CabinetSim follow-up: use hexefx's cabinet IRs locally (never shipped; consumers download their own)

[bdbarnett]

Brad's ruling (2026-09-18 01:15): "If we can use those IRs, I want to." This supersedes the 2026-09-08 synthetic-only ruling for CabinetSim to the extent the licence allows.

The licence, checked per file: the repository hexeguitar/hexefx_audiolib_F32 is MIT, but src/filter_ir_cabsim_irs.cpp (the ten IRs: six guitar cabinets, three bass, plus ir_10/ir_11 guitar, each 3328 samples at 44.1 kHz with a gain word) and the cabsim code carry a GPL-3.0 header of their own. So:

1. Reference use, now: measuring our synthetic IR against them and designing from them is not redistribution. A Phase 5 or follow-up task can grade CabinetSim's synthetic response against these ten (cliff, roll-off, the two maxima, the low-end bell) and say how far the synthetic design is from a real cabinet.
2. Shipping them as CabinetSim patches needs the author's relicensing (MIT or CC-BY) — that contact is Brad's to make. If it comes, the IRs become patches with the notice kept, and the class's impulse path (already there: 256-sample partitions, 5.333 ms) carries them.

Not in Phase 4's chain: CabinetSim ships synthetic in Phase 4 as ruled; this is a follow-up. Survey: anchor docs/effects-internal/dossiers/sources-hexefx.md.

[bdbarnett]

Brad's ruling, 2026-09-18 02:00, supersedes the relicensing idea: the IRs are never shipped, whatever their licence. He wants to use them himself, and consumers get a link to download them on their own. So the work is: (1) a small local tool (in the anchor's private tooling, not the package) that turns hexeguitar/hexefx_audiolib_F32/src/filter_ir_cabsim_irs.cpp into per-cabinet WAV/raw files on disk, gitignored; (2) CabinetSim's existing impulse path documented for loading such a file, with the README pointing at the author's repository and its licence rather than at any copy of ours; (3) the reference use — grading the synthetic response against the ten real cabinets — as a measurement task when the follow-up opens. No contact with the author is needed.