fix(changelog): skip popup on first install

First-time users have no context for the changelog — suppress the
auto-popup and badge so they can explore the extension first.  The
changelog remains accessible manually.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: Nagi-ovo

src/pages/content/changelog/__tests__/changelog.test.ts

@@ -1,7 +1,10 @@
-import { describe, expect, it } from 'vitest';
+import { beforeEach, describe, expect, it, vi } from 'vitest';
+
+import { StorageKeys } from '@/core/types/common';
 
 import {
   extractLocalizedContent,
+  hasUnreadChangelog,
   resolveChangelogImageUrl,
   rewriteChangelogImageUrls,
 } from '../index';
@@ -160,3 +163,29 @@ describe('rewriteChangelogImageUrls', () => {
     expect(result).toBe(source);
   });
 });
+
+describe('hasUnreadChangelog', () => {
+  beforeEach(() => {
+    vi.restoreAllMocks();
+  });
+
+  it('returns false on first install (no dismissed version stored)', async () => {
+    (chrome.storage.local.get as ReturnType<typeof vi.fn>).mockResolvedValue({});
+    expect(await hasUnreadChangelog()).toBe(false);
+  });
+
+  it('returns true when dismissed version differs from current', async () => {
+    (chrome.storage.local.get as ReturnType<typeof vi.fn>).mockResolvedValue({
+      [StorageKeys.CHANGELOG_DISMISSED_VERSION]: '0.0.1',
+    });
+    expect(await hasUnreadChangelog()).toBe(true);
+  });
+
+  it('returns false when dismissed version matches current', async () => {
+    const { EXTENSION_VERSION } = await import('@/core/utils/version');
+    (chrome.storage.local.get as ReturnType<typeof vi.fn>).mockResolvedValue({
+      [StorageKeys.CHANGELOG_DISMISSED_VERSION]: EXTENSION_VERSION,
+    });
+    expect(await hasUnreadChangelog()).toBe(false);
+  });
+});

src/pages/content/changelog/index.ts

@@ -505,6 +505,19 @@ async function showChangelogModal(
     const result = await chrome.storage.local.get(StorageKeys.CHANGELOG_DISMISSED_VERSION);
     const dismissedVersion = result[StorageKeys.CHANGELOG_DISMISSED_VERSION] as string | undefined;
     if (dismissedVersion === EXTENSION_VERSION) return null;
+    // First install — user has never seen any changelog, so the current
+    // version's notes aren't meaningful.  Silently dismiss and let them
+    // explore the extension first.
+    if (!dismissedVersion) {
+      try {
+        await chrome.storage.local.set({
+          [StorageKeys.CHANGELOG_DISMISSED_VERSION]: EXTENSION_VERSION,
+        });
+      } catch {
+        // Ignore
+      }
+      return null;
+    }
   }
 
   // 2. Try to load the changelog for the target version
@@ -583,6 +596,7 @@ export async function hasUnreadChangelog(): Promise<boolean> {
   try {
     const result = await chrome.storage.local.get(StorageKeys.CHANGELOG_DISMISSED_VERSION);
     const dismissed = result[StorageKeys.CHANGELOG_DISMISSED_VERSION] as string | undefined;
+    if (!dismissed) return false;
     return dismissed !== EXTENSION_VERSION;
   } catch {
     return false;