fix(items): finish corpse pickup and combat switching

Port retail's first-slot ShowPendingInPlayer path for double-click loot and carry the current owned-container destination through deferred pickup. Retire the previous ground-container view as soon as a replacement is requested so its range close cannot cancel ACE's active MoveTo chain.

Preserve active-combat weapon intent across ACE's authoritative wand-to-missile stance tail while leaving peace-mode switches unchanged.

Release build succeeds and all 5,885 tests pass with five intentional skips.

Co-authored-by: OpenAI Codex <codex@openai.com>

docs/research/2026-07-12-retail-weapon-switch-pseudocode.md

@@ -111,6 +111,17 @@ on server-confirmed WieldObject(item):
        and pending.blockingItem is none:
         clear pending
 
+        if the transaction began in an active combat mode:
+            // ACE compatibility boundary; see below.
+            retain the ready mode implied by the confirmed equip location
+
+on combat-mode notices after confirmed WieldObject:
+    if the first notice is the retained ready mode:
+        clear the retained mode; the server already settled correctly
+    else if notices form NonCombat -> retained ready mode -> NonCombat:
+        clear the retained mode
+        request that ready mode from ACE's trailing NonCombat notice
+
 on PrivateUpdatePropertyInt(property = CombatMode, value):
     if value is exactly NonCombat, Melee, Missile, or Magic:
         CombatState.SetCombatMode(value)
@@ -119,11 +130,28 @@ on PrivateUpdatePropertyInt(property = CombatMode, value):
 ## Animation ownership
 
 The client must not synthesize a local bow-to-sword animation. In peace mode,
-ACE leaves `CombatMode` as `NonCombat`. In combat mode, ACE selects the new
-weapon's stance and sends the authoritative motion stream plus PropertyInt 40.
-The inventory controller only sequences the two wire requests and waits for
-the old weapon's confirmed move; the existing motion and equipped-child
-render paths consume the server events.
+ACE leaves `CombatMode` as `NonCombat`. The inventory controller sequences the
+two wire requests and waits for the old weapon's confirmed move; the existing
+motion and equipped-child render paths consume the server events.
+
+### ACE active-combat compatibility boundary
+
+A connected 2026-07-17 trace of Magic wand -> missile weapon showed ACE emit
+`Magic -> Melee -> NonCombat -> Missile -> NonCombat`. This is a consequence of
+ACE `Player_Inventory.TryShuffleStance` plus its queued dequip callbacks: the
+server does select Missile for the new weapon, but a later queued callback
+publishes NonCombat after the authoritative `WieldObject`. Retail's client does
+not need a second request against the retail server.
+
+acdream therefore preserves the user's desired ready mode only when AutoWield
+begins in active combat. Authoritative `WieldObject` arms settlement. A server
+whose first subsequent notice is already the desired mode needs no request.
+Local ACE instead emits `NonCombat -> desired mode -> NonCombat`; the client
+sends one normal `ChangeCombatMode` request from that trailing notice,
+necessarily after the queued callback that caused it. All resulting state and animation remain server-
+authoritative. No update is ignored, delayed, or locally fabricated, and a
+transaction begun in peace sends no mode request. This narrow server-
+compatibility adaptation is recorded as AP-118.
 
 The request is not complete when `GetAndWieldItem` is merely sent. Retail
 `UIAttemptWield` records `prevRequest = IR_WIELD` and leaves the item waiting

docs/research/2026-07-17-retail-external-container-looting-pseudocode.md

@@ -22,6 +22,10 @@ Named Sept-2013 retail symbols:
 - `UIElement_ItemList::ListenToElementMessage @ 0x004E4D50`
 - `ClientUISystem::SetGroundObject @ 0x00564510`
 - `ClientUISystem::OnViewContents @ 0x00565870`
+- `CPlayerSystem::PlaceInBackpack @ 0x0055D8C0`
+- `gmInventoryUI::RecvNotice_ShowPendingInPlayer @ 0x004A6B50`
+- `gmInventoryUI::RecvNotice_EndPendingInPlayer @ 0x004A68B0`
+- `UIElement_ItemList::ItemList_InsertItem @ 0x004E3F40`
 - `ACCWeenieObject::UIAttemptPutInContainer @ 0x0058D680`
 - `ACCWeenieObject::UIAttemptSplitToContainer @ 0x0058D7D0`
 - `ItemHolder::AttemptToPlaceInContainer @ 0x00588140`
@@ -69,9 +73,22 @@ thumb, and arrow sprites from LayoutDesc `0x2100003E`.
 ```text
 UseWorldObject(objectId):
     decision = ItemHolder policy
-    if decision is SetGroundObject:
-        expectedExternalRoot = objectId
     send Use(objectId)
+    if decision is SetGroundObject:
+        SetGroundObject(objectId, notifyServer = true)
+
+SetGroundObject(newRoot, notifyServer):
+    if currentExternalRoot == newRoot:
+        return
+    oldRoot = currentExternalRoot
+    if oldRoot != 0:
+        retire oldRoot's temporary contents tree
+        publish SetGroundObject(0) to the external panel
+        if notifyServer:
+            send NoLongerViewingContents(oldRoot)
+    currentExternalRoot = newRoot
+    expectedExternalRoot = newRoot
+    // The panel remains empty until ViewContents for newRoot is accepted.
 
 UseCorpse(corpseId):
     // A corpse is a TYPE_CONTAINER carrying BF_STUCK | BF_CORPSE.
@@ -86,11 +103,6 @@ OnViewContents(containerId, orderedEntries):
     if containerId != expectedExternalRoot:
         return
 
-    old = currentExternalRoot
-    if old != 0 and old != containerId:
-        objectTable.StopViewingContentsTree(old)
-        send NoLongerViewingContents(old) exactly once
-
     currentExternalRoot = containerId
     expectedExternalRoot = containerId
     externalPanel.SetGroundObject(containerId)
@@ -138,6 +150,14 @@ OnExternalItemDoubleClick(itemId):
     ItemHolder.UseObject(itemId)
     // Because item.ContainerId is currentExternalRoot, retail policy emits
     // PlaceInBackpack; the server remains authoritative for the move.
+    destination = current open owned pack
+    destinationList.RemoveTrailingEmptyItem()
+    destinationList.AddEmptySlot(at index 0)
+    destinationList.AddItem(itemId)
+    destinationList.pendingItem.SetWaitingState(true)
+    send PutItemInContainer(itemId, destination, placement = 0)
+    // The pending item therefore reserves the FIRST slot and shifts the
+    // existing packed list to the right until the server confirms or rejects.
 
 DragExternalItemToOwnedInventory(itemId, placement, splitAmount):
     if splitAmount < full stack:
@@ -171,8 +191,10 @@ DragOwnedItemToExternalContainer(itemId, placement, splitAmount):
 ## Architectural mapping
 
 - `ExternalContainerState` in Core owns only expected/current external-root
-  identity and transition ordering. It filters ACE's nested `ViewContents`
-  packets so they cannot replace the visible root.
+  identity and transition ordering. A replacement request retires current
+  presentation immediately, matching `SetGroundObject`; accepted
+  `ViewContents` later opens the requested root. It filters ACE's nested
+  `ViewContents` packets so they cannot replace the visible root.
 - `ExternalContainerLifecycleController` in App observes those transitions,
   retires the replaced root's temporary preview tree, then owns the
   replacement-only `NoLongerViewingContents` network side effect. The wire