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
```yaml
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.