Speed and Prewarm are arithmetic on the clock, not a second loop (#87)

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Architecture.md

@@ -105,7 +105,10 @@ of 500 particles is reproducible, holds still for a check, and needs no state be
 source stood when each one was born. Both are pure and tested without a browser. The other side of
 that choice: **freezing such a thing means moving its origin, not pausing a counter** — the clock
 belongs to the library and keeps running, so a preview let go after a minute on hold has to be
-rebased to the second it was stopped at, or it resumes a minute further on.
+rebased to the second it was stopped at, or it resumes a minute further on. The good side: a row
+that changes *when* rather than *what* costs nothing but a term on that one argument — a particle
+source's `Time scale` is a factor on it and `Prewarm` a summand, so neither needs a frame of
+simulation nor a line in the drawing code.
 Comments state contracts
 and reasons, not what the code does: a `/** */` on every export whose name does not say it all,
 `//` only for a decision or gotcha.

Development.md

@@ -12,7 +12,7 @@ npm run check        # typecheck + lint + format:check + tests, the gate CI runs
                      #   code is lost (tail's is reported), so a red run reads as green
 npm run build        # writes dist/ and regenerates index.html
 ./build.sh           # the same under `set -o pipefail`, for callers that pipe the output
-node tools/seed-e2e.mjs && node tools/e2e.mjs                 # 816 editor checks, screenshots in /tmp/gm-e2e-*.png
+node tools/seed-e2e.mjs && node tools/e2e.mjs                 # 821 editor checks, screenshots in /tmp/gm-e2e-*.png
 GM_STEPS=20 node tools/e2e.mjs                                # or 1-12, or 6,20 — a subset while working on one step
 ./e2e.sh start [GM_STEPS]                                     # the same run detached, see below
 ./e2e.sh status                                               # live progress, or the last run's result
@@ -156,4 +156,4 @@ widths to find click points. The **render device is not in this repo** — `/dev
 and a 1 GB `/dev/shm` come from `container.options` in the runner's own `config.yaml`, which
 applies to every job on that runner. Without them chromium falls back to llvmpipe, which gets
 WebGL 1.0 only. Measured in the job container: `ANGLE (Intel, Vulkan 1.3.230, HD Graphics 630)`,
-WebGL 2.0, and the same 816 checks as here.
+WebGL 2.0, and the same 821 checks as here.

Particles.md

@@ -27,7 +27,8 @@ nothing.
 
 Right of it, past a divider that drags, the **preview** panel emits the asset's own particles from
 its middle, wearing **the rows the asset itself carries** — edit `Rate` or `Lifetime` on the asset
-and the panel changes with them, including how far the slider reaches (three lifetimes). Rows the
+and the panel changes with them, including how far the slider reaches (three lifetimes, which a
+`Time scale` of 2 covers in half the seconds). Rows the
 asset leaves alone fall back to the type's defaults: 20 a second, one second each, a plain 16 px
 square. It stands beside the graph rather than under it because a graph is read across: width is
 what it can spare, height is not. `Hold` stops the clock where it is and turns into `Run`; the
@@ -78,6 +79,8 @@ mirror), so hanging one on a moving ship turns the whole spray with it. Its own
 | **Rate** | 20 | Particles per second, for a continuous source. |
 | **Burst count** | 20 | How many go out per burst. |
 | **Lifetime** | 1 s | How long one particle lives — **the scale that gives `Age` its meaning**. |
+| **Time scale** | 1 | How fast the source's own clock runs: 2 is twice the speed, so it emits twice as often and a particle is gone in half the time. Every row above is read on that clock, which is why none of them has to be touched to slow a whole effect down. 0 holds the picture where it is. |
+| **Prewarm** | off | Start one lifetime in, which is the second a stream first stands full. Without it a fire lit by a scene fade-in begins as a single spark and takes a lifetime to look like a fire. Nothing to a *Burst*, whose particles are all gone by that second. |
 | **Max particles** | 500 | The most alive at once; past it the oldest are dropped. |
 | **Size** | 16 | The particle's size in pixels, which the graph's `scaleX`/`scaleY` multiply. |
 | **Texture** | none | The picture each particle is drawn with. Without one it is a plain square. |