OpenNest/docs/cutting-planner.md

Unified cutting planner: direct-XY proposals

OpenNest.Engine.CuttingPlanning.CuttingPlanService plans contiguous whole-part programs. It can retain fixed programs or jointly choose internal contour order, entries and whole-part order using explicitly confirmed cutting parameters. It returns an owned proposal; Apply installs Ready plate-scoped proposals atomically after an exact freshness check. There is no desktop command yet: existing desktop sequencing, assignment and posting review are unchanged.

Capture before worker planning

Create a CuttingPlanRequest, then call Capture while source placements, programs and settings are stable. Pass that snapshot to Plan on a worker; Plan(request) combines these steps synchronously. The modeled starting point defaults to Vector.Zero, not a discovered controller position.

var request = new CuttingPlanRequest(plate, startPoint: start,
    confirmedParameters: parameters, expansionBudget: 20000,
    maxEntries: 16, preservePartOrder: false);
var snapshot = CuttingPlanService.Capture(request, cancellationToken);
var result = CuttingPlanService.Plan(snapshot, cancellationToken);

• A plate-scoped request plans the plate's current parts and records its exact state for Apply. A detached part list (new CuttingPlanRequest(parts, ...)) plans the same way but can never be applied. An empty plate is a Ready no-op.
• Omitting confirmedParameters preserves the original fixed-program contract: locked and unlocked programs stay fixed; only whole-part order may change.
• Supplying confirmed parameters enables regeneration for unlocked placements. eligibleParts can restrict it to an explicit reference-based subset; an empty subset retains all programs but still checks their leads against owned material. Locked placements never regenerate. Foreign or duplicate eligible identities are invalid; eligibility without confirmed parameters is invalid.
• preservePartOrder fixes whole-part order, not eligible internal contour choices.
• Parameters are caller-confirmed inputs. The service does not recover missing operator settings or silently change lead styles to find a solution.

Capture owns clean geometry, placed programs and required settings. Source Part references are identity handles only: workers never read their mutable state. Clean geometry accounts for the base program's existing rotation before applying placement rotation; placement translation is applied once. Subprogram copying must not rotate shared programs through their property setters. No live drawings are attached to preview plates, so capture/search do not change quantity accounting. Planning works from this historical snapshot; Apply compares it with live state. Original clean and executable graphs are type/mode-checked before cloning can erase unknown semantics. Exact placed/proposed copies preserve authored motion feed/exact-stop flags, symbolic bindings and shared subprogram identity; unsupported graphs are refused. The geometry-only clean transform uses per-parent copies so legacy rotation does not visit a globally shared descendant twice; it never changes the fixed payload.

Cutting dependencies

Capture builds whole-part prerequisites from owned values, and both the search and the final replay enforce them:

• A cutoff precedes every part its nominal line crosses within its span, using the same rule as automatic sequencing: nominal position and limits against the part's placed bounds, matched by drawing reference, never by name or trimmed segments. A cutoff whose definition is missing precedes every part. Cutoffs need a plate-scoped request; they are always fixed programs, need no lead-in, are not material for lead validation and, being open cuts, never become rapid obstacles. Rapids into and out of them are still checked.
• A part whose perimeter lies strictly inside a cutout of another part precedes that host. Bounds only select candidate pairs; containment is proven on native clean material. Touching or crossing boundaries, or material that cannot be captured, refuse as UnsupportedGeometry naming both parts. A part in a concave pocket outside the host's material has no dependency.
• A preserved manual order that violates a prerequisite, or a cycle, is a ConstraintConflict. Replay rechecks the captured prerequisites and refuses a violating order rather than trusting the search.

Search and exact output

With regeneration, the bounded deterministic search considers whole-part order, internal contour order and native entry candidates together. Internal contours precede their own perimeter; parts remain contiguous. Backtracking can revisit an earlier entry when a later part cannot be reached safely.

Candidates use native closest points, vertices, midpoints and circle angles in stable order, capped by maxEntries. Circle rounding, clamping, corner resolution and tab trimming happen during emission. Validation uses the actual emitted motions, never the nominal entry point alone. Existing lead styles are not shortened, disabled or substituted as a search fallback.

Every candidate rapid is checked against contours already completed, including earlier holes in the same part. Future contours are not yet obstacles. Actual lead-in and lead-out line/arc paths must stay in target scrap and avoid other placed material; holes in other parts remain scrap. Tangent/coincident contacts outside the genuine target contour joint and numerically uncertain queries refuse. Material capture supports a simple closed perimeter minus disjoint, non-nested holes; unsupported topology is not a bounding-box approximation.

Candidates rank by actual modeled rapid distance with stable source/contour/entry ordinals. Hash values and drawing names are not tie breakers. The expansion budget counts rejected candidates and frontier ranking as well as accepted moves, before emission; it is not a wall-clock timeout. Callers can cancel. Exhaustion may occur before already-generated siblings are traversed; it returns a refusal, not an unranked fallback or a proof of geometric impossibility.

Selected programs are replayed from the beginning with a fresh checker and fresh lead validation, without regenerating them or trusting cached search verdicts. Before replay, expected-emission geometry is independently built from the owned choices/settings, not from the candidate payload. Replay checks actual selected code against it and independently accounts for directed native boundary coverage: no partial, duplicated, retraced or reversed cuts, except the exact selected tab. Equivalent subdivisions and merged collinear moves remain valid. Captured source identity and pose binding use exact scalar bits, not geometric tolerance. Arrival positions use actual departures, including lead-outs and subprograms. ProposedOrder retains source identities/poses; CopyProgram() returns an independent deep copy of each exact captured/generated program. ContourChoices are nominal choice metadata, not a substitute for reading actual execution. Neither obtaining a proposal nor copying its programs installs them on live parts.

Results and refusal

Ready and IndependentlyReplayed describe the modeled proposal only. In the no-parameter fixed route, replay checks rapid crossings, missing leads and incomplete retention; it does not add regeneration-mode material/lead checks. In regeneration mode, replay also checks actual lead paths and contour accounting against owned clean material. Neither mode certifies final NC, production cutting readiness or physical machine safety.

Findings and source ordinals use the original zero-based source list, not proposed sequence positions. A non-ready result contains no proposed order or unsafe fallback.

• ConstraintConflict: fixed programs or explored fixed routing violate the modeled constraints. Locked internal crossings cannot be repaired by regeneration.
• UnsupportedGeometry: unsupported motion/material semantics or an incomplete check. Open nominal outlines, ambiguous release states or containment, cutoffs in a detached part list and scribe-only source drawings are not silently accepted.
• InvalidInput: malformed/missing/duplicate placements or settings, invalid geometry, empty input, invalid eligibility or nonpositive bounds.
• NoSolutionWithinBudget: the bounded/capped search found no complete proposal; it does not prove no possible geometric route exists.
• Cancelled: capture, search or replay cancelled without live mutation.

Malformed original executed graphs are refused, not salvaged. Valid but incomplete old programs can regenerate from clean geometry. Regenerated programs retain genuine configured tab gaps; stale tab settings do not establish retention. In confirmed- parameters mode, locked/ineligible programs must cover the complete directed clean boundary: an open fixed program has no certified selected tab metadata and is refused, not repaired, even if it may have been intentionally tabbed. The no-parameter route retains its narrower compatibility contract. A lead-out that may bridge a tab, or a malformed emitted arc, is refused, not automatically repaired. Tabbed lead-outs leave from the trimmed cut end, but a lead-out after an open contour still needs manual review of its retention gap, so confirmed-parameters planning refuses it.

Apply

var commit = CuttingPlanService.Apply(results, cancellationToken); // one result per plate

Call it on the thread that owns the plates, with Ready, independently replayed results from plate-scoped requests; anything else is InvalidInput. Apply never replans. Each plate is compared exactly with the state captured with its request: part list instance and order, plate quantity/size/quadrant, cutoff definitions, and for every part its program reference and exact content (an in-place edit counts), drawing program, pose bits, lead-in/lock flags, settings reference and bounds. Any difference on any plate returns Stale and changes nothing; a result can therefore be applied at most once.

The whole scope is validated and its bounds staged first; cancellation is checked immediately before the install. Order changes through ObservableList.Reorder semantics: same references, no PartAdded/PartRemoved, so drawing quantities, sentinel plates and plate lists are untouched. Regenerated parts receive a fresh owned copy of the replayed program and of the settings captured with the request, keep their pose and lock, and are marked as having lead-ins. Fixed programs are not replaced. An exception during install restores every plate exactly and returns Failed. After the whole scope is installed, each changed plate raises Plate.PartsReordered once; an observer exception is reported in RefreshErrors on an Applied result, not as a rollback.

Remaining integration boundaries

The service does not establish clean-material non-overlap, scrap release by open cutoff cuts or sheet edges, or physical retention strength. It does not write CNC or set posting consent. A Ready proposal can still be unsuitable for cutting.

Later slices add desktop integration (including PartsReordered refresh hooks) and legacy automatic-path retirement. Windows interaction, supplied-job coverage and actual posted order remain separate acceptance gates. Fresh pre-post verification is still required; it is not a physical safety qualification.

Portable regression gate

dotnet test OpenNest.Tests/OpenNest.Tests.csproj -c Release --filter 'FullyQualifiedName~CuttingPlanning|FullyQualifiedName~PostVerificationAnalyzerTests'

Synthetic fixtures exercise whole-part routing and internal-hole crossing repair, locked/ineligible refusal, actual native lead paths, shared subprograms, ownership, entry/whole-part backtracking, deterministic budgets, cancellation and fresh replay rejection. Retained emission characterizations cover styles, winding, corner rules, circle rounding/clamping and tabs; unsupported cases remain explicit refusals.