added library reordering & prefix rename

src/library.js

@@ -171,10 +171,45 @@ function newGame({ id, name, exePath, workdir, mode }) {
   }
 }
 
+// The registry array IS the library order, so a drag & drop reorder rewrites
+// it whole. Ids the caller did not send keep their relative order at the end:
+// a renderer that raced an import must never drop an entry.
+function reorderGames(ids) {
+  const games = loadGames()
+  const rest = new Map(games.map(g => [g.id, g]))
+  const out = []
+  for (const id of Array.isArray(ids) ? ids : []) {
+    const g = rest.get(String(id))
+    if (!g) continue
+    rest.delete(String(id))
+    out.push(g)
+  }
+  for (const g of games) if (rest.has(g.id)) out.push(g)
+  saveGames(out)
+  return out
+}
+
+// Follows a prefix rename through the app registry. Raw JSON on purpose:
+// loadGames()/saveGames() would resolve and re-relativize every path against
+// a prefix folder that was just renamed. The stored paths of prefix imports
+// are relative to the prefix root, so only the name reference changes.
+function renamePrefixRefs(oldName, newName) {
+  const games = readJson(REGISTRY, [])
+  let updated = 0
+  for (const g of games) {
+    if (g.prefix === oldName) {
+      g.prefix = newName
+      updated++
+    }
+  }
+  if (updated) writeJson(REGISTRY, games)
+  return updated
+}
+
 function resolvePrefixDir(game) {
   if (game.prefix) return prefixPath(game.prefix)
   const defs = readJson(path.join(DIRS.DATA, 'prefixes.json'), { default: 'default', prefixes: [] })
   return prefixPath(defs.default || 'default')
 }
 
-module.exports = { loadGames, saveGames, portableGame, getGame, addGame, updateGame, removeGame, loadSettings, saveSettings, newGame, newGameId, resolvePrefixDir, clearPlaytime, readPlaySeconds, writePlaySeconds, playtimeFile }
+module.exports = { loadGames, saveGames, portableGame, getGame, addGame, updateGame, removeGame, reorderGames, renamePrefixRefs, loadSettings, saveSettings, newGame, newGameId, resolvePrefixDir, clearPlaytime, readPlaySeconds, writePlaySeconds, playtimeFile }