Six correctness fixes to the diffusion stack, found reviewing the merged
phase PRs on this branch:
- load_pipeline: restore the try/finally guard around the speed/quant/
placement span. A failure after apply_speed_optims (e.g. OOM in quant or
the memory plan) left TF32/cudnn flags flipped process-wide and the
half-built pipe resident in VRAM. Now restores the flags and frees VRAM
on a failed load.
- sd-cli Popen binds to the parent (PR_SET_PDEATHSIG via child_popen_kwargs,
matching the llama.cpp sites), so a parent crash mid-generation can't
orphan it holding VRAM/RAM.
- Native begin_load uses the filename-fallback family detector the route
validated with, so a local .gguf whose family keyword lives only in the
basename no longer dead-ends 400 on a no-GPU host.
- Generate error handler matches exact sentinel messages instead of the
"cancelled" substring, fixing a 409 misroute and a raw sd-cli output leak.
- find_sd_cpp_binary honors UNSLOTH_STUDIO_HOME/STUDIO_HOME like the
installer, so a custom Studio home resolves.
- Drop the redundant _tf32_prev bookkeeping; snapshot/restore_backend_flags
is now the single owner of the TF32/cudnn restore.
The two client-state messages are now shared constants so the 409-vs-500
contract can't drift. Adds a regression test for each behavioral fix.
d0c5cf6e07