Files
Miguel Ángel 9734578e60 feat(registry): bring back the video-primitive moves (#3169)
Restores the 208 catalog items reverted after their previews 404'd in
production, this time on the payload mechanism rather than the .html files
that caused the outage.

The generator no longer writes a preview document to docs/public. That writer,
and the machinery under it, existed only to produce files the docs host
discards, so it is gone rather than bypassed. Items now embed the composition
itself via a payload, which is what the previous change already does for the
items that were already in the catalog.

The variables explorer is parked, not restored: it drove its preview through
the same unpublished .html path, so it would have shown an empty frame. Items
that declare variables get the live player plus the static variables table, and
reconnecting the explorer to payloads is a follow-up.
2026-08-10 18:46:03 -04:00
..

echo-trail

The generalized onion skin: a moving element renders with N ghosted copies of itself, each ghost showing the element where it was at t minus i * delta, opacity stepped down per ghost. One traversal along an authored path; as the element decelerates into rest the echoes collapse into it and vanish, leaving a clean settled hold.

3.5s authored, elastic HOLD, exit none by default.

Variables

id type default notes
echoes number 4 Ghost copy count, clamped 2 to 6.
delta number 0.09 Lag between successive ghosts in seconds, clamped 0.03 to 0.3.
path enum sweep sweep is a shallow S left to right; rise climbs bottom-center to upper-center; arc rises over the top left to right.
accent enum green Subject accent color: green rides --brand, blue rides --accent, violet rides --accent-2.
exit enum none none holds until the cut; fade departs opacity-only; up rises out.

Subject slot

The subject is a slot. Place an inert template anywhere in the HOST page (templates never render, and the runtime wipes the host clip's own children on mount, so the slot lives at document level):

<template data-slot="echo-trail-subject">
  <div class="my-badge">Shipped</div>
</template>

Ghosts are deep clones of the subject content. With no slot, the primitive renders a token card (surface, hairline border, accent dot, two skeleton lines, contract tokens only).

Mount

<div
  class="clip"
  data-composition-id="echo-trail"
  data-composition-src="./echo-trail.html"
  data-variable-values='{"path":"arc","echoes":5,"delta":0.12,"accent":"violet"}'
  data-start="0"
  data-duration="3.5"
  data-track-index="0"
></div>

Elastic root: no data-width/data-height; it fills whatever box the host clip gives it. Timeline registers under the literal echo-trail key.

Notes

  • Deterministic: ghost i's position at time t is path(ease(clamp01((t - i * delta) / travel))) and its opacity is its stepped base times a separation ramp (distance to the lead); both are recomputed from tl.time() on every update. No Math.random, no wall clock, no incremental state; eventful seeks (suppressEvents=false, the engine's render path) land identical frames in any order and either direction.
  • The separation ramp is what makes the echoes collapse: before motion starts and after the lead rests, every ghost is coincident with the lead and its opacity is exactly zero, so the HOLD is truly still.
  • Ghosts render beneath the lead (inserted before it) with a slight per-ghost scale step for depth; transforms are set once at mount, per-update writes touch only left/top/opacity.
  • The envelope accounts for the tail: IN = travel + echoes * delta + settle, so the last ghost has converged inside IN even at the largest lag.