four-bar PASS

Planar crank-rocker four-bar linkage from sources/four-bar-spec.md (the only source, authoritative, text): a 160 x 60 x 5 ground plate with Ø6 pivot holes at O2 (0, 0) and O4 (100, 0), and three stadium links 5 thick and 16 wide with R8 ends and Ø6 holes (crank O2-A 40, coupler A-B 100, rocker O4-B 80 between hole centres). Four separate solids, each drafted and modelled in its own frame and stack

clip play ground (modelled) crank (modelled) coupler (modelled) rocker (modelled)

gates

[A] parts_pass	PASS
[A] bom_complete	PASS
[A] joint_fidelity	PASS
[A] clearances	PASS
[A] motion_clear	PASS
[A] fluid_domain	n/a
[B] export_agreement	PASS
[B] performance	n/a
[B] conservation	n/a
[B] refinement	n/a
[C] source_hygiene	PASS
[C] boundaries_complete	n/a
[C] provenance	PASS
[C] evidence_separation	PASS

observables

id	status	value ± u_numerical	mesh-resolved	case
rockerAngle	ok	deg	-
rockerSwing	ok	64.667 deg	-
couplerX	ok	mm	-
couplerY	ok	mm	-

A value its mesh ladder does not resolve is not evidence of performance; report.md gives each prediction's validation basis.