Design notes

qtviz is designed in the open. The full specification, architecture records, decision log, and research notes live in the repo's design/ directory — see its README for a guided tour.

Good starting points:

• spec.md — the concrete specification: the Element model, the data layer, backends, events.
• 2.0-mark-ir-and-surface.md — the current (2.0) architecture: the Mark IR, the uniform channel vocabulary, and the record of what shipped.
• development-plan.md — design invariants, the build sequence, and the verification strategy (tiered tests
• a backend/adapter conformance suite).
• discussion-items.md — the decision log ([D#]): every non-obvious choice, its options, and the rationale. Bracketed [Dnn] tags in code, commits, and tests resolve here or in the arc document that introduced them.

The historical working notes — milestone plans, roadmaps, parity audits — are preserved unedited in design/archive/.

Core ideas

• Pure, value-hashed Elements. An Element says what to plot, not how; it carries no Qt and no backend state, so it is trivially testable and composable.
• Registered backends and data adapters. The core never imports a backend or a container library — each is registered, so adding an engine or a data container is purely additive.
• Lazy-first data layer. One DataRef contract covers eager and out-of-core containers; expensive resolution runs off the GUI thread.
• Offline by construction. No network at render time; the webengine backend bundles its JavaScript from the installed packages.