C10 invariant caching and FFT transfer

Benchmark record: anonymous acquisition A, warm prepared CUDA interaction. This is a report-only measurement, not a replacement release baseline. Private source identity and screenshots are retained only in the evidence archive.

This pass keeps the full 512 × 512 × 192 × 192 acquisition, all 8,807 bright-field pixels, 14 aberration coefficients (12 active higher-order terms), sample tilt and depth. No input binning, correction approximation, precision reduction or FFT downsampling is introduced.

What remains in the implementation

The widget copies the already-computed full-resolution WebGPU FFT magnitude into an owned colormap slot, instead of uploading the same array back from the CPU. The owned slot is reusable at the same shape. The copy is submitted before the FFT workspace can be reused. Deferred paints or different GPU devices use the existing CPU-array upload. The CPU FFT array remains available for existing inspection/export behavior, so this does not remove FFT readback.

A real browser WebGPU test checked every float32 bit at 1024² and 2048². The owned display copy also remained unchanged after the next FFT reused its source workspace. Alternating 30 transfer observations, excluding five warmups, gave:

Full FFT array	CPU upload median	GPU copy median
1024²	0.4 ms	0.4 ms
2048²	2.4 ms	0.3 ms

These are transfer-operation measurements, not notebook FPS.

CUDA cache experiments

The physical CUDA device was an RTX PRO 6000 Blackwell Max-Q Workstation Edition (300 W). Reference and candidate alternated for 24 changing-C10 observations per sampling factor, excluding the first three from the warm medians. Full output arrays were compared on every observation.

Experiment	2× reference → candidate, ms	4× reference → candidate, ms	Outcome
Fixed higher-order coefficients in generated kernel	29.030 → 28.448	30.376 → 29.794	Exact; small gain, additional compilation/cache lifecycle; not retained
Cached aperture support masks	29.026 → 32.482	30.367 → 31.042	Exact, slower; rejected
Iterate cached mask bits	29.166 → 32.433	30.516 → 30.996	Exact, slower; rejected
Cache BF probe terms	29.792 → 29.711	31.221 → 31.117	Exact, negligible gain; not retained
Specialize geometry plus fixed optics	29.822 → 28.401	31.282 → 29.815	Not bit-exact; rejected

The first four variants passed 48 exact full-output checks each. The last changed phase by up to about 9.1e-6 and was rejected rather than relaxing the contract. No production CUDA kernel is changed by this pass. Existing compact support and prepared-data caches remain in use.

Actual notebook image updates

The C10 sweep requested 60 updates/s. The existing CUDA notebook ran in the in-app browser with phase and FFT visible and WebGPU rendering on Apple Metal. Counts below are new scientific canvas paints, not animation callbacks or requested rates. Phase is 1024² at 2× and 2048² at 4×; FFT keeps the full grid.

Implementation	2× phase / FFT, fps	4× phase / FFT, fps
Baseline	31.58 / 31.58	21.18 / 21.18
Pinned asynchronous host-transfer prototype	32.55 / 32.56	22.13 / 22.13
Retained GPU FFT copy, first interval	30.33 / 30.31	22.90 / 22.90
Retained GPU FFT copy, repeated interval	30.20 / 30.20	24.44 / 24.43

These sequential intervals include normal variation; the retained change does not demonstrate a 2× notebook speedup. The isolated 4× transfer is faster, but the notebook results do not support a universal percentage speedup. The async prototype was removed: the small observed gain did not justify shipping its extra callback/ownership lifecycle without further cancellation and concurrency validation. Its initial scheduling failure is preserved with the raw evidence.

60 fps remains unmet. Warm reconstruction around 29–31 ms still exceeds the 16.7 ms frame budget before notebook delivery and rendering. The experiments show that more caching alone does not halve that work; they do not establish a hardware performance ceiling. The next substantial improvement must reduce correction arithmetic or its scheduling cost while preserving the exact model.

Verification and provenance

Direct C10 keyboard movement, FFT histogram changes, 2×/4× switching and saved joint-fit restoration were exercised. The final full 2048² phase was identical to the frozen saved-fit phase. The notebook was left paused at 4×. The saved calibration file was not overwritten.

Frontend tests: 396 passed, 6 skipped. TypeScript checking and the complete widget build passed. Production Python and CUDA code were unchanged; no MPS, release or installed-package qualification is claimed.

Experiment: 20261024-ssb-c10-specialization. Raw records, frozen sources, failed variants and browser frame counters are preserved privately. The CUDA kernel source SHA-256 remained d38d2eb354011403790e000dd4dca9c680da2cf11e55c312de77f248292295aa.