diff --git a/docs/research/2026-05-21-a6-p3-slice1-retail-mech-b-research.md b/docs/research/2026-05-21-a6-p3-slice1-retail-mech-b-research.md
index 73af9f4..6ca5c54 100644
--- a/docs/research/2026-05-21-a6-p3-slice1-retail-mech-b-research.md
+++ b/docs/research/2026-05-21-a6-p3-slice1-retail-mech-b-research.md
@@ -16,25 +16,25 @@ Retail decomp at `acclient_2013_pseudo_c.txt` lines 309573–309593 (address
 // 0052c130  enum TransitionState __thiscall CEnvCell::find_env_collisions(
 //               class CEnvCell const* this, class CTransition* arg2)
 {
-    // [309573] Check entry restrictions (object ethereal? door closed? etc.)
+    // Check entry restrictions (object ethereal? door closed? etc.)
     enum TransitionState result = CObjCell::check_entry_restrictions(this, arg2);
 
     if (result == OK_TS) {
-        // [309575] Clear obstruction-ethereal so BSP collision is live.
+        // 0052c144 Clear obstruction-ethereal so BSP collision is live.
         arg2->sphere_path.obstruction_ethereal = 0;
 
         if (this->structure->physics_bsp != 0) {
-            // [309578] Project sphere into cell-local space.
+            // 0052c169 Project sphere into cell-local space.
             SPHEREPATH::cache_localspace_sphere(&arg2->sphere_path, &this->pos, 1f);
 
-            // [309580] Run BSP: INITIAL_PLACEMENT → placement_insert path;
+            // 0052c175 Run BSP: INITIAL_PLACEMENT → placement_insert path;
             //          all other insert_types → find_collisions path.
             if (arg2->sphere_path.insert_type != INITIAL_PLACEMENT_INSERT)
                 result = BSPTREE::find_collisions(this->structure->physics_bsp, arg2, 1f);
             else
                 result = BSPTREE::placement_insert(this->structure->physics_bsp, arg2);
 
-            // [309585] On collision with environment (non-Contact objects only).
+            // 0052c1a5 On collision with environment (non-Contact objects only).
             if (result != OK_TS && (arg2->object_info.state & 1) == 0)
                 arg2->collision_info.collided_with_environment = 1;
         }
@@ -55,11 +55,10 @@ synthesis path anywhere in this function.
 
 **Function:** `CTransition::validate_transition`  
 **Retail address:** `0050aa70`  
-**Decomp line range:** `acclient_2013_pseudo_c.txt` lines 272540–272700  
-**Identified via:** The awk step above returned: `272530 CTransition::check_collisions`,
-meaning the most recent function header before line 272540 was
-`CTransition::check_collisions` at line 272530. The `validate_transition`
-function header appears at line 272538 (`0050aa70`).
+**Decomp line range:** `acclient_2013_pseudo_c.txt` lines 272547–272700  
+**Identified via:** The `validate_transition` function header appears at line
+272547 (`0050aa70`). Line 272538 is inside the preceding
+`CTransition::check_collisions` function.
 
 The LKCP-restore block runs at lines 272565–272582 (addresses `0050aaed`–`0050ab4c`).
 
@@ -189,6 +188,8 @@ else
     oi.State &= ~ObjectInfoState.OnWalkable;
 ```
 
+> **Note:** `SetContactPlane` also re-latches `LastKnownContactPlane`, `LastKnownContactPlaneCellId`, and `LastKnownContactPlaneIsWater` (TransitionTypes.cs:258-261). Passing LKCP as the source means the re-latch is a no-op on those fields — functionally safe, but worth knowing if you later decide to inline the writes instead of using `SetContactPlane`.
+
 **Note on the LKCP-update strategy divergence (Gap 3):** Retail's `validate_transition`
 at `0050acff` does `last_known_contact_plane_valid = contact_plane_valid`
 unconditionally — this means when contact is invalid and stays invalid, LKCP is
@@ -256,7 +257,7 @@ slice 1.
 ## References
 
 - `acclient_2013_pseudo_c.txt` lines 309570–309595 (`CEnvCell::find_env_collisions`)
-- `acclient_2013_pseudo_c.txt` lines 272538–272700 (`CTransition::validate_transition`)
+- `acclient_2013_pseudo_c.txt` lines 272547–272700 (`CTransition::validate_transition`)
 - `src/AcDream.Core/Physics/TransitionTypes.cs` lines 2751–2873 (`ValidateTransition`)
 - `src/AcDream.Core/Physics/TransitionTypes.cs` lines 1514–1777 (`FindEnvCollisions`)
 - `src/AcDream.Core/Physics/PhysicsEngine.cs` lines 640–692 (`RunTransitionResolve`)