diff --git a/src/AcDream.Core/Physics/SpawnPlacementSettler.cs b/src/AcDream.Core/Physics/SpawnPlacementSettler.cs
index 86263c87..519a6146 100644
--- a/src/AcDream.Core/Physics/SpawnPlacementSettler.cs
+++ b/src/AcDream.Core/Physics/SpawnPlacementSettler.cs
@@ -58,7 +58,28 @@ public static class SpawnPlacementSettler
         if (!settle.Ok || !settle.InContact)
             return false;
 
-        body.Position = settle.Position;
+        // #276: adopt the settle's RESOLVED cell, not just its position.
+        // Retail's CPhysicsObj::SetPositionInternal(CTransition const*)
+        // @0x00515330 commits both sphere_path.curr_pos.objcell_id and its
+        // frame, including EnvCells.
+        //
+        // A bare `body.Position = settle.Position` is sufficient only while
+        // the body is OUTDOOR: that setter mirrors the world delta into the
+        // landblock-local frame and LandDefs.AdjustToOutside then recomputes
+        // the 24 m cell index from it. It cannot do so for an EnvCell — an
+        // EnvCell id is not derivable from a position, so the mirror
+        // deliberately preserves it (PhysicsBody.cs, the `not (>= 1 and
+        // <= 0x40)` arm). settle.CellId is therefore the ONLY carrier of a
+        // cell identity across an indoor seam, and dropping it stranded the
+        // body in the placement cell until some later resolve corrected it.
+        //
+        // Identical guarded shape to the per-tick resolve writeback
+        // (RuntimeOrdinaryPhysicsUpdater): a transition reporting no cell
+        // falls back to the source cell rather than zeroing residency.
+        uint resolvedCellId = settle.CellId != 0
+            ? settle.CellId
+            : cellId;
+        body.CommitTransitionPosition(resolvedCellId, settle.Position);
         PhysicsObjUpdate.CommitSetPositionTransition(
             body,
             settle.InContact,
diff --git a/tests/AcDream.Core.Tests/Physics/SpawnPlacementSettlerTests.cs b/tests/AcDream.Core.Tests/Physics/SpawnPlacementSettlerTests.cs
index a3e60a1c..2563d12e 100644
--- a/tests/AcDream.Core.Tests/Physics/SpawnPlacementSettlerTests.cs
+++ b/tests/AcDream.Core.Tests/Physics/SpawnPlacementSettlerTests.cs
@@ -75,6 +75,61 @@ public sealed class SpawnPlacementSettlerTests
         Assert.Equal(originalPosition, body.Position);
     }
 
+    /// <summary>
+    /// #276: the settle must adopt the transition's RESOLVED cell, not only
+    /// its position. Retail's
+    /// <c>CPhysicsObj::SetPositionInternal(CTransition const*)</c>
+    /// (<c>0x00515330</c>) commits both <c>curr_pos.objcell_id</c> and the
+    /// frame.
+    ///
+    /// <para>
+    /// The body is seeded with an ENVCELL id over plain outdoor terrain,
+    /// which is what makes this discriminating. A bare
+    /// <c>body.Position = settle.Position</c> mirrors the world delta into
+    /// the local frame and lets <c>AdjustToOutside</c> recompute the cell —
+    /// but only for outdoor ids; the mirror deliberately PRESERVES an
+    /// EnvCell id, because one cannot be derived from a position. So the old
+    /// code leaves the stale EnvCell in place and only the resolved-cell
+    /// adoption reaches the outdoor cell the body physically settled in.
+    /// This is the "outdoor/EnvCell seam" half of #276, in the outward
+    /// direction.
+    /// </para>
+    /// </summary>
+    [Fact]
+    public void SettleLeavingAnEnvCell_AdoptsTheTransitionsResolvedOutdoorCell()
+    {
+        const uint StaleEnvCell = Landblock | 0x0100u;
+        PhysicsEngine engine = BuildFlatEngine();
+        PhysicsBody body = AirborneBody(new Vector3(12f, 12f, 0.25f));
+        body.StageDormantCellFrame(
+            StaleEnvCell,
+            body.Position,
+            body.Position);
+        Assert.Equal(StaleEnvCell, body.CellPosition.ObjCellId);
+
+        bool settled = SpawnPlacementSettler.TrySettle(
+            engine,
+            body,
+            body.Position,
+            Cell,
+            Radius,
+            Height,
+            ObjectInfoState.EdgeSlide,
+            movingEntityId: 0x70000001u,
+            static () => { },
+            static () => { });
+
+        Assert.True(settled);
+        Assert.True(body.InContact);
+
+        // The discriminating assertion: the body no longer claims the EnvCell
+        // it never physically occupied, and its cell is an OUTDOOR landcell
+        // (low word 1..0x40) of the same landblock it settled in.
+        Assert.NotEqual(StaleEnvCell, body.CellPosition.ObjCellId);
+        Assert.Equal(Landblock, body.CellPosition.ObjCellId & 0xFFFF0000u);
+        Assert.InRange(body.CellPosition.ObjCellId & 0xFFFFu, 1u, 0x40u);
+    }
+
     private static bool TrySettle(PhysicsEngine engine, PhysicsBody body) =>
         SpawnPlacementSettler.TrySettle(
             engine,