Engine Card — SVG · Avatar Agent Studio

SVG

svg Medium — a normal phone is fine

A procedurally generated character drawn as real vector shapes — head and torso, built from a seed, scaling to any screen without ever blurring.

Builds live SVG DOM elements, not pixels. It owns its own engine and render loop; the mount here is a thin uniform wrapper around it.

What it can express

A character generated from a seed — the whole figure — proportions, features, colouring — is derived procedurally from a seed string, so a name produces a consistent person
Bust or half-body framing — the only two framings the engine renders; bust crops the viewBox tighter around the head and shoulders
Four named expressions — smile, thoughtful, enthusiastic and concerned — each a real blend of six-ish facial channels plus a head pose, not a swapped picture
Head pose inside the expression — thoughtful rolls the head −2.4° and pitches it 0.8°; enthusiastic lifts the chin — posture is part of the emotion
Named facial channels — mouthSmileLeft/Right, cheekRaiseLeft/Right, eyeSquintLeft/Right, browInnerUp, browDown, mouthFrown, mouthNarrow — a real rig vocabulary
Gesture and idle motion — the motion mixer runs beats, offers and points between phrases with a seeded, non-repeating pool
Resolution independence — because it is vector, the same avatar is crisp on a watch and on a 4K display, and it can be exported as a standalone .svg file
It pauses when you cannot see it — the only engine of the six that stops working when scrolled off-screen or when the tab is hidden — a genuine battery saving
Reduced-motion aware — honours prefers-reduced-motion live, and re-checks when the setting changes mid-session

Moods: 25 protocol moods folded onto the engine's own four expressions plus neutral — the honest nearest of four, weighted by intensity. This card will not claim 25 distinct faces: there are four.

What it costs a device

measured on this box	375×667	1440×900
cold mount → first frame	435 ms	390 ms
rAF fps — idle	60	57
rAF fps — speaking	59	56
CPU cores busy — idle	0.41	1.12
CPU cores busy — speaking	0.84	1.67
worst frame gap (p95)	16.7 ms	16.8 ms
over the wire	299 KB	299 KB
JS heap	10 MB	10 MB

The most viewport-sensitive 2D engine by a wide margin: 0.41 → 1.12 cores idle just from 375 to 1440, and 1.67 cores while speaking — the only 2D engine measured above one full core. Speaking doubles its cost, unlike every other 2D engine here.

Why medium: Vector shapes are rasterized by the browser at display resolution, so cost climbs with screen area, and speaking doubles it again. It stays smooth, but it is the 2D engine most likely to warm a phone on a large screen.

Dials it really exposes today

seedgenerates the whole character; the same seed always yields the same personany string or number; default 'niko'

framinghow much of the body is in frame'bust' or 'half' — anything else is forced to 'half'

detail levelhow much fine geometry is drawn — the engine's own quality dial'low' · 'medium' · 'high'

motionIntensityscales all idle and gesture motion0–1, clamped; default 1

reducedMotionforce the calm profile regardless of the OS settingboolean

setExpression(name, weight)the full engine API is exposed on the mount for advanced hostsone of the four + neutral, with a 0–1 weight

seal → .alive.jsonexports the character as a portable packagespec/seed section

Try it

SVG Master — presets, dice, HUD, second avatar, SVG exportopen/alive-site/svg-body.html Universal Stage — SVG beside the other fouropen/alive-site/universal-stage.html

Honest limits

It is NOT a full body. The engine renders bust or half only — the spec calls full-body "post-slice" and the guard forces anything else back to half. Documents describing an "SVG full-body" engine are ahead of the code.
It cannot wink. Both eyelids are wired to a single blink value every frame, so no code path can close one eye — the geometry would support it, the drive does not.
Four expressions carry all 25 moods. Nuance between, say, "proud" and "cheeky" does not exist here — both land on smile at different weights.
The heaviest 2D engine on a big screen, and the only one measured above a full CPU core — 1.67 cores while speaking at 1440, four times its own 375 cost.
You cannot load this engine alone. The mount contract statically imports every 2D engine, so ASCII, Sketch, SVG and Kinetic each pull the same ~299 KB module graph — measured byte-identical across all four.

Numbers are software-renderer numbers. Measured 2026-08-04 on the estate box (18 vCPU, load 2.8–5.3 during the run) under chromium_headless_shell-1232 + SwiftShader, 3 runs per cell, median reported. SwiftShader rasterizes on the CPU, so a real phone GPU changes the picture — most of all for 3D. Read the ordering between engines, not the absolute figures. Evidence for every claim: CARD-FACTS.md. Harness: work/measure-engines.mjs.