diff --git a/package.json b/package.json
index 1b87556..7b19b75 100644
--- a/package.json
+++ b/package.json
@@ -1,11 +1,10 @@
 {
   "name": "sd-metadata-extractor",
-  "version": "1.1.0",
+  "version": "1.0.4",
   "description": "Metadata extractor for AI-generated images (Stable Diffusion, NovelAI, ComfyUI, etc.)",
   "main": "index.js",
   "scripts": {
-    "version": "node update-version.js && git add -A",
-    "postversion": "git push && git push --tags"
+    "version": "node update-version.js"
   },
   "repository": {
     "type": "git",
diff --git a/update-version.js b/update-version.js
index f134351..cae59f4 100644
--- a/update-version.js
+++ b/update-version.js
@@ -1,12 +1,42 @@
-// Sync version to __init__.py
+/**
+ * Run by npm during "npm version" (patch/minor/major).
+ */
 const fs = require('fs');
 const path = require('path');
 
+const root = __dirname;
+
 try {
-  const pkgPath = path.join(__dirname, 'package.json');
-  const pkg = JSON.parse(fs.readFileSync(pkgPath, 'utf8'));
+  const pkg = JSON.parse(fs.readFileSync(path.join(root, 'package.json'), 'utf8'));
   const version = pkg.version;
+  const versionTag = 'v' + version;
+
+  // Today's date (YYYY-MM-DD)
+  const today = new Date().toISOString().slice(0, 10);
+
+  // 1. CHANGELOG.md
+  const changelogPath = path.join(root, 'CHANGELOG.md');
+  let changelog = fs.readFileSync(changelogPath, 'utf8');
+  const newSection = `## ${versionTag}
+*${today}*
+
+-
+
+`;
+  changelog = newSection + changelog;
+  fs.writeFileSync(changelogPath, changelog);
+
+  // 2. imgextract.html and standalone.html — replace version in footer
+  const versionRegex = /v\d+\.\d+\.\d+/;
+  for (const name of ['imgextract.html', 'standalone.html']) {
+    const htmlPath = path.join(root, 'static', name);
+    let html = fs.readFileSync(htmlPath, 'utf8');
+    html = html.replace(versionRegex, versionTag);
+    fs.writeFileSync(htmlPath, html);
+  }
+
+  console.log('Updated version to', versionTag, 'in CHANGELOG.md, imgextract.html, standalone.html');
 } catch (err) {
-  console.warn('update-version.js:', err.message);
+  console.error('update-version.js:', err.message);
+  process.exit(1);
 }
-process.exit(0);