Raised by the user: "it should read the actual sampler schedule." They were right,
and this is a bigger deal than anchor_shift.
Both FunPack samplers derive their phase boundaries from len(sigmas) — the tensor
they are handed. anchor_shift runs a scene as two sample_custom calls over slices of
one schedule, so each half re-derived every phase INSIDE the slice:
_sample_const_rf_full (Hybrid Euler 2S, and the LTXAV path of it)
- quality phase: late_start = pct of the SLICE. On the user's 9-step schedule at
high_quality_pct 0.35 the quality phase starts at sigma 0.603; split at 0.482 it
starts at 0.812 in pass 1 and 0.482 in pass 2.
- motion-pulse anchors keyed by step index within the slice
- eta decay + velocity-bias ratio measured against the slice's first sigma
- the euler->Heun correction ramp restarted per call
sample_funpack_distilled_flow
- final-correction window: the last N steps OF THE SLICE, so pass 1 ran a "final"
Heun correction in the middle of the trajectory
- AB2 ramp w = i/(total-1) restarted from 0 in pass 2
- velocity-bias sigma ratio against the slice's first sigma
So turning anchor_shift on silently re-timed the sampler's own machinery in both
halves. Present since 015f274 and a far better explanation for a visible joint or a
thin ending than anything in the shift itself.
Fix: _schedule_view(sigmas, schedule_context) -> (real schedule, step offset). The
chain sampler passes {"sigmas": <the scene's schedule>, "offset": <slice start>} via
extra_options (the same chunk-scoped mechanism the alg_guide_* options already use,
always written even as None so it cannot leak into a later chunk). Both samplers take
the kwarg; every phase-relative quantity now reads the schedule and every step index
is step_abs = i + offset. No context = a normal single call = sigmas IS the schedule,
offset 0, byte-identical behaviour.
_anchor_shift_split_sigmas also returns pass 2's index into the schedule, and its
docstring now states the boundary rule the way the user framed it: walk the schedule,
the last pre-shift step is the one whose NEXT sigma has crossed the threshold. On
1.000 0.955 0.893 0.812 0.715 0.603 0.482 0.241 0.121 0.0 with shift 0.482 and restart
0.812 that gives pass 1 = 1.000..0.482 and pass 2 = 0.812..0.0, which is now asserted
directly as a test on that schedule.
Not changed, deliberately: sample_funpack_hybrid_euler_2s's own non-CONST loop (LTXAV
always takes the RF port, so no anchor_shift run reaches it) and segmented detailing's
stage-2 tail (a separate refine pass over a finished latent with its own schedule by
design, not a slice of one).
Suite at baseline: 22 pre-existing failures, 283 passing (+4).
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
