fix(ui): select retained items on mouse down

Port UIElement_ListBox's press-time selection ordering through the shared retained item-list contract. Inventory, loot, paperdoll, and physical shortcuts now update canonical selection before release or drag promotion, while target-mode consumption suppresses drag and release-time activation.

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

docs/plans/2026-04-11-roadmap.md

@@ -35,7 +35,10 @@ the configurable `SelectRight` action's retail release-completed gesture,
 including drag cancellation, then reuses the canonical
 picker/selection/appraisal path. The parallel retained ItemList branch now
 selects and appraises occupied inventory, external-container, paperdoll, and
-physical-shortcut cells through the same request owner. Slice 3's first connected gate exposed
+physical-shortcut cells through the same request owner. Its shared physical
+left-click contract now also matches retail's press-time selection: the
+selection frame updates on MouseDown before drag promotion, while completed
+click/double-click remains the activation boundary. Slice 3's first connected gate exposed
 three deeper defects, now corrected: the response enum mislabeled ACE's
 creature bit `0x0100` and dropped monster packets while retaining the busy
 cursor; the imported 310 x 400 examination layout was incorrectly hosted as

docs/plans/2026-05-12-milestones.md

@@ -104,6 +104,10 @@ instead of appraising the release point.
 Retail's separate retained ItemList right-click branch now covers physical
 backpack, loot, paperdoll, and toolbar item cells through the same selection
 and appraisal owner.
+The same shared ItemList contract now ports retail's left-button-down
+selection timing across inventory, loot, paperdoll, and physical shortcuts:
+selection is visible before release or drag promotion, while use/open/equip
+remains release-completed.
 Slice 3's first connected gate found and corrected the real remaining defects:
 ACE creature flag `0x0100` was mislabeled as a weapon profile and left the
 appraisal busy reference held, retail's examination UI had been mounted as a

docs/plans/2026-07-23-world-interaction-completion.md

@@ -222,9 +222,10 @@ present in the authored base name. Empty `AddItemInfo` calls are retained as
 real report fragments, restoring retail's intentional blank rows after
 workmanship, before armor level, around rating/special-property blocks, and at
 the later use/item-level boundaries. Focused wire, projection, object-table,
-title, and boots-layout fixtures protect the full path. The Release solution
-build and 3,533 App tests / 3 skips plus 7,956 complete-solution tests /
-5 skips pass; the connected boots comparison is the remaining visual gate.
+title, and boots-layout fixtures protect the full path. With the subsequent
+right-click and press-time retained-item input ports, the Release solution
+build and 3,548 App tests / 3 skips plus 7,979 complete-solution tests /
+5 skips pass.
 
 The world right-click follow-up ports
 `UIElement_SmartBoxWrapper::MouseUp @ 0x004E5820` and the
@@ -241,6 +242,13 @@ The retained follow-up ports the separate
 backpack, side-bag, loot, paperdoll-slot, or physical toolbar cell now selects
 its item and enters that same appraisal owner on a completed right-click.
 Right-button movement cancels the click and can never begin an item drag.
+The input-latency follow-up ports `UIElement_ListBox::MouseDown @ 0x0046E3A0`
+and the physical left-click branch of
+`UIElement_ItemList::ListenToElementMessage @ 0x004E4D50`. Canonical selection
+and the retained green frame update during left-button down, before the
+three-pixel drag threshold. Target mode is offered first. Opening, using,
+equipping, looting, and shortcut activation remain completed-click or
+double-click actions and are suppressed when target mode consumed the press.
 
 ## Slice 1 — spell-bar overflow arrows