diff --git a/background.js b/background.js
index 2ef4de9..e1f1324 100644
--- a/background.js
+++ b/background.js
@@ -5600,6 +5600,19 @@ function notifyStepError(step, error) {
   if (waiter) waiter.reject(new Error(error));
 }
 
+async function runCompletedStepSideEffects(step, payload, completionState, lastStepId) {
+  await handleStepData(step, payload);
+  if (step === lastStepId) {
+    await appendAndBroadcastAccountRunRecord('success', completionState);
+  }
+}
+
+async function reportCompletedStepSideEffectError(step, error) {
+  const message = getErrorMessage(error);
+  console.warn(LOG_PREFIX, `[completeStepFromBackground] step ${step} post-completion side effect failed:`, error);
+  await addLog(`步骤 ${step} 已完成，但完成后的收尾处理失败：${message}`, 'warn');
+}
+
 async function completeStepFromBackground(step, payload = {}) {
   if (stopRequested) {
     await setStepStatus(step, 'stopped');
@@ -5615,10 +5628,15 @@ async function completeStepFromBackground(step, payload = {}) {
   const completionState = step === lastStepId ? latestState : null;
   await setStepStatus(step, 'completed');
   await addLog(`步骤 ${step} 已完成`, 'ok');
-  await handleStepData(step, payload);
+
   if (step === lastStepId) {
-    await appendAndBroadcastAccountRunRecord('success', completionState);
+    notifyStepComplete(step, payload);
+    void runCompletedStepSideEffects(step, payload, completionState, lastStepId)
+      .catch((error) => reportCompletedStepSideEffectError(step, error));
+    return;
   }
+
+  await runCompletedStepSideEffects(step, payload, completionState, lastStepId);
   notifyStepComplete(step, payload);
 }
 
diff --git a/tests/background-step-completion.test.js b/tests/background-step-completion.test.js
new file mode 100644
index 0000000..3efe6bf
--- /dev/null
+++ b/tests/background-step-completion.test.js
@@ -0,0 +1,127 @@
+const test = require('node:test');
+const assert = require('node:assert/strict');
+const fs = require('node:fs');
+
+const source = fs.readFileSync('background.js', 'utf8');
+
+function extractFunction(name) {
+  const markers = [`async function ${name}(`, `function ${name}(`];
+  const start = markers
+    .map((marker) => source.indexOf(marker))
+    .find((index) => index >= 0);
+  if (start < 0) {
+    throw new Error(`missing function ${name}`);
+  }
+
+  let parenDepth = 0;
+  let signatureEnded = false;
+  let braceStart = -1;
+  for (let i = start; i < source.length; i += 1) {
+    const ch = source[i];
+    if (ch === '(') {
+      parenDepth += 1;
+    } else if (ch === ')') {
+      parenDepth -= 1;
+      if (parenDepth === 0) {
+        signatureEnded = true;
+      }
+    } else if (ch === '{' && signatureEnded) {
+      braceStart = i;
+      break;
+    }
+  }
+  if (braceStart < 0) {
+    throw new Error(`missing body for function ${name}`);
+  }
+
+  let depth = 0;
+  let end = braceStart;
+  for (; end < source.length; end += 1) {
+    const ch = source[end];
+    if (ch === '{') depth += 1;
+    if (ch === '}') {
+      depth -= 1;
+      if (depth === 0) {
+        end += 1;
+        break;
+      }
+    }
+  }
+
+  return source.slice(start, end);
+}
+
+function createApi(events, lastStepId = 10) {
+  return new Function('events', 'lastStepId', `
+let stopRequested = false;
+const LOG_PREFIX = '[test]';
+const STOP_ERROR_MESSAGE = '流程已被用户停止。';
+const LAST_STEP_ID = 10;
+function getErrorMessage(error) {
+  return error?.message || String(error || '');
+}
+async function getState() {
+  events.push({ type: 'getState' });
+  return { stepStatuses: {}, contributionMode: true };
+}
+function getLastStepIdForState() {
+  return lastStepId;
+}
+async function setStepStatus(step, status) {
+  events.push({ type: 'status', step, status });
+}
+async function addLog(message, level) {
+  events.push({ type: 'log', message, level });
+}
+async function appendManualAccountRunRecordIfNeeded() {
+  events.push({ type: 'manual-record' });
+}
+function notifyStepError(step, error) {
+  events.push({ type: 'error', step, error });
+}
+function notifyStepComplete(step, payload) {
+  events.push({ type: 'notify', step, payload });
+}
+async function handleStepData(step, payload) {
+  events.push({ type: 'handle-start', step, payload });
+  await new Promise((resolve) => setTimeout(resolve, 25));
+  events.push({ type: 'handle-done', step });
+}
+async function appendAndBroadcastAccountRunRecord(status, state) {
+  events.push({ type: 'record', status, state });
+}
+${extractFunction('runCompletedStepSideEffects')}
+${extractFunction('reportCompletedStepSideEffectError')}
+${extractFunction('completeStepFromBackground')}
+return { completeStepFromBackground };
+`)(events, lastStepId);
+}
+
+test('completeStepFromBackground releases final step before slow post-completion side effects', async () => {
+  const events = [];
+  const api = createApi(events, 10);
+
+  await api.completeStepFromBackground(10, { localhostUrl: 'http://localhost:1455/auth/callback?code=ok' });
+
+  const types = events.map((event) => event.type);
+  assert.equal(types.indexOf('notify') < types.indexOf('handle-start'), true);
+  assert.equal(types.includes('handle-done'), false);
+  assert.equal(types.includes('record'), false);
+
+  await new Promise((resolve) => setTimeout(resolve, 40));
+
+  const settledTypes = events.map((event) => event.type);
+  assert.equal(settledTypes.includes('handle-done'), true);
+  assert.equal(settledTypes.includes('record'), true);
+});
+
+test('completeStepFromBackground keeps non-final step data handling before completion signal', async () => {
+  const events = [];
+  const api = createApi(events, 10);
+
+  await api.completeStepFromBackground(9, { localhostUrl: 'http://localhost:1455/auth/callback?code=ok' });
+
+  const types = events.map((event) => event.type);
+  assert.equal(types.indexOf('handle-done') < types.indexOf('notify'), true);
+  assert.equal(types.includes('record'), false);
+});