1 files changed, 66 insertions, 0 deletions
diff --git a/internal/world/inbound.go b/internal/world/inbound.go
new file mode 100644
index 0000000..0fbef04
--- /dev/null
+++ b/internal/world/inbound.go
@@ -0,0 +1,66 @@
+package world
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"regexp"
+	"strconv"
+	"strings"
+
+	"gopkg.in/yaml.v3"
+)
+
+// CountExtraInbound returns the number of exits in rooms OTHER than A and C
+// that point into B, plus any A/C exits to B other than the expected
+// (A→dir→B, C→oppositeDir→B). A nonzero result means B has been modified
+// since it was inserted and a remove would silently orphan edges. It walks
+// data/rooms and matches \b<id>\b against raw file contents to skip rooms
+// that don't mention bID at all, then unmarshals only the matching files.
+//
+// Shared by the in-game room-remove command and the admin API so the two
+// removal paths cannot drift.
+func CountExtraInbound(dataDir string, bID, aID, cID int, dir, oppositeDir ExitDir) int {
+	roomsDir := filepath.Join(dataDir, "rooms")
+	re := regexp.MustCompile(fmt.Sprintf(`\b%d\b`, bID))
+	var extra int
+	_ = filepath.WalkDir(roomsDir, func(path string, d os.DirEntry, err error) error {
+		if err != nil || d.IsDir() || filepath.Ext(path) != ".yaml" {
+			return nil
+		}
+		data, rerr := os.ReadFile(path)
+		if rerr != nil {
+			return nil
+		}
+		if !re.MatchString(string(data)) {
+			return nil
+		}
+		idStr := strings.TrimSuffix(filepath.Base(path), ".yaml")
+		rid, serr := strconv.Atoi(idStr)
+		if serr != nil || rid == bID {
+			return nil
+		}
+		var room Room
+		if yerr := yaml.Unmarshal(data, &room); yerr != nil {
+			return nil
+		}
+		if room.Exits == nil {
+			return nil
+		}
+		for ed, exitDef := range room.Exits {
+			if exitDef.Room != bID {
+				continue
+			}
+			// Allowed: A→dir→B and C→oppositeDir→B.
+			if rid == aID && ed == dir {
+				continue
+			}
+			if rid == cID && ed == oppositeDir {
+				continue
+			}
+			extra++
+		}
+		return nil
+	})
+	return extra
+}