Implement retained CSS caret color

docs/validation/code-oss-css-caret-color-804.md

@@ -0,0 +1,35 @@
+# Code OSS CSS caret-color implementation (#804)
+
+## Product trigger
+
+Unchanged Code OSS authors `caret-color:
+var(--vscode-editorCursor-foreground)` on the EditContext text area. WebScene
+previously painted the focused form-control caret with the text foreground.
+
+## Implemented slice
+
+- Adds generated native/managed identity and CSSOM for inherited
+  `caret-color`, including `auto`, `currentColor`, CSS-wide values, mutation,
+  removal, and cascade fallback.
+- Retains the uncommon token in the existing sparse cold style map, so the
+  feature adds no hot per-node field.
+- Resolves the existing kind-14 caret scene command independently from text
+  foreground while preserving element opacity.
+- Treats mutation as paint-only and adds no layout invalidation, extra scene
+  node, timer, platform widget, document scan, browser shell, or Code OSS
+  patch.
+
+## Authored gates
+
+- `contracts/css-caret-color.html`: inheritance, currentColor, computed CSSOM,
+  mutation, and removal.
+- The existing native focus/blink/caret contract now requires distinct text
+  `#123456` and caret `#abcdef` scene colors.
+- `css-caret-color-performance`: 4,096 inputs, ten transitions, zero added
+  layout, bounded scene publication, 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

@@ -158,7 +158,8 @@
     {"id": "overscroll_behavior_y", "name": "overscroll-behavior-y", "aliases": ["overscrollbehaviory"]},
     {"id": "isolation", "name": "isolation"},
     {"id": "will_change", "name": "will-change", "aliases": ["willchange"]},
-    {"id": "text_wrap", "name": "text-wrap", "aliases": ["textwrap"]}
+    {"id": "text_wrap", "name": "text-wrap", "aliases": ["textwrap"]},
+    {"id": "caret_color", "name": "caret-color", "aliases": ["caretcolor"]}
   ],
   "nativeStorageOnlyProperties": [
     "accent-color", "align-content", "animation-direction", "animation-fill-mode", "animation-play-state",
@@ -211,20 +212,20 @@
       "grid_column_end", "border", "border_top", "border_right", "border_bottom", "border_left", "border_inline", "border_block",
       "border_color", "outline", "transform", "transform_origin", "box_shadow", "background", "background_image", "overflow",
       "overflow_x", "overflow_y", "opacity", "fill", "stroke", "cursor", "font", "font_family",
-      "font_weight", "list_style"
+      "font_weight", "list_style", "caret_color"
     ]
   },
   "nativeInheritedProperties": [
     "all", "color", "cursor", "direction", "font", "font-family", "font-size", "font-style",
     "font-weight", "letter-spacing", "line-height", "list-style", "list-style-position", "list-style-type",
-    "text-align", "text-transform", "visibility", "white-space", "word-break", "overflow-wrap", "word-spacing", "-webkit-font-smoothing"
+    "text-align", "text-transform", "visibility", "white-space", "text-wrap", "word-break", "overflow-wrap", "word-spacing", "caret-color", "-webkit-font-smoothing"
   ],
   "nativeMasklessPropertyIds": [
     "content", "aspect_ratio", "vertical_align", "grid_auto_columns", "grid_auto_flow", "table_layout", "border_inline", "border_block",
     "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", "user_select", "overscroll_behavior", "overscroll_behavior_x", "overscroll_behavior_y", "isolation", "will_change", "text_wrap"
+    "object_fit", "object_position", "user_select", "overscroll_behavior", "overscroll_behavior_x", "overscroll_behavior_y", "isolation", "will_change", "text_wrap", "caret_color"
   ],
   "managedKnownProperties": [
     "align-content", "align-items", "align-self", "all", "background", "background-color",
@@ -246,7 +247,7 @@
     "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", "user-select",
-    "overscroll-behavior", "overscroll-behavior-x", "overscroll-behavior-y", "isolation", "will-change", "text-wrap"
+    "overscroll-behavior", "overscroll-behavior-x", "overscroll-behavior-y", "isolation", "will-change", "text-wrap", "caret-color"
   ],
   "supportedPropertyExtras": [
     "animation", "animation-delay", "animation-direction", "animation-duration", "animation-fill-mode",

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

@@ -236,6 +236,8 @@ inline constexpr std::array native_typed_property_identity_catalog{
     native_typed_property_identity{"willchange", css_property_id::will_change},
     native_typed_property_identity{"text-wrap", css_property_id::text_wrap},
     native_typed_property_identity{"textwrap", css_property_id::text_wrap},
+    native_typed_property_identity{"caret-color", css_property_id::caret_color},
+    native_typed_property_identity{"caretcolor", css_property_id::caret_color},
 };
 
 inline constexpr std::array<std::string_view, 62> native_storage_only_property_catalog{
@@ -462,6 +464,7 @@ inline constexpr std::array native_modeled_property_mask_catalog{
     false,
     false,
     false,
+    false,
 };
 
 inline constexpr bool generated_property_has_modeled_mask(
@@ -472,9 +475,10 @@ inline constexpr bool generated_property_has_modeled_mask(
         && native_modeled_property_mask_catalog[index];
 }
 
-inline constexpr std::array<std::string_view, 22> native_inherited_property_catalog{
+inline constexpr std::array<std::string_view, 24> native_inherited_property_catalog{
     "-webkit-font-smoothing",
     "all",
+    "caret-color",
     "color",
     "cursor",
     "direction",
@@ -491,6 +495,7 @@ inline constexpr std::array<std::string_view, 22> native_inherited_property_cata
     "overflow-wrap",
     "text-align",
     "text-transform",
+    "text-wrap",
     "visibility",
     "white-space",
     "word-break",
@@ -667,6 +672,7 @@ inline constexpr std::array native_property_grammar_catalog{
     native_property_grammar::keyword,
     native_property_grammar::keyword,
     native_property_grammar::keyword,
+    native_property_grammar::complex,
 };
 
 inline constexpr native_property_grammar generated_property_grammar(
@@ -911,5 +917,7 @@ inline css_property_id generated_property_id_lowercase(std::string_view name) no
     if (name == "willchange") return css_property_id::will_change;
     if (name == "text-wrap") return css_property_id::text_wrap;
     if (name == "textwrap") return css_property_id::text_wrap;
+    if (name == "caret-color") return css_property_id::caret_color;
+    if (name == "caretcolor") return css_property_id::caret_color;
     return css_property_id::unknown;
 }

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

@@ -157,3 +157,4 @@ overscroll_behavior_y,
 isolation,
 will_change,
 text_wrap,
+caret_color,

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

@@ -94,6 +94,7 @@ inline constexpr std::array cssom_supported_property_catalog{
     cssom_supported_property_metadata{"bottom", "bottom"},
     cssom_supported_property_metadata{"box-shadow", "boxShadow"},
     cssom_supported_property_metadata{"box-sizing", "boxSizing"},
+    cssom_supported_property_metadata{"caret-color", "caretColor"},
     cssom_supported_property_metadata{"clear", "clear"},
     cssom_supported_property_metadata{"clip-path", "clipPath"},
     cssom_supported_property_metadata{"clip-rule", "clipRule"},
@@ -262,4 +263,4 @@ inline constexpr std::array cssom_supported_property_catalog{
     cssom_supported_property_metadata{"zoom", "zoom"},
 };
 
-inline constexpr auto cssom_style_template_property_accessor_count = 466U;
+inline constexpr auto cssom_style_template_property_accessor_count = 468U;

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

@@ -98,6 +98,20 @@ template<typename Decision,typename Protected,typename LoadSvg>
 bool apply_paint_value(dom_node& node,const std::string& name,const std::string& value,
     Decision& decision,Protected&& is_inline,LoadSvg&& load_svg)
 {
+    if (name == "caret-color") {
+            auto normalized = ascii_lower(trim_value(value));
+            auto& effects = node.style.mutable_textual().effect_values;
+            if (normalized == "inherit" || normalized == "unset") {
+                effects.erase(name);
+            } else {
+                if (normalized == "initial" || normalized == "revert"
+                    || normalized == "revert-layer") normalized = "auto";
+                effects[name] = std::move(normalized);
+            }
+            decision.classification = "supported";
+            decision.semantic_slice = "retained inherited caret paint";
+            return true;
+    }
     if (name == "mask-image") {
             auto& effects = node.style.mutable_textual().effect_values;
             effects.erase("-webscene-mask-markup");

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

@@ -258,6 +258,12 @@ inline void apply_all_unset(
         reset.mutable_textual().will_change = previous.textual().will_change;
         reset.will_change_stacking_context = previous.will_change_stacking_context;
     }
+    if (has_inline({"caret-color"})) {
+        const auto value = previous.textual().effect_values.find("caret-color");
+        if (value != previous.textual().effect_values.end()) {
+            reset.mutable_textual().effect_values["caret-color"] = value->second;
+        }
+    }
 
     // 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

@@ -14,6 +14,7 @@ inline constexpr auto specified_property_samples = std::to_array<specified_prope
         {"isolation","isolate"},
         {"will-change","transform, opacity"},
         {"text-wrap","nowrap"},
+        {"caret-color","#123456"},
     {"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_css_specified_ir.h

@@ -240,6 +240,9 @@ inline specified_css_value compile_specified_value(css_property_id property,std:
     case native_property_grammar::special:return out;
     }
     switch(property){
+    case css_property_id::caret_color:
+        if(css_ir_lower(value)=="auto")keyword();else color();
+        break;
     case css_property_id::aspect_ratio:components();break;
     case css_property_id::contain:case css_property_id::cursor:case css_property_id::font_family:components();break;
     case css_property_id::fill:case css_property_id::stroke:color();break;

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

@@ -756,6 +756,10 @@ inline specified_css_value compile_specified_value(css_property_id property, std
     }
 
     switch (property) {
+    case css_property_id::caret_color:
+        if (specified_ascii_lower(value) == "auto") set_keyword();
+        else set_color();
+        break;
     case css_property_id::aspect_ratio:
         set_component_list(); break;
     case css_property_id::contain:

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

@@ -723,6 +723,15 @@ uint32_t resolved_foreground(const dom_node& node)
     return 0xD1D4DCFFU;
 }
 
+uint32_t resolved_caret_color(const dom_node& node)
+{
+    const auto value = resolved_caret_color_token(node);
+    if (value == "auto" || value == "currentcolor") {
+        return resolved_foreground(node);
+    }
+    return native_document::parse_color(std::string(value));
+}
+
 void append_xml_escaped(std::string_view value, std::string& output, bool attribute)
 {
     for (const auto character : value) {

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

@@ -2245,6 +2245,16 @@ inline std::string_view resolved_text_wrap_mode(const dom_node& node) noexcept
     return "wrap";
 }
 
+inline std::string_view resolved_caret_color_token(const dom_node& node) noexcept
+{
+    for (auto* current = &node; current != nullptr; current = current->parent) {
+        const auto& effects = current->style.textual().effect_values;
+        const auto value = effects.find("caret-color");
+        if (value != effects.end()) return value->second;
+    }
+    return "auto";
+}
+
 // Shared by retained layout/paint and the V8-free CSS service contract so the
 // contract exercises the production marker-suppression path.
 std::string list_marker_text(const dom_node& node);

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

@@ -2967,7 +2967,7 @@ void native_document::append_scene(
                 text_y + 1.0F,
                 caret_x,
                 text_y + std::max(1.0F, line_height - 1.0F),
-                with_opacity(resolved_foreground(node)),
+                with_opacity(resolved_caret_color(node)),
                 node.id});
         }
     }

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

@@ -744,6 +744,7 @@
             std::string_view{"user-select"},
             std::string_view{"isolation"},
             std::string_view{"will-change"},
+            std::string_view{"caret-color"},
             std::string_view{"pointer-events"},
             std::string_view{"visibility"},
             std::string_view{"-webkit-font-smoothing"}

experiments/WebScene.NativeEngine.Probe/native/webscene_v8_runtime_style.inc

@@ -51,6 +51,29 @@
         return "normal";
     }
 
+    static std::string serialized_caret_color(const dom_node& node)
+    {
+        const auto token = resolved_caret_color_token(node);
+        auto color = uint32_t{0xD1D4DCFFU};
+        if (token == "auto" || token == "currentcolor") {
+            color = resolved_current_color_for_cssom(node);
+        } else {
+            color = native_document::parse_color(std::string(token));
+        }
+        std::ostringstream stream;
+        const auto red = static_cast<unsigned>((color >> 24U) & 0xFFU);
+        const auto green = static_cast<unsigned>((color >> 16U) & 0xFFU);
+        const auto blue = static_cast<unsigned>((color >> 8U) & 0xFFU);
+        const auto alpha = static_cast<unsigned>(color & 0xFFU);
+        if (alpha == 0xFFU) {
+            stream << "rgb(" << red << ", " << green << ", " << blue << ')';
+        } else {
+            stream << "rgba(" << red << ", " << green << ", " << blue << ", "
+                << serialize_css_number(static_cast<double>(alpha) / 255.0) << ')';
+        }
+        return stream.str();
+    }
+
     static bool clear_inline_style(dom_node& node, const std::string& name)
     {
         const auto canonical_name = canonical_css_property_name(name);
@@ -286,6 +309,10 @@
                 textual->will_change.clear();
             }
             node.style.will_change_stacking_context = false;
+        } else if (name == "caretColor" || name == "caret-color") {
+            if (auto* textual = node.style.mutable_textual_if_present()) {
+                textual->effect_values.erase("caret-color");
+            }
         } else if (name == "boxSizing" || name == "box-sizing") {
             node.style.border_box = false;
             node.style.inline_property_mask &= ~inline_box_sizing;
@@ -781,7 +808,8 @@
             self->apply_css_declaration(
                 *node, {canonical_name, specified_value, important}, true);
             node->style.inline_property_mask |= property_mask;
-        } else if (value.find("var(") != std::string::npos && property_mask != 0U) {
+        } else if (value.find("var(") != std::string::npos
+            && (property_mask != 0U || canonical_name == "caret-color")) {
             // A CSSOM write is observable immediately. Resolve variable-backed
             // declarations through the same computed-value path used during a
             // cascade instead of feeding raw var() tokens to numeric parsers.
@@ -1016,6 +1044,16 @@
                 std::string semantic_slice;
             } decision;
             css::apply_will_change_value(*node, name, value, decision);
+        } else if (name == "caret-color") {
+            auto normalized = ascii_lower(trim_value(specified_value));
+            auto& effects = node->style.mutable_textual().effect_values;
+            if (normalized == "inherit" || normalized == "unset") {
+                effects.erase("caret-color");
+            } else {
+                if (normalized == "initial" || normalized == "revert"
+                    || normalized == "revert-layer") normalized = "auto";
+                effects["caret-color"] = std::move(normalized);
+            }
         } else if (name == "box-sizing") {
             node->style.border_box = value == "border-box";
             node->style.inline_property_mask |= inline_box_sizing;
@@ -1648,6 +1686,15 @@
             } else if (name == "will-change") {
                 value = node->style.textual().will_change.empty()
                     ? "auto" : node->style.textual().will_change;
+            } else if (name == "caret-color") {
+                if (computed) {
+                    value = serialized_caret_color(*node);
+                } else {
+                    const auto& declarations = node->authored_style().declarations;
+                    const auto authored = declarations.find("caret-color");
+                    value = authored == declarations.end()
+                        ? std::string{} : authored->second;
+                }
             } else if (name == "cursor") {
                 value = resolved_cursor(*node);
             } else if (name == "font-size") {
@@ -2129,6 +2176,15 @@
         } else if (name == "willChange") {
             value = node->style.textual().will_change.empty()
                 ? "auto" : node->style.textual().will_change;
+        } else if (name == "caretColor") {
+            if (computed) {
+                value = serialized_caret_color(*node);
+            } else {
+                const auto& declarations = node->authored_style().declarations;
+                const auto authored = declarations.find("caret-color");
+                value = authored == declarations.end()
+                    ? std::string{} : authored->second;
+            }
         } else if (name == "boxSizing") {
             value = node->style.border_box ? "border-box" : "content-box";
         } else if (name == "borderRadius") {
@@ -2743,6 +2799,16 @@
                 std::string semantic_slice;
             } decision;
             css::apply_will_change_value(*node, "will-change", value, decision);
+        } else if (name == "caretColor") {
+            auto normalized = ascii_lower(trim_value(specified_value));
+            auto& effects = node->style.mutable_textual().effect_values;
+            if (normalized == "inherit" || normalized == "unset") {
+                effects.erase("caret-color");
+            } else {
+                if (normalized == "initial" || normalized == "revert"
+                    || normalized == "revert-layer") normalized = "auto";
+                effects["caret-color"] = std::move(normalized);
+            }
         } else if (name == "boxSizing") {
             node->style.border_box = value == "border-box";
             node->style.inline_property_mask |= inline_box_sizing;

experiments/WebScene.NativeEngine.Probe/native/webscene_v8_runtime_support.inc

@@ -688,6 +688,11 @@ bool valid_cssom_declaration_value(std::string_view property_name, std::string_v
     if (canonical_name == "text-wrap") {
         return normalized_value == "wrap" || normalized_value == "nowrap";
     }
+    if (canonical_name == "caret-color") {
+        const auto compiled = css::compile_specified_value(
+            css_property_id::caret_color, trimmed);
+        return compiled.valid;
+    }
 
     if (canonical_name == "position") {
         return normalized_value == "static" || normalized_value == "relative"