User's idea, and the framing is the point: this is "faking t2v" when it is
really i2v. Every existing way of stopping the anchor from dominating the
opening WEAKENS it first - ALG blurs it and loses character detail, and if you
under-blur you get both failure modes at once; Best-FaceID overlap tokens
approximate it and lose some detail too. This weakens nothing. The anchor is
pinned at full strength, untouched, for as long as it takes to transfer
identity/style/composition - and is then removed from the clip entirely.
Two passes:
pass 1 sigma[0] .. anchor_shift_sigma, anchor pinned as usual
shift drop the first N latent frames, slide everything left, refill the
freed tail, drop the pin (clip LENGTH is unchanged - nothing extra
is ever generated; the dropped head is regrown at the end)
pass 2 restart sigma .. 0, unpinned
Two passes rather than a roll between steps for a specific reason: pass 2
re-enters through comfy's CONST noise scaling (x = s*noise + (1-s)*latent),
which puts the shifted latent back ON the rectified-flow manifold. A raw
in-flight roll skips that, and project_sigmas records that this model cannot
recover from off-manifold latent states - that is what killed churn. Same
on-manifold re-entry that segmented detailing's stage-2 tail already uses.
Every choice is a knob, because WHERE to cut is the entire experiment and I
have no measurement for it: shift sigma (default 0.909, the first step where
structure actually forms - above it nothing has formed and the anchor would be
discarded before doing any work), frames dropped, pass-2 restart sigma
(0 = continue, higher = rewind for more freedom at the joint), what the
regrown tail starts from, and whether audio is rewritten in pass 2 (on by
default: pass 1's audio was scored against frames that have since moved).
Refused, loudly and with the reason in the scene report, on continuation
scenes (the head is carried frames, not an anchor), on scenes carrying guide
frames (the slide would overwrite them) and on scenes with JoyAI audio memory
(resetting audio would destroy the injected tail).
One real bug caught by the new tests while writing them: SIGMAS are float32,
so a threshold typed as 0.725 is a float64 sitting just below the schedule's
float32 0.725, and a bare `v <= s` cut one step LATER than the number entered.
Now matched against core's own isclose tolerance.
11 new tests; suite at baseline (22 pre-existing failures, no new). Editor
checked live: knobs render, gate on the toggle, persist to sampler_inputs.
UNVALIDATED LIVE - the shift sigma is yours to find.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
