fix #211: index login-equipped items under player

Project PlayerDescription equipment through the same contained-by-wielder ownership and ordered contents index as live WieldObject updates. Preserve equip masks and priorities so retail GetObjectAtLocation selects Missile for an already-equipped crossbow instead of sending a server-rejected Melee request.

Co-Authored-By: Codex <codex@openai.com>

docs/research/2026-07-11-combat-default-and-parent-event-pseudocode.md

@@ -60,6 +60,29 @@ GetDefaultCombatMode(showError):
 returns the first entry whose location intersects the requested mask (and whose
 priority intersects the requested priority when that priority is non-zero).
 
+### Login projection invariant
+
+PlayerDescription carries loose inventory and equipped objects as two ordered
+lists. They must feed one player-owned location lookup after parsing:
+
+```text
+OnPlayerDescription(player, inventory, equipped):
+    replace player-owned loose contents with inventory, preserving wire order
+    for each equipped entry in wire order:
+        record item as owned by player
+        record equipped location and layering priority
+        append it to the same ordered player-owned lookup
+```
+
+This is the login equivalent of a live `WieldObject`, which also models the
+item as contained by its wielder with a non-zero equipped location. Keeping
+login equipment outside that lookup makes `GetDefaultCombatMode` miss an
+already-equipped bow/crossbow and request Melee; ACE then correctly rejects the
+mode because a missile weapon is equipped. ACE's
+`Player.HandleActionChangeCombatMode_Inner` performs that rejection, while
+holtburger independently retains PlayerDescription's `equipped_objects` list
+for its suggested-combat-mode decision.
+
 ## ParentEvent wire and freshness
 
 ```text