a16-aurora-blob-transition

name	A16-aurora-blob-transition
description	motion-graphic scene archetype — soft gradient cloud expands/contracts/morphs between adjacent UI-panel-float or prompt-typewriter scenes. it IS the transition. canonical sp-f connective tissue. composes only aurora-blob-continuity in morph mode. usually has zero foreground content — just the blob breathing between scenes.

A16 — aurora-blob transition

Composes

• aurora-blob-continuity (in morph mode — expands, contracts, drifts, recolors)

Scope note

A16 is a transition scene, not a content scene. Its purpose is to be the visual breath between two content scenes (typically A14 → A14 or A14 → A15 → A14). The impl-brief atom inserts A16 between content scenes when the storyboard declares an aurora-morph transition between adjacent SP-F scenes.

Layout

canvas: 1080x1920 (or pack-specified)

aurora_blob:
  diameter: variable (700px hold → 1100px peak → 800px settle)
  color: variable (interpolate from prior scene's color to next scene's color)
  blur_px: 80
  opacity: 0.55 → 0.75 → 0.55
  position: variable (drifts on noise during morph)

no_foreground_content: true   # this is a pure-bg scene

Choreography

phase_1_inherit_from_prior:
  start_frame: 0
  blob_state: same as prior scene's final state

phase_2_pulse_expand:
  start_frame: 0
  effect: aurora-blob-continuity (morph)
  duration_frames: 12
  scale: 1.0 → 1.4
  opacity: 0.55 → 0.75

phase_3_drift_and_recolor:
  start_frame: 12
  duration_frames: 18
  blob_color_interpolate: prior → next
  blob_position_shifts: from prior_anchor → next_anchor

phase_4_settle_to_next:
  start_frame: 30
  duration_frames: 6
  scale: 1.4 → 1.0
  opacity: 0.75 → 0.55

Total: ~36 frames (1.2s) at 30fps.

Style pack compatibility

supported: [SP-F]
preferred_in: [SP-F]
incompatible: [SP-A, SP-B, SP-C, SP-D, SP-E, SP-G]

Pack-locked.

Pack-specific overrides

SP-F (product-demo)

• Color interpolates between scenes' aurora colors (peach by default).
• Blob position drifts via perlin noise (continues the pack's continuous-drift mechanic).
• No type, no UI mocks — purely the blob.

Duration

duration_seconds: [0.8, 1.4]
default: 1.2

Short — it's a transition, not a scene.

Quality Checks

• No foreground content (no type, no UI).
• Aurora state at scene start matches prior scene's final state.
• Aurora state at scene end matches next scene's initial state.
• Color and position interpolate smoothly (no jumps).
• Pulse amplitude visible but not jarring (1.4x scale max).

Failure Modes

• Hard cut visible between scenes. Aurora morph didn't render. Verify the SharedLayer / continuity render path.
• Color jumps muddy. Use OKLCH interpolation, not RGB.
• Pulse too fast/aggressive. Reduce scale peak to 1.2x; extend duration to 18 frames.
• Blob position teleports. Add intermediate keyframe between scene-start and scene-end positions.