fix(web): resolve wasm32 runtime panics; game boots and renders in Firefox

Fixes found while testing the Bevy WASM build in a real browser:

1. chrono wasmbind: add `wasmbind` feature to workspace chrono dep so
   Local::now()/Utc::now() use js-sys::Date on wasm32 (previously
   fell through to std::time::SystemTime which panics on wasm32).

2. std::time::SystemTime: replace all remaining direct SystemTime::now()
   calls (4 sites across game_plugin, difficulty_plugin, time_attack_plugin,
   solitaire_data/storage) with chrono::Utc::now() which is wasm32-safe.

3. user_dir: return empty PathBuf (instead of panicking) when data_dir()
   is None on wasm32; there is no filesystem in the browser so user themes
   are unsupported and a benign empty path is correct.

4. ThemeRegistryPlugin: gate build_registry_on_startup to non-wasm32
   (the filesystem scan for user themes has nothing to scan in the browser;
   only the bundled embedded themes are available).

5. AssetMetaCheck::Never: configure AssetPlugin in solitaire_web to skip
   `.meta` sidecar fetches — we don't ship .meta files, so the default
   AssetMetaCheck::Always produced a 404 flood on every card/background asset.

Result: `http://localhost:<port>/play` boots in Firefox with zero errors
and renders the full Bevy game — home screen, onboarding modal, HUD all
visible. Assets load correctly from /assets/. Chromium has a separate
wgpu-27/ANGLE/GLES shader translation bug (not in our code); Firefox works.

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

Cargo.toml

@@ -22,7 +22,7 @@ rust-version = "1.95"
 serde       = { version = "1", features = ["derive"] }
 serde_json  = "1"
 uuid        = { version = "1", features = ["v4", "serde"] }
-chrono      = { version = "0.4", features = ["serde"] }
+chrono      = { version = "0.4", features = ["serde", "wasmbind"] }
 thiserror   = "2"
 rand        = "0.9"
 async-trait = "0.1"

solitaire_data/src/storage.rs

@@ -6,7 +6,7 @@
 use std::fs;
 use std::io;
 use std::path::{Path, PathBuf};
-use std::time::{SystemTime, UNIX_EPOCH};
+use chrono::Utc;
 
 use serde::{Deserialize, Serialize};
 use solitaire_core::game_state::{GAME_STATE_SCHEMA_VERSION, GameState};
@@ -234,9 +234,7 @@ pub fn load_time_attack_session_from_at(
 /// See [`load_time_attack_session_from_at`] for the rules under which
 /// the call returns `None` (missing file, corrupt JSON, expired window).
 pub fn load_time_attack_session_from(path: &Path) -> Option<TimeAttackSession> {
-    let now = SystemTime::now()
-        .duration_since(UNIX_EPOCH)
-        .map_or(0, |d| d.as_secs());
+    let now = Utc::now().timestamp().max(0) as u64;
     load_time_attack_session_from_at(path, now)
 }
 
@@ -254,9 +252,7 @@ pub fn delete_time_attack_session_at(path: &Path) -> io::Result<()> {
 /// current wall-clock time. Equivalent to constructing the struct
 /// manually and setting `saved_at_unix_secs` to `SystemTime::now()`.
 pub fn time_attack_session_with_now(remaining_secs: f32, wins: u32) -> TimeAttackSession {
-    let now = SystemTime::now()
-        .duration_since(UNIX_EPOCH)
-        .map_or(0, |d| d.as_secs());
+    let now = Utc::now().timestamp().max(0) as u64;
     TimeAttackSession {
         remaining_secs,
         wins,

solitaire_engine/src/assets/user_dir.rs

@@ -82,13 +82,23 @@ fn user_theme_dir_for(data_dir: PathBuf) -> PathBuf {
 /// the panic message names the supported workaround.
 fn detected_platform_data_dir() -> PathBuf {
     solitaire_data::data_dir().unwrap_or_else(|| {
-        panic!(
-            "user_theme_dir(): platform data directory is unavailable. \
-             On Linux check $XDG_DATA_HOME or $HOME; on macOS / Windows \
-             the OS reported no Application Support / AppData path. \
-             As a workaround call solitaire_engine::assets::user_dir::\
-             set_user_theme_dir() before App::run()."
-        )
+        // On wasm32, data_dir() always returns None — there is no filesystem.
+        // User themes are not supported in the browser build; return an empty
+        // path so callers produce a benign empty dir rather than panicking.
+        #[cfg(target_arch = "wasm32")]
+        {
+            PathBuf::new()
+        }
+        #[cfg(not(target_arch = "wasm32"))]
+        {
+            panic!(
+                "user_theme_dir(): platform data directory is unavailable. \
+                 On Linux check $XDG_DATA_HOME or $HOME; on macOS / Windows \
+                 the OS reported no Application Support / AppData path. \
+                 As a workaround call solitaire_engine::assets::user_dir::\
+                 set_user_theme_dir() before App::run()."
+            )
+        }
     })
 }
 

solitaire_engine/src/difficulty_plugin.rs

@@ -14,7 +14,7 @@
 //! because the starting position is effectively random (player-chosen timing
 //! determines which seed in the 40-entry catalog they start at).
 
-use std::time::{SystemTime, UNIX_EPOCH};
+use chrono::Utc;
 
 use bevy::prelude::*;
 use solitaire_core::game_state::{DifficultyLevel, GameMode};
@@ -104,10 +104,9 @@ fn handle_difficulty_request(
 }
 
 fn seed_from_system_time() -> u64 {
-    SystemTime::now()
-        .duration_since(UNIX_EPOCH)
-        .map(|d| d.as_nanos() as u64)
-        .unwrap_or(0xD1FF_0000_DEAD_BEEF)
+    // Use chrono so this works on wasm32 (chrono has the `wasmbind` feature;
+    // std::time::SystemTime panics on wasm32-unknown-unknown).
+    Utc::now().timestamp_nanos_opt().unwrap_or(0) as u64
 }
 
 // ---------------------------------------------------------------------------

solitaire_engine/src/game_plugin.rs

@@ -7,12 +7,12 @@
 //! file is deleted so the next launch starts fresh.
 
 use std::path::PathBuf;
-use std::time::{SystemTime, UNIX_EPOCH};
+
+use chrono::Utc;
 
 use bevy::prelude::*;
 use bevy::tasks::{AsyncComputeTaskPool, Task, futures_lite::future};
 use bevy::window::AppLifecycle;
-use chrono::Utc;
 use solitaire_core::game_state::{DrawMode, GameMode, GameState};
 use klondike::KlondikePile;
 use solitaire_core::solver::{SolverConfig, SolverResult, try_solve};
@@ -312,9 +312,7 @@ fn tick_elapsed_time(
 }
 
 fn seed_from_system_time() -> u64 {
-    SystemTime::now()
-        .duration_since(UNIX_EPOCH)
-        .map_or(0, |d| d.as_nanos() as u64)
+    Utc::now().timestamp_nanos_opt().unwrap_or(0) as u64
 }
 
 /// Walks forward from `initial_seed` (incrementing by 1 with wrapping

solitaire_engine/src/theme/registry.rs

@@ -85,13 +85,18 @@ pub struct ThemeRegistryPlugin;
 
 impl Plugin for ThemeRegistryPlugin {
     fn build(&self, app: &mut App) {
-        app.init_resource::<ThemeRegistry>()
-            .add_systems(Startup, build_registry_on_startup);
+        app.init_resource::<ThemeRegistry>();
+        // User-themes directory scan requires a filesystem. On wasm32 there
+        // is no filesystem so the scan is skipped; the bundled default theme
+        // (from the EmbeddedAssetRegistry) is all that's available.
+        #[cfg(not(target_arch = "wasm32"))]
+        app.add_systems(Startup, build_registry_on_startup);
     }
 }
 
 /// Reads `user_theme_dir()` and replaces the registry's contents with
 /// the bundled default plus every valid user theme.
+#[cfg(not(target_arch = "wasm32"))]
 fn build_registry_on_startup(mut registry: bevy::ecs::system::ResMut<ThemeRegistry>) {
     *registry = build_registry(&user_theme_dir());
 }

solitaire_engine/src/time_attack_plugin.rs

@@ -22,7 +22,8 @@
 //! was closed, the file is treated as missing.
 
 use std::path::PathBuf;
-use std::time::{SystemTime, UNIX_EPOCH};
+
+use chrono::Utc;
 
 use bevy::prelude::*;
 use solitaire_core::game_state::GameMode;
@@ -222,9 +223,9 @@ fn auto_deal_on_time_attack_win(
 /// the system time predates the epoch (impossible under any sane clock,
 /// but the fallback keeps the function infallible).
 fn current_unix_secs() -> u64 {
-    SystemTime::now()
-        .duration_since(UNIX_EPOCH)
-        .map_or(0, |d| d.as_secs())
+    // Use chrono so this works on wasm32 (chrono has the `wasmbind` feature;
+    // std::time::SystemTime panics on wasm32-unknown-unknown).
+    Utc::now().timestamp().max(0) as u64
 }
 
 /// Periodically persists the live `TimeAttackResource` to

solitaire_server/web/pkg/canvas.js

@@ -1,5 +1,3 @@
-/* @ts-self-types="./canvas.d.ts" */
-
 export function start() {
     wasm.start();
 }
@@ -1651,62 +1649,62 @@ function __wbg_get_imports() {
             return ret;
         },
         __wbindgen_cast_0000000000000001: function(arg0, arg1) {
-            // Cast intrinsic for `Closure(Closure { owned: true, function: Function { arguments: [Externref], shim_idx: 114649, ret: Result(Unit), inner_ret: Some(Result(Unit)) }, mutable: true }) -> Externref`.
+            // Cast intrinsic for `Closure(Closure { owned: true, function: Function { arguments: [Externref], shim_idx: 114646, ret: Result(Unit), inner_ret: Some(Result(Unit)) }, mutable: true }) -> Externref`.
             const ret = makeMutClosure(arg0, arg1, wasm_bindgen__convert__closures_____invoke__hf0188236128725a8);
             return ret;
         },
         __wbindgen_cast_0000000000000002: function(arg0, arg1) {
-            // Cast intrinsic for `Closure(Closure { owned: true, function: Function { arguments: [Externref], shim_idx: 9793, ret: Unit, inner_ret: Some(Unit) }, mutable: true }) -> Externref`.
+            // Cast intrinsic for `Closure(Closure { owned: true, function: Function { arguments: [Externref], shim_idx: 9790, ret: Unit, inner_ret: Some(Unit) }, mutable: true }) -> Externref`.
             const ret = makeMutClosure(arg0, arg1, wasm_bindgen__convert__closures_____invoke__h038e9392efba509b);
             return ret;
         },
         __wbindgen_cast_0000000000000003: function(arg0, arg1) {
-            // Cast intrinsic for `Closure(Closure { owned: true, function: Function { arguments: [NamedExternref("Array<any>"), NamedExternref("ResizeObserver")], shim_idx: 9795, ret: Unit, inner_ret: Some(Unit) }, mutable: true }) -> Externref`.
+            // Cast intrinsic for `Closure(Closure { owned: true, function: Function { arguments: [NamedExternref("Array<any>"), NamedExternref("ResizeObserver")], shim_idx: 9792, ret: Unit, inner_ret: Some(Unit) }, mutable: true }) -> Externref`.
             const ret = makeMutClosure(arg0, arg1, wasm_bindgen__convert__closures_____invoke__hb8334c8e03ee5ee1);
             return ret;
         },
         __wbindgen_cast_0000000000000004: function(arg0, arg1) {
-            // Cast intrinsic for `Closure(Closure { owned: true, function: Function { arguments: [NamedExternref("Array<any>")], shim_idx: 9793, ret: Unit, inner_ret: Some(Unit) }, mutable: true }) -> Externref`.
+            // Cast intrinsic for `Closure(Closure { owned: true, function: Function { arguments: [NamedExternref("Array<any>")], shim_idx: 9790, ret: Unit, inner_ret: Some(Unit) }, mutable: true }) -> Externref`.
             const ret = makeMutClosure(arg0, arg1, wasm_bindgen__convert__closures_____invoke__h038e9392efba509b_3);
             return ret;
         },
         __wbindgen_cast_0000000000000005: function(arg0, arg1) {
-            // Cast intrinsic for `Closure(Closure { owned: true, function: Function { arguments: [NamedExternref("Event")], shim_idx: 9793, ret: Unit, inner_ret: Some(Unit) }, mutable: true }) -> Externref`.
+            // Cast intrinsic for `Closure(Closure { owned: true, function: Function { arguments: [NamedExternref("Event")], shim_idx: 9790, ret: Unit, inner_ret: Some(Unit) }, mutable: true }) -> Externref`.
             const ret = makeMutClosure(arg0, arg1, wasm_bindgen__convert__closures_____invoke__h038e9392efba509b_4);
             return ret;
         },
         __wbindgen_cast_0000000000000006: function(arg0, arg1) {
-            // Cast intrinsic for `Closure(Closure { owned: true, function: Function { arguments: [NamedExternref("FocusEvent")], shim_idx: 9793, ret: Unit, inner_ret: Some(Unit) }, mutable: true }) -> Externref`.
+            // Cast intrinsic for `Closure(Closure { owned: true, function: Function { arguments: [NamedExternref("FocusEvent")], shim_idx: 9790, ret: Unit, inner_ret: Some(Unit) }, mutable: true }) -> Externref`.
             const ret = makeMutClosure(arg0, arg1, wasm_bindgen__convert__closures_____invoke__h038e9392efba509b_5);
             return ret;
         },
         __wbindgen_cast_0000000000000007: function(arg0, arg1) {
-            // Cast intrinsic for `Closure(Closure { owned: true, function: Function { arguments: [NamedExternref("KeyboardEvent")], shim_idx: 9793, ret: Unit, inner_ret: Some(Unit) }, mutable: true }) -> Externref`.
+            // Cast intrinsic for `Closure(Closure { owned: true, function: Function { arguments: [NamedExternref("KeyboardEvent")], shim_idx: 9790, ret: Unit, inner_ret: Some(Unit) }, mutable: true }) -> Externref`.
             const ret = makeMutClosure(arg0, arg1, wasm_bindgen__convert__closures_____invoke__h038e9392efba509b_6);
             return ret;
         },
         __wbindgen_cast_0000000000000008: function(arg0, arg1) {
-            // Cast intrinsic for `Closure(Closure { owned: true, function: Function { arguments: [NamedExternref("PageTransitionEvent")], shim_idx: 9793, ret: Unit, inner_ret: Some(Unit) }, mutable: true }) -> Externref`.
+            // Cast intrinsic for `Closure(Closure { owned: true, function: Function { arguments: [NamedExternref("PageTransitionEvent")], shim_idx: 9790, ret: Unit, inner_ret: Some(Unit) }, mutable: true }) -> Externref`.
             const ret = makeMutClosure(arg0, arg1, wasm_bindgen__convert__closures_____invoke__h038e9392efba509b_7);
             return ret;
         },
         __wbindgen_cast_0000000000000009: function(arg0, arg1) {
-            // Cast intrinsic for `Closure(Closure { owned: true, function: Function { arguments: [NamedExternref("PointerEvent")], shim_idx: 9793, ret: Unit, inner_ret: Some(Unit) }, mutable: true }) -> Externref`.
+            // Cast intrinsic for `Closure(Closure { owned: true, function: Function { arguments: [NamedExternref("PointerEvent")], shim_idx: 9790, ret: Unit, inner_ret: Some(Unit) }, mutable: true }) -> Externref`.
             const ret = makeMutClosure(arg0, arg1, wasm_bindgen__convert__closures_____invoke__h038e9392efba509b_8);
             return ret;
         },
         __wbindgen_cast_000000000000000a: function(arg0, arg1) {
-            // Cast intrinsic for `Closure(Closure { owned: true, function: Function { arguments: [NamedExternref("WheelEvent")], shim_idx: 9793, ret: Unit, inner_ret: Some(Unit) }, mutable: true }) -> Externref`.
+            // Cast intrinsic for `Closure(Closure { owned: true, function: Function { arguments: [NamedExternref("WheelEvent")], shim_idx: 9790, ret: Unit, inner_ret: Some(Unit) }, mutable: true }) -> Externref`.
             const ret = makeMutClosure(arg0, arg1, wasm_bindgen__convert__closures_____invoke__h038e9392efba509b_9);
             return ret;
         },
         __wbindgen_cast_000000000000000b: function(arg0, arg1) {
-            // Cast intrinsic for `Closure(Closure { owned: true, function: Function { arguments: [Option(NamedExternref("Blob"))], shim_idx: 9803, ret: Unit, inner_ret: Some(Unit) }, mutable: true }) -> Externref`.
+            // Cast intrinsic for `Closure(Closure { owned: true, function: Function { arguments: [Option(NamedExternref("Blob"))], shim_idx: 9800, ret: Unit, inner_ret: Some(Unit) }, mutable: true }) -> Externref`.
             const ret = makeMutClosure(arg0, arg1, wasm_bindgen__convert__closures_____invoke__h618c0cad9a289a93);
             return ret;
         },
         __wbindgen_cast_000000000000000c: function(arg0, arg1) {
-            // Cast intrinsic for `Closure(Closure { owned: true, function: Function { arguments: [], shim_idx: 9797, ret: Unit, inner_ret: Some(Unit) }, mutable: true }) -> Externref`.
+            // Cast intrinsic for `Closure(Closure { owned: true, function: Function { arguments: [], shim_idx: 9794, ret: Unit, inner_ret: Some(Unit) }, mutable: true }) -> Externref`.
             const ret = makeMutClosure(arg0, arg1, wasm_bindgen__convert__closures_____invoke__h277d9d6b389a2871);
             return ret;
         },

solitaire_web/src/lib.rs

@@ -9,6 +9,7 @@
 //! - Storage is handled automatically by `WasmStorage` (localStorage-backed),
 //!   wired by `CoreGamePlugin` via `default_storage_backend()`.
 
+use bevy::asset::AssetMetaCheck;
 use bevy::prelude::*;
 use bevy::window::{Window, WindowPlugin};
 use solitaire_data::LocalOnlyProvider;
@@ -21,19 +22,27 @@ pub fn start() {
 
     App::new()
         .add_plugins(
-            DefaultPlugins.set(WindowPlugin {
-                primary_window: Some(Window {
-                    // Bind to the existing <canvas id="bevy-canvas"> in play.html.
-                    // Without this, Bevy appends its own canvas to <body>.
-                    canvas: Some("#bevy-canvas".into()),
-                    // Let CSS size the canvas; Bevy follows the element's size.
-                    fit_canvas_to_parent: true,
-                    // Prevent the browser stealing keyboard events and scroll.
-                    prevent_default_event_handling: true,
+            DefaultPlugins
+                .set(WindowPlugin {
+                    primary_window: Some(Window {
+                        // Bind to the existing <canvas id="bevy-canvas"> in play.html.
+                        // Without this, Bevy appends its own canvas to <body>.
+                        canvas: Some("#bevy-canvas".into()),
+                        // Let CSS size the canvas; Bevy follows the element's size.
+                        fit_canvas_to_parent: true,
+                        // Prevent the browser stealing keyboard events and scroll.
+                        prevent_default_event_handling: true,
+                        ..default()
+                    }),
+                    ..default()
+                })
+                // Bevy's default AssetPlugin fetches a `.meta` sidecar file for
+                // every asset before loading the asset itself. We don't ship
+                // `.meta` files, so skip the check to avoid a flood of 404s.
+                .set(AssetPlugin {
+                    meta_check: AssetMetaCheck::Never,
                     ..default()
                 }),
-                ..default()
-            }),
         )
         // LocalOnlyProvider disables cloud sync — correct for the web build
         // since SyncPlugin is cfg-gated out on wasm32 anyway.