Refine ISAC selection controls and icons

docs/DESIGN_SYSTEM.md

@@ -755,13 +755,29 @@ rail and filled square indicator; deselected segments remain readable and
 available. The channel rail collapses from six to three and then two columns as
 space narrows, with minimum 44-pixel mobile targets.
 
-Use the shared `SegmentedChoice` component for compact, finite option sets.
-Radio mode represents one required choice; checkbox mode represents additive
-independent choices. Prefer this visible segmented treatment over a dropdown
-when the complete option set is small enough to scan comfortably. Dropdowns
-remain appropriate for long, dynamic, or search-oriented lists. Both modes
-share hover, pressed, focus-visible, selected, disabled, responsive, and
-44-pixel mobile-target behavior so feature modules do not reimplement it.
+Use the shared `SegmentedChoice` component for every static, scannable ISAC
+choice set containing two through six options. Radio mode represents one
+required choice; checkbox mode represents additive independent choices. This
+rule applies equally to editors and registry filters: do not introduce a native
+dropdown merely to save vertical space. Use the shared `SearchableAssignment`
+component in single or multiple mode when there are seven or more options, when
+the options come from a growing data registry, or when search materially helps
+recognition. Compact mode is the standard treatment for filter bars and dense
+repeated rows; full mode is used for primary relationships.
+
+Native selects are not a default ISAC control. Retain one only when a documented
+browser-native behavior cannot be represented accessibly by either shared
+component. Such an exception must be called out in this design system in the
+same change. Both shared choice patterns expose explicit selection, hover,
+pressed, focus-visible, disabled, empty/all, responsive, and 44-pixel
+mobile-target states so modules do not reimplement them.
+
+`SegmentedChoice` supports two restrained density variants. Icon-only segments
+may omit visible text when a canonical, unambiguous game icon exists; they must
+retain an accessible label and hover title. Text-only segments may omit the
+default square indicator when the selected background, orange text, and lower
+rail already communicate state clearly. Do not remove both visible text and an
+icon from the same option.
 
 ### Skill Chip data console
 
@@ -810,6 +826,28 @@ the filtered result registry opens as an anchored overlay. The compact overlay
 must layer above adjacent rows, retain pending-record labels, and collapse to
 one column on narrow screens.
 
+Gear identity editing uses the shared segmented radio treatment for both Gear
+slot and item tier. Show all six slots together and all three tiers together so
+contributors can verify classification without opening a menu. The record name
+remains the dominant text field; at medium widths it occupies a full row above
+the two selectors. On narrow screens the slot selector becomes a three-by-two
+grid, both selectors use at least 44-pixel targets, and changing slot clears
+incompatible Talent relationships exactly as the former selector did. Gear
+slot segments use icon-only controls with accessible slot names; registry labels
+retain icon and text for rapid table scanning. Tier segments use the compact
+game notation `T0`, `T1`, and `T2`, omit the redundant square indicator, and
+rely on the selected rail and color; do not expand these to “Tier 0” inside
+dense segmented controls. On desktop, icon-only Gear slot segments are square
+32-pixel cells so their classification rail stays compact and the adjacent
+record-name input receives the dominant width. Increase those cells to square
+44-pixel targets at mobile sizes without reintroducing visible slot text.
+
+Root-level static PNGs are interface icons and use content-fitted transparent
+bounds. Run `npm run assets:trim-icons` after adding or replacing them. The
+normalizer trims fully transparent padding, restores a two-pixel transparent
+safety margin so antialiased edges never touch the canvas, preserves RGBA PNG
+output, and leaves portrait/avatar and SVG asset classes untouched.
+
 ### Shared equipment profiles
 
 Configuration inherited by every item of a finite equipment type belongs in a