feat(engine): art pass — PNG assets, custom font, and keyring v4 upgrade

Art pass (Phase 4):
- Generate placeholder PNG assets: face.png, back_0–4.png, bg_0–4.png via
  solitaire_assetgen gen_art binary (16×16 RGBA, embedded via include_bytes!)
- Add FiraMono-Medium font (assets/fonts/main.ttf) embedded at compile time
- Add FontPlugin: loads font at startup, exposes FontResource; gracefully
  falls back to default handle when Assets<Font> absent (MinimalPlugins tests)
- Wire CardImageSet into card_plugin: face/back PNGs replace solid-colour
  sprites when available; tests continue using colour fallback via MinimalPlugins
- Wire BackgroundImageSet into table_plugin: bg PNGs replace solid-colour
  background; empty set inserted when Assets<Image> absent in tests
- Fix hint highlight system (input_plugin): tint sprite.color directly instead
  of replacing the whole Sprite (which would discard the image handle)
- Export FontPlugin, FontResource, CardImageSet from solitaire_engine::lib
- Register FontPlugin in solitaire_app before other plugins

Dependency upgrades (latest releases):
- keyring "2" → keyring "4" + keyring-core "1" (v4 split architecture into
  separate core library crate)
- auth_tokens.rs: Entry::new now returns Result; delete_password →
  delete_credential; NoDefaultStore error variant handled
- solitaire_app: add keyring::use_native_store(true) at startup for Linux
  Secret Service / macOS Keychain / Windows Credential Store selection

ARCHITECTURE.md: fix Edition 2025→2021, update asset pipeline section,
add FontPlugin/CardImageSet/BackgroundImageSet to plugin and resource tables,
update Section 14 to reflect actual include_bytes!() rendering approach,
add Decision Log entries for embedded PNG and font decisions

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

ARCHITECTURE.md

@@ -3,7 +3,7 @@
 > **Version:** 1.1  
 > **Language:** Rust (Edition 2021)  
 > **Engine:** Bevy (latest stable)  
-> **Last Updated:** 2026-04-20
+> **Last Updated:** 2026-04-29
 
 ---
 
@@ -67,18 +67,19 @@ solitaire_quest/
 ├── Dockerfile                  # Multi-stage server build
 ├── docker-compose.yml          # Server + Caddy reverse proxy
 │
-├── assets/                     # Audio embedded at compile time via include_bytes!()
-│   ├── cards/                  # Reserved for future art pass (currently unused)
-│   │   ├── faces/
-│   │   └── backs/
-│   ├── backgrounds/            # Reserved for future art pass (currently unused)
-│   ├── fonts/                  # Reserved for future art pass (currently unused)
+├── assets/                     # Assets embedded at compile time via include_bytes!()
+│   ├── cards/
+│   │   ├── faces/face.png      # placeholder (16×16 cream/ivory)
+│   │   └── backs/back_0.png – back_4.png    # placeholder patterns
+│   ├── backgrounds/bg_0.png – bg_4.png      # placeholder textures
+│   ├── fonts/main.ttf          # FiraMono-Medium (170K, OFL)
 │   └── audio/
 │       ├── card_deal.wav
 │       ├── card_flip.wav
 │       ├── card_place.wav
 │       ├── card_invalid.wav
-│       └── win_fanfare.wav
+│       ├── win_fanfare.wav
+│       └── ambient_loop.wav
 │
 ├── solitaire_core/             # Pure Rust game logic — zero external deps beyond rand/serde
 ├── solitaire_sync/             # Shared API types — used by client and server
@@ -143,6 +144,7 @@ Owns:
 - All Bevy UI screens (Home, Stats, Achievements, Settings, Profile)
 - Audio playback systems
 - Sync status display
+- Card, background, and font asset loading (embedded via `include_bytes!()` — no `AssetServer` dependency)
 
 ### `solitaire_server`
 **Dependencies:** `solitaire_sync`, `axum`, `sqlx`, `jsonwebtoken`, `bcrypt`, `tower-governor`, `tracing`, `tokio`, `dotenvy`.
@@ -237,6 +239,7 @@ Done
 |---|---|---|
 | `CardPlugin` | — | Card entity spawning, sprite management, drag-and-drop |
 | `TablePlugin` | — | Pile markers, background, layout calculation |
+| `FontPlugin` | — | Embeds FiraMono-Medium font at compile time; exposes `FontResource` handle |
 | `AnimationPlugin` | — | Slide, flip, win cascade, toast animations |
 | `FeedbackAnimPlugin` | — | Shake, settle, and deal-stagger animations |
 | `AutoCompletePlugin` | Enter | Executes auto-complete when the HUD badge is lit |
@@ -286,6 +289,20 @@ struct StatsResource(StatsSnapshot);
 struct ProgressResource(PlayerProgress);
 struct AchievementsResource(Vec<AchievementRecord>);
 struct SettingsResource(Settings);
+
+// Pre-loaded card face and back PNG handles
+struct CardImageSet {
+    face: Handle<Image>,            // shared face image for all face-up cards
+    backs: [Handle<Image>; 5],      // indexed by selected_card_back setting
+}
+
+// Project-wide font handle (FiraMono-Medium embedded at compile time)
+struct FontResource(Handle<Font>);
+
+// Pre-loaded background PNG handles
+struct BackgroundImageSet {
+    handles: Vec<Handle<Image>>,    // indices 0–4 match selected_background setting
+}
 ```
 
 ### Key Bevy Events
@@ -743,7 +760,7 @@ Audio uses `bevy_kira_audio`. All sound files are `.wav`.
 | `card_place.wav` | Valid card placement |
 | `card_invalid.wav` | Invalid move attempt |
 | `win_fanfare.wav` | Game won |
-| `ambient_loop` | Looping background music — uses `card_flip.wav` looped at very low volume as a placeholder until a dedicated track is added |
+| `ambient_loop.wav` | Looping background music |
 
 Volume is controlled by two independent sliders in Settings (`sfx_volume`, `music_volume`), each stored in `Settings` and applied as `bevy_kira_audio` channel volumes.
 
@@ -755,30 +772,49 @@ Audio systems listen for Bevy events and never block the game thread.
 
 ### Rendering approach
 
-Cards, backgrounds, and UI are rendered **procedurally** — no image files are used. Cards are Bevy `Sprite` entities (colored rectangles) with `Text` children showing rank and suit symbols. Card back colors and background colors are selected by index from compile-time color tables in `card_plugin.rs` and `table_plugin.rs`. All UI text uses Bevy's built-in default font.
+Cards are Bevy `Sprite` entities with `Handle<Image>` from `CardImageSet`. Face-up cards use `face.png` (a single shared image). Face-down cards use `backs/back_N.png` indexed by `settings.selected_card_back`. `Text2d` labels are still overlaid for rank and suit symbols. `CardImageSet` is populated at startup from `include_bytes!()` — no `AssetServer`.
 
-This means the `assets/cards/`, `assets/backgrounds/`, and `assets/fonts/` directories are reserved for a future art pass and are currently empty (`.gitkeep` only).
+Backgrounds are Bevy `Sprite` entities with `Handle<Image>` from `BackgroundImageSet`. `BackgroundImageSet` is populated at startup from `include_bytes!()`.
+
+The font `FiraMono-Medium` is embedded via `include_bytes!()` at startup by `FontPlugin` and exposed as `FontResource` for use by all UI and text systems.
+
+The `assets/` directory layout:
+
+```
+assets/
+├── cards/
+│   ├── faces/face.png          # placeholder (16×16 cream/ivory)
+│   └── backs/back_0.png – back_4.png    # placeholder patterns
+├── backgrounds/bg_0.png – bg_4.png      # placeholder textures
+├── fonts/main.ttf              # FiraMono-Medium (170K, OFL)
+└── audio/
+    ├── card_deal.wav
+    ├── card_flip.wav
+    ├── card_place.wav
+    ├── card_invalid.wav
+    ├── win_fanfare.wav
+    └── ambient_loop.wav
+```
 
 ### Audio
 
-All five sound effect WAV files are embedded at compile time via `include_bytes!()` in `audio_plugin.rs`. There is no runtime asset loading — the binary is fully self-contained.
+All sound effect WAV files are embedded at compile time via `include_bytes!()` in `audio_plugin.rs`. There is no runtime asset loading — the binary is fully self-contained.
 
-| File | Size |
+| File | Trigger |
 |---|---|
-| `card_deal.wav` | SFX |
-| `card_flip.wav` | SFX |
-| `card_place.wav` | SFX |
-| `card_invalid.wav` | SFX |
-| `win_fanfare.wav` | SFX |
-
-The ambient music loop reuses `card_flip.wav` at very low volume as a placeholder; a dedicated `ambient_loop.wav` can be dropped into `assets/audio/` and wired into `audio_plugin.rs` when ready.
+| `card_deal.wav` | New game deal animation |
+| `card_flip.wav` | Card flips face-up |
+| `card_place.wav` | Valid card placement |
+| `card_invalid.wav` | Invalid move attempt |
+| `win_fanfare.wav` | Game won |
+| `ambient_loop.wav` | Looping background music |
 
 ### Future art pass
 
-When image-based card art is added, the recommended approach is:
-- Embed assets via `bevy::asset::embedded_asset!()` macro (keeps the binary self-contained)
+The placeholder PNG files can be replaced with real artwork without any code changes — just drop in new PNGs and rebuild. The texture atlas approach described below is still the recommended upgrade path for card faces:
 - Use a texture atlas (`assets/cards/atlas.png` + layout descriptor) for card faces
 - Individual PNGs for card backs and backgrounds (5 each)
+- All assets remain embedded via `include_bytes!()` to keep the binary self-contained
 
 ---
 
@@ -975,3 +1011,5 @@ Using `axum::test` and an in-memory SQLite database:
 | `SyncProvider` trait, not `SyncBackend` match arms | `SyncPlugin` stays backend-agnostic and testable; new backends can be added without touching the plugin | 2026-04-20 |
 | Dropped WebDAV backend | Redundant once the self-hosted server exists; removing it reduces surface area and simplifies settings UI | 2026-04-20 |
 | Dropped GPGS backend | Redundant with the self-hosted server; adds JNI complexity for no user-visible benefit on the target platforms | 2026-04-28 |
+| PNG assets embedded via `include_bytes!()` | Using `Image::from_buffer()` in startup systems rather than `AssetServer::load()` keeps the binary self-contained and eliminates runtime file-not-found errors | 2026-04-29 |
+| FiraMono-Medium font embedded via `include_bytes!()` | Exposed through `FontResource`; avoids runtime font loading errors on headless systems and ensures consistent text rendering across all platforms | 2026-04-29 |

Cargo.toml

@@ -25,7 +25,8 @@ rand        = "0.8"
 async-trait = "0.1"
 tokio       = { version = "1", features = ["full"] }
 dirs        = "6"
-keyring     = "2"
+keyring     = "4"
+keyring-core = "1"
 reqwest     = { version = "0.13", features = ["json", "rustls", "rustls-native-certs"], default-features = false }
 
 solitaire_core   = { path = "solitaire_core" }

solitaire_app/Cargo.toml

@@ -12,3 +12,4 @@ path = "src/main.rs"
 bevy             = { workspace = true }
 solitaire_engine = { workspace = true }
 solitaire_data   = { workspace = true }
+keyring          = { workspace = true }

solitaire_app/src/main.rs

@@ -3,12 +3,24 @@ use solitaire_data::{load_settings_from, provider_for_backend, settings_file_pat
 use solitaire_engine::{
     AchievementPlugin, AnimationPlugin, AudioPlugin, AutoCompletePlugin, CardAnimationPlugin,
     CardPlugin, ChallengePlugin, CursorPlugin, DailyChallengePlugin, FeedbackAnimPlugin,
-    GamePlugin, HelpPlugin, HomePlugin, HudPlugin, InputPlugin, LeaderboardPlugin,
+    FontPlugin, GamePlugin, HelpPlugin, HomePlugin, HudPlugin, InputPlugin, LeaderboardPlugin,
     OnboardingPlugin, PausePlugin, ProfilePlugin, ProgressPlugin, SelectionPlugin, SettingsPlugin,
     StatsPlugin, SyncPlugin, TablePlugin, TimeAttackPlugin, WeeklyGoalsPlugin, WinSummaryPlugin,
 };
 
 fn main() {
+    // Initialise the platform keyring store before any token operations.
+    // On Linux this uses the Secret Service (GNOME Keyring / KWallet); on
+    // macOS it uses the Keychain; on Windows it uses the Credential store.
+    // If the platform has no OS keyring (e.g. a headless CI box), keyring
+    // operations will fail gracefully with TokenError::KeychainUnavailable.
+    if let Err(e) = keyring::use_native_store(true) {
+        eprintln!(
+            "warn: could not initialise OS keyring ({e}); \
+             server sync login will be unavailable"
+        );
+    }
+
     // Load settings before building the app so we can construct the right
     // sync provider. Falls back to defaults if no settings file exists yet.
     let settings: Settings = settings_file_path()
@@ -32,6 +44,7 @@ fn main() {
                 ..default()
             }),
         )
+        .add_plugins(FontPlugin)
         .add_plugins(GamePlugin)
         .add_plugins(TablePlugin)
         .add_plugins(CardPlugin)

solitaire_assetgen/Cargo.toml

@@ -5,9 +5,17 @@ license.workspace = true
 edition.workspace = true
 publish = false
 
-# Dev-only utility: synthesizes placeholder SFX WAV files into `assets/audio/`.
+# Dev-only utility: synthesizes placeholder SFX WAV files into `assets/audio/`
+# and placeholder PNG images into `assets/cards/` and `assets/backgrounds/`.
 # Not depended on by any other workspace crate.
 
+[dependencies]
+png = "0.17"
+
 [[bin]]
 name = "gen_sfx"
 path = "src/bin/gen_sfx.rs"
+
+[[bin]]
+name = "gen_art"
+path = "src/bin/gen_art.rs"

solitaire_assetgen/src/bin/gen_art.rs

@@ -0,0 +1,229 @@
+//! Generates placeholder PNG assets for card faces, card backs, and table
+//! backgrounds. All images are 16×16 pixels — Bevy's Sprite scales them via
+//! `custom_size`, so small files keep the repository lightweight.
+//!
+//! Run with:
+//! ```
+//! cargo run -p solitaire_assetgen --bin gen_art
+//! ```
+
+use std::fs::File;
+use std::io::BufWriter;
+use std::path::Path;
+
+// ---------------------------------------------------------------------------
+// PNG helper
+// ---------------------------------------------------------------------------
+
+/// Write a 16×16 RGBA image to `path`.  `pixels` is a flat `[R,G,B,A, ...]`
+/// byte array with exactly 16 * 16 * 4 = 1024 bytes.
+fn save_png(path: &Path, pixels: &[u8; 1024]) {
+    let file = File::create(path)
+        .unwrap_or_else(|e| panic!("cannot create {}: {e}", path.display()));
+    let mut w = BufWriter::new(file);
+    let mut encoder = png::Encoder::new(&mut w, 16, 16);
+    encoder.set_color(png::ColorType::Rgba);
+    encoder.set_depth(png::BitDepth::Eight);
+    let mut writer = encoder
+        .write_header()
+        .unwrap_or_else(|e| panic!("png header error for {}: {e}", path.display()));
+    writer
+        .write_image_data(pixels)
+        .unwrap_or_else(|e| panic!("png data error for {}: {e}", path.display()));
+}
+
+/// Build a flat 16×16 RGBA pixel array using a per-pixel closure.
+fn make_image<F: Fn(u32, u32) -> [u8; 4]>(f: F) -> [u8; 1024] {
+    let mut pixels = [0u8; 1024];
+    for y in 0u32..16 {
+        for x in 0u32..16 {
+            let rgba = f(x, y);
+            let i = ((y * 16 + x) * 4) as usize;
+            pixels[i..i + 4].copy_from_slice(&rgba);
+        }
+    }
+    pixels
+}
+
+// ---------------------------------------------------------------------------
+// Card face
+// ---------------------------------------------------------------------------
+
+/// Cream/ivory solid fill — represents a blank card face.
+fn make_face() -> [u8; 1024] {
+    make_image(|_, _| [0xF8, 0xF8, 0xF0, 0xFF])
+}
+
+// ---------------------------------------------------------------------------
+// Card backs  (match the colours used in card_plugin.rs `card_back_colour()`)
+// ---------------------------------------------------------------------------
+
+/// back_0 — blue base with semi-transparent white horizontal stripes every 4 px.
+fn make_back_0() -> [u8; 1024] {
+    make_image(|_, y| {
+        if y % 4 < 2 {
+            [0xFF, 0xFF, 0xFF, 40]
+        } else {
+            [0x26, 0x4D, 0x8C, 0xFF]
+        }
+    })
+}
+
+/// back_1 — red base with semi-transparent white diagonal stripes.
+fn make_back_1() -> [u8; 1024] {
+    make_image(|x, y| {
+        if (x + y) % 4 < 2 {
+            [0xFF, 0xFF, 0xFF, 40]
+        } else {
+            [0x8C, 0x1A, 0x1A, 0xFF]
+        }
+    })
+}
+
+/// back_2 — green base with white dots at every 4-px grid intersection.
+fn make_back_2() -> [u8; 1024] {
+    make_image(|x, y| {
+        if x % 4 == 0 && y % 4 == 0 {
+            [0xFF, 0xFF, 0xFF, 0xFF]
+        } else {
+            [0x0D, 0x66, 0x1A, 0xFF]
+        }
+    })
+}
+
+/// back_3 — purple base with a white diamond centred at (8, 8).
+fn make_back_3() -> [u8; 1024] {
+    make_image(|x, y| {
+        let dx = (x as i32 - 8).unsigned_abs();
+        let dy = (y as i32 - 8).unsigned_abs();
+        if dx + dy <= 4 {
+            [0xFF, 0xFF, 0xFF, 0xFF]
+        } else {
+            [0x59, 0x14, 0x85, 0xFF]
+        }
+    })
+}
+
+/// back_4 — teal base with a 1-px white border.
+fn make_back_4() -> [u8; 1024] {
+    make_image(|x, y| {
+        if x == 0 || x == 15 || y == 0 || y == 15 {
+            [0xFF, 0xFF, 0xFF, 0xFF]
+        } else {
+            [0x0D, 0x66, 0x6B, 0xFF]
+        }
+    })
+}
+
+// ---------------------------------------------------------------------------
+// Backgrounds
+// ---------------------------------------------------------------------------
+
+/// bg_0 — dark green felt with very faint lighter grid lines every 8 px.
+fn make_bg_0() -> [u8; 1024] {
+    make_image(|x, y| {
+        if x % 8 == 0 || y % 8 == 0 {
+            [0xFF, 0xFF, 0xFF, 30]
+        } else {
+            [0x1A, 0x4D, 0x1A, 0xFF]
+        }
+    })
+}
+
+/// bg_1 — dark wood brown with faint horizontal grain lines every 2 px.
+fn make_bg_1() -> [u8; 1024] {
+    make_image(|_, y| {
+        if y % 2 == 0 {
+            [0xFF, 0xFF, 0xFF, 20]
+        } else {
+            [0x40, 0x2D, 0x1A, 0xFF]
+        }
+    })
+}
+
+/// bg_2 — navy with faint star/dot pattern (offset rows) every 8 px.
+fn make_bg_2() -> [u8; 1024] {
+    make_image(|x, y| {
+        let row_offset: u32 = if (y / 4) % 2 == 0 { 0 } else { 4 };
+        if (x + row_offset) % 8 == 0 && y % 8 == 0 {
+            [0xFF, 0xFF, 0xFF, 0xFF]
+        } else {
+            [0x0D, 0x14, 0x38, 0xFF]
+        }
+    })
+}
+
+/// bg_3 — burgundy with a faint diamond-grid pattern.
+fn make_bg_3() -> [u8; 1024] {
+    make_image(|x, y| {
+        if (x + y) % 8 == 0 {
+            [0xFF, 0xFF, 0xFF, 30]
+        } else {
+            [0x4D, 0x0D, 0x14, 0xFF]
+        }
+    })
+}
+
+/// bg_4 — charcoal with faint pixel noise (alternating pixels every 3 columns).
+fn make_bg_4() -> [u8; 1024] {
+    make_image(|x, y| {
+        if (x + y) % 2 == 0 && x % 3 == 0 {
+            [0xFF, 0xFF, 0xFF, 20]
+        } else {
+            [0x1F, 0x1F, 0x24, 0xFF]
+        }
+    })
+}
+
+// ---------------------------------------------------------------------------
+// Entry point
+// ---------------------------------------------------------------------------
+
+fn workspace_root() -> std::path::PathBuf {
+    let crate_dir = std::path::PathBuf::from(env!("CARGO_MANIFEST_DIR"));
+    crate_dir.parent().unwrap().to_path_buf()
+}
+
+fn main() {
+    let root = workspace_root();
+
+    // Ensure output directories exist.
+    std::fs::create_dir_all(root.join("assets/cards/faces")).unwrap();
+    std::fs::create_dir_all(root.join("assets/cards/backs")).unwrap();
+    std::fs::create_dir_all(root.join("assets/backgrounds")).unwrap();
+
+    // Card face.
+    let path = root.join("assets/cards/faces/face.png");
+    save_png(&path, &make_face());
+    println!("wrote {}", path.display());
+
+    // Card backs.
+    let backs = [
+        make_back_0(),
+        make_back_1(),
+        make_back_2(),
+        make_back_3(),
+        make_back_4(),
+    ];
+    for (i, pixels) in backs.iter().enumerate() {
+        let path = root.join(format!("assets/cards/backs/back_{i}.png"));
+        save_png(&path, pixels);
+        println!("wrote {}", path.display());
+    }
+
+    // Backgrounds.
+    let bgs = [
+        make_bg_0(),
+        make_bg_1(),
+        make_bg_2(),
+        make_bg_3(),
+        make_bg_4(),
+    ];
+    for (i, pixels) in bgs.iter().enumerate() {
+        let path = root.join(format!("assets/backgrounds/bg_{i}.png"));
+        save_png(&path, pixels);
+        println!("wrote {}", path.display());
+    }
+
+    println!("gen_art: all placeholder PNG assets generated successfully.");
+}

solitaire_data/Cargo.toml

@@ -13,6 +13,6 @@ chrono         = { workspace = true }
 thiserror      = { workspace = true }
 async-trait    = { workspace = true }
 dirs           = { workspace = true }
-keyring        = { workspace = true }
+keyring-core   = { workspace = true }
 reqwest        = { workspace = true }
 tokio          = { workspace = true }

solitaire_data/src/auth_tokens.rs

@@ -8,9 +8,15 @@
 //! [`TokenError::KeychainUnavailable`] — callers should fall back to prompting
 //! the user to log in again.
 //!
+//! Before calling any function in this module the application must initialise
+//! the default keyring store exactly once at startup by calling
+//! `keyring::use_native_store` (e.g. in `solitaire_app::main` before building
+//! the Bevy `App`). If no default store is set, all operations in this module
+//! will return [`TokenError::KeychainUnavailable`].
+//!
 //! # Note: no unit tests — requires live OS keychain.
 
-use keyring::Entry;
+use keyring_core::Entry;
 use thiserror::Error;
 
 /// Errors that can occur when reading or writing tokens in the OS keychain.
@@ -30,12 +36,13 @@ pub enum TokenError {
 /// Service name used to namespace all keychain entries for this application.
 const SERVICE: &str = "solitaire_quest_server";
 
-/// Map a `keyring::Error` to the appropriate `TokenError`.
-fn map_keyring_err(err: keyring::Error, username: &str) -> TokenError {
+/// Map a `keyring_core::Error` to the appropriate `TokenError`.
+fn map_keyring_err(err: keyring_core::Error, username: &str) -> TokenError {
     let msg = err.to_string();
     match err {
-        keyring::Error::NoStorageAccess(_) => TokenError::KeychainUnavailable(msg),
-        keyring::Error::NoEntry => TokenError::NotFound(username.to_string()),
+        keyring_core::Error::NoStorageAccess(_) => TokenError::KeychainUnavailable(msg),
+        keyring_core::Error::NoDefaultStore => TokenError::KeychainUnavailable(msg),
+        keyring_core::Error::NoEntry => TokenError::NotFound(username.to_string()),
         _ => TokenError::Keyring(msg),
     }
 }
@@ -88,17 +95,17 @@ pub fn load_refresh_token(username: &str) -> Result<String, TokenError> {
 pub fn delete_tokens(username: &str) -> Result<(), TokenError> {
     match Entry::new(SERVICE, &format!("{username}_access"))
         .map_err(|e| map_keyring_err(e, username))?
-        .delete_password()
+        .delete_credential()
     {
-        Ok(()) | Err(keyring::Error::NoEntry) => {}
+        Ok(()) | Err(keyring_core::Error::NoEntry) => {}
         Err(e) => return Err(map_keyring_err(e, username)),
     }
 
     match Entry::new(SERVICE, &format!("{username}_refresh"))
         .map_err(|e| map_keyring_err(e, username))?
-        .delete_password()
+        .delete_credential()
     {
-        Ok(()) | Err(keyring::Error::NoEntry) => {}
+        Ok(()) | Err(keyring_core::Error::NoEntry) => {}
         Err(e) => return Err(map_keyring_err(e, username)),
     }
 

solitaire_engine/src/card_plugin.rs

@@ -47,6 +47,19 @@ pub const CARD_FACE_COLOUR: Color = Color::srgb(0.98, 0.98, 0.95);
 pub const RED_SUIT_COLOUR: Color = Color::srgb(0.78, 0.12, 0.15);
 pub const BLACK_SUIT_COLOUR: Color = Color::srgb(0.08, 0.08, 0.08);
 
+/// Pre-loaded [`Handle<Image>`]s for card face and back PNG textures.
+///
+/// Loaded once at startup by [`load_card_images`].  When this resource is
+/// present, card sprites use the PNG artwork; otherwise they fall back to
+/// solid-colour sprites (used in tests with `MinimalPlugins`).
+#[derive(Resource)]
+pub struct CardImageSet {
+    /// Shared face image used for all face-up cards.
+    pub face: Handle<Image>,
+    /// One handle per unlockable card-back design (indices 0–4).
+    pub backs: [Handle<Image>; 5],
+}
+
 /// Alternative face tint for red-suit cards in color-blind mode — a subtle
 /// blue wash that distinguishes them from black-suit cards without colour alone.
 const CARD_FACE_COLOUR_RED_CBM: Color = Color::srgba(0.85, 0.92, 1.0, 1.0);
@@ -160,6 +173,7 @@ impl Plugin for CardPlugin {
             .add_message::<SettingsChangedEvent>()
             .add_message::<CardFlippedEvent>()
             .add_message::<CardFaceRevealedEvent>()
+            .add_systems(Startup, load_card_images)
             .add_systems(PostStartup, (sync_cards_startup, update_stock_empty_indicator_startup))
             .add_systems(
                 Update,
@@ -180,6 +194,81 @@ impl Plugin for CardPlugin {
     }
 }
 
+/// Loads card face and back PNGs at startup and inserts [`CardImageSet`].
+///
+/// The PNGs are embedded at compile time via `include_bytes!()`.  Missing
+/// files are compile errors, not runtime panics.  Under `MinimalPlugins`
+/// (tests) this system is still registered but `Assets<Image>` is unavailable,
+/// so it does nothing and the plugin falls back to solid-colour sprites.
+fn load_card_images(images: Option<ResMut<Assets<Image>>>, mut commands: Commands) {
+    let Some(mut images) = images else {
+        // Assets<Image> is absent (e.g. MinimalPlugins in tests) — skip so
+        // tests can still run.  The plugin falls back to solid-colour sprites.
+        return;
+    };
+    use bevy::asset::RenderAssetUsages;
+    use bevy::image::{CompressedImageFormats, ImageSampler, ImageType};
+
+    let load = |bytes: &[u8]| {
+        Image::from_buffer(
+            bytes,
+            ImageType::Extension("png"),
+            CompressedImageFormats::NONE,
+            true,
+            ImageSampler::default(),
+            RenderAssetUsages::RENDER_WORLD,
+        )
+        .expect("valid card PNG")
+    };
+
+    let face = images.add(load(include_bytes!("../../assets/cards/faces/face.png")));
+    let backs = [
+        images.add(load(include_bytes!("../../assets/cards/backs/back_0.png"))),
+        images.add(load(include_bytes!("../../assets/cards/backs/back_1.png"))),
+        images.add(load(include_bytes!("../../assets/cards/backs/back_2.png"))),
+        images.add(load(include_bytes!("../../assets/cards/backs/back_3.png"))),
+        images.add(load(include_bytes!("../../assets/cards/backs/back_4.png"))),
+    ];
+    commands.insert_resource(CardImageSet { face, backs });
+}
+
+/// Builds the [`Sprite`] for a card, using PNG artwork when [`CardImageSet`] is
+/// available and falling back to a solid-colour sprite in tests.
+fn card_sprite(
+    card: &Card,
+    card_size: Vec2,
+    back_colour: Color,
+    color_blind: bool,
+    card_images: Option<&CardImageSet>,
+    selected_back: usize,
+) -> Sprite {
+    if let Some(set) = card_images {
+        let image = if card.face_up {
+            set.face.clone()
+        } else {
+            let idx = selected_back.min(set.backs.len() - 1);
+            set.backs[idx].clone()
+        };
+        Sprite {
+            image,
+            color: Color::WHITE,
+            custom_size: Some(card_size),
+            ..default()
+        }
+    } else {
+        let body_colour = if card.face_up {
+            face_colour(card, color_blind)
+        } else {
+            back_colour
+        };
+        Sprite {
+            color: body_colour,
+            custom_size: Some(card_size),
+            ..default()
+        }
+    }
+}
+
 /// When card-back selection changes in Settings, re-render all cards so the
 /// new back colour is applied immediately (without waiting for a state change).
 fn resync_cards_on_settings_change(
@@ -201,14 +290,14 @@ fn sync_cards_startup(
     slide_dur: Option<Res<EffectiveSlideDuration>>,
     settings: Option<Res<SettingsResource>>,
     entities: Query<(Entity, &CardEntity, &Transform)>,
+    card_images: Option<Res<CardImageSet>>,
 ) {
     if let Some(layout) = layout {
         let slide_secs = slide_dur.map_or(0.15, |d| d.slide_secs);
-        let back_colour = settings
-            .as_ref()
-            .map_or_else(|| card_back_colour(0), |s| card_back_colour(s.0.selected_card_back));
+        let selected_back = settings.as_ref().map_or(0, |s| s.0.selected_card_back);
+        let back_colour = card_back_colour(selected_back);
         let color_blind = settings.as_ref().is_some_and(|s| s.0.color_blind_mode);
-        sync_cards(commands, &game.0, &layout.0, slide_secs, back_colour, color_blind, &entities);
+        sync_cards(commands, &game.0, &layout.0, slide_secs, back_colour, color_blind, &entities, card_images.as_deref(), selected_back);
     }
 }
 
@@ -220,17 +309,17 @@ fn sync_cards_on_change(
     slide_dur: Option<Res<EffectiveSlideDuration>>,
     settings: Option<Res<SettingsResource>>,
     entities: Query<(Entity, &CardEntity, &Transform)>,
+    card_images: Option<Res<CardImageSet>>,
 ) {
     if events.read().next().is_none() {
         return;
     }
     if let Some(layout) = layout {
         let slide_secs = slide_dur.map_or(0.15, |d| d.slide_secs);
-        let back_colour = settings
-            .as_ref()
-            .map_or_else(|| card_back_colour(0), |s| card_back_colour(s.0.selected_card_back));
+        let selected_back = settings.as_ref().map_or(0, |s| s.0.selected_card_back);
+        let back_colour = card_back_colour(selected_back);
         let color_blind = settings.as_ref().is_some_and(|s| s.0.color_blind_mode);
-        sync_cards(commands, &game.0, &layout.0, slide_secs, back_colour, color_blind, &entities);
+        sync_cards(commands, &game.0, &layout.0, slide_secs, back_colour, color_blind, &entities, card_images.as_deref(), selected_back);
     }
 }
 
@@ -242,6 +331,8 @@ fn sync_cards(
     back_colour: Color,
     color_blind: bool,
     entities: &Query<(Entity, &CardEntity, &Transform)>,
+    card_images: Option<&CardImageSet>,
+    selected_back: usize,
 ) {
     let positions = card_positions(game, layout);
 
@@ -266,10 +357,10 @@ fn sync_cards(
             Some(&(entity, cur)) => {
                 update_card_entity(
                     &mut commands, entity, card, position, z, layout,
-                    slide_secs, back_colour, color_blind, cur,
+                    slide_secs, back_colour, color_blind, cur, card_images, selected_back,
                 )
             }
-            None => spawn_card_entity(&mut commands, card, position, z, layout, back_colour, color_blind),
+            None => spawn_card_entity(&mut commands, card, position, z, layout, back_colour, color_blind, card_images, selected_back),
         }
     }
 }
@@ -358,21 +449,23 @@ fn face_colour(card: &Card, color_blind: bool) -> Color {
     }
 }
 
-fn spawn_card_entity(commands: &mut Commands, card: &Card, pos: Vec2, z: f32, layout: &Layout, back_colour: Color, color_blind: bool) {
-    let body_colour = if card.face_up {
-        face_colour(card, color_blind)
-    } else {
-        back_colour
-    };
+fn spawn_card_entity(
+    commands: &mut Commands,
+    card: &Card,
+    pos: Vec2,
+    z: f32,
+    layout: &Layout,
+    back_colour: Color,
+    color_blind: bool,
+    card_images: Option<&CardImageSet>,
+    selected_back: usize,
+) {
+    let sprite = card_sprite(card, layout.card_size, back_colour, color_blind, card_images, selected_back);
 
     commands
         .spawn((
             CardEntity { card_id: card.id },
-            Sprite {
-                color: body_colour,
-                custom_size: Some(layout.card_size),
-                ..default()
-            },
+            sprite,
             Transform::from_xyz(pos.x, pos.y, z),
             Visibility::default(),
         ))
@@ -405,21 +498,13 @@ fn update_card_entity(
     back_colour: Color,
     color_blind: bool,
     cur: Vec3,
+    card_images: Option<&CardImageSet>,
+    selected_back: usize,
 ) {
-    let body_colour = if card.face_up {
-        face_colour(card, color_blind)
-    } else {
-        back_colour
-    };
-
     let target = Vec3::new(pos.x, pos.y, z);
 
     // Always refresh the visual appearance.
-    commands.entity(entity).insert(Sprite {
-        color: body_colour,
-        custom_size: Some(layout.card_size),
-        ..default()
-    });
+    commands.entity(entity).insert(card_sprite(card, layout.card_size, back_colour, color_blind, card_images, selected_back));
 
     // Slide to the new position when it differs meaningfully; snap otherwise.
     if (cur.truncate() - target.truncate()).length() > 1.0 && slide_secs > 0.0 {
@@ -653,20 +738,24 @@ fn tick_hint_highlight(
     mut query: Query<(Entity, &mut HintHighlight, &mut Sprite, &CardEntity)>,
     game: Res<GameStateResource>,
     settings: Option<Res<SettingsResource>>,
+    card_images: Option<Res<CardImageSet>>,
 ) {
     let back_idx = settings.as_ref().map_or(0, |s| s.0.selected_card_back);
+    let use_images = card_images.is_some();
     for (entity, mut hint, mut sprite, card_entity) in query.iter_mut() {
         hint.remaining -= time.delta_secs();
         if hint.remaining <= 0.0 {
-            // Restore normal face-up colour.
-            let is_face_up = game.0.piles.values()
-                .flat_map(|p| p.cards.iter())
-                .find(|c| c.id == card_entity.card_id)
-                .is_some_and(|c| c.face_up);
-            sprite.color = if is_face_up {
-                CARD_FACE_COLOUR
+            // Restore the normal sprite colour.
+            // When image-based rendering is active, WHITE is the neutral tint;
+            // otherwise restore the solid colour appropriate to the card state.
+            sprite.color = if use_images {
+                Color::WHITE
             } else {
-                card_back_colour(back_idx)
+                let is_face_up = game.0.piles.values()
+                    .flat_map(|p| p.cards.iter())
+                    .find(|c| c.id == card_entity.card_id)
+                    .is_some_and(|c| c.face_up);
+                if is_face_up { CARD_FACE_COLOUR } else { card_back_colour(back_idx) }
             };
             commands
                 .entity(entity)

solitaire_engine/src/font_plugin.rs

@@ -0,0 +1,36 @@
+// Register FontPlugin in solitaire_engine/src/lib.rs before use.
+
+//! Embeds FiraMono-Medium as the project font and exposes it via [`FontResource`].
+
+use bevy::prelude::*;
+
+/// Holds the project-wide [`Handle<Font>`] loaded at startup.
+#[derive(Resource)]
+pub struct FontResource(pub Handle<Font>);
+
+/// Loads FiraMono-Medium at startup and inserts [`FontResource`].
+pub struct FontPlugin;
+
+impl Plugin for FontPlugin {
+    fn build(&self, app: &mut App) {
+        app.add_systems(Startup, load_font);
+    }
+}
+
+fn load_font(fonts: Option<ResMut<Assets<Font>>>, mut commands: Commands) {
+    let Some(mut fonts) = fonts else {
+        // Assets<Font> absent (e.g. MinimalPlugins in tests) — insert default.
+        commands.insert_resource(FontResource(Handle::default()));
+        return;
+    };
+    let bytes: &'static [u8] = include_bytes!("../../assets/fonts/main.ttf");
+    match Font::try_from_bytes(bytes.to_vec()) {
+        Ok(font) => {
+            commands.insert_resource(FontResource(fonts.add(font)));
+        }
+        Err(e) => {
+            warn!("failed to load main.ttf: {e}; falling back to Bevy default font");
+            commands.insert_resource(FontResource(Handle::default()));
+        }
+    }
+}

solitaire_engine/src/hud_plugin.rs

@@ -14,6 +14,7 @@ use solitaire_core::pile::PileType;
 use crate::auto_complete_plugin::AutoCompleteState;
 use crate::daily_challenge_plugin::DailyChallengeResource;
 use crate::events::InfoToastEvent;
+use crate::font_plugin::FontResource;
 use crate::game_plugin::GameMutation;
 use crate::resources::GameStateResource;
 use crate::selection_plugin::SelectionState;
@@ -98,9 +99,13 @@ impl Plugin for HudPlugin {
     }
 }
 
-fn spawn_hud(mut commands: Commands) {
+fn spawn_hud(font_res: Option<Res<FontResource>>, mut commands: Commands) {
     let white = TextColor(Color::srgba(1.0, 1.0, 1.0, 0.80));
-    let font = TextFont { font_size: 18.0, ..default() };
+    let font = TextFont {
+        font: font_res.as_ref().map(|f| f.0.clone()).unwrap_or_default(),
+        font_size: 18.0,
+        ..default()
+    };
     commands
         .spawn((
             Node {

solitaire_engine/src/input_plugin.rs

@@ -252,7 +252,7 @@ fn handle_keyboard_hint(
     mut confirm: ResMut<KeyboardConfirmState>,
     mut hint_cycle: ResMut<HintCycleIndex>,
     mut commands: Commands,
-    card_entities: Query<(Entity, &CardEntity, &Sprite)>,
+    mut card_entities: Query<(Entity, &CardEntity, &mut Sprite)>,
     mut info_toast: MessageWriter<InfoToastEvent>,
     mut hint_visual: MessageWriter<HintVisualEvent>,
 ) {
@@ -308,16 +308,14 @@ fn handle_keyboard_hint(
         .and_then(|p| p.cards.last().filter(|c| c.face_up))
         .map(|c| c.id);
     if let Some(card_id) = top_card_id {
-        for (entity, card_entity, _sprite) in card_entities.iter() {
+        for (entity, card_entity, mut sprite) in card_entities.iter_mut() {
             if card_entity.card_id == card_id {
+                // Tint the card gold without replacing the Sprite (which would
+                // discard the image handle set by CardImageSet).
+                sprite.color = Color::srgba(1.0, 1.0, 0.4, 1.0);
                 commands.entity(entity)
                     .insert(HintHighlight { remaining: 2.0 })
-                    .insert(HintHighlightTimer(2.0))
-                    .insert(Sprite {
-                        color: Color::srgba(1.0, 1.0, 0.4, 1.0),
-                        custom_size: Some(layout_res.0.card_size),
-                        ..default()
-                    });
+                    .insert(HintHighlightTimer(2.0));
                 break;
             }
         }

solitaire_engine/src/lib.rs

@@ -6,6 +6,7 @@ pub mod animation_plugin;
 pub mod auto_complete_plugin;
 pub mod audio_plugin;
 pub mod card_plugin;
+pub mod font_plugin;
 pub mod feedback_anim_plugin;
 pub mod challenge_plugin;
 pub mod cursor_plugin;
@@ -59,9 +60,10 @@ pub use feedback_anim_plugin::{
 pub use auto_complete_plugin::AutoCompletePlugin;
 pub use audio_plugin::{AudioPlugin, AudioState, SoundLibrary};
 pub use card_plugin::{
-    CardEntity, CardLabel, CardPlugin, HintHighlight, HintHighlightTimer, RightClickHighlight,
-    RightClickHighlightTimer,
+    CardEntity, CardImageSet, CardLabel, CardPlugin, HintHighlight, HintHighlightTimer,
+    RightClickHighlight, RightClickHighlightTimer,
 };
+pub use font_plugin::{FontPlugin, FontResource};
 pub use cursor_plugin::CursorPlugin;
 pub use events::{
     AchievementUnlockedEvent, CardFaceRevealedEvent, CardFlippedEvent, DrawRequestEvent,

solitaire_engine/src/table_plugin.rs

@@ -11,9 +11,21 @@ use solitaire_core::pile::PileType;
 use solitaire_data::settings::Theme;
 
 use crate::events::HintVisualEvent;
-use crate::layout::{compute_layout, Layout, LayoutResource, TABLE_COLOUR};
+use crate::layout::{compute_layout, Layout, LayoutResource};
+#[cfg(test)]
+use crate::layout::TABLE_COLOUR;
 use crate::settings_plugin::{SettingsChangedEvent, SettingsResource};
 
+/// Holds pre-loaded [`Handle<Image>`]s for the 5 selectable table backgrounds.
+///
+/// Loaded once at startup by [`load_background_images`].  Index 0 is the
+/// default; indices 1–4 are unlockable.
+#[derive(Resource)]
+pub struct BackgroundImageSet {
+    /// One handle per background slot (indices 0–4).
+    pub handles: Vec<Handle<Image>>,
+}
+
 /// Z-depth used for the background — below everything.
 const Z_BACKGROUND: f32 = -10.0;
 /// Z-depth used for pile markers — below cards (which start at 0) but above
@@ -50,6 +62,7 @@ impl Plugin for TablePlugin {
         app.add_message::<WindowResized>()
             .add_message::<SettingsChangedEvent>()
             .add_message::<HintVisualEvent>()
+            .add_systems(Startup, load_background_images.before(setup_table))
             .add_systems(Startup, setup_table)
             .add_systems(
                 Update,
@@ -63,7 +76,50 @@ impl Plugin for TablePlugin {
     }
 }
 
+/// Loads the 5 background PNG files at startup and stores their
+/// [`Handle<Image>`]s in [`BackgroundImageSet`].
+///
+/// The PNGs are embedded at compile time via `include_bytes!()`.  If a file
+/// is missing the build will fail with a clear error rather than a runtime
+/// panic.
+fn load_background_images(images: Option<ResMut<Assets<Image>>>, mut commands: Commands) {
+    let Some(mut images) = images else {
+        // Assets<Image> is absent (e.g. MinimalPlugins in tests) — insert an
+        // empty set so setup_table can proceed using a default handle.
+        commands.insert_resource(BackgroundImageSet { handles: Vec::new() });
+        return;
+    };
+    const BG_BYTES: [&[u8]; 5] = [
+        include_bytes!("../../assets/backgrounds/bg_0.png"),
+        include_bytes!("../../assets/backgrounds/bg_1.png"),
+        include_bytes!("../../assets/backgrounds/bg_2.png"),
+        include_bytes!("../../assets/backgrounds/bg_3.png"),
+        include_bytes!("../../assets/backgrounds/bg_4.png"),
+    ];
+    let handles = BG_BYTES
+        .iter()
+        .map(|bytes| {
+            use bevy::image::{CompressedImageFormats, ImageSampler, ImageType};
+            let image = Image::from_buffer(
+                bytes,
+                ImageType::Extension("png"),
+                CompressedImageFormats::NONE,
+                true,
+                ImageSampler::default(),
+                bevy::asset::RenderAssetUsages::RENDER_WORLD,
+            )
+            .expect("valid background PNG");
+            images.add(image)
+        })
+        .collect();
+    commands.insert_resource(BackgroundImageSet { handles });
+}
+
 /// Returns the felt colour for a given theme.
+///
+/// Only used in tests — the runtime path now picks a PNG image via
+/// [`BackgroundImageSet`] rather than a solid colour.
+#[cfg(test)]
 fn theme_colour(theme: &Theme) -> Color {
     match theme {
         Theme::Green => Color::srgb(TABLE_COLOUR[0], TABLE_COLOUR[1], TABLE_COLOUR[2]),
@@ -74,6 +130,10 @@ fn theme_colour(theme: &Theme) -> Color {
 
 /// Effective table background colour: unlocked background index overrides the
 /// Theme when `selected_background > 0`.
+///
+/// Only used in tests — the runtime path now picks a PNG image via
+/// [`BackgroundImageSet`] rather than a solid colour.
+#[cfg(test)]
 fn effective_background_colour(theme: &Theme, selected_background: usize) -> Color {
     match selected_background {
         0 => theme_colour(theme),
@@ -93,6 +153,7 @@ fn setup_table(
     windows: Query<&Window>,
     existing_camera: Query<(), With<Camera>>,
     settings: Option<Res<SettingsResource>>,
+    bg_images: Option<Res<BackgroundImageSet>>,
 ) {
     // Only spawn a camera if one does not already exist (e.g. a parent app
     // may have added one in tests).
@@ -107,23 +168,34 @@ fn setup_table(
         .unwrap_or(Vec2::new(1280.0, 800.0));
     let layout = compute_layout(window_size);
 
-    let initial_colour = settings
+    let selected_bg = settings
         .as_ref()
-        .map(|s| effective_background_colour(&s.0.theme, s.0.selected_background))
-        .unwrap_or_else(|| Color::srgb(TABLE_COLOUR[0], TABLE_COLOUR[1], TABLE_COLOUR[2]));
+        .map(|s| s.0.selected_background)
+        .unwrap_or(0);
 
-    spawn_background(&mut commands, window_size, initial_colour);
+    let image_handle = bg_images
+        .as_ref()
+        .and_then(|set| set.handles.get(selected_bg).cloned())
+        .unwrap_or_default();
+
+    spawn_background(&mut commands, window_size, image_handle);
     spawn_pile_markers(&mut commands, &layout);
     commands.insert_resource(LayoutResource(layout));
 }
 
-fn spawn_background(commands: &mut Commands, window_size: Vec2, color: Color) {
-    // Spawn a felt-coloured rectangle that always covers the window. We give
-    // it the window size plus headroom so resizing up doesn't expose edges
-    // before the resize handler runs.
+/// Spawns the felt background sprite using a PNG image handle.
+///
+/// The sprite covers the window at twice the window size so brief resize gaps
+/// are never visible.  The image is tinted `Color::WHITE` (no tint) so the PNG
+/// pixel data is rendered as-is.
+fn spawn_background(commands: &mut Commands, window_size: Vec2, image: Handle<Image>) {
+    // Spawn a sprite covering the window. We give it the window size plus
+    // headroom so resizing up doesn't expose edges before the resize handler
+    // runs.
     commands.spawn((
         Sprite {
-            color,
+            image,
+            color: Color::WHITE,
             custom_size: Some(window_size * 2.0),
             ..default()
         },
@@ -132,16 +204,30 @@ fn spawn_background(commands: &mut Commands, window_size: Vec2, color: Color) {
     ));
 }
 
+/// Reacts to settings changes by updating the background sprite's image handle.
+///
+/// When [`BackgroundImageSet`] is available the selected PNG handle is applied
+/// directly (color is kept at `Color::WHITE` so the PNG pixel data shows
+/// unmodified).  If the resource is not yet ready the sprite is left unchanged.
 fn apply_theme_on_settings_change(
     mut events: MessageReader<SettingsChangedEvent>,
     mut backgrounds: Query<&mut Sprite, With<TableBackground>>,
+    bg_images: Option<Res<BackgroundImageSet>>,
 ) {
     let Some(ev) = events.read().last() else {
         return;
     };
-    let colour = effective_background_colour(&ev.0.theme, ev.0.selected_background);
+    let Some(set) = bg_images else {
+        // BackgroundImageSet not ready yet — leave sprite unchanged.
+        return;
+    };
+    let selected = ev.0.selected_background;
+    let Some(handle) = set.handles.get(selected).cloned() else {
+        return;
+    };
     for mut sprite in &mut backgrounds {
-        sprite.color = colour;
+        sprite.image = handle.clone();
+        sprite.color = Color::WHITE;
     }
 }