L4 live-adapter record — Fusion 2704.1.53 — 2026-09-06

Milestone M2. Records what was measured against the running kernel while building the adapter, per CLAUDE.md section 11 and PRD 14.4. Every figure below came from a probe run through tools/fusion_exec.py; none is inferred.

Fusion version	2704.1.53
Python	3.14.0
Platform	macOS x86_64
Documents opened	0 — every body from TemporaryBRepManager
Probes	p09_adapter_api_shapes, p10_edge_closure_and_length, p11_open_edge_control, p12_adapter_smoke

Confirmed API shapes (probe 09)

Claim	Verdict	Evidence
getParameterExtents() -> (ok, start, end)	CONFIRMED	arity 3, first element True
getStrokes tolerance is centimeters, honored as chordal deviation	CONFIRMED	0.000990087 mm achieved for a 0.001 mm request
Cylinder exposes origin, axis, radius	CONFIRMED
Cone exposes origin, axis, radius, halfAngle	CONFIRMED
Cone.origin is not the apex	CONFIRMED	separation measured non-zero; PRD 6.3
Torus exposes origin, axis, majorRadius, minorRadius	CONFIRMED
isinstance(face.geometry, adsk.core.Cylinder) discriminates	CONFIRMED
BRepEdge.isClosed	REFUTED — does not exist	raises AttributeError

Edge closure (probes 10, 11)

BRepEdge has no isClosed. Closure must come from vertex geometry:

Test	Result
startVertex is endVertex on a closed cope curve	False — identity is a trap
startVertex.geometry.isEqualTo(endVertex.geometry)	True
|P(end) − P(start)|	0.000000000000 mm

Control. Every edge in tools/probes/fixtures.py is closed — 10 of 10 across cylinder, cone, torus, coped tube, severed tube and bent tube, all bodies of revolution. A discriminator only ever observed answering True is untested, so a box was added: 12 edges, 12 reported open. Without that control the test could not fail.

Arc length (probe 10) — PRD 6.4 [CHANGED v1→v2]

Analytic ground truth, which is the whole design of the measurement:

Quantity	Value
getLengthAtParameter, circle r = 14.3 mm	89.849549893 mm
BRepEdge.length, same edge	89.849549893 mm
Analytic 2πr	89.849549893 mm
Error	0.000000000 mm
Inscribed chord sum, n = 20 000	short by 3.69e-07 mm

So the function is exact on analytic geometry, and PRD 6.4’s preference over chord summation stands.

Surface-surface intersection curves — the guarantee does not carry:

Axis angle	getLengthAtParameter	chord sum n = 200 000	chord − getLength	relative
30°	148.924974988 mm	148.927406465 mm	+0.002431476 mm	+1.633e-05
45°	118.581262478 mm	118.586505359 mm	+0.005242881 mm	+4.421e-05
60°	105.505783493 mm	105.510396829 mm	+0.004613336 mm	+4.372e-05
75°	99.599232880 mm	99.600681149 mm	+0.001448268 mm	+1.454e-05
90°	97.867166722 mm	97.870609281 mm	+0.003442559 mm	+3.517e-05

A converged inscribed chord sum cannot exceed the arc length of the curve it samples, so the two functions describe different curves. Not monotonic in the angle; isTolerant is False and tolerance 0.0 on all five. Which value is true is [OPEN-13].

Product code executed on kernel geometry (probe 12)

The first end-to-end run of the real adapter/ + core/ path, not a probe reimplementation.

Step	Result
cylinder_parameters_of radius	14.300000000 mm — millimeters at the boundary (ADR-011)
stroke_edge	456 points, worst radial deviation 0.000000000 mm
outward_axis_for_cut_end	+z, correctly opposite the cut
Tier A closure vs 2πr	0.000000000 mm
render_cylinder_template	valid PDF

That closure figure reproduces PRD 11.9(c) through the product code.

Hazard reproduced by accident — PRD 7.13

Taking “the first cylindrical face” of a coped tube returns the cutting tool’s surface:

Face	Radius	Axis	Area
0	16.0000 mm	(+0.866, 0, +0.500)	857.9129 mm²
1	14.3000 mm	(0, 0, +1.000)	7739.4401 mm²

Here the areas differ by 9×, so “largest” happens to work — but PRD 7.13 measured a severing cut whose two candidates differ by 0.0112 %, where it does not. Host-face selection is a deliberate act (FR-1), never a scan.

New stub/runtime divergences

Joining the seven in PRD 7.11:

• BRepEdge.isClosed — in the stub, absent at runtime.

• getPointAtParameter raises RuntimeError: 3 past the parameter end rather than returning ok = False. Float rounding on start + (end−start)·i/n at i == n is enough to trigger it; clamp the parameter.