Current D:\ECHO Source Architecture

This page summarizes local D:\ECHO source at commit 75d84ae8e. It describes repository implementation, not what every website or Steam release ships. Check the installed build and release notes for availability.

Responsibilities

Layer	Responsibility	Source
React Renderer	Pages, settings, playback controls, state display	`src/renderer`
Preload + Electron Main	Typed IPC, windows, Steamworks, tasks, platform integration	`src/preload`, `src/main`
Echo Core	Library queries, search, sorting, likes, playlists, parts of scan writes	`core`, `src/main/core`
Native Audio Host	Decode, PCM, DSP, devices, playback clock, actual completion	`native/audio-host`, `src/main/audio`

Echo Core is the gradually adopted C# / .NET library service. It is separate from the C++ native audio host. Database initialization, scan preparation, file watching, and some compatibility paths remain in Electron/TypeScript. A Renderer control appearing enabled does not prove the native signal path is active.

Renderer → Typed Preload / IPC → Electron Main
                                ├─ Library service → Echo Core → shared SQLite library
                                └─ AudioSession → Native Audio Host → output device

Find a feature

Question	Start with
Scanning, CUE, osu! / Geometry Dash import	`src/main/library`, `src/renderer/pages/FoldersPage.tsx`
Smart playlist rules and results	`src/renderer/components/playlists`, `src/main/library/LibraryStore.ts`
Audio CD	`src/renderer/pages/AudioCdPage.tsx`, `src/main/audio`
Whether output or DSP really applied	`src/main/audio`, `native/audio-host`, host state and fallback reasons
System media controls	Windows SMTC/taskbar, Linux MPRIS, macOS Swift host code
Workshop content and boundaries	`src/main/workshop`, `docs/workshop-sdk`

Platform and release scope

Windows is the current Steam release line. Linux has AppImage/deb development builds and MPRIS code. macOS has Apple Silicon development builds, CoreAudio, and Swift integrations. Source or build support alone does not establish a validated Steam release. The Steam edition also has its own data, DLC entitlement, and Workshop boundary; legacy code remaining in the repository does not imply inclusion in the final depot.

For source work, read D:\ECHO\docs\engineering\README.md and AGENTS.md. For user tasks, see Smart Playlists, Audio CDs and CUE Albums, and Import Audio Sources.