Add three-axis milling with independent CAM and Fusion validation (#1682)

Thanks @CypherNaught-0x.

docs/cam-next-milestone.md

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+# Adaptive clearing and 3D milling
+
+Status: planned implementation following the first milling PR. The strategies and
+ball-end tooling below are not implemented or qualified yet.
+
+## Scope and delivery order
+
+Retain vertical, fixed-axis three-axis machining, rectangular stock, rigid setups,
+explicit feeds/speeds and fail-closed posting. Indexed/multi-axis work and physical
+controller qualification remain outside scope.
+
+1. **Tool and verifier foundation.** Add ball-end mills with explicit cutting length,
+   shank and holder dimensions, a pending document migration, command/UI editing and
+   tool-tip semantics. Qualify swept spherical cutting envelopes independently on
+   stationary, horizontal and sloping motions, including holder/shank clearance.
+2. **Adaptive clearing.** Introduce explicit optimal load, maximum stepdown, entry
+   and linking settings. Maintain material state during planning; bound actual radial
+   engagement through corners and narrow passages. Generate smooth clearing loops
+   with proved entry/link clearances. Ordinary offset pocketing is not adaptive clearing.
+3. **3D roughing.** Slice the protected target at bounded Z levels, include radial
+   and axial stock allowances, and support rest roughing from a fingerprinted preceding
+   stock state. Reject unsupported undercuts, uncertain topology and inaccessible
+   regions. Removed material must never be inferred solely from a preceding path's name.
+4. **3D finishing.** Deliver parallel finishing for shallow surfaces and constant-Z
+   finishing for steep surfaces, with ball tools, cutter-contact offsets, bounded
+   chord error and explicit cusp/stepover settings. Scallop finishing follows only
+   after its surface-spacing and connector bounds are independently qualified.
+5. **Integrated acceptance.** Exercise editing, generation/cancellation, simulation,
+   diagnosis, exports, save/reopen and stale-result refusal through commands and the
+   visible Manufacture workspace. Keep portable jobs incremental and bounded.
+
+## Independent validation
+
+Keep the generator, NC interpreter and stock verifier separate. Extend typed motions
+and provenance only where required; preserve the reference post's initialized machine
+state and reject unsupported controller behavior. Inspect every emitted NC block.
+
+Original fixtures cover a sloped plane, convex dome, concave bowl, saddle, stepped
+boss, steep wall, islands connected by a narrow neck, interrupted cuts, rest stock,
+shifted origins and tool changes. Each fixture declares protected surfaces, allowed
+rough stock, finished regions, accessibility and independent dimensional expectations.
+Hand-calculated sphere-plane contact and cusp-height cases qualify the verifier first.
+Fault injections include the wrong ball radius, omitted roughing stock, excess
+engagement, reversed arcs, connecting gouges, rapid-through-stock and holder contact.
+
+Acceptance retains 0.01 mm dimensional tolerance, 0.001 mm post/interpolation budget
+and 0.0025 mm verifier uncertainty. Local surface distances and hole/wall dimensions
+accompany volume differences. Refine uncertain regions; exhausting resources yields
+inconclusive and blocks posting. For roughing, verify protected geometry and allowed
+stock per operation instead of requiring identical intermediate material removal.
+Engagement checks report their definition, sampling/bound uncertainty and the NC line.
+
+## Fusion comparison packages
+
+Use the same original recipes in local Fusion and SolidCraft. Reconcile units, tools,
+stock, frames, allowances, entry/links and operation settings before comparison.
+Record version, available capabilities, post identity/hash/properties and timestamps.
+Capture NC Program output, setup HTML and final simulation stock after every operation;
+use Save Stock when automated export is unavailable. Preserve the actual Accuracy
+setting and report an unexposed numeric resolution as not reported.
+
+Both posted programs pass through the independent interpreter and verifier. Compare
+each against intended geometry and Fusion stock, with line-linked diagnostics, path
+overlays, surface differences, volume, distance, retract count and time estimates.
+Missing artifacts or unavailable licensed strategies cannot count as passing parity.
+Require complete passing packages for each delivered strategy before declaring parity.
+All Fusion-produced artifacts and derived comparisons stay in ignored local storage;
+commit only original recipes, harness code and independently authored expectations.
+
+## Dependency decisions
+
+Keep the existing pinned Cavalier 0.9.0 adapter for planar offsets/islands and Parry
+0.31.1 for bounded collision/distance queries. Both need geometry-specific guards;
+neither provides an adaptive machining algorithm or an independent stock proof.
+Cavalier documents rounded joins and arc-size constraints; retain current degeneracy
+and scale tests. Parry's double-precision mesh and point-query APIs are candidates for
+cutter-contact acceleration; benchmark against a simple original implementation first.
+No additional runtime dependency is justified yet. Reuse the existing robust predicates,
+Spade and spatial index; consider property testing as a development-only dependency.
+
+Primary references inspected on 2026-10-16:
+
+- [Autodesk adaptive roughing overview](https://help.autodesk.com/cloudhelp/ENU/Fusion-CAM/files/3D-ADAPTIVE-READ.htm)
+- [Autodesk adaptive parameters](https://help.autodesk.com/cloudhelp/ENU/Fusion-CAM/files/GUID09E44604-DAD8-47D6-ADC6-C100869DE724.htm)
+- [Autodesk parallel finishing](https://help.autodesk.com/cloudhelp/ENU/Fusion-CAM/files/3D-PARALLEL-STEPS.htm)
+- [Cavalier 0.9.0](https://docs.rs/crate/cavalier_contours/0.9.0)
+- [Parry 0.31.1 triangle mesh](https://docs.rs/parry3d-f64/0.31.1/parry3d_f64/shape/struct.TriMesh.html)
+- [Parry 0.31.1 point queries](https://docs.rs/parry3d-f64/0.31.1/parry3d_f64/query/point/trait.PointQuery.html)
+
+Each implementation arc runs focused analytic/fault tests, then repository quality
+and Wasm gates. The oracle command must require the strategies actually claimed by
+that milestone, without relaxing the first milestone's completeness requirements.