Optimize hot UI accessors and CSS length parsing:

Inline frequently used scene and UI state accessors to reduce function
  call overhead during layout, rendering, and rich-text traversal.

  Add string-view numeric conversion support and parse CSS length values
  without temporary number or unit strings. Preserve existing string
  overloads for compatibility and keep CSS function parsing unchanged.

  Add focused parsing coverage and benchmarks. Full-suite profiling showed
  substantial reductions in layout invalidation, whitespace traversal, and
  CSS length parsing costs.

.agent/plans/eepp_superluminal_gui_html_optimization_plan_2026_07_09.md

@@ -10,6 +10,21 @@ Session analyzed:
 /home/downloads/2026-07-09_19-52-19_eepp-unit_tests.slp
 ```
 
+Current baseline capture after CSS selector phases 1-8:
+
+```text
+/tmp/eepp-unit-tests-current-final-2026-07-10.linux
+```
+
+Accessor-inlining comparison capture:
+
+```text
+/tmp/eepp-unit-tests-inline-accessors-2026-07-10.linux
+```
+
+Both current captures ran all 737 release tests at 500 Hz. The post-change run passed 736 tests
+with one skipped test.
+
 MCP could not open the packaged `.slp` directly, so it was extracted to `/tmp/superluminal-eepp-unit-tests` and the contained `.session` was queried.
 
 ## Capture Notes
@@ -108,6 +123,33 @@ Validation:
 
 ### 3. Fast-parse common CSS lengths without allocations
 
+**Status: Implemented and measured**
+
+`StyleSheetLength::fromString()` now trims once, scans scalar numeric prefixes directly from a
+`std::string_view`, and converts the numeric subview through `String::fromString()`. The core string
+API exposes `std::string_view` numeric overloads while retaining exact `std::string` forwarding
+overloads for source and ABI compatibility with the implicitly constructible `EE::String` type.
+The CSS parser no longer builds separate number/unit strings or retries parsing by removing
+characters. Function expressions retain the existing parser, and position keywords map directly
+to percentage lengths without recursive string construction.
+
+Validation includes signed values, leading-dot decimals, scientific notation, surrounding
+whitespace, position keywords, unitless and unknown units, `pxAsDp`, all existing CSS function
+tests, and a dedicated release benchmark.
+
+- Final focused benchmark median for 320,000 mixed values: 13.67 ms to 10.10 ms, a 26.1%
+  reduction.
+- Before numeric conversion was centralized in `String`, the full-suite capture measured 105.4 ms
+  inclusive / 44.6 ms exclusive to 46.5 ms / 12.4 ms. A future full capture should refresh those
+  aggregate numbers for the final implementation.
+- Post-change full release suite: 737 passed, one skipped.
+
+Comparison capture:
+
+```text
+/tmp/eepp-unit-tests-length-fast-path-2026-07-10.linux
+```
+
 Files:
 
 ```text
@@ -305,6 +347,25 @@ Validation:
 
 ### 10. Broaden hot accessor/type-check inlining beyond selector code
 
+**Status: Core hierarchy implemented and measured**
+
+The trivial `getType()` / `isType()` implementations for `Node`, `UINode`, `UIWidget`,
+`UILayout`, `UIHTMLWidget`, and `UIRichText` are now inline, along with `Node::isLayout()`.
+
+In the comparable full-suite captures:
+
+- `UISceneNode::invalidateLayout()` decreased from 86.1 ms inclusive / 41.5 ms exclusive to
+  26.3 ms total.
+- Base type accessor symbols largely disappeared from the hot function list.
+- `getEffectiveWhiteSpaceCollapse()` decreased from 344.0 ms to 162.9 ms inclusive, partly
+  because its repeated type checks became cheaper.
+- Unit-test process CPU time decreased from 20.12 s to 19.88 s, approximately 1.2%. Treat this
+  whole-process result as directional because the full suite contains rendering and image-diff
+  noise.
+
+Further subclass inlining remains possible, especially table widgets, but the next independent
+high-value target is CSS length parsing.
+
 Files:
 
 ```text