facett-graphview — a domain-agnostic, scalable 2D graph render engine, vello-backed, that runtime-selects its backend by hardware: vello (GPU/wgpu compute) when a usable GPU exists, vello_cpu (multithreaded SIMD) as the no-GPU fallback. The eventual single home for every graph surface — nornir's arch/dep/release dashboards, korp, graph-DB browsing — aiming to beat Graphviz on interactivity + scale.

The shared API (a future drop-in for nornir's draw_graph)

The model — [GraphModel] (nodes id/label/pos/fill/stroke + edges from/to/color/dashed/label) and the caller-supplied [Decorations] overlay (per-node ring/badge + emphasis edges) — mirrors nornir's src/viz/graph_render.rs SHARED API exactly, so that egui routine can swap its painter for this engine without changing its callers. Decorations stay caller-supplied and domain-agnostic: facett never learns what a "release gate" is.

Backends (vello is NOT GPU-only)

[Backend] {GpuVello, CpuVello}; [decide] turns a [GpuProbe] into a pick (probe → choose, mirroring nornir's embedder runtime-select). The CPU path ([cpu::render]) is the proven reference — vello_cpu already ships transitively inside epaint 0.34, so it always builds here. The GPU path is a real, version-aligned seam (vello 0.9 ↔ wgpu 29 ↔ egui-wgpu 0.34), wired behind the gpu cargo feature; see [gpu].

Render entry point

[render_to_rgba] dispatches on the chosen [Backend] and returns straight RGBA8 pixels (PNG / egui-texture ready). Today both backends route through the CPU rasterizer (the GPU readback path is the #17 follow-up); the dispatch seam is in place.

What is STUBBED (documented, not built — see .nornir/design.md)

LOD / viewport-culling, clustering / aggregation, edge-bundling, streaming layout, and the data-source adapters (nornir dep graph / FalkorDB / pipeline). Clear TODOs live at each seam.