Session story · 2026-09-13
Session: 2026-09-13, 00:37 → 07:49 UTC (transcript 330e8a64, one bench night) · Ran: V0, V1, V2, T87, V6, T88, T89, V7–V9 · Parked: arb playback
The previous sitting had ended with 41 unverified commits and a queue in docs/BENCH_QUEUE.md. V0 came first because Phase 0 had changed how the app loads its blobs at startup. T87 promised the generator's arb-mode register, the last unknown before multitone.
The working belief was: once arb mode is decoded, multitone is wiring.
Chris opened with: "OK the app connected to the machine. V0 - all i did was clean build, run and connect."
Do the queued changes work on hardware, and can Cascade play an arbitrary waveform?
V0, and an inert picker. Connect exercised 40,065 packets with 75 image references, and the first FFT replayed 122,703 with no warnings, so the split worked. The FFT itself read −94 dBV with "Ch A looks SILENT". acquireSpectrum never set the input mode, and the blob left the analyzer on XLR. Claude's "no cabling, GenMon" instruction was wrong, and the CSV had recorded input_mode,Generator Mon for a run on XLR.
V1 and V2. Averaging passed: unaveraged SINAD spread 21.5 dB, AVG=16 spread 1.7 dB, tone moved 0.000 dB. Two of Claude's pre-written criteria fired and were themselves wrong; one asked a noise figure with sd ≈ 8 dB for 0.3 dB precision. V2 confirmed sizes to 32768 and found SINAD moving 43 dB with transform size while THD held steady.
T87. The THD oracle passed on hardware through APWIN: −40.0537, −60.0620, −80.0195 dB against files containing −40, −60, −80. The capture gave EC 40 0A FF FF F9 ... <mode>, 0C sine, 04 arb. Asked how to run V3, Claude checked and found neither V3 nor V4 was runnable: it had listed them as ready though nothing in the app wrote those registers.
V6, and a bug of Claude's. With AP's image suppressed, THD vs Frequency failed. It was Claude's error: Phase 0's grep for literal resource names had missed four blobs loaded through variables, and Claude had moved them out of the bundle. Real count: 11 referenced, 3 dead. Then the FFT, without the image, returned one identical word in all 314 bins and the app processed it into a measurement. The control THD run failed too, with the image present. "I think the problem was that i didn't touch the input picker. when i switched it to DUT mode it seemed to work, then i switched it to Generator mode and it had output too. it's only when i left it on default not touching it that it didn't work" Chris was right. setInputMode skipped the write when the app's cached mode matched, and connect only re-asserted non-default modes. The same root cause had produced two wrong diagnoses that night.
SINAD, deliberately not fixed. Claude traced the V2 spread to three contaminants: DC skirt at N=1024, window sidelobes at N=16384, real noise only at 32768. The obvious fix degraded T77's 0.047 dB agreement to 0.44 dB. Chris: "no. i am the only one looking, so i will just not use those numbers."
Language for you. Claude listed the multitone steps in its own shorthand. "i don't really understand the way you've worded most of those 1-4. i think they are mainly language for you. I remember you started drifting this way a week or 2 ago." Claude restated it plainly and built waveform upload. A fixture from APWIN's real download caught two packing errors at packet 15.
Six attempts at arb. The upload went before the FFT blob, which put the generator back to sine. Removing an analyzer commit gave a working FFT on a sine. Restoring it made the waveform reach the analyzer, at −20.03 dBV, and the FFT time out. Re-applying FFT config did not help. Claude stopped and wrote T88. APWIN, with an FFT loaded, wrote 01/05 where T87 had 00/04. That fix also timed out, as did a verbatim replay of APWIN's sequence, which left the analyzer registers reading 00 00 00. Claude then recognised a trap the project had already recorded: it was splicing a sequence from one APWIN session onto state replayed from another, and those writes are relative.
The quit bug. Chris had queued, mid-turn: "By the way for some time now I have not been able to "quit" the app through the app menu. i have to force quit it from Xcode's stop button or the Activity Monitor" ConsoleLog.stop() read the pipe to EOF before restoring stdout, on the main thread. That had been broken since 2026-09-04.
T89 and the V7 series. Chris captured T89 with USBPcap running before APWIN: "I used "plan a" and it worked. We weren't doing that before, because it had caused problems." Claude built one self-consistent arb+FFT blob, blanked AP's waveform bytes, and spliced its own. The arb file played at 65,536 Hz: 1375.95 Hz, not 1 kHz. V7 to V7e each changed one thing and timed out. V7e showed the same garbage, -12.36 dBV @ 8928.0 Hz, every run, which Claude said it should have noticed earlier. V7f added a sine control. The arb run then displayed the sine run's spectrum after timing out, so timeouts are now discarded. V7g completed for the first time, with a tone near 5995 Hz.
Is this the sort of troubleshooting that you can do while directly connected? "is this the sort of troubleshooting that you can do while directly connected instead of having me run it again and again?" Claude drove the 2522 from Python with pyusb: init and an 85k-packet replay in 11 seconds, but the acquisition timed out. It stopped reimplementing and put an ARB RATE SWEEP button in the app. V8 was void: the sweep inherited 0 dBV and clipped. V8b, at −20 dBV, read 5984.0 Hz for 64 and for 256 cycles. Chris queued: "remind me why we are chasing this arb mode?" Claude answered (multitone, and the THD oracle) and reported the cause: the blob began with 8a 02 21 fd b4, 6000.00 Hz, T89's MARKER 6000, which Claude had put in the procedure. Every "success" had been a sine at its own marker. With the markers stripped, V9 read 1024.0 Hz, the blob's last real frequency, as predicted beforehand. Arb was parked.
The identify phase. "we were previously looking for the point where APWIN identifies the machine, and now we have a packet cap that includes APWIN starting up. is that useful" It was. Two bit-serial reads, 1024 and 2048 bits, decoded as 93C46-style EEPROM reads of 128-byte images. Claude then found coldstart.pcapng had held this phase since April, and the images were byte-identical across three cold starts. Chris gave the serial, 21847; it was not in either image. A native read matched both images in 0.4 s per chain, after a first comparison that passed by parsing an empty image. "i don't think it would need the SN - just the model" The module type byte turned out to mean present, not which model.
| Believed | Then | What overturned it |
|---|---|---|
| the FFT INPUT picker routes | it was inert after a blob | V0 silent capture |
| THD was broken by Phase 0 or V6 | cached input mode skipped the write | Chris touching the picker |
| 7 of 14 blobs unreferenced | 11 referenced via variables | THD failing in V6 |
T87's 04 selects arb in any context | 05 with an FFT loaded | T88 |
| V7g was a breakthrough | it measured MARKER 6000 | V8b identical peaks; blob's first write |
| arb engages from a replayed blob | it never did | V9 read the blob's last frequency |
| the identify phase was never captured | coldstart.pcapng had it since April | looking |
| the type byte identifies the model | every populated address returns 0x0B | native read with reset preamble |
docs/T87_GenArbMode_v1.apb, docs/T88_ArbWithFFT_v1.apb, T89, T89.png, v7.pngsession_20260912-173538 (V1/V2), -184814, -185809, -190725, -191856, -195120, -200056, -205451, -210153, -211800, -222729 through -232556, -235036, session_20260913-000106, -001416check_resources.py, ArbSequence.swift, probe_arb_rate.py, compare_arb_wire.py, read_unit_eeprom.py, UnitEEPROM.swift, apib_arbfft_full.regs.bin, docs/coldstart.pcapngAveraging, sizes to 32768, the input-routing fix, the constant-spectrum check and the quit fix shipped. 56 tests pass. Parked: arb playback, after nine bench runs. Open: noise integration (SINAD/THD+N valid only at N=8192 on-bin), InputFormat and lowpass controls, and model identification.