the combat log speaks, and the swim line follows your native form

- the client synthesises its combat-log chat lines: 44 chat types over 34 GlobalString families from 7 packets, the reference's own four hops (classify both endpoints → chat type → string key → format), text resolved out of the player's own GlobalStrings — so damage meters and Quiver's TranqAnnouncer have something to parse; wow-re's byte round corrected six gates (owner is charmed-by then created-by, "party" is your subgroup, friend-or-foe is CanAttack, the range gate, the miss defaults, the damage-shield chat type)
- the collision prism follows the NATIVE display, not the rendered one: a druid in bear form keeps the druid's swim, splash and wade lines and a morph keeps the human's — worst divergence on shipped data 0.72 yd (tauren moonkin), the sign flipping by form
- the creature swim gate is on both legs: a unit that loses its flag mid-water is driven out of swim at any depth, as the reference drops a charmed creature to the seabed on the next tick

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

crates/benilla-protocol/src/messages/update_object/fields/mod.rs

@@ -101,6 +101,18 @@ const FIELD_UNIT_BOUNDINGRADIUS: u16 = 129;
 const FIELD_UNIT_COMBATREACH: u16 = 130;
 const FIELD_UNIT_BASE_MANA: u16 = 162;
 const FIELD_UNIT_DISPLAYID: u16 = 131;
+/// `UNIT_FIELD_NATIVEDISPLAYID` (`OBJECT_END(6) + 0x7E` = 132, PUBLIC — vmangos
+/// `UpdateFields_1_12_1.h:77`; it is the index between DISPLAYID (131) and MOUNTDISPLAYID (133),
+/// both of which are independently pinned above). The unit's **unshifted** appearance: the server
+/// writes it once at spawn/login and leaves it alone through every transform — a druid form
+/// (`Aura::HandleAuraModShapeshift` sets DISPLAYID and restores it *from* this field), a GM
+/// `.modify morph`, a polymorph. `UNIT_FIELD_DISPLAYID` is what you see; this is what the unit is.
+///
+/// The client reads it for exactly one thing benilla cares about: the **mover collision prism**
+/// (`0x60b270` fetches its DBC row at `[unit+0x110]+0x1f8`, while its sibling `0x60ae10` uses
+/// `+0x1f4` = DISPLAYID against the same array) — so a shapeshift does *not* resize the collision
+/// box (wow-re `mover-collision-scalars.md`, `remote-swim-decision.md` §4; decision 1574).
+const FIELD_UNIT_NATIVEDISPLAYID: u16 = 132;
 /// `UNIT_FIELD_MOUNTDISPLAYID` (`OBJECT_END(6) + 0x7F` = 133, PUBLIC — vmangos
 /// `UpdateFields_1_12_1.h:78`; byte-verified client-side at `[unit+0x110]+0x1fc` = index 0x85,
 /// wow-re `rf39-field-index-map.md`/`d1.md`, HARD). A raw `CreatureDisplayInfo` id: the mount the

crates/benilla-protocol/src/messages/update_object/fields/unit.rs

@@ -56,6 +56,13 @@ impl ObjectFields {
     pub fn unit_displayid(&self) -> Option<i32> {
         self.get_i32(FIELD_UNIT_DISPLAYID)
     }
+    /// `UNIT_FIELD_NATIVEDISPLAYID` (units + players) — the unit's **unshifted** appearance, which
+    /// no transform touches. The collision prism is derived from *this*, not from
+    /// [`Self::unit_displayid`]: a druid in bear form keeps the druid's swim/splash/foam lines
+    /// (decision 1574). `None` when absent — the caller falls back to the render display.
+    pub fn unit_native_displayid(&self) -> Option<i32> {
+        self.get_i32(FIELD_UNIT_NATIVEDISPLAYID)
+    }
     /// `UNIT_FIELD_MOUNTDISPLAYID` — the `CreatureDisplayInfo` id of the mount this unit rides;
     /// `0` (or absent) = not mounted. The one and only mounted signal on the wire (decision 0441).
     pub fn unit_mount_display_id(&self) -> u32 {