refactor: split main.ts into domain runtimes

docs/architecture/README.md

@@ -3,7 +3,7 @@
 # Architecture Map
 
 Status: active
-Last verified: 2026-03-26
+Last verified: 2026-03-31
 Owner: Kyle Yasuda
 Read when: runtime ownership, composition boundaries, or layering questions
 
@@ -24,6 +24,27 @@ The desktop app keeps `src/main.ts` as composition root and pushes behavior into
 ## Current Shape
 
 - `src/main/` owns composition, runtime setup, IPC wiring, and app lifecycle adapters.
+- `src/main/*.ts` wrapper runtimes sit between `src/main.ts` and `src/main/runtime/**`
+  so the composition root stays thin while exported `createBuild*MainDepsHandler`
+  APIs remain internal plumbing. Key domain runtimes:
+  - `anilist-runtime` – AniList token management, media tracking, retry queue
+  - `cli-startup-runtime` – CLI command dispatch and initial-args handling
+  - `discord-presence-lifecycle-runtime` – Discord Rich Presence lifecycle
+  - `first-run-runtime` – first-run setup wizard
+  - `ipc-runtime` – IPC handler registration and composition
+  - `jellyfin-runtime` – Jellyfin session, playback, mpv orchestration
+  - `main-startup-runtime` – top-level startup orchestration (app-ready → CLI → headless)
+  - `main-startup-bootstrap` – wiring helper that builds startup runtime inputs
+  - `mining-runtime` – Anki card mining actions
+  - `mpv-runtime` – mpv client lifecycle
+  - `overlay-ui-runtime` – overlay window management, visibility, tray
+  - `overlay-geometry-runtime` – overlay bounds resolution
+  - `shortcuts-runtime` – global shortcut registration
+  - `startup-sequence-runtime` – headless known-word refresh and deferred startup sequencing
+  - `stats-runtime` – immersion tracker, stats server, stats CLI
+  - `subtitle-runtime` – subtitle prefetch, tokenization, caching
+  - `youtube-runtime` – YouTube playback flow
+  - `yomitan-runtime` – Yomitan extension loading and settings
 - `src/main/boot/` owns boot-phase assembly seams so `src/main.ts` can stay focused on lifecycle coordination and startup-path selection.
 - `src/core/services/` owns focused runtime services plus pure or side-effect-bounded logic.
 - `src/renderer/` owns overlay rendering and input behavior.