OpenNest/docs/performance/fill-performance.md

Fill performance measurements

Documentation follow-up — 2026-09-25: the user explicitly approved the previously blocked instruction update, then chose AGENTS.md as the shared source of truth for multiple coding agents. CLAUDE.md imports it with @AGENTS.md for compatibility. The shared instructions document the delivered comparer/group/extents workflow, Debug work counters, measurement limitations, and safeguards already reflected in README. The instruction-document sync blocker is resolved; references to it in the historical slice records below describe their delivery-time status. No production code or measured results changed.

Count-first comparer slice — 2026-09-25

This historical Task 1 section covers only the count-first DefaultFillComparer change. Geometry, custom-comparer score elimination, ML work, and whole-job optimization had not been implemented or measured in that slice. Task 1b is reported separately below.

Source and environment

Final staged review corrected two delegate declarations to the repository's var style. The complete original/optimized measurement pair was then rerun with that identical final harness; all timing tables below are from those final runs, not mixed with earlier samples. The original production comparer was temporarily restored only for the before measurement and reinstated in finally.

• Baseline: 1b862dc1a896df502935b900094c15c3300999c5 on master.
• Optimized source: the count-first implementation delivered with this report; use git log -1 --format=%H -- OpenNest.Engine/Fill/DefaultFillComparer.cs to resolve its implementation commit.
• The original comparer was measured before adding the fast path. Tests and the Debug-only diagnostic were already present; the diagnostic call is compiled out in Release.
• Original comparer SHA-256: 8d436b88831d3187b319d52084131773f998c94ff4a227262cf15e4d27013b8f.
• Optimized comparer SHA-256: 2444d30ddc92fa662f5ad50ac2cca0a7c50da3aee15f0fc932d58cf64023333d.
• Identical before/after measurement harness SHA-256: 6a3b911748e31027bab6922d9d54f89b6fd7257884e1eecc5461db032089c7bf (OpenNest.Tests/Fill/FillPerformanceTests.cs).
• Machine: hermes, KVM guest, 4 vCPUs presented as AMD Ryzen 9 5900X; Ubuntu 24.04.5 LTS x64; Linux 6.8.0-142-generic. No CPU pinning.
• Build SDK: 10.0.112. Measured runtime, emitted by the test: .NET 8.0.31; Release; stopwatch frequency 1,000,000,000 ticks/second.

Workload and timing scope

All inputs are fixture-independent, finite, nonoverlapping 2×1 rectangles inside a (0,0,256,256) work area, arranged in 64 columns. The larger layout has 2,048 parts at pitch 4; the smaller layout has 2,047 at pitch 3 (higher density despite lower count). The equal-count control compares 2,048 parts at pitch 3 against the larger layout.

Each implementation gets two warmup batches of 50,000 calls per case, then seven measured batches. Unequal-count batches contain 500,000 calls; equal-count batches contain 10,000. Argument order alternates each call, with half forward and half reverse. Actual/reference batch order alternates between repetitions. The reference is the prior scoring expression, FillScore.Compute(a, area) > FillScore.Compute(b, area), not a duplicate comparer class.

Inputs, cached drawing areas/bounds, and JIT paths are warm. There is no fill-cache operation or cache reset in this workload. Construction, layout validation, correctness assertions, and output are outside timing. Delegate/loop/result-consumption overhead and JIT optimization are included. Returned true counts are checked after each batch.

Allocated bytes are measured around synchronous work with GC.GetAllocatedBytesForCurrentThread, not process-wide memory or RSS. Every batch of both implementations, before and after, reported zero allocated managed bytes on the measured thread.

Results

Nanoseconds per call, minimum / median / maximum over seven batches:

Case	Implementation	Before	After
unequal-counts	Comparer	11901.864 / 11979.646 / 12194.228	1.800 / 1.878 / 3.221
unequal-counts	Reference expression	11654.151 / 12085.460 / 12269.212	12093.576 / 12247.735 / 12419.104
equal-count-control	Comparer	11617.457 / 12455.571 / 12814.497	11874.469 / 12372.208 / 12666.589
equal-count-control	Reference expression	11576.379 / 12344.544 / 12983.099	11736.897 / 12565.047 / 12864.353

The unequal-count median batch decreased from 5,989.823190 ms to 0.939182 ms. Their ratio is approximately 6,378× for this warm, repeated local-operation workload only. The optimized path is close to loop/JIT overhead; its nanosecond estimate is not an isolated method-latency guarantee. The unchanged reference varied slightly between processes, illustrating host/runtime variability. Do not extrapolate the ratio to nesting jobs.

Equal-count medians remained in the same range as the reference; these runs show no material regression, not evidence of an equal-count optimization. No elapsed-time thresholds are enforced in CI.

Behavioral and work-removal evidence

• Characterization covers null/empty guard order, lower-count rejection, count winning against density, both density directions for equal counts, and exact ties retaining the current result.
• A deterministic matrix of 33 valid layouts checks all 1,089 ordered pairs against the reference expression, including empty, self, translated, and reordered cases. It snapshots caller part/drawing/program identities, positions, rotations, bounds, and motion endpoints.
• A Debug-only PerfCounters.FillScoreComputations diagnostic follows the existing conditional counter pattern. Concrete lists and nonvirtual getters do not offer a practical direct scan spy without broader production changes.
• Before the fast path, both unequal-count work assertions failed with expected 0, actual 2 score computations; the other three work cases passed. Afterward, all five passed: unequal/empty cases compute no scores, while nonempty equal-count cases compute both scores. Counter tests run in the existing nonparallel FillCacheCollection and reset counters in finally.
• Debug instrumentation does not establish Release behavior by reading zero counters; Release evidence is the compiled-out call convention, source fast path, equivalent outputs, and timings above.

Test results

Run	Passed	Skipped	Failed
Original full main suite, Release	1,140	12	0
Original full engine suite, Release	300	0	0
Final full main suite, Release	1,154	13	0
Final full main suite, Debug	1,159	13	0
Final full engine suite, Release	300	0	0

The 12 original skips are optional ChrFontTests: ChrFontPath not configured in test-config.json or file not found. The additional final skip is the opt-in performance test. The five extra Debug cases are the score-work tests. The performance test passed with the opt-in value 1, and was separately verified to skip when unset and when set to 0.

The implementer's broader comparer/score selection passed 28 Release tests before and after, and 33 Debug tests afterward (it also selected NestProgressTests.BestDensity_MatchesFillScoreFormula). Parent re-verification using the plan's narrower FillComparerTests|FillScoreTests filter passed 27 Release tests, and the five Debug work tests passed separately. Existing unrelated compiler warnings remain; no failures are hidden as baseline bugs. Source formatting and git diff --check passed.

Reproduction

OPENNEST_RUN_FILL_PERF=1 dotnet test OpenNest.Tests/OpenNest.Tests.csproj -c Release \
  --filter 'Category=FillPerformance' --logger 'console;verbosity=detailed'
dotnet test OpenNest.Tests/OpenNest.Tests.csproj -c Debug \
  --filter 'FullyQualifiedName~DefaultFillComparerWorkTests'

Normal suite runs skip the measurement. The installed Xunit.SkippableFact 1.4.13 names its inverse skip predicate Skip.IfNot, not Skip.Unless; no package change was needed. README documents both shell and PowerShell invocation.

The corresponding CLAUDE.md workflow edit was denied by the protected-file permission gate. That file was left unchanged; this documentation sync remains blocked pending explicit approval. No retry or alternate write was attempted.

No Windows UI runtime tests, actual ONNX inference, representative production corpus, or whole-job benchmark was run for this slice. These results do not complete the broader initial optimization batch.

Raw measured batches

Times in milliseconds; allocations were 0 bytes for every actual/reference batch below. Preserved from matching raw TRX and console outputs before removing temporary test artifacts.

State	Case	Batch	Comparer ms	Reference ms
pre	unequal-counts	1	6097.114079	6093.454749
pre	unequal-counts	2	5950.931964	6031.795978
pre	unequal-counts	3	6010.884370	5827.075456
pre	unequal-counts	4	5989.823190	6019.619401
pre	unequal-counts	5	5953.063588	6134.606110
pre	unequal-counts	6	6051.466272	6042.729937
pre	unequal-counts	7	5973.554301	6083.705108
pre	equal-count-control	1	126.868005	129.830987
pre	equal-count-control	2	124.555712	128.105601
pre	equal-count-control	3	125.615121	124.509854
pre	equal-count-control	4	128.144975	120.288678
pre	equal-count-control	5	121.787519	123.445436
pre	equal-count-control	6	116.562527	115.763791
pre	equal-count-control	7	116.174565	118.153899
post	unequal-counts	1	0.931488	6123.867689
post	unequal-counts	2	0.933221	6046.787840
post	unequal-counts	3	0.939182	6209.551894
post	unequal-counts	4	1.610389	6120.239321
post	unequal-counts	5	1.210914	6145.847134
post	unequal-counts	6	0.945585	6160.595776
post	unequal-counts	7	0.899788	6097.613482
post	equal-count-control	1	122.282550	121.856075
post	equal-count-control	2	124.576228	123.526717
post	equal-count-control	3	123.722076	125.650465
post	equal-count-control	4	126.342491	128.643534
post	equal-count-control	5	126.665891	125.683547
post	equal-count-control	6	118.822360	126.622891
post	equal-count-control	7	118.744694	117.368968

Task 1b — skip unused group-pattern scores — 2026-09-25

Scope and provenance

Only the two candidate additions in FillHelpers.FillPattern changed: horizontal and vertical results compute FillScore when comparer == null, otherwise store default. The ConcurrentBag, angle scheduling, fill calls, result iteration, strict default-score comparison, and custom-comparer calls are unchanged. No geometry, bounds, scoring formula, ML, or Tasks 2+ optimization is included.

• Before source: master HEAD b318950a543d2a6c4fd0b305e5e3ae2bbee3c6d9, already containing Task 1. FillHelpers.cs was confirmed unchanged against HEAD before measurement. The actual unchanged production method was measured, not a reference approximation.
• Before OpenNest.Engine/Strategies/FillHelpers.cs SHA-256: 3f01f15b673d33626e49e06f4a381dc7331b33ec0b8850acf56dff4aa71e9198.
• After OpenNest.Engine/Strategies/FillHelpers.cs SHA-256: a1c8a1bc155dbe62439f8345a3a54e06147a5404a6a46835a30b66d52cceccfa.
• Identical before/after OpenNest.Tests/Fill/FillPerformanceTests.cs SHA-256: a5594148a2b11e37f5d47925c96774855eb622befb54b6736e98112ae8662873. This extends the historical Task 1 harness; it does not replace its measurements above.
• Identical red/green OpenNest.Tests/Strategies/FillHelpersTests.cs SHA-256: 35fee6661bd23091708041b0dc7e3b0517ad859bbf05e3ead95082fe7025fed9.
• Tracked C# source/project manifests before and after differ only in FillHelpers.cs; the new, untracked test file is covered separately by the hash above. There was no temporary production restoration or alternate implementation during these measurements.
• Host hermes: Ubuntu 24.04.5 LTS x64, Linux 6.8.0-142-generic, KVM guest, four vCPUs presented as AMD Ryzen 9 5900X. No CPU pinning or host isolation. SDK 10.0.112; test-emitted runtime .NET 8.0.31, Release, stopwatch frequency 1,000,000,000 ticks/second.

Workload and method

The opt-in GroupPattern_ReportsDefaultAndCustomComparer test uses two finite, nonoverlapping synthetic rectangles: 2×1 at (11,13) and 1×2 at (13.5,14.5). Work area is (3,5,5,9), part spacing 0.25, and the only candidate angle is 0 radians. Horizontal fill returns eight parts; vertical returns seven. The default path selects horizontal. A custom comparer deliberately prefers fewer parts, selecting vertical against FillScore.

Each mode gets two warmup batches of 2,000 calls and seven measured batches of 20,000 calls. Default/custom order alternates in both warmup and measured repetitions. Before and after run in separate test processes using the same harness and inputs, with the two-line production change between them. Both run the real Parallel.ForEach/fill/bag/selection path. One angle avoids cross-worker bag tie-order ambiguity; it does not represent multi-angle parallel scaling.

Setup, correctness/layout assertions, and output are outside timing. Fill geometry, candidate construction, scheduling, garbage collection, scoring/selection, delegate/loop overhead, and result-count consumption are included. Each batch consumes every result count (160,000 default or 140,000 custom parts); its last result is checked for exact drawing identity, part order, locations, and rotations against direct horizontal/vertical fills. Preflight and batch checks establish finite, positive-area, in-bounds, nonoverlapping layouts. Behavioral tests separately check input non-mutation. No cache reset or forced collection is inserted between batches; JIT paths and source drawing data are warm, but each call still constructs its candidates.

Allocation measurement is omitted for this parallel workload. The current-thread allocation probe in the older synchronous comparer benchmark above would not measure all fill workers and must not be interpreted as total group-fill allocations.

Results and limitations

Minimum / median / maximum over seven batches, calculated from raw TRX rows with Python statistics.median:

Mode	Before batch ms	After batch ms	Before µs/call	After µs/call
Default scoring	12349.821045 / 12588.985384 / 12798.229355	12373.077829 / 12613.732653 / 12696.177150	617.491 / 629.449 / 639.911	618.654 / 630.687 / 634.809
Custom fewer-parts comparer	12430.689835 / 12733.580886 / 12944.521123	12537.190933 / 12624.207441 / 12905.258236	621.534 / 636.679 / 647.226	626.860 / 631.210 / 645.263

The custom-comparer median decreased 0.86%, while the default control increased 0.20%. Before/after ranges overlap. These sequential process measurements on a shared VM do not establish a reliable fill-time speedup. The benchmark includes geometry and scheduling, not isolated score latency, and its small candidate lists limit the amount of removed work. The concrete result is removal of two unused score computations per successful single-angle custom-comparer call, established by Debug diagnostics below. A custom comparer may still compute any scores it requires.

This is a local group-fill microbenchmark, not a whole-job speedup estimate, production-corpus result, multi-angle throughput test, Windows UI runtime test, or ONNX inference test. There are no timing gates. The full main/engine-suite counts in the historical section above belong to Task 1; the independent Task 1b full-suite results are recorded below.

Behavior and real red/green evidence

FillHelpersTests adds 17 behavior cases in both configurations and four Debug-only work cases:

• Valid staggered rectangle groups exercise higher-count wins in both directions and equal-count density wins in both directions. The deliberately reversed-score comparer must select the opposite layout, even against count or density.
• Recording comparers assert exactly one call, horizontal candidate versus vertical current, the original work-area object, and the exact selected list reference. One angle keeps both writes on a single bag queue. Tie cases verify default selection retains the first bag result and custom comparison still executes, with both accept and reject outcomes.
• Layout comparisons preserve count, drawing reference identity, order, positions, rotations, and bounds. Input snapshots cover part/drawing/program/code identities, poses, bounds values, drawing area, and motion endpoints; a nonzero rotation case checks cloning without changing caller programs. Input angle lists and work areas are also checked where applicable.
• Empty angle lists, empty groups, and valid groups too large for the work area return null, make no comparer calls, and compute no scores. No invalid or null parts are used.
• Existing process-wide PerfCounters.FillScoreComputations is reused, with the existing nonparallel FillCacheCollection and reset in finally. No new production diagnostic or testing seam was added.

Before changing production, all characterization passed. Three new work assertions genuinely failed:

Debug case	Expected	Before actual	After actual
Non-scoring custom comparer, area 5×9	0	2	0
Non-scoring custom comparer, area 10×4	0	2	0
Custom comparer explicitly computes two scores	2	4	2
No comparer, default-score control	2	2	2

The scoring-comparer control proves the helper does not bypass the supplied comparer or its score work. Release counter increments compile away; zero Release counters are not used as evidence of work removal.

Run	Passed	Skipped	Failed
Before targeted Release	47	0	0
Before targeted Debug (intentional RED)	48	0	3
After targeted Release	47	0	0
After targeted Debug (GREEN)	51	0	0
Existing DefaultFillComparerWorkTests, Debug, after	5	0	0
Group-pattern measurement, Release, before	1	0	0
Group-pattern measurement, Release, after	1	0	0
Group-pattern gate, environment unset	0	1	0
Group-pattern gate, environment 0	0	1	0
Parent full main suite, Release	1,171	14	0
Parent full main suite, Debug	1,180	14	0
Parent full engine suite, Release	300	0	0

The targeted filter is FillHelpersTests|FillPipelineTests|FillComparerTests|FillScoreTests using FullyQualifiedName~ for each term. The five older Debug comparer-work cases have a different class-name suffix, so they were run separately. Existing compiler warnings remain outside the changed code; no warnings were emitted for the new test/harness or changed helper. git diff --check passed. The parent independently reconciled all 14 raw timing rows against TRX and console output, verified source snapshots/hashes and the sole production-source difference, and reran the full suites. The 14 skips are the 12 existing optional CHR-font tests plus both opt-in benchmarks. README now documents the group-pattern filter, parallel-allocation limitation, and helper checks. The previously denied CLAUDE.md workflow sync remains blocked pending explicit approval; no retry or alternate write was attempted.

Raw measured batches

Times in milliseconds for 20,000 actual production calls per mode per batch. Odd batches run default first; even batches run custom first.

State	Batch	Default ms	Custom ms
before	1	12798.229355	12733.580886
before	2	12446.484280	12838.273225
before	3	12349.821045	12543.308696
before	4	12638.532022	12944.521123
before	5	12588.985384	12547.909410
before	6	12475.834989	12430.689835
before	7	12603.474398	12883.844997
after	1	12613.732653	12795.834020
after	2	12659.052180	12624.207441
after	3	12696.177150	12537.190933
after	4	12476.409124	12611.963585
after	5	12683.978429	12905.258236
after	6	12373.077829	12553.051166
after	7	12462.758852	12731.211633

Evidence files and reproduction

Raw test/measurement logs, TRX, source snapshots/manifests, and exploratory artifacts were retained under /home/aj/.hermes/cache/scratch/opennest-fill-1b-20260925/ through independent spec and subsequent quality/integration review. Both reviews passed with no findings and reconciled the source hashes, genuine red/green failures, raw timings, and full-suite outcomes. The parent verified the same evidence and formatting checks. Temporary artifacts were then removed before commit; all measured batch rows, source hashes, environment details, and test summaries needed for this report are preserved above.

Run the current group-pattern benchmark alone (the category filter also runs the historical comparer benchmark):

OPENNEST_RUN_FILL_PERF=1 dotnet test OpenNest.Tests/OpenNest.Tests.csproj -c Release \
  --filter 'FullyQualifiedName~GroupPattern_ReportsDefaultAndCustomComparer' \
  --logger 'console;verbosity=detailed'

dotnet test OpenNest.Tests/OpenNest.Tests.csproj -c Release \
  --filter 'FullyQualifiedName~FillHelpersTests|FullyQualifiedName~FillPipelineTests|FullyQualifiedName~FillComparerTests|FullyQualifiedName~FillScoreTests'
dotnet test OpenNest.Tests/OpenNest.Tests.csproj -c Debug \
  --filter 'FullyQualifiedName~FillHelpersTests|FullyQualifiedName~FillPipelineTests|FullyQualifiedName~FillComparerTests|FullyQualifiedName~FillScoreTests'
dotnet test OpenNest.Tests/OpenNest.Tests.csproj -c Debug \
  --filter 'FullyQualifiedName~DefaultFillComparerWorkTests'

To reproduce before/after independently, use separate disposable worktrees at the baseline revision and the delivered revision, copy the identical measured harness/tests into both, and verify their hashes before rebuilding and running. Do not substitute a test-only approximation for the before production path or mix measurements from changed harnesses.

Task 2 — eliminate discarded extents pitch geometry — 2026-09-25

Scope, proof, and compatibility

FillExtents.BuildColumn now uses pair.Bbox.Width + partSpacing directly for finite pair height and finite, nonnegative spacing. The source comment records the equivalence: the old helper returns that pitch for negative/no-hit slide distances; otherwise minSlide >= 0, so Max(pairHeight - minSlide, pairHeight + partSpacing) selects the same pitch. Boundary creation, two temporary clones, and vertical slide queries were discarded work in that domain.

The caller audit found that NestJobValidator rejects negative/nonfinite spacing, but the public constructor, Plate.PartSpacing, PlateFillService, and ExtentsFillStrategy do not establish that invariant for all interactive/public callers. The legacy calculation and its helpers therefore remain behind a negative/nonfinite-spacing or nonfinite-height guard. No validation or exception policy was added. Pair construction still prepares both boundaries. Tiling, adjustment, overlap fallbacks, progress, cancellation, bounds recomputation, and horizontal repetition are untouched. Task 3 and ML work are not included.

Source and measurement provenance

• Resumed base: cec7396da6d62386ef4817a6eb0e1b573ddd58de on master, with unfinished Task 2 edits. The final implementation is delivered with this report; resolve its commit with git log -1 --format=%H -- OpenNest.Engine/Fill/FillExtents.cs.
• Original FillExtents.cs SHA-256: e4110022f142ec4f954a00b8569dea5d451dbd5216756b0b6bf6a9595f2a83d0.
• Optimized FillExtents.cs SHA-256: efaacfca83a6d94bb7fdc65ba4da4be09c97c14c9c4e161491d48d64a69d1be3.
• Identical final before/after harness FillPerformanceTests.cs SHA-256: bb2adf31fa3348d1b84c239b01cdffa50fffc92193af3d1a4122461a93181cda.
• Identical behavior/work tests FillExtentsTests.cs SHA-256: b43508e30ab9683a123c4e00a0478e92cc1467fcf1afc5c6778f8fb2d548f02b.
• Frozen test reference LegacyFillExtents.cs SHA-256: b50b3b64014446d9688facc0b711b59cf126b64037fdf667603ce3d85859a324. Reversing only the type/constructor rename and public-to-internal visibility change reproduced the baseline file byte-for-byte. The full reference is retained because the tests compare intermediate progress and private column-adjustment/fallback behavior as well as final layouts.
• Before tests/measurements temporarily restored the actual original production file, with restoration of the optimized file in finally. Source/project manifests matched across measurements except for FillExtents.cs; diagnostics and all tests were identical. No reference implementation or reflection is inside timing.
• Host: hermes, Ubuntu 24.04.5 LTS x64, Linux 6.8.0-142-generic, KVM guest with four vCPUs presented as AMD Ryzen 9 5900X. SDK 10.0.112. All measured tests emitted .NET 8.0.31, Release, and a 1,000,000,000 Hz stopwatch. Shared VM, no CPU pinning or host isolation.
• The resumed exploratory logs were not used for final numerical estimates: the full measurement pair was rerun after test formatting, then repeated in reverse process order. All final raw rows are preserved below; no best-run selection or mixing of harness versions.

Behavior and deterministic work evidence

35 new Release behavior cases cover a 16-case shape/spacing/rotation matrix (rectangle, right triangle, concave L, native quarter-arc profile; spacing 0 and 0.5), nonzero work-area origins, no-fit parts/pairs, pre-cancellation, adjusted columns, overlap fallback at a 30-degree triangle angle, negative spacing, nonfinite no-fit calls, and isolated unsupported negative-spacing column calculations. Exact ordered comparisons include drawing reference identity, location, rotation, bounds, program geometry, and progress messages/layouts. Caller program/code identities and values, cached area, work-area values, and clone program-sharing/rotation ownership are checked. Main supported fixtures are finite, positive-area, in-bounds, and nonoverlapping; exact legacy equivalence preserves their spacing behavior rather than introducing a new spacing algorithm.

Two dedicated differential cases explicitly retain a pre-existing limitation: at zero spacing in a (3,5,40,27) area, rectangle/native-arc fills overrun the right edge by approximately 1e-5. Those cases are not counted as valid-layout evidence and are not silently repaired by this optimization. The normal validity matrix and benchmark instead use (3,5,45,27). Nonfinite spacing is tested only through bounded no-fit or isolated negative-infinity column paths, not unrestricted legacy tiling that could fail to terminate.

PerfCounters.PartBoundaryPreparations follows the existing Debug-only conditional increment pattern. Four new work assertions run in the existing nonparallel FillCacheCollection, resetting counters in finally:

Case (each at spacing 0 and 0.5)	Required	Original production	Optimized production
Four repeated BuildColumn calls	0 preparations	8 (genuine RED)	0
Full triangle fill, initial plus rebuilt column	2 preparations	6 (genuine RED)	2

The two remaining full-fill preparations are the necessary BuildPair work, also asserted independently. Every full-fill work case returns the same 24-part layout. Six column-adjustment cases establish both accepted adjustment and fallback: four retain nonoverlapping adjusted columns, and two reject overlapping adjusted columns in favor of the unchanged initial column. The selected column and final layout remain in bounds. Release counter calls compile away; zero Release counters are not evidence of skipping work.

Workload and results

The opt-in benchmark uses a closed right triangle (0,0)-(10,0)-(0,8)-(0,0), work area (3,5,45,27), rotation 0, and spacing 0 or 0.5. Both modes return 24 parts and rebuild their column once. Each spacing gets two 50-call warmups and seven 200-call measured batches per process. Spacing order alternates per batch. The first pair runs original then optimized; the repeat runs optimized then original. These are separate rebuilt test processes, not an interleaved in-process implementation comparison.

Timing includes real synchronous production fill, geometry preparation, tiling, adjustment, overlap checking/fallback, GC, delegates/loops, and count consumption. Setup, reference fills, assertions, and output are outside timing. Every batch consumes 4,800 parts and checks its last layout against the frozen reference. Source drawing data/JIT paths are warm; no forced collection, cache reset, file fixture, or network dependency is involved.

Microseconds per fill, minimum / median / maximum over seven batches:

Process pair	Spacing	Before µs/fill	After µs/fill	Median change
Forward	0	2205.240 / 2281.382 / 2332.728	2158.270 / 2186.747 / 2207.422	-4.15%
Forward	0.5	2244.825 / 2310.086 / 2330.661	2155.409 / 2190.618 / 2215.091	-5.17%
Reverse	0	2165.221 / 2229.736 / 2403.664	2165.604 / 2210.005 / 2316.437	-0.88%
Reverse	0.5	2224.011 / 2302.593 / 2330.944	2187.911 / 2203.634 / 2266.720	-4.30%

The measured medians decrease in both process orders, but the ranges overlap (especially zero spacing) and the gain varies with run order. These shared-VM samples support a modest local improvement, not a stable percentage guarantee or whole-job speedup. No reproducible material regression was observed and there is no elapsed-time test gate.

Synchronous current-thread allocations are identical in every measured batch for a given implementation/spacing:

Spacing	Before bytes/batch	After bytes/batch	Before bytes/fill	After bytes/fill	Saved bytes/fill	Reduction
0	174939200	167924800	874696	839624	35072	4.01%
0.5	226099200	205708800	1130496	1028544	101952	9.02%

These are GC.GetAllocatedBytesForCurrentThread managed-allocation differences around synchronous fills, not retained memory, RSS, or parallel-job totals. The deterministic result is removal of discarded boundary preparation; the allocation savings reproduce in both process orders.

Tests and serial reviews

Run	Passed	Skipped	Failed
Original targeted Release	43	0	0
Original targeted Debug (intentional RED)	43	0	4
Optimized targeted Release	43	0	0
Optimized targeted Debug	47	0	0
Each of four final opt-in Release measurement runs	1	0	0
Extents opt-in gate unset	0	1	0
Extents opt-in gate 0	0	1	0
Full main Release	1206	15	0
Full main Debug	1219	15	0
Full engine Release	300	0	0

The targeted filter is FillExtentsTests|StrategyOverlapTests with FullyQualifiedName~ on each term. Full-suite TRX outcomes were parsed rather than inferred from console totals: main Release has 1,221 total results, Debug 1,234, engine 300. All skips are the 12 optional CHR-font fixtures and three opt-in performance tests. The adapter confirms .NET 8.0.31 in all full runs. Rebuilding the engine emits the existing CirclePacking/Item.cs CS0108/CS0114 warnings; rebuilding the test project also emits its existing nullable/xUnit warnings. The frozen LegacyFillExtents.cs:30 adds one benign CS8625 warning because the unchanged legacy reportProgress = null default is copied into the nullable-enabled test project. It is retained verbatim for reference fidelity, not presented as a pre-existing test warning. No new production warnings or unexpected test failures were found.

Per the user's no-subagents instruction, spec review and subsequent quality/integration review were performed serially by the same agent, not independently. Spec review checked the algebraic guard, caller audit, exact frozen reference, behavior/ownership/cancellation/overlap coverage, genuine red/green work assertions, and Task 2-only scope. Quality review checked the production/test diff, Debug counter isolation and Release compilation convention, absence of new secrets or unsafe I/O, runtime/harness provenance, and all final raw TRX rows against console output. No blocking findings remained after the test-only whitespace correction. Changed-file dotnet format whitespace --verify-no-changes and git diff --check passed.

README documents the extents benchmark and work-test commands. The previously denied CLAUDE.md workflow sync remains blocked pending explicit approval; it was not retried. No representative corpus, Windows UI runtime test, or actual ONNX inference was run. This slice does not complete Tasks 3–5 or authorize gated follow-ups.

Raw measured batches

Milliseconds per 200 actual production fills. Each row contains both implementations from one process pair; every batch produced 4,800 parts. Allocation totals for every row are the constant spacing-specific values above.

Process pair	Spacing	Batch	Before ms	After ms
forward	0	1	463.229998	439.473112
forward	0	2	466.545605	437.349468
forward	0	3	450.826218	441.484339
forward	0	4	456.276359	438.751402
forward	0	5	462.975196	434.451956
forward	0	6	445.596554	433.705799
forward	0	7	441.048033	431.653954
forward	0.5	1	465.387515	443.018255
forward	0.5	2	462.017170	441.358437
forward	0.5	3	466.132129	438.198245
forward	0.5	4	450.824107	431.081841
forward	0.5	5	462.570224	438.123662
forward	0.5	6	454.096721	433.895019
forward	0.5	7	448.964925	437.877448
reverse	0	1	480.732828	463.287364
reverse	0	2	445.947233	434.966923
reverse	0	3	450.506707	442.001094
reverse	0	4	433.764890	446.086663
reverse	0	5	437.597684	448.988001
reverse	0	6	433.044245	433.120823
reverse	0	7	448.325975	439.151450
reverse	0.5	1	460.518547	447.369861
reverse	0.5	2	461.616765	437.593637
reverse	0.5	3	466.188871	453.049694
reverse	0.5	4	463.178063	453.343928
reverse	0.5	5	453.526082	440.726846
reverse	0.5	6	444.802234	440.614301
reverse	0.5	7	448.043300	437.582121

Reproduction and evidence retention

OPENNEST_RUN_FILL_PERF=1 dotnet test OpenNest.Tests/OpenNest.Tests.csproj -c Release \
  --filter 'FullyQualifiedName~Extents_ReportsRepeatedColumnRebuilds' \
  --logger 'console;verbosity=detailed'
dotnet test OpenNest.Tests/OpenNest.Tests.csproj -c Release \
  --filter 'FullyQualifiedName~FillExtentsTests|FullyQualifiedName~StrategyOverlapTests'
dotnet test OpenNest.Tests/OpenNest.Tests.csproj -c Debug \
  --filter 'FullyQualifiedName~FillExtentsTests|FullyQualifiedName~StrategyOverlapTests'

For an independent before/after comparison, keep the delivered tests/diagnostics identical in two disposable trees and use the baseline FillExtents.cs only in the before tree. Rebuild each configuration and verify the source/harness hashes. Do not change production spacing policy to reproduce invalid-domain cases or substitute the frozen test type for the measured production method.

Final logs, TRX files, source restoration snapshot, manifests, and parsed rows were held in /home/aj/.hermes/cache/scratch/opennest-task2-resume-20260925/ through review. The report preserves all final timing rows, allocation totals, source hashes, runtime and test summaries; temporary evidence and the superseded resumed exploration directory are removed before commit. Next planned hardening is the separately reviewable redundant-bounds slice with threshold-fit and canonical-frame safety, not a geometry repair bundled into this change.

Task 3 — remove provably redundant bounds walks — 2026-09-25

Scope and per-site decisions

Part.Offset translates the cached BoundingBox arithmetically and Part.Clone copies it exactly, so several UpdateBounds() calls in the extents/pattern paths recompute a box that just changed by pure translation. Recomputation is mathematically equivalent but not bitwise identical to accumulated translates, and the extents pipeline compares boxes at Tolerance.Epsilon fit thresholds. Each candidate removal therefore had to keep every characterized layout, box, and threshold branch bitwise identical (the differential harness compares (X, Y, Length, Width) and location tuples with exact double equality, not tolerance — Vector.Equals itself is tolerance-based, so location/coordinate snapshots were switched to scalar tuples to expose ulp deltas).

Site	Decision	Evidence
BuildPair after Offset(startOffset, 0)	Removed	All characterization green; slide uses locations, not cached bounds.
BuildPair after Offset(-dist, 0)	Removed	All characterization green.
TryShiftDirection after Offset(partSpacing, 0)	Removed	The retained post-vertical-shift recompute covers both offsets.
TryShiftDirection after Offset(0, verticalShift)	Retained	Rotated triangle spacing 0.5: box Y 5.6025660004937174 → 5.6025660004937183. Compactor.Push box thresholds consume this box.
AnchorToWorkArea part1/part2 recompute	Retained	Part2-only removal changed rectangle differential X 13.499999999999998 → 13.5 and arc pair height 8.0000000000000036 → 8; part1 removal changed X 3.1000000000000005 → 3.100000000000001. Part1-only removal failed 6 of 101 characterization cases; part2-only removal failed 25 of 101, including overlap fallback. The anchor workArea.X - bbox.Left round-trip lands a ulp away from X += anchor.
BuildRotatedPattern after Clone()	Retained	Accumulated-translation input at angle 0: box 1.3000000000000003 → 1.3. Source comments now record why each retained site stays.

No change to Part.Offset, Part.Clone, Part.Rotate, Part.UpdateBounds, PairBbox, pattern.UpdateBounds(), the Task 2 pitch guard, or LegacyFillExtents.cs (frozen SHA-256 b50b3b64014446d9688facc0b711b59cf126b64037fdf667603ce3d85859a324 unchanged). PerfCounters.PartBoundsUpdates (Debug-only, incremented at the top of Part.UpdateBounds) was added per the plan.

Source and measurement provenance

• Base: 4ec92c95ec10c5c877e9fb0f34f197d7e23b87b0 on master. Final implementation is delivered with this report; resolve with git log -1 --format=%H -- OpenNest.Engine/Fill/FillExtents.cs.
• FillExtents.cs SHA-256 before efaacfca83a6d94bb7fdc65ba4da4be09c97c14c9c4e161491d48d64a69d1be3 (Task 2 delivered) → after 13be137690ad5f60e0fe3874ec0cb0b93e9864b97d7eee7f3aa65c9b962053a4.
• FillHelpers.cs before a1c8a1bc155dbe62439f8345a3a54e06147a5404a6a46835a30b66d52cceccfa → after 0a35075a573c7f17f9c8095a5a7bd56d0a4ea935ec1c9d8da2c4c9d78e0a9af0 (comment-only; site retained).
• Identical before/after harness FillPerformanceTests.cs SHA-256 93ec06c5b59aecfe5cb9311380afea507cc134e77df7535036fb451ab0f63e29.
• Before timings ran the actual pre-change production files (restored temporarily, restored back in finally); after timings the delivered files. Same machine, serial Release: hermes, Ubuntu 24.04.5 LTS x64, KVM, four vCPUs presented as AMD Ryzen 9 5900X, SDK 10.0.112, .NET 8.0.31, 1 GHz stopwatch. Shared VM, no pinning.

Work-removal evidence (genuine red/green)

New Debug counter tests (serialized in FillCacheCollection, reset in finally) failed first on the unmodified production code: Fill_BoundsWork_PerformsFewerUpdates expected fewer than 13 part-bounds updates, actual 13 (both spacings); the group-construction work assertion expected 0/2 updates at angles 0/0.37, actual 2/4. After the change: full triangle fill 13 → 10 updates with 24 bitwise-identical parts (both spacings). The group assertions were rewritten to pin the retained counts (2 at angle 0, 4 at 0.37 = retained clone recompute + rotate recompute per part) because removing the clone recompute failed behavior characterization — disclosed partial delivery, not an optimized site. Pattern.UpdateBounds aggregates boxes and does not call Part.UpdateBounds, so it is outside this counter. Per fill the three removals save three UpdateBounds calls (three Box allocations — 144 bytes) reproduced exactly in every measured batch.

Characterization added (all passing pre-change, 133 targeted Release)

• 16 extents threshold cases: pair-fit, column-tiling, and column-count branches on both sides of Tolerance.Epsilon, nonzero work-area origin, progress layouts, input snapshots.
• 16 adjacent-double pair/column cases (BitIncrement/BitDecrement neighborhoods with asserted both-side decisions) and 16 adjacent-double TryShiftDirection width-acceptance cases (binary-searched rejected/accepted doubles located using only the frozen pre-change path, ±shifts).
• 12 BuildRotatedPattern cases: translated, accumulated-translation, pre-rotated, canonical-frame, native-arc, and nonzero-program-origin groups at angles 0 and 0.37, checking exact poses/bounds against a local pre-change reference, input non-mutation, clone program ownership, and no double rotation of pre-rotated inputs.
• Frozen-legacy differentials, threshold branch equality, and per-site removal trials (each candidate removed alone, characterization run, restored) reconcile the per-site table above; the trial logs were retained through review in the scratch directory and removed afterwards, with the resulting ulp deltas and failure counts recorded in this report.

Tests (parent independently reran the full suites on the final tree)

Suite	Passed	Skipped	Failed
Targeted Release (`FillExtentsTests	FillHelpersTests	CanonicalFrameTests	StripeFillerTests`)
AGENTS.md Debug work filter	137	0	0
Full main Release	1266	16	0
Full main Debug	1283	16	0
Full engine Release	300	0	0

Skips are the 12 optional CHR-font fixtures plus four opt-in benchmarks (the new rotated-pattern case adds one). Gate verified: unset and 0 skip all category tests. .NET 8.0.31 adapters confirmed. Changed-file dotnet format whitespace --verify-no-changes and git diff --check passed; no new production warnings.

Reviews

Implementation, spec review, and quality/integration review ran as three independent agent sessions (the earlier same-agent serial constraint was lifted by the user for this session). Spec review initially found one Important issue — the canonical fixture consumed a stale Source.Angle and duplicated the pre-rotated scenario — plus one Minor report-wording error; both were fixed (fixture now refreshes the canonical angle and asserts a nonzero source-to-canonical transformation; the failure counts are stated as 6/101 and 25/101), and the strengthened fixture additionally surfaced a benign test-assertion normalization issue at a baked 2π rotation, fixed by normalizing both sides. Subsequent independent quality/integration review returned PASS with no Critical, Important, or Minor findings: production diff traced through slide/Compactor consumers, counter isolation, adjacent-double oracle independence, hash/median/allocation reconciliation against raw logs, integration sweep across fill-strategy and jobs callers, and disclosure honesty were all verified by that reviewer. Pre-existing DXF-fixture-dependent tests still return early without their Windows fixture; no Windows UI runtime test or ONNX inference was run.

Results

All before/after timing ranges overlap: elapsed-time improvement is inconclusive, consistent with three saved Program.BoundingBox() walks being small against full fills. Allocation savings are exact and reproduce in every batch: extents spacing 0 839,624 → 839,480 bytes/fill and spacing 0.5 1,028,544 → 1,028,400 bytes/fill (−144 B/fill). Rotated-pattern construction is an unchanged-code control: identical allocations per call at both angles.

Extents: milliseconds per 200 production fills, seven batches each, alternating spacing order, warmup excluded. Rotated-pattern: milliseconds per 5,000 constructions of a 32-part native-arc group.

Workload	Batch	Before ms	After ms
extents spacing 0	1	461.646777	502.378600
extents spacing 0	2	439.442203	446.609639
extents spacing 0	3	450.272109	457.012036
extents spacing 0	4	433.095759	454.402604
extents spacing 0	5	443.489319	447.382522
extents spacing 0	6	433.504166	448.477156
extents spacing 0	7	441.588374	439.879594
extents spacing 0.5	1	460.691045	439.973796
extents spacing 0.5	2	457.895526	443.225746
extents spacing 0.5	3	444.315207	451.898487
extents spacing 0.5	4	436.733945	447.851680
extents spacing 0.5	5	451.266260	431.428815
extents spacing 0.5	6	438.338321	455.657180
extents spacing 0.5	7	448.995034	438.982789
rotated-pattern angle 0	1	92.121779	95.085965
rotated-pattern angle 0	2	85.115166	83.764479
rotated-pattern angle 0	3	84.692335	82.859009
rotated-pattern angle 0	4	90.233547	85.003329
rotated-pattern angle 0	5	85.081651	83.281808
rotated-pattern angle 0	6	78.809908	77.355562
rotated-pattern angle 0	7	78.280977	80.372130
rotated-pattern angle 0.37	1	184.337007	186.875744
rotated-pattern angle 0.37	2	170.493990	155.509393
rotated-pattern angle 0.37	3	153.992846	155.681698
rotated-pattern angle 0.37	4	155.207434	156.663232
rotated-pattern angle 0.37	5	158.498327	149.814054
rotated-pattern angle 0.37	6	157.148604	150.090405
rotated-pattern angle 0.37	7	150.252399	150.547539

Medians: extents spacing 0 2207.942 → 2242.386 µs/call, spacing 0.5 2244.975 → 2216.129 µs/call; rotated-pattern angle 0 17.016 → 16.656 µs/call, angle 0.37 31.430 → 31.102 µs/call. Every batch produced the expected part counts (extents 4,800; rotated-pattern 160,000) and layout assertions ran on the timed path's output outside timing. Current-thread synchronous allocations only; no whole-job or RSS claims.

Reproduction and limitations

OPENNEST_RUN_FILL_PERF=1 dotnet test OpenNest.Tests/OpenNest.Tests.csproj -c Release \
  --filter 'Category=FillPerformance' --logger 'console;verbosity=detailed'
dotnet test OpenNest.Tests/OpenNest.Tests.csproj -c Release \
  --filter 'FullyQualifiedName~FillExtentsTests|FullyQualifiedName~FillHelpersTests|FullyQualifiedName~CanonicalFrameTests|FullyQualifiedName~StripeFillerTests'
dotnet test OpenNest.Tests/OpenNest.Tests.csproj -c Debug \
  --filter 'FullyQualifiedName~DefaultFillComparerWorkTests|FullyQualifiedName~FillHelpersTests|FullyQualifiedName~FillExtentsTests|FullyQualifiedName~StrategyOverlapTests'

This is a partial delivery by design: three of six candidate recomputations were removable; the three retained sites are documented with their observed ulp deltas, and their UpdateBounds calls must not be removed without re-running the threshold and overlap-fallback characterization. Timing is inconclusive; only allocation and work-counter removal are demonstrated. No representative production corpus, Windows UI runtime test, or ONNX inference was run. Task 4 and gated follow-ups are not included.

Task 4a — scalar-only feature extraction — 2026-09-25

Scope

FeatureExtractor.Extract always built a 32×32 bitmask — 1024 Polygon.ContainsPoint ray-cast tests plus a 1,024-byte array — even though the only production consumer at runtime (the AngleCandidateBuilder ML branch) reads nothing from PartFeatures.Bitmask. This slice adds Extract(Drawing, bool includeBitmask); the original one-argument signature is preserved as a source- and binary-compatible wrapper that keeps the training bitmap. Every scalar formula, tolerance, material filter, and the canonical-frame normalization run identically in both modes. Training consumers (OpenNest.Training) are unchanged, and AngleCandidateBuilder is not yet switched over — Task 4b gates the inference call site. No production behavior changes for any existing caller.

PerfCounters.FeatureBitmaskCells (Debug-only, incremented inside the bitmask scan loop) was added to prove the point-in-polygon work is genuinely skipped.

Source provenance

• Base: 6863c8bdb1c7d98eb5b7c45153e062e7cb335464 on master. Final implementation is delivered with this report.
• FeatureExtractor.cs SHA-256 before 1094d386595c0513fcb6db1e5ba7b2c7a0b8c19cf351f6cf9a462356156fdd15 → after 2d7b45350abd94d7e728c962aca06f4a86920d0328d8025c75f51ebc7e5ed6b3.
• PerfCounters.cs before 0790401ae0433e416c4ac40d678403407497226d6bd40057b7c4e959da6e0582 → after b596437210719981940ebf7ae03b31b7493f44002cf545bbe638c35bebf5b65d.
• Harness FillPerformanceTests.cs at measurement time: before/after runs identical at c257b27a5a4335278c99b8f623540b5580b51d1cc9d31a04bc8d8641a9c722a0 (new method added to base 93ec06c5b59aecfe5cb9311380afea507cc134e77df7535036fb451ab0f63e29; existing methods byte-identical). The delivered tree ships 27c213f202e46cdd9a1e46bb0263784277f2aecc17469ddd83c5db26c1b129aa — disclosure/comment wording only, timed code paths identical.
• Environment: same shared KVM VM as prior slices — Ubuntu 24.04.5 LTS x64, four vCPUs presented as AMD Ryzen 9 5900X, SDK 10.0.112, .NET 8.0.31 adapters confirmed, 1 GHz stopwatch, serial Release.

Work-removal evidence (genuine red/green)

The change is additive, so red was demonstrated by neutralizing the new flag in the delivered overload (forcing always-bitmap construction — exactly the original production behavior): on the final tree 8 of 38 Debug cases failed — the five ScalarOnlyOverload_OmitsBitmap theory cases, ScribeAndRapidMarks_DoNotAffectEitherOverload, and RotatedInput_FeaturesMatchAxisAlignedEquivalent with Assert.Null() Failure: Value is not null, plus ScalarOnlyOverload_RunsNoBitmaskCellScan failing the same assertion inside its counted window. Restoring the flag turned all 38 Debug tests green. On the delivered tree: default extraction counts exactly 1,024 bitmask cells per call (matching the documented scan), scalar-only counts 0, and failed extraction (rapid-only program) counts 0.

New OpenNest.Tests/ML/FeatureExtractorTests.cs (35 behavior cases plus 3 Debug counter cases, serialized in FillCacheCollection for the counter tests): exact-equality scalar snapshots across both overloads on five shapes (rectangle, right triangle, L-shape concave profile, native-arc ring, native circle); explicit-true bitmap equality bit-for-bit against the default overload; default training-bitmap shape/content preservation (1,024 cells, 0/1 only, mixed for ring/L-shape, all-set for a full rectangle); rotated-input invariance against an axis-aligned equivalent; canonical-copy input; scribe/rapid marks ignored by both overloads with identical bitmaps; input non-mutation; determinism across repeated extraction. Because ExplicitTrue_MatchesDefaultOverloadBitForBit alone cannot detect a rasterization change applied to both overloads (the default delegates to it), the five fixtures are additionally pinned against frozen SHA-256 hashes of the bitmaps emitted by the actual pre-change implementation at 6863c8b (captured by running the original code, cross-checked by the spec reviewer against an in-memory HEAD compilation). Pre-existing edge behavior is characterized, not changed: rapid-only drawings throw ArgumentOutOfRangeException in ShapeProfile and null drawings throw NullReferenceException identically through both overloads.

Tests

Suite	Passed	Skipped	Failed
Targeted Release (`FeatureExtractorTests	CanonicalFrameTests`)	40	0
Targeted Debug (FeatureExtractorTests)	38	0	0
Full main Release	1,301	17	0
Full main Debug	1,321	17	0
Full engine Release	300	0	0

Skips: 12 optional CHR-font fixtures plus five opt-in benchmarks (the new feature-extraction case adds one). Gate verified: unset skips all five category tests. Changed-file dotnet format whitespace --verify-no-changes and git diff --check passed; no new production warnings.

Results

Same-harness, same-machine, serial Release; ring OD=20 ID=8 (perimeter plus one circular cutout); warmup 2×200, measured 7×1,000 calls, alternating mode order, correctness checks outside timing; allocations are current-thread synchronous only. The before run exercised the original always-bitmap implementation in both modes (harness scalar lambda temporarily pointed at the full path); the after run is the delivered tree.

Batch	Before full ms / B	Before scalar-mode ms / B	After full ms / B	After scalar-only ms / B
1	154.692010 / 35,338,120	154.066548 / 35,332,896	197.474351 / 35,338,120	31.020699 / 34,252,896
2	161.643928 / 35,338,120	151.896080 / 35,332,896	157.026495 / 35,332,896	29.342949 / 34,252,896
3	149.279498 / 35,332,896	155.797847 / 35,332,896	154.219132 / 35,332,896	32.988987 / 34,268,256
4	153.772483 / 35,332,896	153.226512 / 35,332,896	161.453458 / 35,332,688	41.092334 / 34,252,688
5	155.591257 / 35,338,120	155.760388 / 35,332,896	151.984770 / 35,332,688	30.768833 / 34,252,688
6	153.993059 / 35,332,896	154.410087 / 35,332,896	153.549576 / 35,332,688	29.824879 / 34,252,688
7	155.984019 / 35,338,120	159.061932 / 35,332,896	157.327152 / 35,332,688	29.530524 / 34,252,688

Medians (µs/call): before scalar-mode (original behavior) 154.410 → after scalar-only 30.769 (−80.1%). Allocations: medians 35,332.896 → 34,252.688 B/call. Within the after run, full minus scalar-only per batch is 1,085.224 / 1,080.000 / 1,064.640 / 1,080.000 / 1,080.000 / 1,080.000 / 1,080.000 B/call (median 1,080.000): the 1,048-byte byte[1024] allocation plus ~32 B from the harness's in-window bitmap-count consumption (a reviewer probe on .NET 8.0.31 measured 1,048 and 32 respectively) — i.e. extraction-plus-consumption overhead, not 1,080 B of production extraction alone; the production GenerateBitmask loop itself allocates nothing beyond the array. Before scalar-mode and before-full rows agree within noise, confirming the harness adaptation introduced no bias. Timing likewise includes that enumeration in full mode.

Default-overload (training) timing is inconclusive: after-full median 157.026 vs before-full 154.692 µs/call (+1.5%, inside the overlapping batch ranges; the after run's batch 1 at 197.474 is a warmup-adjacent outlier included unmodified). Overlapping ranges establish neither regression nor non-regression for the full mode.

Reproduction and limitations

OPENNEST_RUN_FILL_PERF=1 dotnet test OpenNest.Tests/OpenNest.Tests.csproj -c Release \
  --filter 'FullyQualifiedName~FeatureExtraction_ReportsFullAndScalarOnly' --logger 'console;verbosity=detailed'
dotnet test OpenNest.Tests/OpenNest.Tests.csproj -c Release \
  --filter 'FullyQualifiedName~FeatureExtractorTests|FullyQualifiedName~CanonicalFrameTests'

This is a capability slice, not yet a production speedup: the inference call site keeps using the default overload until Task 4b gates predictor availability, so real nesting runs show no change from this commit. The measured gain applies to inference callers once wired. No representative production corpus, Windows UI runtime test, or ONNX inference was performed; the Debug counter increments compile away in Release.

Task 4b — gate angle features on predictor availability — 2026-09-26

Scope and contract

AngleCandidateBuilder now checks AnglePredictor.IsAvailable before extraction, and available inference requests includeBitmask: false. The public parameterless constructor remains; readonly per-instance delegates provide isolated test doubles without process-global overrides. The prediction default threshold (0.3), Width then Length argument order, prediction-prefix duplicates, tolerance-based appended-angle deduplication, base/sweep order, constraints, classification shortcuts and known-good pruning are unchanged. The legacy repeated-addition sweep includes a value just below π: 37 sweep entries, not an integer-indexed 36-angle replacement.

IsAvailable and PredictAngles use the same initializer. The existing lock/volatile one-attempt pattern lives in the narrow internal SingleAttemptLoader<T> (generic solely to test with reference objects instead of ONNX files). Completion is published in finally, after assignment or definitive failure; a concurrent reader waits rather than seeing transient unavailability. Missing and failed loads remain cached for the process lifetime; no model reload policy, independent availability cache, model-file changes, packages or projects were added. Training extraction is unchanged.

Provenance and verification

• Base: d70505b7c0e41692a031971fb437bbb165493b9f on master; this section accompanies the final implementation commit. The baseline was an isolated git archive with only the identical measurement harness added. Production/project comparison found only AngleCandidateBuilder.cs and AnglePredictor.cs changed; actual baseline production was measured, not a reimplementation.
• Environment: Ubuntu 24.04.5 LTS x64 shared KVM VM, four vCPUs presented as AMD Ryzen 9 5900X; SDK 10.0.112. Test adapters and benchmark output confirm .NET 8.0.31; Stopwatch frequency 1,000,000,000 ticks/s. Serial Release processes, forward then reversed before/after order.
• Parent applied whitespace-only fixes to the builder constructor and the loader concurrency test after implementation-agent tests; full suites were rerun afterward. Published measurements use the final source/harness hashes below. An initial short no-model warmup showed transient timing spread; it was replaced in both trees by 2×20,000 warmup calls and 7×20,000 measured calls. Only the complete rerun pairs below are acceptance measurements.

Source	Before SHA-256	Delivered/measurement SHA-256
OpenNest.Engine/Fill/AngleCandidateBuilder.cs	5182f69f604332e1b8bfb46d807c8f830194a88b47f4fd4e90bcea6e91e522c4	97bbb82680b90d950f480c65dffab8702bd9402ef849639286d7fc90f1b6b162
OpenNest.Engine/ML/AnglePredictor.cs	84bc0eafffe84447dc83e3c7084e5562a67409572fa413f78abe6e7102ba3c72	047e3bdb8d9aec1add49ba36e5b7947d1b375e6099a3f36f54061b6ae4d16f7a
OpenNest.Engine/ML/FeatureExtractor.cs	2d7b45350abd94d7e728c962aca06f4a86920d0328d8025c75f51ebc7e5ed6b3	2d7b45350abd94d7e728c962aca06f4a86920d0328d8025c75f51ebc7e5ed6b3
OpenNest.Tests/Fill/FillPerformanceTests.cs	f90412c87393f8542769aae5abef5e340b827003c134d0bf525efef3a3fefa62	f90412c87393f8542769aae5abef5e340b827003c134d0bf525efef3a3fefa62

The harness hash in both columns is the newly added identical harness, not the original base harness. Existing feature-extraction timed code is unchanged.

Genuine RED/GREEN evidence (temporary source mutations restored in finally): removing the availability gate failed the exact call sequence (expected availability only, actual availability/extraction/prediction); forcing true failed the scalar flag assertion; the real-extractor Debug integration check counted 1,024 bitmap cells instead of 0; publishing before the blocked load failed all three concurrent-reader cases (success, missing, throwing). Restored targeted suites pass. Counter tests use the nonparallel FillCacheCollection and reset in finally. Release-zero counters are not evidence. The loader concurrency test observes a blocked dedicated reader, not merely an unscheduled task; ten additional process runs passed all three cases.

Verification	Passed	Skipped	Failed
Pre-change builder characterization	17	0	0
Targeted Release (builder/predictor/extractor)	77	0	0
Targeted Debug (builder/predictor/extractor)	81	0	0
Full main Release, final code	1,335	18	0
Full main Debug, final code	1,356	18	0
Full engine Release, final code	300	0	0
Performance category, variable unset	0	6	0
Performance category, variable 0	0	6	0
Each enabled two-case measurement process (four runs)	2	0	0

Full-suite skips are 12 optional CHR-font fixtures plus six opt-in benchmarks. Parent parsed TRX outcomes and reconciled all published raw measurement rows against console output. Changed-file whitespace verification and git diff --check passed. Existing optional-fixture, frozen-reference nullable and obsolete API warnings remain outside this slice.

Warm no-model path measurements

Closed concave L vertices (0,0),(20,0),(20,6),(8,6),(8,14),(0,14), primary angle 0.13 radians, work area (3,5,120,80), ForceFullSweep=true. Public production builder, no delegate substitution. Missing-model initialization, construction, assertions and output occur outside timing. Exact ordered angles are checked against the pre-change fallback expression. Each process has two 20,000-call warmups and seven 20,000-call batches. Loop/result-count consumption and GC are included; allocations are synchronous current-thread bytes, not process RSS. The benchmark skips if a model exists and never removes it.

Batch	Before forward ms / B	After forward ms / B	After reverse ms / B	Before reverse ms / B
1	1217.927296 / 503,670,984	55.374701 / 119,200,000	52.644238 / 119,200,000	1184.910444 / 503,670,984
2	1187.003770 / 503,660,640	54.922257 / 119,200,000	53.317338 / 119,200,000	1245.986050 / 503,660,640
3	1191.853980 / 503,660,640	53.574434 / 119,200,000	52.454731 / 119,200,000	1234.360386 / 503,660,640
4	1207.375477 / 503,660,640	52.648817 / 119,200,000	51.054148 / 119,200,000	1247.194291 / 503,660,640
5	1212.013076 / 503,670,984	52.498333 / 119,200,000	51.060020 / 119,200,000	1236.030807 / 503,670,984
6	1223.337623 / 503,660,640	51.969916 / 119,200,000	51.673347 / 119,200,000	1265.240358 / 503,660,640
7	1249.298485 / 503,660,640	51.376286 / 119,200,000	52.600186 / 119,200,000	1264.421373 / 503,660,640

Process	µs/call min / median / max	B/call min / median / max
before-measure	59.350 / 60.601 / 62.465	25,183.0320 / 25,183.0320 / 25,183.5492
after-measure	2.569 / 2.632 / 2.769	5,960.0000 / 5,960.0000 / 5,960.0000
after-repeat	2.553 / 2.623 / 2.666	5,960.0000 / 5,960.0000 / 5,960.0000
before-repeat	59.246 / 62.299 / 63.262	25,183.0320 / 25,183.0320 / 25,183.5492

Measured median warm-path time changes are -95.66% and -95.79% in the two process orders. Median allocations fall from 25,183.032 to 5,960 B/call (19,223.032 B/call, 76.33%). After allocations are exactly 5,960 B/call in every batch; baseline totals have small variations disclosed above. These results support a local warm no-model improvement, not a stable cross-machine latency guarantee or a whole-nesting-job speedup. No cold-start or failed-model timing is claimed.

Separate extraction control

Existing FeatureExtraction_ReportsFullAndScalarOnly: native-arc ring OD20/ID8, two 200-call warmups, seven 1,000-call batches per mode, alternating mode order. This is a separate extraction benchmark, not available-model inference. Feature extraction is identical across these trees; the full versus scalar difference is the already-delivered Task 4a capability, now used by the builder. Timing/bytes include the harness's bitmap-count consumption for full mode (see Task 4a's ~32-byte consumption disclosure), so the delta is not solely production extraction allocation. Process-to-process differences are shared-VM noise/control observations, not a Task 4b extraction speedup claim.

Process	Batch	Full ms / B	Scalar-only ms / B
before-measure	1	217.757693 / 35,332,688	37.378244 / 34,263,032
before-measure	2	170.635584 / 35,332,688	34.053642 / 34,252,688
before-measure	3	172.566367 / 35,343,032	34.951535 / 34,252,688
before-measure	4	170.000626 / 35,332,688	33.384049 / 34,273,376
before-measure	5	169.570514 / 35,332,688	34.399103 / 34,252,688
before-measure	6	171.122593 / 35,332,688	33.865496 / 34,283,720
before-measure	7	168.040086 / 35,332,688	32.055312 / 34,263,032
after-measure	1	227.885101 / 35,332,896	32.285726 / 34,252,896
after-measure	2	175.358064 / 35,338,120	30.359862 / 34,252,896
after-measure	3	184.505182 / 35,332,896	31.867147 / 34,252,896
after-measure	4	169.872394 / 35,332,896	29.338054 / 34,252,896
after-measure	5	168.238732 / 35,338,120	30.606238 / 34,252,896
after-measure	6	189.879784 / 35,332,896	30.637576 / 34,252,896
after-measure	7	174.944123 / 35,332,896	30.820803 / 34,252,896
after-repeat	1	272.298581 / 35,332,896	52.314757 / 34,252,896
after-repeat	2	194.604106 / 35,338,120	52.072921 / 34,252,896
after-repeat	3	159.231266 / 35,332,896	33.244075 / 34,252,896
after-repeat	4	152.710834 / 35,332,896	31.001913 / 34,252,896
after-repeat	5	154.032296 / 35,338,120	31.102123 / 34,252,896
after-repeat	6	150.289445 / 35,332,896	29.016949 / 34,252,896
after-repeat	7	156.205127 / 35,332,896	30.082710 / 34,252,896
before-repeat	1	215.909255 / 35,332,688	37.149342 / 34,252,688
before-repeat	2	188.558239 / 35,332,688	35.593749 / 34,252,688
before-repeat	3	198.129599 / 35,343,032	38.193683 / 34,252,688
before-repeat	4	186.170223 / 35,332,688	36.974173 / 34,252,688
before-repeat	5	193.646279 / 35,332,688	46.604443 / 34,252,688
before-repeat	6	195.491390 / 35,332,688	50.731669 / 34,252,688
before-repeat	7	191.895666 / 35,332,688	40.247489 / 34,252,688

Process	Full µs/call min / median / max	Scalar µs/call min / median / max
before-measure	168.040 / 170.636 / 217.758	32.055 / 34.054 / 37.378
after-measure	168.239 / 175.358 / 227.885	29.338 / 30.638 / 32.286
after-repeat	150.289 / 156.205 / 272.299	29.017 / 31.102 / 52.315
before-repeat	186.170 / 193.646 / 215.909	35.594 / 38.194 / 50.732

Reproduction, review and remaining limits

OPENNEST_RUN_FILL_PERF=1 dotnet test OpenNest.Tests/OpenNest.Tests.csproj -c Release \
  --filter 'FullyQualifiedName~IrregularAngles_ReportsWarmNoModelPath|FullyQualifiedName~FeatureExtraction_ReportsFullAndScalarOnly' \
  --logger 'console;verbosity=detailed'
dotnet test OpenNest.Tests/OpenNest.Tests.csproj -c Release \
  --filter 'FullyQualifiedName~AngleCandidateBuilderTests|FullyQualifiedName~AnglePredictorTests|FullyQualifiedName~FeatureExtractorTests'

Repeat the targeted command in Debug for bitmap work assertions. Shared safeguards moved intact (with Task 4b additions) from near-capacity AGENTS.md into fill verification; the combined AGENTS.md + CLAUDE.md is now 31,434 bytes, below 32 KiB. README and the shared instructions describe availability-gated scalar inference; CLAUDE.md remains the thin import.

Independent spec review PASS, followed by independent quality/integration review APPROVED; neither found Critical, Important or Minor issues. Both reconciled source/harness provenance, raw measurements, summaries, red/green and full-suite evidence. Each independently reran the targeted suites (77 Release, 81 Debug) and both disabled benchmark gates (six skipped each); the spec reviewer ran ten more three-case concurrency processes, and the quality reviewer ran three plus the full engine suite (300 passed). Raw scratch evidence was removed after review, retaining the tables, hashes and test summaries here. No actual ONNX inference or model accuracy test, Windows UI runtime test, or representative production corpus measurement was performed. Task 5 combined acceptance/report remains separate; gated A/B/C follow-ups were not started.