diff --git a/tools/repair_uids.py b/tools/repair_uids.py
new file mode 100644
index 0000000..636b854
--- /dev/null
+++ b/tools/repair_uids.py
@@ -0,0 +1,449 @@
+#!/usr/bin/env python3
+"""Scans and repairs UID mismatches across all KQ4 room scenes.
+
+Fixes two types of drift:
+  1. .tscn.headers have a different UID than the .uid companion file
+  2. Source rooms reference stale target UIDs from .uid companions instead of
+     the current .tscn header UID
+
+After repair, check_transitions.py and build_room_graph.py report consistent results.
+
+Usage:
+    # Detect (show what's wrong)
+    python tools/repair_uids.py --detect
+
+    # Dry run (show what would change)
+    python tools/repair_uids.py --fix --dry-run
+
+    # Apply fixes
+    python tools/repair_uids.py --fix
+
+    # Fix a specific room only
+    python tools/repair_uids.py --fix --room kq4_018_cemetery
+
+    # Verbose output
+    python tools/repair_uids.py --detect -v
+"""
+
+import re
+import sys
+import hashlib
+import json
+from pathlib import Path
+from dataclasses import dataclass, field
+from typing import Optional
+
+
+def generate_godot_uid() -> str:
+    """Generate a fresh Godot-compatible UID (base36 encoded 64-bit random)."""
+    ALPHABET = "0123456789abcdefghijklmnopqrstuvwxyz"
+
+    def to_base36(num: int) -> str:
+        if num == 0:
+            return "0"
+        chars = []
+        while num:
+            num, rem = divmod(num, 36)
+            chars.append(ALPHABET[rem])
+        return "".join(reversed(chars))
+
+    import secrets
+    value = secrets.randbits(64)
+    return f"uid://{to_base36(value)}"
+
+
+@dataclass
+class RoomData:
+    """Parsed data for a single room scene."""
+    name: str
+    path: Path
+    header_uid: Optional[str]  # uid from .tscn [gd_scene ...] line
+    companion_uid: Optional[str]  # uid from .uid file (may be stale or missing)
+    target_uids: list[dict]  # [{"exit_node": str, "target_uid": str}, ...]
+
+
+@dataclass
+class Mismatch:
+    """A single detected UID problem."""
+    category: str  # "companion_mismatch" | "missing_companion" | "stale_target"
+    room_name: str
+    detail: str
+    fixable: bool = True
+    fix_uid: Optional[str] = None
+    source_file: Optional[Path] = None
+
+
+def parse_all_rooms(scenes_dir: Path) -> dict[str, RoomData]:
+    """Parse every kq4_* .tscn scene and return data keyed by room name."""
+    rooms: dict[str, RoomData] = {}
+
+    for tscn in sorted(scenes_dir.glob("kq4_*/kq4_*.tscn")):
+        if "placeholder" in str(tscn):
+            continue
+
+        content = tscn.read_text()
+
+        # Extract header UID
+        header_match = re.search(r'\[gd_scene[^\]]*uid="([^"]+)"', content)
+        header_uid = header_match.group(1) if header_match else None
+
+        # Extract companion .uid file
+        uid_file = Path(str(tscn) + ".uid")
+        companion_uid = uid_file.read_text().strip() if uid_file.exists() else None
+
+        # Extract target UIDs from TransitionPiece nodes
+        target_uids = []
+        transition_pattern = re.compile(
+            r'\[node name="([^"]+)"[^\]]*instance=ExtResource\([^\)]+\)\]\s*\n'
+            r"(([^\[]+(?:\n|$))*)(?=\[|$)",
+            re.MULTILINE,
+        )
+        for match in transition_pattern.finditer(content):
+            node_name = match.group(1)
+            body = match.group(2)
+            target_match = re.search(r'^target = "([^"]+)"', body, re.MULTILINE)
+            if target_match:
+                target_uids.append({
+                    "exit_node": node_name,
+                    "target_uid": target_match.group(1),
+                })
+
+        rooms[tscn.stem] = RoomData(
+            name=tscn.stem, path=tscn,
+            header_uid=header_uid, companion_uid=companion_uid, target_uids=target_uids,
+        )
+
+    return rooms
+
+
+def detect_mismatches(rooms: dict[str, RoomData]) -> list[Mismatch]:
+    """Find all UID problems and return actionable mismatch records."""
+    mismatches: list[Mismatch] = []
+
+    # Build lookup: companion_uid -> room_name (for stale-target detection)
+    companion_to_room: dict[str, str] = {}
+    for rdata in rooms.values():
+        if rdata.companion_uid:
+            companion_to_room[rdata.companion_uid] = rdata.name
+
+    for rname, rd in rooms.items():
+        # 1. Companion doesn't match header (both exist but differ)
+        if rd.header_uid and rd.companion_uid and rd.header_uid != rd.companion_uid:
+            mismatches.append(Mismatch(
+                category="companion_mismatch",
+                room_name=rname,
+                detail=f".uid={rd.companion_uid}  .tscn header={rd.header_uid}",
+                fix_uid=rd.header_uid, source_file=Path(str(rd.path) + ".uid"),
+            ))
+
+        # 2. Missing companion file
+        if rd.header_uid and not rd.companion_uid:
+            mismatches.append(Mismatch(
+                category="missing_companion",
+                room_name=rname,
+                detail=f"No .uid file for header UID {rd.header_uid}",
+                fix_uid=rd.header_uid, source_file=Path(str(rd.path) + ".uid"),
+            ))
+
+        # 3. Stale target references
+        for tgt in rd.target_uids:
+            uid = tgt["target_uid"]
+            if not uid.startswith("uid://"):
+                continue
+            # Target exists in some header -> check companion matches
+            target_room = None
+            for other_name, other_rd in rooms.items():
+                if other_rd.header_uid == uid:
+                    target_room = other_name
+                    break
+
+            if target_room is None:
+                # Check if the stale UID matches a companion that diverged from header
+                mapped_companion = companion_to_room.get(uid)
+                if mapped_companion and mapped_companion != rooms[mapped_companion].name or \
+                   (mapped_companion and rooms[mapped_companion].companion_uid == uid):
+                    # Stale companion lookup — the target room exists but source
+                    # references its OLD companion UID instead of current header
+                    correct_uid = rooms[mapped_companion].header_uid
+                    if uid != correct_uid:
+                        mismatches.append(Mismatch(
+                            category="stale_target",
+                            room_name=rname,
+                            detail=f"{tgt['exit_node']} -> {uid} (correct: {correct_uid} for {mapped_companion})",
+                            fix_uid=correct_uid, source_file=rd.path,
+                        ))
+                elif target_room is None and uid not in companion_to_room:
+                    # Totally orphaned UID — try to auto-resolve via exit node name
+                    suggested = suggest_target_from_node(tgt["exit_node"], rooms)
+                    if suggested:
+                        sugg_uid = rooms[suggested].header_uid
+                        mismatches.append(Mismatch(
+                            category="stale_target",
+                            room_name=rname,
+                            detail=f"{tgt['exit_node']} -> {uid} (not found, likely → {suggested}: {sugg_uid})",
+                            fix_uid=sugg_uid, source_file=rd.path,
+                        ))
+
+    return mismatches
+
+
+def suggest_target_from_node(exit_node_name: str, rooms: dict[str, RoomData]) -> Optional[str]:
+    """Try to guess target room from exit node naming convention.
+
+    Exit nodes are typically named after their destination (e.g., 'kq4_018_cemetery').
+    """
+    # Direct match
+    if exit_node_name in rooms:
+        return exit_node_name
+
+    # kq4_XXX_room_node -> kq4_XXX_room (strip trailing node-like suffix)
+    for rname in rooms:
+        if exit_node_name.startswith(rname):
+            return rname
+        if rname in exit_node_name:
+            return rname
+
+    return None
+
+
+def fix_companion_mismatch(room: RoomData, new_uid: str, dry_run: bool) -> str:
+    """Write the header UID into the .uid companion file."""
+    uid_path = Path(str(room.path) + ".uid")
+    content = f"{new_uid}\n"
+
+    if not dry_run:
+        uid_path.write_text(content)
+    return f"Synchronizing {room.name}: .uid → {new_uid}"
+
+
+def fix_missing_companion(room: RoomData, uid: str, dry_run: bool) -> str:
+    """Create a new .uid companion file with the header UID."""
+    uid_path = Path(str(room.path) + ".uid")
+    content = f"{uid}\n"
+
+    if not dry_run:
+        uid_path.write_text(content)
+    return f"Creating {room.name}: .uid ← {uid} (from .tscn header)"
+
+
+def fix_stale_target(source_room: RoomData, exit_node: str, old_uid: str, new_uid: str, dry_run: bool) -> str:
+    """Replace a stale target UID in the source .tscn file."""
+    content = source_room.path.read_text()
+    if not dry_run:
+        content = content.replace(
+            f'target = "{old_uid}"',
+            f'target = "{new_uid}"',
+        )
+        source_room.path.write_text(content)
+    return f"Updating {source_room.name}/{exit_node}: target {old_uid} → {new_uid}"
+
+
+def run_detect(rooms: dict[str, RoomData], verbose: bool) -> list[Mismatch]:
+    """Detect and display all mismatches. Returns list for further processing."""
+    mismatches = detect_mismatches(rooms)
+
+    if not mismatches:
+        print("No UID mismatches found. All rooms are consistent.")
+        return mismatches
+
+    # Group by category
+    by_category: dict[str, list[Mismatch]] = {}
+    for m in mismatches:
+        by_category.setdefault(m.category, []).append(m)
+
+    total = len(mismatches)
+    print(f"Found {total} UID issues across {len(rooms)} rooms:\n")
+
+    if "companion_mismatch" in by_category:
+        msgs = by_category["companion_mismatch"]
+        print(f"  [{len(msgs)}] Companion files out of sync with .tscn headers:")
+        for m in msgs[:10]:
+            print(f"    {m.room_name}: {m.detail}")
+        if len(msgs) > 10:
+            print(f"    ... and {len(msgs) - 10} more")
+
+    if "missing_companion" in by_category:
+        msgs = by_category["missing_companion"]
+        print(f"  [{len(msgs)}] Missing .uid companion files:")
+        for m in msgs:
+            print(f"    {m.room_name}: {m.detail}")
+
+    if "stale_target" in by_category:
+        msgs = by_category["stale_target"]
+        print(f"  [{len(msgs)}] Stale target UIDs in source rooms:")
+        for m in (msgs[:15] if verbose else msgs[:5]):
+            print(f"    {m.room_name}: {m.detail}")
+        if len(msgs) > 5 and not verbose:
+            print(f"    ... and {len(msgs) - 5} more (use -v for full list)")
+
+    return mismatches
+
+
+def run_fix(rooms: dict[str, RoomData], dry_run: bool, room_filter: Optional[str]) -> int:
+    """Detect and fix all mismatches. Returns count of fixes applied."""
+    mismatches = detect_mismatches(rooms)
+
+    if not mismatches:
+        print("No UID mismatches to fix.")
+        return 0
+
+    if room_filter:
+        mismatches = [m for m in mismatches if m.room_name == room_filter]
+        if not mismatches:
+            print(f"No issues found for {room_filter}.")
+            return 0
+
+    mode = "(DRY RUN) " if dry_run else ""
+    applied = 0
+
+    for m in mismatches:
+        if not m.fixable or not m.fix_uid:
+            continue
+
+        rd = rooms.get(m.room_name)
+        if not rd:
+            continue
+
+        if m.category == "companion_mismatch" and m.source_file:
+            msg = fix_companion_mismatch(rd, m.fix_uid, dry_run)
+            print(f"{mode}✓ {msg}")
+            applied += 1
+
+        elif m.category == "missing_companion":
+            # Check if room needs a new UID generated
+            uid_to_use = m.fix_uid or rd.header_uid
+            if not uid_to_use:
+                uid_to_use = generate_godot_uid()
+                if not dry_run:
+                    # Also update the .tscn header with the new UID
+                    content = rd.path.read_text()
+                    if rd.header_uid:
+                        content = content.replace(f'uid="{rd.header_uid}"', f'uid="{uid_to_use}"')
+                    else:
+                        content = content.replace('[gd_scene format=3', f'[gd_scene format=3 uid="{uid_to_use}"')
+                    rd.path.write_text(content)
+            msg = fix_missing_companion(rd, uid_to_use, dry_run)
+            print(f"{mode}✓ {msg}")
+            applied += 1
+
+        elif m.category == "stale_target":
+            # Extract old UID from detail message
+            detail_parts = m.detail.split(" -> ")
+            if len(detail_parts) >= 2:
+                exit_node = detail_parts[0].split()[-1]
+                old_uid = detail_parts[1]
+                new_uid = m.fix_uid
+                msg = fix_stale_target(rd, exit_node, old_uid or "", new_uid, dry_run)
+
+            # Handle case where target UID doesn't exist in any companion file
+            if "not found" in m.detail.lower():
+                # Extract via regex for more robust parsing
+                import re
+                uid_match = re.search(r"-> (uid://\S+)", m.detail)
+                if uid_match:
+                    old_uid = uid_match.group(1)
+                else:
+                    continue
+                    
+                exit_node_match = re.search(r"(kq4_\S+) -> ", m.detail)
+                exit_node = exit_node_match.group(1) if exit_node_match else "unknown"
+
+                msg = fix_stale_target(rd, exit_node, old_uid, new_uid, dry_run)
+
+            print(f"{mode}✓ {msg}")
+            applied += 1
+
+    return applied
+
+
+def run_verify() -> bool:
+    """Run check_transitions.py and build_room_graph.py to confirm fixes."""
+    root = Path(__file__).resolve().parent.parent
+    check_script = root / "scripts" / "check_transitions.py"
+    graph_script = root / "scripts" / "build_room_graph.py"
+
+    print("\n--- Post-fix verification ---\n")
+    all_clean = True
+
+    if check_script.exists():
+        import subprocess
+        print("$ python scripts/check_transitions.py")
+        result = subprocess.run(["python", str(check_script)], cwd=str(root), capture_output=True, text=True)
+        lines = [l for l in result.stdout.strip().split("\n") if "ERROR:" in l]
+        if lines:
+            all_clean = False
+            print(f"  Still has {len(lines)} error(s):")
+            for l in lines[:10]:
+                print(f"    {l.strip()}")
+            if len(lines) > 10:
+                print(f"    ... and {len(lines) - 10} more")
+        else:
+            OK_count = sum(1 for l in result.stdout.split("\n") if "OK:" in l)
+            print(f"  All {OK_count} transitions valid! ✓\n")
+    else:
+        print(f"[skip] check_transitions.py not found at {check_script}\n")
+
+    if graph_script.exists():
+        import subprocess
+        print("$ python scripts/build_room_graph.py")
+        result = subprocess.run(["python", str(graph_script)], cwd=str(root), capture_output=True, text=True)
+        output = result.stdout.strip().split("\n")
+        for line in output[:8]:
+            print(f"  {line}")
+
+        # Check if all rooms are connected or note component issues
+        for l in output:
+            if "component" in l.lower():
+                if "all rooms connected" not in l.lower():
+                    comp_count = re.search(r"(\d+)", l)
+                    if comp_count and int(comp_count.group(1)) > 1:
+                        print(f"  Note: {l.strip()} (some rooms disconnected by missing transitions)")
+    else:
+        print(f"[skip] build_room_graph.py not found at {graph_script}\n")
+
+    return all_clean
+
+
+def main() -> None:
+    import argparse
+    parser = argparse.ArgumentParser(
+        description="Detect and repair UID mismatches in KQ4 room scenes",
+        formatter_class=argparse.RawDescriptionHelpFormatter,
+        epilog=__doc__,
+    )
+    parser.add_argument("--detect", action="store_true", help="Only detect mismatches")
+    parser.add_argument("--fix", action="store_true", help="Apply fixes for found mismatches")
+    parser.add_argument("--dry-run", action="store_true", help="Show what would change without writing")
+    parser.add_argument("--room", help="Limit to a specific room name (e.g., kq4_018_cemetery)")
+    parser.add_argument("-v", "--verbose", action="store_true", help="Verbose output")
+
+    args = parser.parse_args()
+
+    root = Path(__file__).resolve().parent.parent
+    scenes_dir = root / "scenes"
+
+    if not scenes_dir.exists():
+        print(f"ERROR: Scenes directory not found at {scenes_dir}", file=sys.stderr)
+        sys.exit(1)
+
+    rooms = parse_all_rooms(scenes_dir)
+
+    if args.detect and not args.fix:
+        mismatches = run_detect(rooms, args.verbose)
+        if mismatches:
+            sys.exit(0)
+
+    if args.fix:
+        applied = run_fix(rooms, args.dry_run, args.room)
+        print(f"\nApplied {applied} fix(es)" + (" (dry run — no changes made)" if args.dry_run else ""))
+        if not args.dry_run and applied > 0:
+            try:
+                clean = run_verify()
+                if not clean:
+                    sys.exit(1)
+            except Exception as e:
+                print(f"[verification warning] {e}")
+
+
+if __name__ == "__main__":
+    main()