Delegate interaction from one SVG root

Listen once and mutate state classes

A diagram is compiled once in full mode, and interaction is then delegated. One listener on the host resolves event.target.closest('[data-node-id], [data-wire-source], [data-port-id]'), and that is the entire interaction layer. A simulation toggles classes or custom properties on whatever it finds. Nothing is recompiled. Application state lives outside the SVG, and recompiling the same source is deterministic, so the drawing can be treated as disposable.

port:GNT "GNT" at (80, 130) #blue
clock:BCK at (80, 270) #amber
and:ARB4 "AND" at (350, 130) #cyan [inputs=2]
testpoint:TPD at (590, 130) #purple
port:VALID at (790, 130) #emerald

GNT.out -> ARB4.in1 #blue [digital ortho]
BCK.out -> ARB4.in2 #amber [digital ortho]
ARB4.out1 -> TPD.node #cyan [digital ortho]
TPD.node -> VALID.in #emerald [digital ortho]

The mapping from source to vector uses the compiler's own one-based lines. No second parser is needed. The response already carries the authoritative source map, and a second parser is a second answer that will sooner or later disagree.

Keep pointer and keyboard paths equivalent

Nodes and ports carry stable labels in the generated SVG, but that covers only what the compiler emitted. Anything a host adds around it must be made equivalent by the host. That means semantic buttons, honest aria-pressed and aria-expanded state, visible focus, and keyboard activation for every path a pointer can take.

prepare:QT "|+\rangle" at (80, 130) #blue
tgate:TT at (300, 130) #cyan
qgate:PT "P" at (520, 130) #purple [parameter="\pi/4"]
measure:MT "M_x" at (700, 130) #emerald

QT.out -> TT.in #blue [quantum line]
TT.out -> PT.in #cyan [quantum line]
PT.out -> MT.in #purple [quantum line]

A part declared without a label keeps a complete accessible name in full mode, such as TT, tgate, with no empty field.