Plantasonic

Ownership is written down per repository, as what it owns and what it explicitly does not. The platform owns runtime orchestration, tokens, themes, templates and the AI workflow, and does not own narrative, brand or game logic. The engines own synthesis and rendering, and do not own interface, runtime or presets at the application level. The applications own the experience and do not own engine logic or token definitions. A capability graduates into the shared layer when a second product needs it, and not before; until then it stays where it was born.

The sound engine and the ASCII engine are separate repositories, consumed as versioned dependencies through platform adapters and surfaced as plugins with their own lifecycle. The application asks the platform for sound and for glyphs; it never reaches into an engine, and no engine knows an application exists. The alternative, which this replaced, was vendoring: a copy of the design system lived inside the reference app, seventy-four thousand lines of it, and every fix had to be made twice. Both engines now have their own case studies here, which is the clearest proof the boundary is real.

A shared system that flattens every product into the same look is a failure, so identity lives in a theme manifest that sits above the tokens rather than in them. Four slots are declared: Default, active in the reference app; Signal 9 and Plantasia, supported by the platform and deliberately unbuilt here; and one reserved. An application declares its theme in shell config and is forbidden from hardcoding hex values, which is the rule that makes the separation hold in practice rather than in principle. Theme preference is restored before first paint so nothing flashes.

There is a documented toolchain from design to deployed application: Figma as the source of truth, the Figma MCP server carrying design context into the tooling, the design system as the layer that decides what the tokens and components actually are, and rapid UI generation against those patterns as the last step rather than the first. Repositories export AI context files so an assistant starts with the architecture instead of guessing it. Generation accelerates exploration and documentation; the boundaries between repositories stay human-led, because that decision is the whole product.

Plantasia came first: an interface concept drawn from plant sonification and ambient music culture, favouring calm generative visuals over dense controls. It was the calm counterweight to my denser interface work, and it let the visual system lead. Almost everything in Plantasonic is downstream of it: the sound engine carries the name, the levers are growth, bloom, roots, mold and bacteria rather than oscillators and filters, the worlds are ecologies rather than patches, and the instrument is meant to feel like cultivating something evolving instead of programming a machine. Plantasia survives as a theme slot the platform supports.

• Six repositories with one dependency direction: the platform SDK and its templates, the design system, the sound engine, the ASCII engine, this reference application, and Signal 9 Live as the product application. TypeScript and Vite throughout.
• The design system ships tokens, a Bootstrap 5 theme, an application shell and the Creative Workspace: an overlay-first layout where the stage fills the frame and the transport, preset browser, inspector and status HUD float above it at named anchors, with presets for visualizer, installation, presentation, studio and performance modes.
• Engines arrive through platform adapters registered as plugins, each declaring its contributions and able to be disabled at runtime without taking the rest of the instrument down.
• Quality gates as scripts rather than good intentions: a thin-app architecture guard that fails if the application starts owning what the platform owns, plus integration, platform, design-SDK, preset and visual-language checks before ship.

Capturing this page found two bugs and fixed one of each kind. Mold and Nebula, the two glitch-heavy worlds, used to render for about two seconds and then go black while the status HUD still read Visual running: the ASCII engine's canvas renderer built an alpha bucket index that could come out NaN, and indexing the bucket array with it threw. The engine now ignores non-finite input, guards the bucket, and stabilises the simulation that was generating the NaN, so all five worlds run indefinitely. What the fix exposed is that something still sends NaN in: the engine logs one warning naming the control (density, strength and glitchAmount), which points at the platform's visual adapter passing audio levels through before the analyser has data. The values are now ignored instead of fatal, and the real fix belongs in the adapter.

The rest stands as is. The preset browser lists Seed twice. Below roughly a thousand pixels of viewport height the status HUD overlaps the inspector, because one is anchored top-right and the other centre-right with no collision rule between them. Signal 9 and Plantasia are theme slots the platform supports, not themes built in this application. And one fix was made here rather than only reported: the reference app had stopped importing the Creative Workspace stylesheet when the vendored design system was replaced by the real dependency, which collapsed the instrument stage to a strip and scattered its floating panels.