feat: add independent flex shrink for Web and MyGo

docs/api-migrations.md

@@ -1,5 +1,33 @@
 # LUI API migration guide
 
+## Unreleased: independent flex shrink on Web and MyGo
+
+`row`, `column` and `box` accept `?shrink:float`. The typed `ShrinkValue`
+property uses wire name `shrink` and accepts only finite, nonnegative floats.
+Only these three standard kinds admit it. Web maps it to CSS `flex-shrink`;
+MyGo uses the existing `Element.Shrink` without an SDK or dependency update.
+Generic, SwiftUI and Kotlin profiles reject explicit shrink values; Apple and
+Android also reject direct standard wire patches rather than ignoring them.
+Extensions/raw markup do not gain a shrink property or escape hatch.
+
+Omitting or removing shrink preserves/restores the existing default factor 1.
+Setting or removing it does not change `grow` or flex basis. Existing callers
+need no changes. New callers must use a host supporting this property and a
+LUI version that knows the new wire name; older hosts reject that opt-in.
+
+For a bounded, clipped single-line strip, opt in on each direct pill container:
+
+```ocaml
+row ~flex_wrap:`nowrap
+  [row ~shrink:0. [text ~value:"First" []];
+   row ~shrink:0. [text ~value:"Second" []]]
+```
+
+Use the existing typed overflow property on the strip for clipping. Shrink on
+the strip itself does not disable shrinking its children. Remove unnecessary
+child `grow` props to keep intrinsic sizing; do not substitute `grow:0` for
+`shrink:0`, because MyGo's `Grow` also changes an auto basis to zero percent.
+
 ## Unreleased: opt-in container focus-within observation (Web and MyGo)
 
 `row`, `column` and `box` accept `?on_focus_within:(bool -> unit)` on

platform/android/lui/src/main/kotlin/dev/lui/LuiKindRules.kt

@@ -316,6 +316,7 @@ internal object LuiKindRules {
      * op is admissible for the node's kind. */
     fun supports(kind: LuiNodeKind, property: String, value: LuiWireValue): Boolean {
         if (property == "focus-within-enabled") return false
+        if (property == "shrink") return false
         when (property) {
             "virtual-total-count", "virtual-generation", "virtual-indices", "virtual-scroll-index" ->
                 return kind == LuiNodeKind.virtualList && schemaValueSupported(property, value)

platform/android/lui/src/main/kotlin/dev/lui/LuiWireSchema.kt

@@ -296,6 +296,7 @@ enum class LuiProperty(val wireName: String) {
     indeterminate("indeterminate"),
     toggleDetailEnabled("toggle-detail-enabled"),
     focusWithinEnabled("focus-within-enabled"),
+    shrink("shrink"),
     ;
 
     companion object {
@@ -338,13 +339,13 @@ object LuiSchemaMatrix {
         LuiNodeKind.checkbox to setOf(LuiProperty.gap, LuiProperty.labelOpacity, LuiProperty.indicatorBorderColor, LuiProperty.checkedIndicatorBorderColor),
         LuiNodeKind.radio to setOf(LuiProperty.gap, LuiProperty.labelOpacity),
         LuiNodeKind.grid to setOf(LuiProperty.main, LuiProperty.cross),
-        LuiNodeKind.row to setOf(LuiProperty.orientation, LuiProperty.focusWithinEnabled),
-        LuiNodeKind.column to setOf(LuiProperty.focusWithinEnabled),
+        LuiNodeKind.row to setOf(LuiProperty.orientation, LuiProperty.focusWithinEnabled, LuiProperty.shrink),
+        LuiNodeKind.column to setOf(LuiProperty.focusWithinEnabled, LuiProperty.shrink),
         LuiNodeKind.listItem to setOf(LuiProperty.display),
         LuiNodeKind.dialog to setOf(LuiProperty.description, LuiProperty.background, LuiProperty.foreground, LuiProperty.borderColor, LuiProperty.borderWidth, LuiProperty.cornerRadius, LuiProperty.gap, LuiProperty.transition),
         LuiNodeKind.drawer to setOf(LuiProperty.transition),
         LuiNodeKind.sheet to setOf(LuiProperty.transition),
-        LuiNodeKind.box to setOf(LuiProperty.inert, LuiProperty.focusWithinEnabled),
+        LuiNodeKind.box to setOf(LuiProperty.inert, LuiProperty.focusWithinEnabled, LuiProperty.shrink),
         LuiNodeKind.popover to setOf(LuiProperty.collisionPadding),
         LuiNodeKind.dropdownMenu to setOf(LuiProperty.collisionPadding),
         LuiNodeKind.tooltip to setOf(LuiProperty.collisionPadding),

platform/apple/Sources/LUIAppleBackend/LUIWireProtocol.swift

@@ -300,6 +300,8 @@ enum LUIWireValue: Decodable, Equatable {
         case .grow:
             guard let value = doubleValue else { return false }
             return value.isFinite && value >= 0
+        case .shrink:
+            return false
         case .edge:
             guard let value = stringValue else { return false }
             return Self.edges.contains(value)
@@ -1089,6 +1091,7 @@ struct LUIRetainedTree {
 
     private static func supports(_ property: LUIProperty, on kind: LUINodeKind) -> Bool {
         if property == .focusWithinEnabled { return false }
+        if property == .shrink { return false }
         switch property {
         case .virtualTotalCount, .virtualGeneration, .virtualIndices, .virtualScrollIndex:
             return kind == .virtualList
@@ -1124,6 +1127,7 @@ struct LUIRetainedTree {
                 kind == .popover || kind == .link ||
                 isHorizontalGroup(kind)
         case .grow: kind != .avatar && kind != .tooltip && !isModalSurface(kind)
+        case .shrink: false
         case .columns: kind == .grid
         case .gridColumnSpan:
             kind != .root && kind != .dialog && kind != .drawer && kind != .sheet

platform/apple/Sources/LUIAppleBackend/LUIWireSchema.swift

@@ -289,6 +289,7 @@ enum LUIProperty: String, Decodable, Hashable {
     case indeterminate = "indeterminate"
     case toggleDetailEnabled = "toggle-detail-enabled"
     case focusWithinEnabled = "focus-within-enabled"
+    case shrink = "shrink"
 }
 
 enum LUISchemaMatrix {
@@ -318,13 +319,13 @@ enum LUISchemaMatrix {
         .checkbox: [.gap, .labelOpacity, .indicatorBorderColor, .checkedIndicatorBorderColor],
         .radio: [.gap, .labelOpacity],
         .grid: [.main, .cross],
-        .row: [.orientation, .focusWithinEnabled],
-        .column: [.focusWithinEnabled],
+        .row: [.orientation, .focusWithinEnabled, .shrink],
+        .column: [.focusWithinEnabled, .shrink],
         .listItem: [.display],
         .dialog: [.description, .background, .foreground, .borderColor, .borderWidth, .cornerRadius, .gap, .transition],
         .drawer: [.transition],
         .sheet: [.transition],
-        .box: [.inert, .focusWithinEnabled],
+        .box: [.inert, .focusWithinEnabled, .shrink],
         .popover: [.collisionPadding],
         .dropdownMenu: [.collisionPadding],
         .tooltip: [.collisionPadding],

platform/mygo/capabilities.json

@@ -30,15 +30,15 @@
         "extensions_test.go:TestLayoutGeometry",
         "layout_test.go:TestLayoutSharedTypographyAndSpacingRestoreInheritedValues"
       ],
-      "contractHash": "5b37ca2312b59c73d5ca14e59389ed49a11b1dc3710bdee1409ce9675f9d8c50"
+      "contractHash": "2b0005ed2f3e54d3678748d9eb0a731c4ad075ae07bddb12fc87d58413bfb99f"
     },
     "column": {
       "route": "render.go; style.go",
       "evidence": [
         "extensions_test.go:TestLayoutGeometry",
         "layout_test.go:TestLayoutSharedTypographyAndSpacingRestoreInheritedValues"
       ],
-      "contractHash": "6f35e51043ab8ae815796b2dd3a147f0a5e01b0fe15b9bab93f588710264f720"
+      "contractHash": "e1c4ba75a65b5346c3a0231c00d01f0ebaffd12eba823b625f75aa77c36e0bf8"
     },
     "grid": {
       "route": "render.go; style.go",
@@ -117,7 +117,7 @@
         "style_test.go:TestLayoutStyleViewportFractionsAndContainerFrameRemoval",
         "style_test.go:TestLayoutStyleShadowOpacityStatesAndRemoval"
       ],
-      "contractHash": "028237d9cea015c951093e45aa35dc7c3493f8a22f27106e43dfc506da741866"
+      "contractHash": "f5ed3d53bdef46b4bf03eef8188877933fa0c005203581850747ecd1423f2c49"
     },
     "text": {
       "route": "render.go; style.go",
@@ -2338,6 +2338,12 @@
       "evidence": [
         "controls_test.go:TestControlsCheckboxMixedDetail"
       ]
+    },
+    "shrink": {
+      "route": "style.go; MyGo Element.Shrink",
+      "evidence": [
+        "style_test.go:TestLayoutStyleViewportFractionsAndContainerFrameRemoval"
+      ]
     }
   },
   "events": {