Generate shared CSS property identity metadata

.gitignore

@@ -281,6 +281,7 @@ __pycache__/
 # Cake - Uncomment if you are using it
 tools/**
 # !tools/packages.config
+!tools/generate_css_property_metadata.py
 !tools/webidl-v8-bindings/
 !tools/webidl-v8-bindings/dom-exposure.json
 !tools/webidl-v8-bindings/generate.mjs

docs/validation/css-property-identity-20260917.md

@@ -0,0 +1,82 @@
+# Generated CSS property identity validation (2026-09-17)
+
+This stage of #235 removes the remaining independent managed and native
+CSSStyleDeclaration property lists. It builds on the effective-property registry
+merged in #309; it does not alter the selector timing, containment, or stylesheet
+finalization work owned by #238 and #297.
+
+## Structural result
+
+`experiments/WebScene.NativeEngine.Probe/native/css_property_metadata.json` is now
+the checked-in source for three related property views:
+
+- 105 stable managed storage properties, in ID order;
+- 95 additional CSSOM-supported names; and
+- 61 effective box-property entries used by native cascade masks and expansion.
+
+The generator validates and emits:
+
+- the existing 61-entry native effective-property table;
+- a 214-entry native CSSOM table containing canonical CSS names and precomputed IDL
+  names; and
+- managed arrays for stable storage IDs and the same 214 supported CSSOM names,
+  plus the direct name-to-ID switch.
+
+The native V8 template previously maintained 152 handwritten IDL names separately
+from the managed catalog. It now consumes the generated CSS/IDL pairs. The pairs
+are compile-time string views, so template setup does not allocate strings to
+convert 214 property names at runtime. Six compatibility names that existed only
+in the native list (`animation`, `box-shadow`, `contain`, `grid-row-gap`,
+`grid-column-gap`, and `webkit-font-smoothing`) were retained in the shared catalog.
+
+Managed direct-storage IDs remain byte-for-byte ordered as before. The generator
+test pins all 105 names with a SHA-256 sequence fingerprint in addition to checking
+the generated outputs. Case-insensitive access still uses the existing frozen-map
+fallback, while exact lower-case access retains the direct switch.
+
+The shared union also closes an observed CSSOM drift: 14 logical effective names,
+including `inset-block-end`, `border-block-width`, `border-inline-color`,
+`padding-block-start`, and `margin-block-end`, were understood by native style
+application but absent from one or both named-property exposure lists.
+
+The generator itself is now explicitly tracked. The repository's broad `tools/**`
+ignore rule had excluded the script introduced with #309 even though CI invoked it;
+the new `.gitignore` exception prevents clean checkouts from losing that build input.
+
+## Browser-shaped regression
+
+`tests/WebPlatformSubset/contracts/cssom-inline-declaration-validity.html` now has a
+fifth subtest covering named exposure and assignment for logical inset, border,
+padding, and margin properties. Results:
+
+- Google Chrome 153.0.8010.48: 5/5;
+- native current CSSParser: 5/5; and
+- native legacy parser: 5/5.
+
+The native engine initially failed the new subtest because `inset-block-end` was
+missing from its handwritten V8 template list. Replacing that list with generated
+metadata is the regression fix; adding only managed tests would not have caught it.
+
+An adjacent native `cssom-` sweep passes all nine CSS-specific documents. The filter
+also selects `dom-document-cssom-hosted-page-primitives.html`; its unrelated
+`document.cookie` assertion failed both with default and fresh storage, leaving the
+combined sweep at 9/10 documents and 60/61 subtests. No property-exposure assertion
+failed.
+
+## Build and test evidence
+
+- metadata generator tests: 6/6, followed by a clean `--check`;
+- WebScene.Css tests: 383/383 on .NET 8 and 383/383 on .NET 10;
+- full `WebScene.sln` Release build: success with 16 pre-existing nullable warnings
+  and zero errors;
+- full managed solution tests: 1,774 passed, 30 platform-dependent tests skipped;
+- current-parser native CSS parser CTest: 1/1;
+- NativeWeb CSS service/shared-style/compiler CTests: 3/3; and
+- both current- and legacy-parser native engine libraries rebuilt successfully.
+
+This stage centralizes identity and exposure, not all CSS semantics. Property initial
+values, inheritance, serialization, grammar selection, complex shorthand expansion,
+origins, and CSS-wide keyword behavior remain later metadata slices in #235.
+
+Machine-readable evidence is in
+`docs/validation/evidence/css-property-identity-20260917.json`.

docs/validation/evidence/css-property-identity-20260917.json

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+{
+  "date": "2026-09-17",
+  "issue": 235,
+  "catalog": {
+    "managedKnownProperties": 105,
+    "managedKnownPropertyOrderSha256": "fc4d77c515998b6df1f119ff7e09b0b82cc812744c34f1c44c6fd142067b1fb2",
+    "supportedPropertyExtras": 95,
+    "effectiveProperties": 61,
+    "unifiedSupportedProperties": 214,
+    "previousNativeHandwrittenIdlNames": 152
+  },
+  "generatedOutputs": {
+    "nativeEffectivePropertyTable": 61,
+    "nativeCssomCssIdlPairs": 214,
+    "managedKnownNames": 105,
+    "managedSupportedNames": 214,
+    "managedDirectIdSwitchEntries": 105
+  },
+  "contracts": {
+    "chrome": {
+      "version": "153.0.8010.48",
+      "passed": 5,
+      "total": 5
+    },
+    "nativeCurrentParser": {
+      "passed": 5,
+      "total": 5
+    },
+    "nativeLegacyParser": {
+      "passed": 5,
+      "total": 5
+    }
+  },
+  "tests": {
+    "managedSolutionBuild": {
+      "result": "pass",
+      "warnings": 16,
+      "newWarnings": 0,
+      "errors": 0
+    },
+    "generator": {
+      "passed": 6,
+      "total": 6,
+      "generatedCheck": "pass"
+    },
+    "managedCssNet8": {
+      "passed": 383,
+      "total": 383
+    },
+    "managedCssNet10": {
+      "passed": 383,
+      "total": 383
+    },
+    "managedSolution": {
+      "passed": 1774,
+      "skipped": 30,
+      "failed": 0
+    },
+    "nativeCurrentCssParser": {
+      "passed": 1,
+      "total": 1
+    },
+    "nativeWebCss": {
+      "passed": 3,
+      "total": 3
+    }
+  },
+  "adjacentCssomSweep": {
+    "documentsPassed": 9,
+    "documentsTotal": 10,
+    "subtestsPassed": 60,
+    "subtestsTotal": 61,
+    "propertyExposureFailures": 0,
+    "unrelatedFailure": "dom-document-cssom-hosted-page-primitives document.cookie"
+  }
+}

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

@@ -1,5 +1,47 @@
 {
   "version": 1,
+  "managedKnownProperties": [
+    "align-content", "align-items", "align-self", "all", "background", "background-color",
+    "background-image", "border", "border-bottom-color", "border-bottom-left-radius",
+    "border-bottom-right-radius", "border-bottom-style", "border-bottom-width", "border-color",
+    "border-left-color", "border-left-style", "border-left-width", "border-radius",
+    "border-right-color", "border-right-style", "border-right-width", "border-style",
+    "border-top-color", "border-top-left-radius", "border-top-right-radius", "border-top-style",
+    "border-top-width", "border-width", "bottom", "box-sizing", "clip-rule", "color",
+    "column-gap", "content", "cursor", "direction", "display", "fill", "fill-rule", "flex",
+    "flex-basis", "flex-direction", "flex-flow", "flex-grow", "flex-shrink", "flex-wrap", "font",
+    "font-family", "font-size", "font-style", "font-variant", "font-weight", "gap",
+    "grid", "grid-template-columns", "grid-template-rows", "height", "inset", "justify-content",
+    "left", "letter-spacing", "line-height", "margin", "margin-bottom", "margin-left",
+    "margin-right", "margin-top", "max-height", "max-width", "min-height", "min-width", "opacity",
+    "order", "overflow", "overflow-x", "overflow-y", "padding", "padding-bottom", "padding-left",
+    "padding-right", "padding-top", "pointer-events", "position", "right", "row-gap", "stroke",
+    "stroke-linecap", "stroke-linejoin", "stroke-width", "text-align", "text-indent", "text-transform",
+    "top", "transform", "visibility", "white-space", "width", "word-spacing", "z-index",
+    "outline", "outline-color", "outline-offset", "outline-style", "outline-width",
+    "grid-template-areas"
+  ],
+  "supportedPropertyExtras": [
+    "animation", "animation-delay", "animation-direction", "animation-duration", "animation-fill-mode",
+    "animation-iteration-count", "animation-name", "animation-play-state", "animation-timing-function",
+    "accent-color", "appearance", "backdrop-filter", "background-attachment", "background-clip",
+    "background-origin", "background-position", "background-position-x", "background-position-y",
+    "background-repeat", "background-size", "border-bottom", "border-collapse", "border-left",
+    "border-right", "border-spacing", "border-top", "clear", "column-count", "columns", "css-float",
+    "box-shadow", "clip-path", "color-scheme", "contain", "empty-cells", "fill-opacity", "filter", "float", "font-stretch",
+    "grid-area", "grid-column", "grid-column-end", "grid-column-start", "grid-row", "grid-row-end",
+    "grid-row-start", "grid-gap", "grid-row-gap", "grid-column-gap", "inset-block", "inset-inline", "inset-inline-start",
+    "inset-inline-end", "margin-block", "margin-inline", "margin-inline-start", "margin-inline-end",
+    "mask-composite", "mask-image", "mask-position", "mask-repeat", "mask-size", "padding-block",
+    "padding-inline", "padding-inline-start", "padding-inline-end", "border-inline-start",
+    "border-inline-end", "border-inline-start-width", "border-inline-end-width",
+    "border-inline-start-color", "border-inline-end-color", "border-start-start-radius",
+    "border-start-end-radius", "border-end-start-radius", "border-end-end-radius", "-moz-transform",
+    "moz-transform", "-webkit-transform", "webkit-transform", "webkit-font-smoothing", "orphans", "resize", "table-layout",
+    "text-decoration", "text-overflow", "vertical-align", "transition", "transition-delay",
+    "transition-duration", "transition-property", "transition-timing-function", "transform-origin",
+    "widows", "zoom"
+  ],
   "properties": [
     {"name": "border-block-color", "mask": ["inline_border"], "expansion": ["border-top-color", "border-bottom-color"], "applyExpansion": true},
     {"name": "border-block-end-color", "mask": ["inline_border"], "alias": "border-bottom-color"},