Architecture

Koharu runs as a desktop application. React invokes typed Tauri commands; native components own durable project state and processing.

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Interface and application

Independent typed channels carry project, canvas, job, download, and resource updates; Agent sign-in and runs stream through per-call channels. Preferences are fetched and saved through commands. The frontend does not use an HTTP client or a generic application event envelope.

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Scene and processing

koharu-scene owns the canonical project, hierarchy, components, relations, patches, revisions, and session undo. koharu-storage persists opaque complete state payloads and immutable blobs. koharu-pipeline owns page-stage scheduling, model lifetime, progress, cancellation, and incremental commits. koharu-ml owns models and the shared device abstraction; koharu-translator owns local and hosted translation connections.

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Rendering and transport

koharu-renderer interprets a page as a portable prepared frame owned by koharu-rasterizer. Browser transport splits its manifest from content-hashed resources. Raster data is tiled with sampling gutters, bounding browser copies, validation, uploads, and eviction. koharu-canvas retains resources across pages and activates a staged frame through WebGPU only when every dependency is ready. Native PNG, PSD, font previews, and Agent previews compose the same full-resolution resources through native readback. koharu-desktop coordinates latest-wins preparation and exact-generation manifests and resources. The webview owns the visible window surface.

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Native runtime boundary

Safe wrappers koharu-torch, koharu-llama, and koharu-diffusion are separate from unsafe -sys dynamic-loading crates. koharu-runtime discovers, downloads, validates, and loads their packages. Three crates are shared across the diagram and omitted from it: koharu-config owns the typed sections of config.toml, koharu-secrets wraps the operating system credential store, and koharu-metrics collects telemetry.