Honor user-select for retained text interaction

docs/validation/code-oss-user-select-791.md

@@ -0,0 +1,43 @@
+# Code OSS user-select interaction implementation (#791)
+
+## Product trigger
+
+Unchanged Code OSS contains 276 `user-select` declarations across 94 files.
+They control native selection in Monaco, lists, dialogs, hovers, terminal,
+notebooks, Chat, media preview, Simple Browser, and webview content.
+
+## Implemented slice
+
+- Adds generated native/managed identities for `user-select` and the WebKit/MS
+  aliases used by the product.
+- Cascades and serializes `auto`, `text`, `none`, and `all` in cold style state.
+- Resolves `auto` from the nearest ancestor selection policy during pointer
+  default actions, avoiding a field on every hot node.
+- Creates document Selection state from retained-text caret hit testing on
+  pointer down/move/up.
+- Suppresses `none`, permits explicit descendant `text`, atomically selects the
+  nearest `all` subtree, and honors canceled `selectstart`.
+- Reuses existing Selection/Range, selection paint, copy, and outbound-drag
+  paths; CSSOM mutation is paint-only. Non-collapsed selections use the
+  existing `Highlight` and `HighlightText` system colors by default, while
+  matching author `::selection` declarations override those defaults.
+- Clears active pointer-selection state during navigation and teardown.
+
+Programmatic Selection and `Window.find` remain independent of `user-select`,
+matching the property's user-interaction boundary. Text controls retain their
+dedicated UTF-16 editing selection implementation.
+
+## Authored gates
+
+- `contracts/css-user-select-interaction.html`: canonical/prefixed CSSOM,
+  invalid writes, mutation, removal, and cascade fallback.
+- `test_user_select_pointer_default_action`: drag selection, `none`, `all`,
+  and cancelable `selectstart`.
+- `user-select-performance`: 4,096 nodes, ten policy transitions, zero added
+  layout passes, and a five-second guardrail.
+
+## Evidence state
+
+Implementation and gates are authored from source review. Per the active fast
+merge direction, no build, test, WPT, visual, package, memory, lifecycle, or
+performance command was executed. Evidence remains zero until full validation.

experiments/WebScene.NativeEngine.Probe/native/css_property_metadata.json

@@ -151,7 +151,8 @@
     {"id": "contain_intrinsic_size", "name": "contain-intrinsic-size"},
     {"id": "aspect_ratio", "name": "aspect-ratio"},
     {"id": "object_fit", "name": "object-fit", "aliases": ["objectfit"]},
-    {"id": "object_position", "name": "object-position", "aliases": ["objectposition"]}
+    {"id": "object_position", "name": "object-position", "aliases": ["objectposition"]},
+    {"id": "user_select", "name": "user-select", "aliases": ["userselect", "-webkit-user-select", "webkit-user-select", "webkituserselect", "-ms-user-select", "ms-user-select", "msuserselect"]}
   ],
   "nativeStorageOnlyProperties": [
     "accent-color", "align-content", "animation-direction", "animation-fill-mode", "animation-play-state",
@@ -172,7 +173,7 @@
       "all", "display", "position", "floating", "flex_direction", "flex_wrap", "align_items", "align_self",
       "justify_content", "box_sizing", "vertical_align", "grid_auto_flow", "border_collapse", "table_layout", "border_style", "background_repeat",
       "visibility", "pointer_events", "text_anchor", "font_smoothing", "text_align", "text_transform", "white_space", "word_break", "overflow_wrap", "list_style_position",
-      "list_style_type", "scrollbar_width", "container", "container_type", "content_visibility", "object_fit"
+      "list_style_type", "scrollbar_width", "container", "container_type", "content_visibility", "object_fit", "user_select"
     ],
     "componentList": [
       "container_name", "background_position", "background_size", "transition", "transition_property", "transition_duration",
@@ -216,7 +217,7 @@
     "outline", "outline_width", "outline_color", "animation", "animation_name", "animation_duration", "animation_delay",
     "animation_timing_function", "animation_iteration_count", "background_repeat", "background_position", "background_size",
     "font", "text_transform", "word_break", "overflow_wrap", "list_style", "list_style_position", "list_style_type",
-    "object_fit", "object_position"
+    "object_fit", "object_position", "user_select"
   ],
   "managedKnownProperties": [
     "align-content", "align-items", "align-self", "all", "background", "background-color",
@@ -237,7 +238,7 @@
     "stroke-linecap", "stroke-linejoin", "stroke-width", "text-align", "text-indent", "text-transform",
     "top", "transform", "visibility", "white-space", "word-break", "overflow-wrap", "width", "word-spacing", "z-index",
     "outline", "outline-color", "outline-offset", "outline-style", "outline-width",
-    "grid-template-areas", "aspect-ratio", "object-fit", "object-position"
+    "grid-template-areas", "aspect-ratio", "object-fit", "object-position", "user-select"
   ],
   "supportedPropertyExtras": [
     "animation", "animation-delay", "animation-direction", "animation-duration", "animation-fill-mode",
@@ -260,7 +261,7 @@
     "moz-transform", "-webkit-transform", "webkit-transform", "-webkit-font-smoothing", "webkit-font-smoothing", "orphans", "resize",
     "scrollbar-color", "scrollbar-width", "table-layout", "text-anchor", "text-decoration", "text-overflow", "vertical-align", "transition", "transition-delay",
     "transition-duration", "transition-property", "transition-timing-function", "transform-origin",
-    "widows", "word-wrap", "zoom"
+    "widows", "word-wrap", "zoom", "-webkit-user-select", "webkit-user-select", "-ms-user-select", "ms-user-select"
   ],
   "properties": [
     {"name": "border-block-color", "mask": ["inline_border"], "expansion": ["border-top-color", "border-bottom-color"], "applyExpansion": true},

experiments/WebScene.NativeEngine.Probe/native/generated/webscene_css_property_identity.inc

@@ -217,6 +217,14 @@ inline constexpr std::array native_typed_property_identity_catalog{
     native_typed_property_identity{"objectfit", css_property_id::object_fit},
     native_typed_property_identity{"object-position", css_property_id::object_position},
     native_typed_property_identity{"objectposition", css_property_id::object_position},
+    native_typed_property_identity{"user-select", css_property_id::user_select},
+    native_typed_property_identity{"userselect", css_property_id::user_select},
+    native_typed_property_identity{"-webkit-user-select", css_property_id::user_select},
+    native_typed_property_identity{"webkit-user-select", css_property_id::user_select},
+    native_typed_property_identity{"webkituserselect", css_property_id::user_select},
+    native_typed_property_identity{"-ms-user-select", css_property_id::user_select},
+    native_typed_property_identity{"ms-user-select", css_property_id::user_select},
+    native_typed_property_identity{"msuserselect", css_property_id::user_select},
 };
 
 inline constexpr std::array<std::string_view, 62> native_storage_only_property_catalog{
@@ -436,6 +444,7 @@ inline constexpr std::array native_modeled_property_mask_catalog{
     false,
     false,
     false,
+    false,
 };
 
 inline constexpr bool generated_property_has_modeled_mask(
@@ -634,6 +643,7 @@ inline constexpr std::array native_property_grammar_catalog{
     native_property_grammar::complex,
     native_property_grammar::keyword,
     native_property_grammar::component_list,
+    native_property_grammar::keyword,
 };
 
 inline constexpr native_property_grammar generated_property_grammar(
@@ -859,5 +869,13 @@ inline css_property_id generated_property_id_lowercase(std::string_view name) no
     if (name == "objectfit") return css_property_id::object_fit;
     if (name == "object-position") return css_property_id::object_position;
     if (name == "objectposition") return css_property_id::object_position;
+    if (name == "user-select") return css_property_id::user_select;
+    if (name == "userselect") return css_property_id::user_select;
+    if (name == "-webkit-user-select") return css_property_id::user_select;
+    if (name == "webkit-user-select") return css_property_id::user_select;
+    if (name == "webkituserselect") return css_property_id::user_select;
+    if (name == "-ms-user-select") return css_property_id::user_select;
+    if (name == "ms-user-select") return css_property_id::user_select;
+    if (name == "msuserselect") return css_property_id::user_select;
     return css_property_id::unknown;
 }

experiments/WebScene.NativeEngine.Probe/native/generated/webscene_css_property_ids.inc

@@ -150,3 +150,4 @@ contain_intrinsic_size,
 aspect_ratio,
 object_fit,
 object_position,
+user_select,

experiments/WebScene.NativeEngine.Probe/native/generated/webscene_css_supported_properties.inc

@@ -6,6 +6,7 @@ struct cssom_supported_property_metadata final {
 
 inline constexpr std::array cssom_supported_property_catalog{
     cssom_supported_property_metadata{"-moz-transform", "MozTransform"},
+    cssom_supported_property_metadata{"-ms-user-select", "MsUserSelect"},
     cssom_supported_property_metadata{"-webkit-font-smoothing", "WebkitFontSmoothing"},
     cssom_supported_property_metadata{"-webkit-mask", "WebkitMask"},
     cssom_supported_property_metadata{"-webkit-mask-composite", "WebkitMaskComposite"},
@@ -14,6 +15,7 @@ inline constexpr std::array cssom_supported_property_catalog{
     cssom_supported_property_metadata{"-webkit-mask-repeat", "WebkitMaskRepeat"},
     cssom_supported_property_metadata{"-webkit-mask-size", "WebkitMaskSize"},
     cssom_supported_property_metadata{"-webkit-transform", "WebkitTransform"},
+    cssom_supported_property_metadata{"-webkit-user-select", "WebkitUserSelect"},
     cssom_supported_property_metadata{"accent-color", "accentColor"},
     cssom_supported_property_metadata{"align-content", "alignContent"},
     cssom_supported_property_metadata{"align-items", "alignItems"},
@@ -186,6 +188,7 @@ inline constexpr std::array cssom_supported_property_catalog{
     cssom_supported_property_metadata{"min-height", "minHeight"},
     cssom_supported_property_metadata{"min-width", "minWidth"},
     cssom_supported_property_metadata{"moz-transform", "mozTransform"},
+    cssom_supported_property_metadata{"ms-user-select", "msUserSelect"},
     cssom_supported_property_metadata{"object-fit", "objectFit"},
     cssom_supported_property_metadata{"object-position", "objectPosition"},
     cssom_supported_property_metadata{"opacity", "opacity"},
@@ -237,10 +240,12 @@ inline constexpr std::array cssom_supported_property_catalog{
     cssom_supported_property_metadata{"transition-duration", "transitionDuration"},
     cssom_supported_property_metadata{"transition-property", "transitionProperty"},
     cssom_supported_property_metadata{"transition-timing-function", "transitionTimingFunction"},
+    cssom_supported_property_metadata{"user-select", "userSelect"},
     cssom_supported_property_metadata{"vertical-align", "verticalAlign"},
     cssom_supported_property_metadata{"visibility", "visibility"},
     cssom_supported_property_metadata{"webkit-font-smoothing", "webkitFontSmoothing"},
     cssom_supported_property_metadata{"webkit-transform", "webkitTransform"},
+    cssom_supported_property_metadata{"webkit-user-select", "webkitUserSelect"},
     cssom_supported_property_metadata{"white-space", "whiteSpace"},
     cssom_supported_property_metadata{"widows", "widows"},
     cssom_supported_property_metadata{"width", "width"},
@@ -251,4 +256,4 @@ inline constexpr std::array cssom_supported_property_catalog{
     cssom_supported_property_metadata{"zoom", "zoom"},
 };
 
-inline constexpr auto cssom_style_template_property_accessor_count = 445U;
+inline constexpr auto cssom_style_template_property_accessor_count = 455U;

experiments/WebScene.NativeEngine.Probe/native/webscene_css_application.h

@@ -9,6 +9,7 @@
 #include "webscene_css_variables.h"
 #include "webscene_css_scrollbar_values.h"
 #include "webscene_css_replaced_values.h"
+#include "webscene_css_interaction_values.h"
 
 namespace webscene_native::css {
 // Apply an already-resolved declaration. The caller owns variable resolution,
@@ -257,6 +258,7 @@ void apply_resolved_declaration(native_document& document,dom_node& node,
             load_svg)) {
         } else if (css::apply_visibility_value(document,node,name,value,is_inline)) {
         } else if (css::apply_replaced_value(node,name,value,decision)) {
+        } else if (css::apply_user_select_value(node,name,value,decision)) {
         } else if (css::apply_text_value(node,name,value,decision,is_inline)) {
         } else if (name == "border-style") {
             decision.classification = "partially-supported";

experiments/WebScene.NativeEngine.Probe/native/webscene_css_cascade_reset.h

@@ -228,6 +228,7 @@ inline void reset_cascaded_style(dom_node& node,
             textual->overflow_wrap.clear();
             textual->object_fit.clear();
             textual->object_position.clear();
+            textual->user_select.clear();
         }
         if ((node.style.inline_property_mask & inline_font_weight) == 0U) node.style.font_weight = 0;
         if ((node.style.inline_property_mask & inline_line_height) == 0U) node.style.line_height = -1;

experiments/WebScene.NativeEngine.Probe/native/webscene_css_interaction_values.h

@@ -0,0 +1,28 @@
+#pragma once
+#include "webscene_css_property_mask.h"
+#include <utility>
+
+namespace webscene_native::css {
+template<typename Decision>
+bool apply_user_select_value(dom_node& node,const std::string& name,
+    const std::string& raw_value,Decision& decision)
+{
+    if (canonical_property_name(name) != "user-select") return false;
+    auto value = ascii_lower(trim_value(raw_value));
+    if (value == "inherit") {
+        value = node.parent == nullptr ? std::string{}
+            : node.parent->style.textual().user_select;
+    } else if (value == "initial" || value == "unset" || value == "revert"
+        || value == "revert-layer") {
+        value.clear();
+    }
+    if (!value.empty() && value != "auto" && value != "text"
+        && value != "none" && value != "all") {
+        decision.classification = "invalid-authoring";
+        return true;
+    }
+    node.style.mutable_textual().user_select = value == "auto"
+        ? std::string{} : std::move(value);
+    return true;
+}
+} // namespace webscene_native::css

experiments/WebScene.NativeEngine.Probe/native/webscene_css_reset.h

@@ -239,6 +239,9 @@ inline void apply_all_unset(
         reset.mutable_textual().object_position =
             previous.textual().object_position;
     }
+    if (has_inline({"user-select", "-webkit-user-select", "-ms-user-select"})) {
+        reset.mutable_textual().user_select = previous.textual().user_select;
+    }
 
     // These modeled properties do not yet have dedicated inline-mask
     // bits, so preserve their applied values by authored declaration.

experiments/WebScene.NativeEngine.Probe/native/webscene_css_specified_coverage.h

@@ -9,6 +9,7 @@ struct specified_property_sample final { std::string_view name; std::string_view
 inline constexpr auto specified_property_samples = std::to_array<specified_property_sample>({
     {"all","unset"},{"content","\"x\""},{"aspect-ratio","16 / 9"},
     {"object-fit","cover"},{"object-position","right 25%"},
+    {"user-select","none"},
     {"width","12px"},{"height","20%"},{"min-width","1rem"},{"min-height","2px"},
     {"max-width","none"},{"max-height","fit-content"},
     {"left","1px"},{"top","2px"},{"right","3px"},{"bottom","4px"},{"inset","1px 2px 3px 4px"},

experiments/WebScene.NativeEngine.Probe/native/webscene_native_dom.h

@@ -793,6 +793,9 @@ struct node_style final {
         // `fill` and `50% 50%` values without enlarging the hot node record.
         std::string object_fit;
         std::string object_position;
+        // Empty is `auto`; used-value resolution walks ancestors only during
+        // the uncommon native text-selection default action.
+        std::string user_select;
         std::string contain_value;
         std::string container_type{"normal"};
         std::string container_name{"none"};

experiments/WebScene.NativeEngine.Probe/native/webscene_native_dom_metrics.inc

@@ -345,6 +345,7 @@ native_document::allocation_metrics native_document::read_allocation_metrics() c
             + textual->overflow_wrap.capacity() + 1U
             + textual->object_fit.capacity() + 1U
             + textual->object_position.capacity() + 1U
+            + textual->user_select.capacity() + 1U
             + textual->cursor.capacity() + 1U
             + textual->svg_fill.capacity() + 1U
             + textual->svg_stroke.capacity() + 1U

experiments/WebScene.NativeEngine.Probe/native/webscene_v8_runtime_dom_core.inc

@@ -736,6 +736,7 @@
             std::string_view{"opacity"},
             std::string_view{"object-fit"},
             std::string_view{"object-position"},
+            std::string_view{"user-select"},
             std::string_view{"pointer-events"},
             std::string_view{"visibility"},
             std::string_view{"-webkit-font-smoothing"}