feat(ui): drive toolbar use state from selection

Port the retail selected-object availability predicate into Core and project it through the shared interaction owner. The imported hand now follows canonical selection/object notices, keeps weapon and targeted-tool activation on the existing wield/use cursor paths, and ghosts empty or explicitly unusable selections per the connected UX requirement.

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

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

@@ -1,6 +1,7 @@
 # World interaction completion — pre-M4 program
 
-**Status:** Slice 1 code-complete 2026-07-23; connected visual gate pending.
+**Status:** Slice 1 user-accepted 2026-07-23. Slice 2 Use-hand state and command
+path code-complete; connected visual gate pending before Assess continues.
 **Milestone:** M4 prerequisite/preamble.
 **Architecture:** retained gameplay UI over shared selection, object, and
 interaction state. `GameWindow` remains a composition/callback shell.
@@ -52,9 +53,21 @@ spells. Passive object/endowment refresh preserves a manual offset. The mixed
 producing exactly 18 visible 32-pixel favorite cells (nine numbered plus nine
 unnumbered) without consuming the overflow. The initial 57-test/full-suite gate passed;
 the corrective 104-test focus set, 3,472 App tests / 3 skips, Release solution
-build, and 7,845 complete-solution tests / 5 skips pass. The connected gate is
-pending after user feedback on arrow sides, rollover, width, and offset
-persistence.
+build, and 7,845 complete-solution tests / 5 skips pass. The corrected
+18-cell bar and both overflow directions passed the connected gate.
+
+Slice 2 now drives the toolbar hand from canonical `SelectionState` changes and
+live `ClientObjectTable` updates. The pure Core predicate ports
+`gmToolbarUI::HandleSelectionChanged`: combat-use items, armor/clothing/jewelry,
+and `ItemUses` values without `USEABLE_NO` remain active. Clicking still enters
+the existing `ItemInteractionController` command path, so weapons use the
+server-confirmed AutoWield transaction and targeted tools enter the existing
+use-on-target cursor. Empty selection and explicitly unusable spell components
+are ghosted and ignore clicks. Empty-selection ghosting is the user's explicit
+choice over retail's generic `TARGET_MODE_USE` entry and is registered as
+AP-122. The 14-test Core interaction focus, 49-test toolbar focus, Release
+solution build, 3,474 App tests / 3 skips, and 7,848 complete-solution tests /
+5 skips pass.
 
 ## Slice 1 — spell-bar overflow arrows
 
@@ -115,3 +128,27 @@ Named retail references and executable pseudocode are recorded in
 - Existing stack, combat-power, chat, inventory, spellbook, and external
   container scrollbars retain their current behavior.
 - No substantial feature body enters `GameWindow`.
+
+## Slice 2 — status Use/Assess commands
+
+### Use-hand implementation
+
+1. `ItemInteractionPolicy.IsToolbarUseEnabled` is the pure named-retail
+   selection predicate.
+2. `ItemInteractionController.IsToolbarUseEnabled` adapts the selected live
+   object without triggering a request or consuming the use throttle.
+3. `ToolbarController` subscribes to canonical `SelectionState.Changed` and
+   selected-object add/update/remove notices, then sets the imported button's
+   normal or ghosted state through `UiButton.Enabled`.
+4. Enabled clicks retain the one existing activation path:
+   equipment enters `AutoWieldController`, ordinary use enters the normal Use
+   request owner, and targeted items enter `UseItemOnTarget`, which already
+   owns the retail target cursor.
+
+### Remaining Slice 2 work
+
+- Port the magnifying-glass Assess command state and activation.
+- Run the connected Use-hand visual gate: no selection, spell component,
+  weapon, and health kit.
+- Continue directly into the Assess information slice after the combined
+  status-control gate.