TRANSITION REGISTRY

This file is not the catalog of all transitions — that is catalog.md + css-*.md (≈40 CSS + shader). This registry is the curated subset that is Tier-B-ready: pure transform / opacity / filter on the two scene clip wrappers (#el-<sid>), no injected overlay DOM, no per-scene cooperation. Overlay families (staggered blocks, blinds, light leak, grid dissolve, page burn) and shader transitions are deferred to later phases.

How the injector applies a transition

At a break boundary between scene i (from) and scene i+1 (to), the injector:

1. Extends #el-<from> wrapper data-duration by duration_s (holds its final frame — verified: core/src/runtime/init.ts:1393-1410 external-slot branch).
2. Pulls #el-<to> wrapper data-start earlier by duration_s (creates the overlap window).
3. Reassigns all clip data-track-index as a 0/1 ping-pong so the two overlapping wrappers never share a track (a readability convention, not a render constraint, core/src/lint/rules/composition.ts). Higher track composites on top.
4. Stamps the gsap_template into window.__timelines["main"] at T = overlap-start.

Verified by prototype render (2026-05-31): the master-timeline wrapper tween is seeked and rendered (no double-seek with the sub-comp’s own paused timeline — the runtime drives them independently), the extended wrapper holds scene i‘s final frame, and the higher-track incoming wrapper composites over + blends with the outgoing one.

Template placeholders

The injector substitutes these tokens in each gsap_template line:

filter / scaleX / transformOrigin are lint-clean on the master timeline (verified: core/src/lint/rules/gsap.ts has no per-property whitelist and scopes its checks to data-composition-id ranges; the x/y/scale/rotation/opacity whitelist is a scene-worker prompt rule only — it does not bind index.html).

Registry

Default-derivation (used by prep.mjs when the planner omits **Transition:**)

A break boundary with no named transition gets a default:

1. If the incoming scene’s creative brief reads HIGH energy (explosive / kinetic / frenetic keywords), use default_high_energy (zoom-through).
2. Otherwise use default_calm (blur-crossfade) — the universal default. The blur masks any background shift and reads intentional, which keeps the whole video to ~2 transition types (the “repeat 2-3” principle).

Choosing as a planner (the only agent touchpoint)

Pick 2-3 types for the whole video and repeat them — repetition is what reads as professional (see overview.md). This budget counts the Tier-B between-scene types only (the 5 in the registry above); the Tier-A shared-element morph is a worker-authored bridge driven by narrative intent: morph — it is exempt and does not count toward the 2-3. Name the entering transition on each scene:

Omit the anchor to accept the default above. Do NOT write GSAP, touch timing, or edit index.html — the harness stamps the code, computes the overlap, and assigns tracks.