The Linux shepherd-media binary is stateless: shepherdd spawns it per
activity with a --library argument plus flags, so there is nothing to
persist. The Android build has no shepherdd and only one install per
device, so it must keep its own state: the configured libraries, each
library's caching options, and which one is currently selected.

This new crate is the home for that state. It is pure Rust with no UI,
network, subprocess, or Android dependency, so it is testable on the
desktop and reusable by any platform binary:

- AppSettings / LibraryEntry / LibrarySource: the persisted model, with
  source kinds (saf-toml, http-toml, m3u, youtube-playlist) mirroring the
  dispatch the Linux binary already does on its --library argument.
- Library management: add / remove / reorder / select-active with
  validation and typed errors; atomic TOML load/save.
- Caching policy: CacheMode (mirrors the two VideoCache strategies),
  PosterPolicy, and Quality (ytdl_format kept identical to the Linux CLI).

Also captures the full Android architecture design under docs/ai/history.

Step 1 of the Android build; see that design doc for the remaining steps.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RSXDqEiPCKyssHQX9t8HGM

@@ -0,0 +1,411 @@
+//! Playback view: composites the player's GL output into the eframe surface and
+//! draws a touch-friendly control overlay.
+//!
+//! This is adapted from the Linux binary's `ui/playback.rs`, trimmed to touch +

@@ -0,0 +7,4 @@
+//!
+//! [`PosterPolicy::Never`] skips loading entirely. `WifiOnly` currently behaves
+//! like `Always`; gating it on a metered/Wi-Fi connection needs the Android
+//! connectivity JNI bridge, which is not wired yet.

@@ -0,0 +7,4 @@
+//! `NetworkOnMainThreadException` for any network on the main thread — so the
+//! grid screen resolves on a worker and polls the result.
+//!
+//! Not yet handled (they need the Android JNI bridges / youtubedl-android):

@@ -0,0 +7,4 @@
+//! is downloaded afterward so the next play is local. LRU eviction (by file
+//! mtime, touched on each cache hit) keeps the directory within the cap.
+//!
+//! Download and eviction are blocking and run off the UI thread.

@@ -0,0 +83,4 @@
+    // yt-dlp bundled with a Python runtime, called over JNI from the Rust code
+    // (see src/youtube.rs). Brings its own native libs/assets, packaged into
+    // the APK automatically.
+    implementation("io.github.junkfood02.youtubedl-android:library:0.18.1")

@@ -0,0 +84,4 @@
+- The cdylib cross-compiles for `aarch64-linux-android` and exports
+  `android_main` / `ANativeActivity_onCreate`.
+
+## Not yet wired (next steps)