1 files changed, 31 insertions, 12 deletions
diff --git a/internal/admin/id_alloc.go b/internal/admin/id_alloc.go
index d79718b..3a3c973 100644
--- a/internal/admin/id_alloc.go
+++ b/internal/admin/id_alloc.go
@@ -6,24 +6,43 @@ import (
 	"strconv"
 )
 
-func nextRoomIDInDir(dataDir string, fromRoomID int) (int, string, error) {
-	base := filepath.Join(dataDir, "rooms")
+// nextRoomID allocates a free room ID for a new room that will live in the same
+// directory as fromRoomID (so new IDs cluster near their neighbors). Unlike the
+// old per-subdir scan, the candidate is checked against EVERY room ID on disk
+// (via listRoomIDs, which walks the whole data/rooms tree), so it can never
+// collide with an ID that lives in a different subdirectory. The starting point
+// is the local subdir's minimum existing ID (clustering), then the first
+// globally-free ID scanning upward.
+func (s *AdminServer) nextRoomID(fromRoomID int) (int, string, error) {
+	base := filepath.Join(s.dataDir, "rooms")
 	subdir, err := findRoomSubdir(base, fromRoomID)
 	if err != nil {
 		subdir = base
 	}
-	used := map[int]bool{}
-	scanDir(subdir, used)
-	if len(used) == 0 {
-		return 1, subdir, nil
-	}
-	minID := 1<<31 - 1
-	for id := range used {
-		if id < minID {
-			minID = id
+
+	localUsed := map[int]bool{}
+	scanDir(subdir, localUsed)
+	start := 1
+	if len(localUsed) > 0 {
+		minID := 1<<31 - 1
+		for id := range localUsed {
+			if id < minID {
+				minID = id
+			}
 		}
+		start = minID
+	}
+
+	globalUsed, _ := listRoomIDs(s.dataDir)
+	used := make(map[int]bool, len(globalUsed))
+	for _, id := range globalUsed {
+		used[id] = true
+	}
+
+	id := start
+	if id < 1 {
+		id = 1
 	}
-	id := minID
 	for used[id] {
 		id++
 	}