diff --git a/.github/workflows/analyze-inactivity.yml b/.github/workflows/analyze-inactivity.yml
new file mode 100644
index 00000000..ad585556
--- /dev/null
+++ b/.github/workflows/analyze-inactivity.yml
@@ -0,0 +1,58 @@
+name: Scheduled Inactivity Analysis
+
+on:
+  schedule:
+    # Triggers the inactivity scan at 05:45, 11:45, 17:45, and 23:45
+    - cron: "45 5,11,17,23 * * *"
+  workflow_dispatch:
+
+jobs:
+  analyze:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout Code Repository
+        uses: actions/checkout@v4
+        with:
+          path: code-repo
+
+      - name: Checkout Data Repository
+        uses: actions/checkout@v4
+        with:
+          repository: "codepvg/leetcode-ranking-data"
+          token: ${{ secrets.DATA_REPO_TOKEN }}
+          path: data-repo
+
+      - name: Set up Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: "20"
+          cache: "npm"
+          cache-dependency-path: "code-repo/package-lock.json"
+
+      - name: Install Dependencies
+        run: |
+          cd code-repo
+          npm install
+
+      - name: Run Inactivity Analysis Script
+        env:
+          DATA_DIR: "${{ github.workspace }}/data-repo"
+        run: |
+          cd code-repo
+          node scripts/analyze-inactivity.js
+
+      - name: Commit and Push to Data Repo
+        run: |
+          cd data-repo
+          git config --global user.name "github-actions[bot]"
+          git config --global user.email "github-actions[bot]@users.noreply.github.com"
+
+          git add inactive-users.json
+
+          if git diff --staged --quiet; then
+            echo "No changes detected in inactivity data."
+          else
+            git commit -m "chore: update scheduled inactive-users.json snapshot"
+            git push
+          fi
diff --git a/scripts/analyze-inactivity.js b/scripts/analyze-inactivity.js
new file mode 100644
index 00000000..1edf819b
--- /dev/null
+++ b/scripts/analyze-inactivity.js
@@ -0,0 +1,106 @@
+"use strict";
+
+const axios = require("axios");
+const fs = require("fs");
+const path = require("path");
+
+const THRESHOLD_DAYS = 90;
+const MS_IN_A_DAY = 1000 * 60 * 60 * 24;
+
+function atomicWrite(filePath, data) {
+  const dir = path.dirname(filePath);
+  const ext = path.extname(filePath);
+  const base = path.basename(filePath, ext);
+  const tmpPath = path.join(
+    dir,
+    `${base}.tmp.${process.pid}.${Date.now()}${ext}`,
+  );
+
+  fs.writeFileSync(tmpPath, JSON.stringify(data, null, 2), "utf8");
+  fs.renameSync(tmpPath, filePath);
+}
+
+async function fetchData(url) {
+  try {
+    const res = await axios.get(url, { timeout: 15000 });
+    return res.data;
+  } catch (err) {
+    console.error(`API failed for ${url}: ${err.message}`);
+    return null;
+  }
+}
+
+(async () => {
+  const DATA_DIR = process.env.DATA_DIR || path.join(__dirname, "..", "data");
+  console.log(`Using data directory: ${DATA_DIR}`);
+
+  console.log("Loading master user list...");
+  const userFilePath = path.join(DATA_DIR, "users.json");
+  let users = [];
+  try {
+    const rawData = fs.readFileSync(userFilePath, "utf8");
+    users = JSON.parse(rawData);
+    console.log(`Loaded ${users.length} users from users.json`);
+  } catch (err) {
+    console.error("Failed to load users.json: ", err.message);
+    process.exit(1);
+  }
+
+  const baseUrl = "https://leetcode-api-dun.vercel.app/";
+  const inactiveUsers = [];
+  const now = new Date();
+
+  console.log(" ");
+  console.log("Starting daily full sync inactivity analysis...");
+
+  for (const user of users) {
+    const username = user.id;
+
+    const profile = await fetchData(baseUrl + username);
+    if (!profile) {
+      console.log(`${username}: skipped (API error)`);
+      continue;
+    }
+
+    const calendar = profile.submissionCalendar;
+    const timestamps = calendar ? Object.keys(calendar).map(Number) : [];
+
+    if (timestamps.length === 0) {
+      console.log(`${username}: Inactive (no submission calendar history)`);
+      inactiveUsers.push(username);
+      continue;
+    }
+
+    const latestTimestampSeconds = Math.max(...timestamps);
+    const lastActiveDate = new Date(latestTimestampSeconds * 1000);
+
+    const diffTime = Math.abs(now - lastActiveDate);
+    const diffDays = Math.floor(diffTime / MS_IN_A_DAY);
+
+    if (diffDays > THRESHOLD_DAYS) {
+      console.log(`${username}: Inactive (${diffDays} days ago)`);
+      inactiveUsers.push(username);
+    } else {
+      console.log(`${username}: Active (${diffDays} days ago)`);
+    }
+  }
+
+  console.log("...");
+  console.log(" ");
+
+  const outputData = {
+    generatedAt: now.toISOString(),
+    thresholdDays: THRESHOLD_DAYS,
+    inactiveUsers: inactiveUsers.sort(),
+  };
+
+  console.log("Writing inactivity analysis data to inactive-users.json...");
+  const outputPath = path.join(DATA_DIR, "inactive-users.json");
+  try {
+    atomicWrite(outputPath, outputData);
+    console.log("Inactivity analysis data updated successfully!");
+  } catch (err) {
+    console.error("Failed to write inactive-users.json: ", err.message);
+    process.exit(1);
+  }
+})();