Measure: split triangles that cut through curved faces onto the surface (trimmed faces after booleans were measured up to 15% off; 61's keyway volume now matches); oracle step check shows the original volume

Oracle: 53/66.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AS5Tn3xieewUSg3uxrMVdL

ROADMAP.md

@@ -9,7 +9,7 @@ features → parametric timeline) as an open, pure-Rust, agent-drivable applicat
 |---|---|
 | Where are we? | **M0 done; M1/M2 in progress.** Sketch with solver, extrude (taper, two-sided, through all), revolve, fillet/chamfer, holes, patterns, mirror, shell, draft, loft, sweep, split, construction planes, parameters that rebuild the timeline, STEP/STL export, desktop and browser (wasm) app with Fusion-style selection (hover/selected highlights, origin planes, click-to-pick sketch planes, multi-select, window/crossing box selection, animated view cube), CLI, MCP server, oracle harness. |
 | Command parity (in scope) | **139 / 541 (26%)** in-scope commands; SOLID + SKETCH **102 / 291 (35%)** — [docs/parity.md](docs/parity.md) |
-| Fusion oracle | **52 / 66 parts match** (batch 1: 29/29; batch 2 in progress) — [docs/oracle.md](docs/oracle.md) |
+| Fusion oracle | **53 / 66 parts match** (batch 1: 29/29; batch 2 in progress) — [docs/oracle.md](docs/oracle.md) |
 | Tests | 85 (solver, profiles, kernel booleans/blends/measures, expressions, timeline, file formats, camera, engine end-to-end, hostile-input fuzz over every command) |
 | Gates | `cargo xtask ci`: fmt, clippy -D warnings, tests, asset attribution, layering, wasm32 build — green |
 | Weighted parity estimate | **≈ 5%** of Fusion's Design workspace by importance (sketch + basic solids are the core, but surfaces, assemblies, sheet metal, CAM, drawings are untouched) |
@@ -64,7 +64,8 @@ headline counts in-scope tabs only and lists the deferred ones separately.
   (extruded and box-like parts); other coincident configurations can still fail. Fully internal
   voids are not supported. Spheres are built from six pole-free patches so they
   combine reliably.
-- Mass properties come from fine tessellation (curved faces within ~1e-4 relative).
+- Mass properties come from fine tessellation (curved faces within ~1e-4 relative); triangles
+  that cut through curved faces (trimmed faces after booleans) are split onto the surface first.
 - STEP import (our own reader, crates/kernel/src/step_in; all 29 Fusion STEP files pass
   `cargo xtask step-corpus`) reads solids (B-rep with analytic and B-spline geometry), units,
   product names, colours and assemblies; offset surfaces and pcurve-only edges are not read yet,