Watching several finished tracks side by side turned up the problem neither
Phase 8 (too few cuts) nor Phase 9 (no through-line) addressed: the same
scene cast in two different videos looked like the same footage twice.
Section bias is nearly identical between two tracks' drops, so both sampled
their parameters around the same centre, and the library's own averageness
did the rest.
Three answers, none of them a new scene:
Temperament — a per-track hand on every parameter dial: intensity, pace,
detail, and an extremity that decides how far toward the ends of a range
the track is willing to sample. Bias comes from the section and is shared
between tracks; temperament comes from the track and is not.
Overlays — sometimes a second full scene composited over the shot, from a
different family, in a blend that preserves what is underneath and never
above 0.6 opacity. Not always: a stack that always doubled up would read
as permanently cluttered rather than as occasionally layered.
A wider palette — hue now derives from SPECTRAL TILT, the log ratio of
treble to body. The centroid is a number most masters sit in the middle
of, and the plain body/(body+treble) fraction is worse: low frequencies
carry most of the energy in all music, so it read 0.98-1.00 for
everything and four different battery tracks came out within 0.02 of
each other. The ratio is multiplicative, so its logarithm is what
spreads — the same four measure -9.3, -5.0, -4.1, -3.8. Also both ways
round the wheel (violet, magenta and pink were unreachable by
construction), four new schemes, and seeded chroma profile and lightness
curve. Closest battery pair went from 0.005 to 0.113.
Twelve scenes take the library to 36, six per family: Aurora Veil, Vortex
Drift, Tide Rings, Ink Bleed, Dust Chamber, Salt Flat, Cargo Belt, Gate
Corridor, Circuit Bloom, Truchet Fold, Signal Decay, Storm Rift. Weighted
toward the 'space' and 'shape' traits, which were thinnest and so the
signatures most likely to run a track out of cast — the Phase 9 casting
rule means the pool a track draws from is smaller than the library.
Also fixes a real one in shots.js: heavy LRU weighting was not enough to
make a section reach its whole roster, and a five-shot section still came
out 0,2,0,2,0 about a fifth of the time. An unseen companion now wins
outright; which one is still free, so only the coverage is guaranteed.
Block Mosh declared the camera trait, assigned sigCamera(p) to a p it then
never read, and passed the lint's evidence grep. The Phase 9 render gate
measured its response to the camera at exactly zero.
--- tooling ---
Adding a scene was mostly boilerplate and round-trips, which is expensive
in both senses. The irreducible cost is the shader body; everything around
it is now mechanical:
npm run new:scene -- "Name" --family=... --traits=...
writes the module, registers it, and leaves a skeleton that already passes
every gate, with name-derived constants so two skeletons are not twins.
The lint grew the rules that previously needed a GPU to catch: the dead
camera above, prev() with no base image, and large loops with no early
break (with a `// lint: fixed-cost` opt-out for a genuinely fixed-cost
sampling loop). checks.html?scene=Name runs the per-scene acceptance
battery for one scene — ten lines and a verdict instead of rendering the
whole library to find out whether one shader is alive. The same procedure
is a repo skill under .claude/skills/build-visualizer/.
--- checks changed, with the measurements ---
P5 determinism compared two WebGL CONTEXTS, which is not what it is for.
Measured: one context is bit-exact over 40 frames with feedback at 0.6;
two contexts disagree by up to 2/255 whether feedback is on or off. It now
asserts generation is byte-identical (hard) and rendering within 2/255,
since feedback compounds single-level variance.
P10's cross-track comparison measures distance RELATIVE to how much image
there is. Most scenes are mostly dark, so two genuinely different renders
— 25 bars against 53 — scored under 0.02 absolute purely because the black
background agrees with itself.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Engine core: Timeline (fixed dt, audio-mastered in realtime), seeded Rng,
Renderer, Layer/ShaderLayer/SceneLayer, Compositor with blend modes,
feedback and post chain.
Shader scenes are compiled against a fixed uniform contract and define only
`vec4 scene(vec2 uv, vec2 p)`, so adding a scene costs a shader plus a
params block. Deep Nebula ported from party-stage as the first one.
Gate passes, 7/7 in checks.html:
- 300 frames rendered twice are bit-identical
- a fresh Engine reproduces the same frames
- simulated dropped frames change nothing (proves dt is fixed)
- seek matches sequential playback
- 320x180 vs 1280x720 agree within 0.010 (limit 0.06)
- seeded rng reproducible, forked streams independent
- compositor reset clears feedback history
Static gates: no wall-clock or unseeded randomness in deterministic
directories; scene schemas and shader sources agree in both directions.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
