feat(atlas): mark sub-national regions as visited with cascade behavior

- Add visited_regions table migration
- Mark/unmark region endpoints with auto-mark parent country
- Unmark country cascades to its regions; unmark last region cascades to country
- Region modal with mark/unmark flow and bucket list shortcut
- Viewport-based lazy loading of region GeoJSON at zoom >= 6
- i18n: add atlas.markRegionVisitedHint and atlas.confirmUnmarkRegion across all 13 locales

server/src/db/migrations.ts

@@ -563,6 +563,20 @@ function runMigrations(db: Database.Database): void {
         CREATE INDEX IF NOT EXISTS idx_place_regions_region ON place_regions(region_code);
       `);
     },
+    () => {
+      db.exec(`
+        CREATE TABLE IF NOT EXISTS visited_regions (
+          id INTEGER PRIMARY KEY AUTOINCREMENT,
+          user_id INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+          region_code TEXT NOT NULL,
+          region_name TEXT NOT NULL,
+          country_code TEXT NOT NULL,
+          created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
+          UNIQUE(user_id, region_code)
+        );
+        CREATE INDEX IF NOT EXISTS idx_visited_regions_country ON visited_regions(country_code);
+      `);
+    },
   ];
 
   if (currentVersion < migrations.length) {

server/src/routes/atlas.ts

@@ -6,6 +6,8 @@ import {
   getCountryPlaces,
   markCountryVisited,
   unmarkCountryVisited,
+  markRegionVisited,
+  unmarkRegionVisited,
   getVisitedRegions,
   getRegionGeo,
   listBucketList,
@@ -56,6 +58,20 @@ router.delete('/country/:code/mark', (req: Request, res: Response) => {
   res.json({ success: true });
 });
 
+router.post('/region/:code/mark', (req: Request, res: Response) => {
+  const userId = (req as AuthRequest).user.id;
+  const { name, country_code } = req.body;
+  if (!name || !country_code) return res.status(400).json({ error: 'name and country_code are required' });
+  markRegionVisited(userId, req.params.code.toUpperCase(), name, country_code.toUpperCase());
+  res.json({ success: true });
+});
+
+router.delete('/region/:code/mark', (req: Request, res: Response) => {
+  const userId = (req as AuthRequest).user.id;
+  unmarkRegionVisited(userId, req.params.code.toUpperCase());
+  res.json({ success: true });
+});
+
 // ── Bucket List ─────────────────────────────────────────────────────────────
 
 router.get('/bucket-list', (req: Request, res: Response) => {

server/src/services/atlasService.ts

@@ -371,6 +371,32 @@ export function markCountryVisited(userId: number, code: string): void {
 
 export function unmarkCountryVisited(userId: number, code: string): void {
   db.prepare('DELETE FROM visited_countries WHERE user_id = ? AND country_code = ?').run(userId, code);
+  db.prepare('DELETE FROM visited_regions WHERE user_id = ? AND country_code = ?').run(userId, code);
+}
+
+// ── Mark / unmark region ────────────────────────────────────────────────────
+
+export function listManuallyVisitedRegions(userId: number): { region_code: string; region_name: string; country_code: string }[] {
+  return db.prepare(
+    'SELECT region_code, region_name, country_code FROM visited_regions WHERE user_id = ? ORDER BY created_at DESC'
+  ).all(userId) as { region_code: string; region_name: string; country_code: string }[];
+}
+
+export function markRegionVisited(userId: number, regionCode: string, regionName: string, countryCode: string): void {
+  db.prepare('INSERT OR IGNORE INTO visited_regions (user_id, region_code, region_name, country_code) VALUES (?, ?, ?, ?)').run(userId, regionCode, regionName, countryCode);
+  // Auto-mark parent country if not already visited
+  db.prepare('INSERT OR IGNORE INTO visited_countries (user_id, country_code) VALUES (?, ?)').run(userId, countryCode);
+}
+
+export function unmarkRegionVisited(userId: number, regionCode: string): void {
+  const region = db.prepare('SELECT country_code FROM visited_regions WHERE user_id = ? AND region_code = ?').get(userId, regionCode) as { country_code: string } | undefined;
+  db.prepare('DELETE FROM visited_regions WHERE user_id = ? AND region_code = ?').run(userId, regionCode);
+  if (region) {
+    const remaining = db.prepare('SELECT COUNT(*) as count FROM visited_regions WHERE user_id = ? AND country_code = ?').get(userId, region.country_code) as { count: number };
+    if (remaining.count === 0) {
+      db.prepare('DELETE FROM visited_countries WHERE user_id = ? AND country_code = ?').run(userId, region.country_code);
+    }
+  }
 }
 
 // ── Sub-national region resolution ────────────────────────────────────────
@@ -450,11 +476,20 @@ export async function getVisitedRegions(userId: number): Promise<{ regions: Reco
     }
   }
 
-  const result: Record<string, { code: string; name: string; placeCount: number }[]> = {};
+  const result: Record<string, { code: string; name: string; placeCount: number; manuallyMarked?: boolean }[]> = {};
   for (const [country, regions] of Object.entries(regionMap)) {
     result[country] = [...regions.values()];
   }
 
+  // Merge manually marked regions
+  const manualRegions = listManuallyVisitedRegions(userId);
+  for (const r of manualRegions) {
+    if (!result[r.country_code]) result[r.country_code] = [];
+    if (!result[r.country_code].find(x => x.code === r.region_code)) {
+      result[r.country_code].push({ code: r.region_code, name: r.region_name, placeCount: 0, manuallyMarked: true });
+    }
+  }
+
   return { regions: result };
 }