diff --git a/src/AcDream.Core/Physics/PhysicsEngine.cs b/src/AcDream.Core/Physics/PhysicsEngine.cs
index a31740a9..ab20fee9 100644
--- a/src/AcDream.Core/Physics/PhysicsEngine.cs
+++ b/src/AcDream.Core/Physics/PhysicsEngine.cs
@@ -787,6 +787,45 @@ public sealed class PhysicsEngine
                 // Stay outdoors on terrain.
                 targetZ = terrainZ;
                 targetCellId = physics.Terrain.ComputeOutdoorCellId(localCandX, localCandY);
+
+                // #126 (2026-06-11): a zero-delta RESTORE of an OUTDOOR claim
+                // standing far ABOVE terrain means the player logged out on a
+                // walkable surface that is not the ground — a building roof
+                // deck (the AAB3 tower's 0x010A slab, z=127.2 over terrain
+                // 112). Grounding to terrain warps the player THROUGH the
+                // roof into the building's interior volume, outdoor-classified
+                // → the transparent-interior spawn. Retail's restore settles
+                // via AdjustPosition onto real surfaces, not the heightmap.
+                // Ground to the nearest CELL WALKABLE at/below the claim Z
+                // (the #111 walkable query — real floors only, never ceiling
+                // soup); the cell id stays OUTDOOR (the claim is honest: the
+                // player's center on a deck sits above the slab cell's BSP).
+                // GfxObj-shell roofs without cells are not covered — file if
+                // a real case shows.
+                if (snapDiag && currentPos.Z > terrainZ + stepUpHeight)
+                {
+                    float? bestWalkZ = null;
+                    float bestWalkDist = float.MaxValue;
+                    foreach (var cell in physics.Cells)
+                    {
+                        float? wz = WalkableFloorZNearest(
+                            lbPrefix | (cell.CellId & 0xFFFFu), candidatePos, currentPos.Z);
+                        if (wz is null) continue;
+                        if (wz.Value > currentPos.Z + stepUpHeight) continue; // above the claim — not the surface stood on
+                        float dist = MathF.Abs(wz.Value - currentPos.Z);
+                        if (dist < bestWalkDist)
+                        {
+                            bestWalkDist = dist;
+                            bestWalkZ = wz;
+                        }
+                    }
+                    if (bestWalkZ is not null && bestWalkZ.Value > terrainZ)
+                    {
+                        Console.WriteLine(System.FormattableString.Invariant(
+                            $"[snap] OUTDOOR claim 0x{cellId:X8} at z={currentPos.Z:F3} stands on an elevated walkable z={bestWalkZ.Value:F3} (terrain {terrainZ:F3}) — grounding to the walkable, not through it"));
+                        targetZ = bestWalkZ.Value;
+                    }
+                }
             }
         }