores stale deadlines from an old oauth url', async () => {
   const api = new Function(`
 const LOG_PREFIX = '[test]';