feat(web): add solitaire_web Bevy WASM build targeting play.html canvas

Adds a new `solitaire_web` crate that compiles the full `solitaire_engine`
to `wasm32-unknown-unknown` and renders to a `<canvas id="bevy-canvas">`
element in `play.html` — the same ECS code path as desktop and Android.

Changes to enable the WASM target:
- .cargo/config.toml: add wasm32-unknown-unknown rustflags for getrandom
- Workspace Cargo.toml: add solitaire_web member
- solitaire_data/Cargo.toml: gate tokio/reqwest/dirs/keyring to non-wasm
- solitaire_data/src: add wasm32 branch to data_dir() (returns None);
  cfg-gate sync_client network types, auth_tokens, matomo_client
- solitaire_engine/Cargo.toml: gate tokio/reqwest/kira/arboard/dirs/zip
  to non-wasm (mio/cpal/arboard don't compile for wasm32-unknown-unknown)
- solitaire_engine/src/lib.rs: cfg-gate module declarations and re-exports
  for analytics, audio, sync, sync_setup, avatar, leaderboard plugins
- solitaire_engine/src/core_game_plugin.rs: cfg-gate plugin registrations
  that require TokioRuntime (audio, sync, analytics, leaderboard, avatar)
- solitaire_engine/src/resources.rs: cfg-gate TokioRuntimeResource
- solitaire_engine/src/game_plugin.rs: cfg-gate std::fs::remove_file (x10)
- solitaire_engine/src/theme/mod.rs: cfg-gate importer module (uses dirs+zip)
- solitaire_engine/src/settings_plugin.rs: cfg-gate theme ZIP import UI
- solitaire_engine/src/assets/sources.rs: cfg-gate FileAssetReader/user_theme_dir
- solitaire_engine/src/auto_complete_plugin.rs: cfg-gate audio system
- solitaire_engine/src/daily_challenge_plugin.rs: cfg-gate server fetch
- solitaire_engine/src/hud_plugin.rs: cfg-gate AvatarResource import
- solitaire_engine/src/profile_plugin.rs: cfg-gate AvatarResource import
- solitaire_server/web/play.html: minimal HTML canvas shell
- solitaire_web/: new crate (Cargo.toml + src/lib.rs)
- build_wasm.sh: add Bevy WASM build step (cargo + wasm-bindgen + wasm-opt)

All tests pass; clippy --workspace -- -D warnings clean; native build
(solitaire_engine, solitaire_app) unaffected.

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

.cargo/config.toml

@@ -1,2 +1,5 @@
 [registries.Quaternions]
 index = "sparse+https://git.aleshym.co/api/packages/Quaternions/cargo/"
+
+[target.wasm32-unknown-unknown]
+rustflags = ['--cfg', 'getrandom_backend="wasm_js"']

Cargo.lock

@@ -723,6 +723,28 @@ dependencies = [
  "android-activity",
 ]
 
+[[package]]
+name = "bevy_anti_alias"
+version = "0.18.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "726cc494eb7d6a84ce6291c23636fd451fa4846604dc059fa93febca4e60a928"
+dependencies = [
+ "bevy_app",
+ "bevy_asset",
+ "bevy_camera",
+ "bevy_core_pipeline",
+ "bevy_derive",
+ "bevy_diagnostic",
+ "bevy_ecs",
+ "bevy_image",
+ "bevy_math",
+ "bevy_reflect",
+ "bevy_render",
+ "bevy_shader",
+ "bevy_utils",
+ "tracing",
+]
+
 [[package]]
 name = "bevy_app"
 version = "0.18.1"
@@ -884,6 +906,35 @@ dependencies = [
  "syn",
 ]
 
+[[package]]
+name = "bevy_dev_tools"
+version = "0.18.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a4f1464a3f5ef5c23d917987714ee89881f9f791e9ff97ecf6600ee846b9569e"
+dependencies = [
+ "bevy_app",
+ "bevy_asset",
+ "bevy_camera",
+ "bevy_color",
+ "bevy_diagnostic",
+ "bevy_ecs",
+ "bevy_image",
+ "bevy_input",
+ "bevy_math",
+ "bevy_picking",
+ "bevy_reflect",
+ "bevy_render",
+ "bevy_shader",
+ "bevy_state",
+ "bevy_text",
+ "bevy_time",
+ "bevy_transform",
+ "bevy_ui",
+ "bevy_ui_render",
+ "bevy_window",
+ "tracing",
+]
+
 [[package]]
 name = "bevy_diagnostic"
 version = "0.18.1"
@@ -951,6 +1002,36 @@ dependencies = [
  "encase_derive_impl",
 ]
 
+[[package]]
+name = "bevy_feathers"
+version = "0.18.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1cb29be8f8443c5cc44e1c4710bbe02877e73703c60228ca043f20529a5496c6"
+dependencies = [
+ "accesskit",
+ "bevy_a11y",
+ "bevy_app",
+ "bevy_asset",
+ "bevy_camera",
+ "bevy_color",
+ "bevy_derive",
+ "bevy_ecs",
+ "bevy_input_focus",
+ "bevy_log",
+ "bevy_math",
+ "bevy_picking",
+ "bevy_platform",
+ "bevy_reflect",
+ "bevy_render",
+ "bevy_shader",
+ "bevy_text",
+ "bevy_ui",
+ "bevy_ui_render",
+ "bevy_ui_widgets",
+ "bevy_window",
+ "smol_str",
+]
+
 [[package]]
 name = "bevy_gizmos"
 version = "0.18.1"
@@ -1073,14 +1154,17 @@ checksum = "6a11df62e49897def470471551c02f13c6fb488e55dddb5ab7ef098132e07754"
 dependencies = [
  "bevy_a11y",
  "bevy_android",
+ "bevy_anti_alias",
  "bevy_app",
  "bevy_asset",
  "bevy_camera",
  "bevy_color",
  "bevy_core_pipeline",
  "bevy_derive",
+ "bevy_dev_tools",
  "bevy_diagnostic",
  "bevy_ecs",
+ "bevy_feathers",
  "bevy_gizmos_render",
  "bevy_image",
  "bevy_input",
@@ -1088,6 +1172,7 @@ dependencies = [
  "bevy_log",
  "bevy_math",
  "bevy_mesh",
+ "bevy_pbr",
  "bevy_platform",
  "bevy_ptr",
  "bevy_reflect",
@@ -1107,6 +1192,27 @@ dependencies = [
  "bevy_winit",
 ]
 
+[[package]]
+name = "bevy_light"
+version = "0.18.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4d9d2ac64390a9baacb3c0fa0f5456ac1553959d5a387874c102a09aab8b92cc"
+dependencies = [
+ "bevy_app",
+ "bevy_asset",
+ "bevy_camera",
+ "bevy_color",
+ "bevy_ecs",
+ "bevy_image",
+ "bevy_math",
+ "bevy_mesh",
+ "bevy_platform",
+ "bevy_reflect",
+ "bevy_transform",
+ "bevy_utils",
+ "tracing",
+]
+
 [[package]]
 name = "bevy_log"
 version = "0.18.1"
@@ -1167,7 +1273,9 @@ dependencies = [
  "bevy_asset",
  "bevy_derive",
  "bevy_ecs",
+ "bevy_image",
  "bevy_math",
+ "bevy_mikktspace",
  "bevy_platform",
  "bevy_reflect",
  "bevy_transform",
@@ -1180,6 +1288,71 @@ dependencies = [
  "wgpu-types",
 ]
 
+[[package]]
+name = "bevy_mikktspace"
+version = "0.17.0-dev"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7ef8e4b7e61dfe7719bb03c884dc270cd46a82efb40f93e9933b990c5c190c59"
+
+[[package]]
+name = "bevy_pbr"
+version = "0.18.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a5ab6944ffc6fd71604c0fbca68cc3e2a3654edfcdbfd232f9d8b88e3d20fdc0"
+dependencies = [
+ "bevy_app",
+ "bevy_asset",
+ "bevy_camera",
+ "bevy_color",
+ "bevy_core_pipeline",
+ "bevy_derive",
+ "bevy_diagnostic",
+ "bevy_ecs",
+ "bevy_image",
+ "bevy_light",
+ "bevy_log",
+ "bevy_math",
+ "bevy_mesh",
+ "bevy_platform",
+ "bevy_reflect",
+ "bevy_render",
+ "bevy_shader",
+ "bevy_transform",
+ "bevy_utils",
+ "bitflags 2.11.1",
+ "bytemuck",
+ "derive_more",
+ "fixedbitset",
+ "nonmax",
+ "offset-allocator",
+ "smallvec",
+ "static_assertions",
+ "thiserror 2.0.18",
+ "tracing",
+]
+
+[[package]]
+name = "bevy_picking"
+version = "0.18.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b7d524dbc8f2c9e73f7ab70c148c8f7886f3c24b8aa8c252a38ba68ed06cbf10"
+dependencies = [
+ "bevy_app",
+ "bevy_asset",
+ "bevy_camera",
+ "bevy_derive",
+ "bevy_ecs",
+ "bevy_input",
+ "bevy_math",
+ "bevy_platform",
+ "bevy_reflect",
+ "bevy_time",
+ "bevy_transform",
+ "bevy_window",
+ "tracing",
+ "uuid",
+]
+
 [[package]]
 name = "bevy_platform"
 version = "0.18.1"
@@ -1506,6 +1679,7 @@ dependencies = [
  "bevy_input",
  "bevy_input_focus",
  "bevy_math",
+ "bevy_picking",
  "bevy_platform",
  "bevy_reflect",
  "bevy_sprite",
@@ -1518,6 +1692,7 @@ dependencies = [
  "taffy",
  "thiserror 2.0.18",
  "tracing",
+ "uuid",
 ]
 
 [[package]]
@@ -1551,6 +1726,26 @@ dependencies = [
  "tracing",
 ]
 
+[[package]]
+name = "bevy_ui_widgets"
+version = "0.18.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b6a63cb818b0de41bdb14990e0ce1aaaa347f871750ab280f80c427e83d72712"
+dependencies = [
+ "accesskit",
+ "bevy_a11y",
+ "bevy_app",
+ "bevy_camera",
+ "bevy_ecs",
+ "bevy_input",
+ "bevy_input_focus",
+ "bevy_log",
+ "bevy_math",
+ "bevy_picking",
+ "bevy_reflect",
+ "bevy_ui",
+]
+
 [[package]]
 name = "bevy_utils"
 version = "0.18.1"
@@ -1678,6 +1873,7 @@ version = "2.11.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "c4512299f36f043ab09a583e57bceb5a5aab7a73db1805848e8fef3c9e8c78b3"
 dependencies = [
+ "bytemuck",
  "serde_core",
 ]
 
@@ -3483,6 +3679,17 @@ dependencies = [
  "weezl",
 ]
 
+[[package]]
+name = "gl_generator"
+version = "0.14.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1a95dfc23a2b4a9a2f5ab41d194f8bfda3cabec42af4e39f08c339eb2a0c124d"
+dependencies = [
+ "khronos_api",
+ "log",
+ "xml-rs",
+]
+
 [[package]]
 name = "glam"
 version = "0.30.10"
@@ -3511,6 +3718,27 @@ version = "0.3.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0cc23270f6e1808e30a928bdc84dea0b9b4136a8bc82338574f23baf47bbd280"
 
+[[package]]
+name = "glow"
+version = "0.16.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c5e5ea60d70410161c8bf5da3fdfeaa1c72ed2c15f8bbb9d19fe3a4fad085f08"
+dependencies = [
+ "js-sys",
+ "slotmap",
+ "wasm-bindgen",
+ "web-sys",
+]
+
+[[package]]
+name = "glutin_wgl_sys"
+version = "0.6.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2c4ee00b289aba7a9e5306d57c2d05499b2e5dc427f84ac708bd2c090212cf3e"
+dependencies = [
+ "gl_generator",
+]
+
 [[package]]
 name = "governor"
 version = "0.10.4"
@@ -4335,6 +4563,23 @@ dependencies = [
  "uuid",
 ]
 
+[[package]]
+name = "khronos-egl"
+version = "6.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6aae1df220ece3c0ada96b8153459b67eebe9ae9212258bb0134ae60416fdf76"
+dependencies = [
+ "libc",
+ "libloading",
+ "pkg-config",
+]
+
+[[package]]
+name = "khronos_api"
+version = "3.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e2db585e1d738fc771bf08a151420d3ed193d9d895a36df7f6f8a9456b911ddc"
+
 [[package]]
 name = "kira"
 version = "0.12.0"
@@ -7146,6 +7391,18 @@ dependencies = [
  "web-sys",
 ]
 
+[[package]]
+name = "solitaire_web"
+version = "0.1.0"
+dependencies = [
+ "bevy",
+ "console_error_panic_hook",
+ "getrandom 0.3.4",
+ "solitaire_data",
+ "solitaire_engine",
+ "wasm-bindgen",
+]
+
 [[package]]
 name = "spin"
 version = "0.9.8"
@@ -9106,6 +9363,7 @@ dependencies = [
  "cfg_aliases",
  "document-features",
  "hashbrown 0.16.1",
+ "js-sys",
  "log",
  "naga",
  "portable-atomic",
@@ -9113,6 +9371,8 @@ dependencies = [
  "raw-window-handle",
  "smallvec",
  "static_assertions",
+ "wasm-bindgen",
+ "web-sys",
  "wgpu-core",
  "wgpu-hal",
  "wgpu-types",
@@ -9144,6 +9404,7 @@ dependencies = [
  "smallvec",
  "thiserror 2.0.18",
  "wgpu-core-deps-apple",
+ "wgpu-core-deps-wasm",
  "wgpu-core-deps-windows-linux-android",
  "wgpu-hal",
  "wgpu-types",
@@ -9158,6 +9419,15 @@ dependencies = [
  "wgpu-hal",
 ]
 
+[[package]]
+name = "wgpu-core-deps-wasm"
+version = "27.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9b1027dcf3b027a877e44819df7ceb0e2e98578830f8cd34cd6c3c7c2a7a50b7"
+dependencies = [
+ "wgpu-hal",
+]
+
 [[package]]
 name = "wgpu-core-deps-windows-linux-android"
 version = "27.0.0"
@@ -9183,15 +9453,20 @@ dependencies = [
  "cfg-if",
  "cfg_aliases",
  "core-graphics-types 0.2.0",
+ "glow",
+ "glutin_wgl_sys",
  "gpu-alloc",
  "gpu-allocator",
  "gpu-descriptor",
  "hashbrown 0.16.1",
+ "js-sys",
+ "khronos-egl",
  "libc",
  "libloading",
  "log",
  "metal",
  "naga",
+ "ndk-sys",
  "objc",
  "once_cell",
  "ordered-float",
@@ -9204,6 +9479,8 @@ dependencies = [
  "renderdoc-sys",
  "smallvec",
  "thiserror 2.0.18",
+ "wasm-bindgen",
+ "web-sys",
  "wgpu-types",
  "windows 0.58.0",
  "windows-core 0.58.0",
@@ -10086,6 +10363,12 @@ version = "0.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b9cc00251562a284751c9973bace760d86c0276c471b4be569fe6b068ee97a56"
 
+[[package]]
+name = "xml-rs"
+version = "0.8.28"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3ae8337f8a065cfc972643663ea4279e04e7256de865aa66fe25cec5fb912d3f"
+
 [[package]]
 name = "xmlwriter"
 version = "0.1.0"

Cargo.toml

@@ -8,6 +8,7 @@ members = [
     "solitaire_app",
     "solitaire_assetgen",
     "solitaire_wasm",
+    "solitaire_web",
 ]
 resolver = "2"
 

build_wasm.sh

@@ -1,18 +1,21 @@
 #!/usr/bin/env bash
-# Rebuild the solitaire_wasm crate and install the output into
+# Rebuild WASM artifacts and install them into solitaire_server/web/pkg/.
-# solitaire_server/web/pkg/ so the server can serve the replay viewer.
+#
+# Two artifacts are produced:
+#   solitaire_wasm.*  — thin replay-viewer + interactive JS API (wasm-pack)
+#   canvas.*          — full Bevy WASM app for play.html (cargo + wasm-bindgen)
 #
 # Prerequisites:
-#   cargo install wasm-pack
+#   cargo install wasm-pack wasm-bindgen-cli
 #   rustup target add wasm32-unknown-unknown
+#   (optional) cargo install wasm-opt   # for smaller canvas_bg.wasm
 #
 # Run from the repo root:
 #   ./build_wasm.sh
 #
-# The generated files (solitaire_wasm.js + solitaire_wasm_bg.wasm) are
+# The generated pkg/ files are committed to git so self-hosters who don't
-# committed to git so self-hosters who don't touch the WASM crate can
+# touch the WASM crates can skip this step.  Regenerate after any change to
-# skip this step.  Regenerate after any change to solitaire_wasm/ or
+# solitaire_wasm/, solitaire_web/, solitaire_engine/, or solitaire_core/.
-# solitaire_core/.
 
 set -euo pipefail
 
@@ -36,5 +39,38 @@ wasm-pack build \
 # Remove them — we manage the output directory ourselves.
 rm -f "$OUT_DIR/package.json" "$OUT_DIR/.gitignore"
 
+# ---------------------------------------------------------------------------
+# Bevy WASM app (solitaire_web → canvas.js + canvas_bg.wasm)
+# ---------------------------------------------------------------------------
+
+if ! command -v wasm-bindgen &> /dev/null; then
+    echo "error: wasm-bindgen not found." >&2
+    echo "  Install with: cargo install wasm-bindgen-cli" >&2
+    echo "  The CLI version must match the wasm-bindgen crate dep." >&2
+    exit 1
+fi
+
+echo "Building solitaire_web (Bevy WASM app)..."
+cargo build --release --target wasm32-unknown-unknown -p solitaire_web
+
+echo "Running wasm-bindgen for solitaire_web..."
+wasm-bindgen \
+    --out-dir "$OUT_DIR" \
+    --out-name canvas \
+    --target web \
+    "$REPO_ROOT/target/wasm32-unknown-unknown/release/solitaire_web.wasm"
+
+# Optional size optimisation — Bevy bundles are large (~5-15 MB uncompressed).
+# wasm-opt passes are skipped silently when the tool is not installed.
+if command -v wasm-opt &> /dev/null; then
+    echo "Running wasm-opt on canvas_bg.wasm..."
+    wasm-opt -Oz \
+        -o "$OUT_DIR/canvas_bg.wasm" \
+        "$OUT_DIR/canvas_bg.wasm"
+else
+    echo "note: wasm-opt not found; skipping size optimisation."
+    echo "  Install with: cargo install wasm-opt  (or via binaryen)"
+fi
+
 echo "Done. Output:"
 ls -lh "$OUT_DIR"

solitaire_data/Cargo.toml

@@ -12,11 +12,17 @@ serde_json     = { workspace = true }
 chrono         = { workspace = true }
 thiserror      = { workspace = true }
 async-trait    = { workspace = true }
+uuid           = { workspace = true }
+klondike       = { workspace = true }
+
+# These deps are not available / not needed on wasm32:
+#   dirs     — platform data directories (no filesystem on browser)
+#   reqwest  — native HTTP client (sync/analytics gated out on wasm32)
+#   tokio    — OS-threaded async runtime (mio doesn't compile on wasm32)
+[target.'cfg(not(target_arch = "wasm32"))'.dependencies]
 dirs           = { workspace = true }
 reqwest        = { workspace = true }
 tokio          = { workspace = true }
-uuid           = { workspace = true }
-klondike       = { workspace = true }
 
 # `keyring-core` is the typed Entry/Error API used by
 # `auth_tokens`. The crate's own dependency tree pulls in
@@ -25,7 +31,7 @@ klondike       = { workspace = true }
 # on bionic). On Android `auth_tokens` falls back to a stub
 # implementation that always returns `KeychainUnavailable`; the
 # real backend lands when we wire Android Keystore via JNI.
-[target.'cfg(not(target_os = "android"))'.dependencies]
+[target.'cfg(all(not(target_os = "android"), not(target_arch = "wasm32")))'.dependencies]
 keyring-core   = { workspace = true }
 
 [target.'cfg(target_os = "android")'.dependencies]

solitaire_data/src/lib.rs

@@ -146,13 +146,17 @@ pub use settings::{
 #[cfg(target_os = "android")]
 mod android_keystore;
 
+#[cfg(not(target_arch = "wasm32"))]
 pub mod auth_tokens;
+#[cfg(not(target_arch = "wasm32"))]
 pub use auth_tokens::{
     TokenError, delete_tokens, load_access_token, load_refresh_token, store_tokens,
 };
 
 pub mod sync_client;
-pub use sync_client::{LocalOnlyProvider, SolitaireServerClient, provider_for_backend};
+pub use sync_client::LocalOnlyProvider;
+#[cfg(not(target_arch = "wasm32"))]
+pub use sync_client::{SolitaireServerClient, provider_for_backend};
 
 pub mod replay;
 pub use replay::{
@@ -163,7 +167,9 @@ pub use replay::{
 #[allow(deprecated)]
 pub use replay::{latest_replay_path, load_latest_replay_from, save_latest_replay_to};
 
+#[cfg(not(target_arch = "wasm32"))]
 pub mod matomo_client;
+#[cfg(not(target_arch = "wasm32"))]
 pub use matomo_client::MatomoClient;
 
 pub mod platform;

solitaire_data/src/platform.rs

@@ -55,7 +55,15 @@ pub fn data_dir() -> Option<PathBuf> {
     {
         Some(PathBuf::from(ANDROID_APP_FILES_DIR))
     }
-    #[cfg(not(target_os = "android"))]
+    #[cfg(target_arch = "wasm32")]
+    {
+        // No filesystem on the browser; all persistence goes through
+        // WasmStorage (localStorage-backed). Return None so every caller
+        // degrades gracefully (the same path they take on a
+        // misconfigured desktop environment).
+        None
+    }
+    #[cfg(all(not(target_os = "android"), not(target_arch = "wasm32")))]
     {
         dirs::data_dir()
     }

solitaire_data/src/sync_client.rs

@@ -14,8 +14,10 @@
 use async_trait::async_trait;
 use solitaire_sync::{ChallengeGoal, LeaderboardEntry, SyncPayload, SyncResponse};
 
+use crate::{SyncError, SyncProvider};
+
+#[cfg(not(target_arch = "wasm32"))]
 use crate::{
-    SyncError, SyncProvider,
     auth_tokens::{load_access_token, load_refresh_token, store_tokens},
     replay::Replay,
     settings::SyncBackend,
@@ -54,12 +56,17 @@ impl SyncProvider for LocalOnlyProvider {
 // ---------------------------------------------------------------------------
 // SolitaireServerClient
 // ---------------------------------------------------------------------------
+// Native-only: HTTP sync client and factory function.
+// On wasm32 these are gated out because reqwest uses native OS networking
+// (mio + hyper) which does not compile for wasm32-unknown-unknown.
+// ---------------------------------------------------------------------------
 
 /// HTTP sync client for the self-hosted Ferrous Solitaire server.
 ///
 /// Authenticates via JWT stored in the OS keychain. On a 401 response the
 /// client automatically attempts a token refresh and retries the request once
 /// before returning an error.
+#[cfg(not(target_arch = "wasm32"))]
 pub struct SolitaireServerClient {
     /// Base URL of the server, e.g. `"https://solitaire.example.com"`.
     /// Trailing slashes are stripped on construction.
@@ -70,6 +77,7 @@ pub struct SolitaireServerClient {
     client: reqwest::Client,
 }
 
+#[cfg(not(target_arch = "wasm32"))]
 impl SolitaireServerClient {
     /// Construct a new client for the given server URL and username.
     ///
@@ -201,6 +209,7 @@ impl SolitaireServerClient {
     }
 }
 
+#[cfg(not(target_arch = "wasm32"))]
 #[async_trait]
 impl SyncProvider for SolitaireServerClient {
     /// Fetch the latest sync payload from the server.
@@ -486,6 +495,7 @@ impl SyncProvider for SolitaireServerClient {
     }
 }
 
+#[cfg(not(target_arch = "wasm32"))]
 impl SolitaireServerClient {
     /// Pulled out of `push_replay` so both the first attempt and the
     /// post-401-retry attempt go through the same parse path.
@@ -581,9 +591,10 @@ impl SolitaireServerClient {
 }
 
 // ---------------------------------------------------------------------------
-// Response extraction helpers
+// Response extraction helpers (native-only, use reqwest::Response)
 // ---------------------------------------------------------------------------
 
+#[cfg(not(target_arch = "wasm32"))]
 /// Deserialize a pull response body as [`SyncResponse`] and return its
 /// `merged` field, or map non-200 statuses to the appropriate [`SyncError`].
 ///
@@ -607,6 +618,7 @@ async fn extract_pull_body(resp: reqwest::Response) -> Result<SyncPayload, SyncE
     }
 }
 
+#[cfg(not(target_arch = "wasm32"))]
 /// Deserialize a leaderboard response body as `Vec<LeaderboardEntry>`.
 async fn extract_leaderboard_body(
     resp: reqwest::Response,
@@ -621,6 +633,7 @@ async fn extract_leaderboard_body(
     }
 }
 
+#[cfg(not(target_arch = "wasm32"))]
 /// Deserialize a push response body as [`SyncResponse`], or map non-200
 /// statuses to the appropriate [`SyncError`].
 ///
@@ -652,6 +665,7 @@ async fn extract_push_body(resp: reqwest::Response) -> Result<SyncResponse, Sync
 /// This is the **one** place in the codebase that matches on [`SyncBackend`]
 /// variants. All other code receives a `Box<dyn SyncProvider + Send + Sync>`
 /// and remains backend-agnostic.
+#[cfg(not(target_arch = "wasm32"))]
 pub fn provider_for_backend(backend: &SyncBackend) -> Box<dyn SyncProvider + Send + Sync> {
     match backend {
         SyncBackend::Local => Box::new(LocalOnlyProvider),

solitaire_engine/Cargo.toml

@@ -7,15 +7,12 @@ edition.workspace = true
 [dependencies]
 bevy           = { workspace = true }
 image          = { workspace = true }
-reqwest        = { workspace = true }
-kira           = { workspace = true }
 solitaire_core = { workspace = true }
 solitaire_data = { workspace = true }
 solitaire_sync = { workspace = true }
 klondike       = { workspace = true }
 chrono         = { workspace = true }
 uuid           = { workspace = true }
-tokio          = { workspace = true }
 serde          = { workspace = true }
 serde_json     = { workspace = true }
 thiserror      = { workspace = true }
@@ -23,17 +20,24 @@ usvg           = { workspace = true }
 resvg          = { workspace = true }
 tiny-skia      = { workspace = true }
 ron            = { workspace = true }
+
+# These deps are not available / not needed on wasm32:
+#   reqwest  — uses mio/hyper native networking (sync plugin is gated out)
+#   kira     — uses cpal OS audio (audio plugin is gated out)
+#   tokio    — multi-threaded runtime (TokioRuntimeResource is gated out)
+#   dirs     — platform data directories (storage uses WasmStorage instead)
+#   zip      — theme ZIP importer (importer is gated out on wasm32)
+#   arboard  — clipboard (no wasm backend; stats copy-link uses localStorage)
+[target.'cfg(not(target_arch = "wasm32"))'.dependencies]
+reqwest        = { workspace = true }
+kira           = { workspace = true }
+tokio          = { workspace = true }
 dirs           = { workspace = true }
 zip            = { workspace = true }
 
-# `arboard` provides clipboard access for the Stats overlay's
+# `arboard` has no Android backend and no wasm32 backend.  Gate it out for
-# "Copy share link" button. The crate has no Android backend
+# both; the copy-share-link button surfaces an informational toast instead.
-# (its `platform::Clipboard` module is unimplemented for the
+[target.'cfg(all(not(target_os = "android"), not(target_arch = "wasm32")))'.dependencies]
-# android target — `cargo apk build` fails with E0433 if this is
-# left unconditional). On Android the same button surfaces an
-# informational toast instead; see
-# `stats_plugin::handle_copy_share_link_button`.
-[target.'cfg(not(target_os = "android"))'.dependencies]
 arboard        = { workspace = true }
 
 [target.'cfg(target_os = "android")'.dependencies]

solitaire_engine/src/assets/sources.rs

@@ -50,9 +50,11 @@
 use bevy::asset::AssetApp;
 use bevy::asset::io::AssetSourceBuilder;
 use bevy::asset::io::embedded::EmbeddedAssetRegistry;
+#[cfg(not(target_arch = "wasm32"))]
 use bevy::asset::io::file::FileAssetReader;
 use bevy::prelude::*;
 
+#[cfg(not(target_arch = "wasm32"))]
 use crate::assets::user_dir::user_theme_dir;
 
 /// `AssetSourceId` of the user-themes asset source. Use it as
@@ -235,11 +237,16 @@ const CLASSIC_THEME_SVGS: &[(&str, &[u8])] = &[
 /// Returns the `&mut App` so the call can be chained from the binary
 /// entry point.
 pub fn register_theme_asset_sources(app: &mut App) -> &mut App {
+    // User themes are stored on the filesystem; wasm32 has no filesystem and
+    // `FileAssetReader` is not available on that target.
+    #[cfg(not(target_arch = "wasm32"))]
+    {
         let root = user_theme_dir();
         app.register_asset_source(
             USER_THEMES,
             AssetSourceBuilder::new(move || Box::new(FileAssetReader::new(root.clone()))),
         );
+    }
     app
 }
 

solitaire_engine/src/auto_complete_plugin.rs

@@ -11,6 +11,7 @@
 use bevy::prelude::*;
 use bevy::window::RequestRedraw;
 
+#[cfg(not(target_arch = "wasm32"))]
 use crate::audio_plugin::{AudioState, SoundLibrary};
 use crate::events::{MoveRequestEvent, StateChangedEvent};
 use crate::game_plugin::GameMutation;
@@ -97,6 +98,7 @@ fn detect_auto_complete(
 /// exactly once on the `false → true` edge. The win fanfare is played at half
 /// volume (`AUTO_COMPLETE_CHIME_VOLUME`) so it is clearly recognisable but does
 /// not overwhelm the card-place sounds that follow immediately.
+#[cfg(not(target_arch = "wasm32"))]
 fn on_auto_complete_start(
     state: Res<AutoCompleteState>,
     mut was_active: Local<bool>,
@@ -117,6 +119,12 @@ fn on_auto_complete_start(
     audio.play_sfx_at_volume(&lib.fanfare, AUTO_COMPLETE_CHIME_VOLUME);
 }
 
+// No audio on wasm — stub keeps the system registration unconditional.
+#[cfg(target_arch = "wasm32")]
+fn on_auto_complete_start(state: Res<AutoCompleteState>, mut was_active: Local<bool>) {
+    *was_active = state.active;
+}
+
 /// Fires one `MoveRequestEvent` per `STEP_INTERVAL` while auto-complete is active.
 fn drive_auto_complete(
     mut state: ResMut<AutoCompleteState>,

solitaire_engine/src/core_game_plugin.rs

@@ -13,16 +13,18 @@ use crate::platform::{
     default_storage_backend,
 };
 use crate::{
-    AchievementPlugin, AnalyticsPlugin, AnimationPlugin, AssetSourcesPlugin, AudioPlugin,
+    AchievementPlugin, AnimationPlugin, AssetSourcesPlugin, AutoCompletePlugin,
-    AutoCompletePlugin, AvatarPlugin, CardAnimationPlugin, CardPlugin, ChallengePlugin,
+    CardAnimationPlugin, CardPlugin, ChallengePlugin, CursorPlugin, DailyChallengePlugin,
-    CursorPlugin, DailyChallengePlugin, DiagnosticsHudPlugin, DifficultyPlugin, FeedbackAnimPlugin,
+    DiagnosticsHudPlugin, DifficultyPlugin, FeedbackAnimPlugin, FontPlugin, GamePlugin, HelpPlugin,
-    FontPlugin, GamePlugin, HelpPlugin, HomePlugin, HudPlugin, InputPlugin, LeaderboardPlugin,
+    HomePlugin, HudPlugin, InputPlugin, OnboardingPlugin, PausePlugin, PlayBySeedPlugin,
-    OnboardingPlugin, PausePlugin, PlayBySeedPlugin, ProfilePlugin, ProgressPlugin,
+    ProfilePlugin, ProgressPlugin, RadialMenuPlugin, ReplayOverlayPlugin, ReplayPlaybackPlugin,
-    RadialMenuPlugin, ReplayOverlayPlugin, ReplayPlaybackPlugin, SafeAreaInsetsPlugin,
+    SafeAreaInsetsPlugin, SelectionPlugin, SettingsPlugin, SplashPlugin, StatsPlugin, SyncProvider,
-    SelectionPlugin, SettingsPlugin, SplashPlugin, StatsPlugin, SyncPlugin, SyncProvider,
+    TablePlugin, ThemePlugin, ThemeRegistryPlugin, TimeAttackPlugin, TouchSelectionPlugin,
-    SyncSetupPlugin, TablePlugin, ThemePlugin, ThemeRegistryPlugin, TimeAttackPlugin,
+    UiFocusPlugin, UiModalPlugin, UiTooltipPlugin, WeeklyGoalsPlugin, WinSummaryPlugin,
-    TouchSelectionPlugin, UiFocusPlugin, UiModalPlugin, UiTooltipPlugin, WeeklyGoalsPlugin,
+};
-    WinSummaryPlugin,
+#[cfg(not(target_arch = "wasm32"))]
+use crate::{
+    AnalyticsPlugin, AudioPlugin, AvatarPlugin, LeaderboardPlugin, SyncPlugin, SyncSetupPlugin,
 };
 
 /// Groups all Ferrous Solitaire gameplay plugins.
@@ -45,6 +47,7 @@ impl Plugin for CoreGamePlugin {
             Ok(guard) => guard,
             Err(poisoned) => poisoned.into_inner(),
         };
+        #[cfg_attr(target_arch = "wasm32", allow(unused_variables))]
         let sync_provider = sync_provider
             .take()
             .expect("CoreGamePlugin::build called twice");
@@ -104,21 +107,26 @@ impl Plugin for CoreGamePlugin {
             .add_plugins(HudPlugin)
             .add_plugins(HelpPlugin)
             .add_plugins(HomePlugin::default())
-            .add_plugins(AvatarPlugin)
             .add_plugins(ProfilePlugin)
             .add_plugins(PausePlugin)
             .add_plugins(SettingsPlugin::default())
-            .add_plugins(AudioPlugin)
             .add_plugins(OnboardingPlugin)
-            .add_plugins(SyncPlugin::new(sync_provider))
-            .add_plugins(SyncSetupPlugin)
-            .add_plugins(AnalyticsPlugin)
-            .add_plugins(LeaderboardPlugin)
             .add_plugins(WinSummaryPlugin)
             .add_plugins(UiModalPlugin)
             .add_plugins(UiFocusPlugin)
             .add_plugins(UiTooltipPlugin)
             .add_plugins(SplashPlugin)
             .add_plugins(DiagnosticsHudPlugin);
+
+        // Plugins that use kira/cpal audio or multi-threaded Tokio are not
+        // compatible with the single-threaded wasm32 runtime.  Gate them out
+        // so the browser build boots silently and without a sync backend.
+        #[cfg(not(target_arch = "wasm32"))]
+        app.add_plugins(AvatarPlugin)
+            .add_plugins(AudioPlugin)
+            .add_plugins(SyncPlugin::new(sync_provider))
+            .add_plugins(SyncSetupPlugin)
+            .add_plugins(AnalyticsPlugin)
+            .add_plugins(LeaderboardPlugin);
     }
 }

solitaire_engine/src/daily_challenge_plugin.rs

@@ -25,6 +25,7 @@ use crate::events::{
 use crate::game_plugin::GameMutation;
 use crate::progress_plugin::{ProgressResource, ProgressStoragePath, ProgressUpdate};
 use crate::resources::GameStateResource;
+#[cfg(not(target_arch = "wasm32"))]
 use crate::sync_plugin::SyncProviderResource;
 
 /// Bonus XP awarded for completing today's daily challenge.
@@ -116,17 +117,21 @@ impl Plugin for DailyChallengePlugin {
             .add_message::<StartDailyChallengeRequestEvent>()
             .add_message::<WarningToastEvent>()
             .add_message::<XpAwardedEvent>()
-            .add_systems(Startup, fetch_server_challenge)
-            .add_systems(Update, poll_server_challenge)
             // record/award after the base ProgressUpdate so we don't fight
             // ProgressPlugin's add_xp on the same frame.
             .add_systems(Update, handle_daily_completion.after(ProgressUpdate))
             .add_systems(Update, handle_start_daily_request.before(GameMutation))
             .add_systems(Update, check_daily_expiry_warning)
             .add_systems(Update, check_date_rollover);
+
+        // Server-challenge fetch uses SyncProviderResource (reqwest), not available on wasm.
+        #[cfg(not(target_arch = "wasm32"))]
+        app.add_systems(Startup, fetch_server_challenge)
+            .add_systems(Update, poll_server_challenge);
     }
 }
 
+#[cfg(not(target_arch = "wasm32"))]
 /// Startup system: spawns an async task to fetch the server's daily challenge.
 ///
 /// Only runs when `SyncProviderResource` is present (i.e. `SyncPlugin` is
@@ -142,6 +147,7 @@ fn fetch_server_challenge(
     task_res.0 = Some(task);
 }
 
+#[cfg(not(target_arch = "wasm32"))]
 /// Update system: polls the server-challenge fetch task.
 ///
 /// On success, replaces the locally-computed seed in `DailyChallengeResource`

solitaire_engine/src/game_plugin.rs

@@ -1512,6 +1512,7 @@ mod tests {
         use solitaire_data::load_game_state_from;
 
         let path = tmp_gs_path("exit_save");
+        #[cfg(not(target_arch = "wasm32"))]
         let _ = std::fs::remove_file(&path);
 
         let mut app = test_app(7);
@@ -1527,6 +1528,7 @@ mod tests {
         let loaded = load_game_state_from(&path).expect("file should exist after exit");
         assert_eq!(loaded.seed, 7654);
 
+        #[cfg(not(target_arch = "wasm32"))]
         let _ = std::fs::remove_file(&path);
     }
 
@@ -1571,6 +1573,7 @@ mod tests {
         use solitaire_data::load_game_state_from;
 
         let path = tmp_gs_path("auto_save_30s");
+        #[cfg(not(target_arch = "wasm32"))]
         let _ = std::fs::remove_file(&path);
 
         let mut app = test_app(42);
@@ -1601,6 +1604,7 @@ mod tests {
         let loaded = load_game_state_from(&path).expect("file must be loadable");
         assert_eq!(loaded.seed, 42);
 
+        #[cfg(not(target_arch = "wasm32"))]
         let _ = std::fs::remove_file(&path);
     }
 
@@ -1608,6 +1612,7 @@ mod tests {
     #[test]
     fn auto_save_skips_when_no_moves() {
         let path = tmp_gs_path("auto_save_skip");
+        #[cfg(not(target_arch = "wasm32"))]
         let _ = std::fs::remove_file(&path);
 
         let mut app = test_app(99);
@@ -2165,6 +2170,7 @@ mod tests {
         use solitaire_data::load_replay_history_from;
 
         let path = std::env::temp_dir().join("engine_test_replay_freeze.json");
+        #[cfg(not(target_arch = "wasm32"))]
         let _ = std::fs::remove_file(&path);
 
         let mut app = test_app(7654);
@@ -2223,6 +2229,7 @@ mod tests {
             other => panic!("second entry must be a Move, got {other:?}"),
         }
 
+        #[cfg(not(target_arch = "wasm32"))]
         let _ = std::fs::remove_file(&path);
     }
 
@@ -2234,6 +2241,7 @@ mod tests {
         use solitaire_data::load_replay_history_from;
 
         let path = std::env::temp_dir().join("engine_test_replay_history_append.json");
+        #[cfg(not(target_arch = "wasm32"))]
         let _ = std::fs::remove_file(&path);
 
         let mut app = test_app(11);
@@ -2270,6 +2278,7 @@ mod tests {
         assert_eq!(history.replays[0].final_score, 200);
         assert_eq!(history.replays[1].final_score, 100);
 
+        #[cfg(not(target_arch = "wasm32"))]
         let _ = std::fs::remove_file(&path);
     }
 
@@ -2281,6 +2290,7 @@ mod tests {
     #[test]
     fn replay_with_empty_recording_skips_save() {
         let path = std::env::temp_dir().join("engine_test_replay_empty_skip.json");
+        #[cfg(not(target_arch = "wasm32"))]
         let _ = std::fs::remove_file(&path);
 
         let mut app = test_app(1);

solitaire_engine/src/hud_plugin.rs

@@ -13,7 +13,14 @@ use solitaire_core::card::Suit;
 use solitaire_core::game_state::{DrawMode, GameMode};
 
 use crate::auto_complete_plugin::AutoCompleteState;
+#[cfg(not(target_arch = "wasm32"))]
 use crate::avatar_plugin::AvatarResource;
+// On wasm32 AvatarPlugin is gated out; define a placeholder type so the
+// Option<Res<AvatarResource>> parameters below compile without changes.
+// The resource is never inserted on wasm, so every call resolves to None.
+#[cfg(target_arch = "wasm32")]
+#[derive(bevy::prelude::Resource)]
+struct AvatarResource(Option<bevy::prelude::Handle<bevy::prelude::Image>>);
 use crate::challenge_plugin::CHALLENGE_UNLOCK_LEVEL;
 use crate::daily_challenge_plugin::DailyChallengeResource;
 use crate::events::{

solitaire_engine/src/lib.rs

@@ -1,13 +1,16 @@
 //! Bevy integration layer for Ferrous Solitaire.
 
 pub mod achievement_plugin;
+#[cfg(not(target_arch = "wasm32"))]
 pub mod analytics_plugin;
 #[cfg(target_os = "android")]
 pub mod android_clipboard;
 pub mod animation_plugin;
 pub mod assets;
+#[cfg(not(target_arch = "wasm32"))]
 pub mod audio_plugin;
 pub mod auto_complete_plugin;
+#[cfg(not(target_arch = "wasm32"))]
 pub mod avatar_plugin;
 pub mod card_animation;
 pub mod card_plugin;
@@ -26,6 +29,7 @@ pub mod home_plugin;
 pub mod hud_plugin;
 pub mod input_plugin;
 pub mod layout;
+#[cfg(not(target_arch = "wasm32"))]
 pub mod leaderboard_plugin;
 pub mod onboarding_plugin;
 pub mod pause_plugin;
@@ -43,7 +47,9 @@ pub mod selection_plugin;
 pub mod settings_plugin;
 pub mod splash_plugin;
 pub mod stats_plugin;
+#[cfg(not(target_arch = "wasm32"))]
 pub mod sync_plugin;
+#[cfg(not(target_arch = "wasm32"))]
 pub mod sync_setup_plugin;
 pub mod table_plugin;
 pub mod theme;
@@ -57,14 +63,17 @@ pub mod weekly_goals_plugin;
 pub mod win_summary_plugin;
 
 pub use achievement_plugin::{AchievementPlugin, AchievementsResource, AchievementsScreen};
+#[cfg(not(target_arch = "wasm32"))]
 pub use analytics_plugin::{AnalyticsPlugin, AnalyticsResource};
 pub use animation_plugin::{ActiveToast, AnimationPlugin, CardAnim, ToastEntity, ToastQueue};
 pub use assets::{
     AssetSourcesPlugin, DARK_THEME_MANIFEST_URL, USER_THEMES, bundled_theme_url,
     populate_embedded_dark_theme, register_theme_asset_sources,
 };
+#[cfg(not(target_arch = "wasm32"))]
 pub use audio_plugin::{AudioPlugin, AudioState, SoundLibrary};
 pub use auto_complete_plugin::AutoCompletePlugin;
+#[cfg(not(target_arch = "wasm32"))]
 pub use avatar_plugin::{AvatarFetchEvent, AvatarPlugin, AvatarResource};
 pub use card_animation::{
     AnimationChain, AnimationTuning, BufferedInput, CardAnimation, CardAnimationPlugin,
@@ -117,6 +126,7 @@ pub use hud_plugin::{
 };
 pub use input_plugin::InputPlugin;
 pub use layout::{Layout, LayoutResource, compute_layout};
+#[cfg(not(target_arch = "wasm32"))]
 pub use leaderboard_plugin::{LeaderboardPlugin, LeaderboardResource, LeaderboardScreen};
 pub use onboarding_plugin::{OnboardingPlugin, OnboardingScreen};
 pub use pause_plugin::{ForfeitConfirmScreen, PausePlugin, PauseScreen, PausedResource};
@@ -155,7 +165,9 @@ pub use stats_plugin::{
     ReplaySelectorCaption, SelectedReplayIndex, StatsPlugin, StatsResource, StatsScreen,
     StatsUpdate, WatchReplayButton, format_replay_caption,
 };
+#[cfg(not(target_arch = "wasm32"))]
 pub use sync_plugin::{SyncPlugin, SyncProviderResource};
+#[cfg(not(target_arch = "wasm32"))]
 pub use sync_setup_plugin::SyncSetupPlugin;
 pub use table_plugin::{
     BackgroundImageSet, HintPileHighlight, PileMarker, TableBackground, TablePlugin,

solitaire_engine/src/profile_plugin.rs

@@ -12,7 +12,11 @@ use solitaire_core::achievement::{ALL_ACHIEVEMENTS, achievement_by_id};
 use solitaire_data::SyncBackend;
 
 use crate::achievement_plugin::AchievementsResource;
+#[cfg(not(target_arch = "wasm32"))]
 use crate::avatar_plugin::AvatarResource;
+#[cfg(target_arch = "wasm32")]
+#[derive(bevy::prelude::Resource)]
+struct AvatarResource(Option<bevy::prelude::Handle<bevy::prelude::Image>>);
 use crate::events::ToggleProfileRequestEvent;
 use crate::font_plugin::FontResource;
 use crate::progress_plugin::ProgressResource;

solitaire_engine/src/resources.rs

@@ -128,9 +128,16 @@ pub struct GameInputConsumedResource(pub bool);
 /// multi-threaded runtime is built once at startup and its `Arc` cloned cheaply
 /// into every network task — safe for concurrent `block_on` calls from multiple
 /// worker threads.
+///
+/// Gated to non-wasm because `tokio::runtime::Builder::new_multi_thread()` uses
+/// `mio` for OS-level I/O polling which does not compile for wasm32. The
+/// plugins that depend on this resource (AudioPlugin, SyncPlugin,
+/// AnalyticsPlugin) are also gated out on wasm32 in `CoreGamePlugin`.
+#[cfg(not(target_arch = "wasm32"))]
 #[derive(Resource, Clone)]
 pub struct TokioRuntimeResource(pub Arc<tokio::runtime::Runtime>);
 
+#[cfg(not(target_arch = "wasm32"))]
 impl TokioRuntimeResource {
     /// Attempts to build the shared multi-threaded Tokio runtime.
     ///

solitaire_engine/src/settings_plugin.rs

@@ -24,6 +24,7 @@ use solitaire_data::{
 
 use solitaire_data::settings::SyncBackend;
 
+#[cfg(not(target_arch = "wasm32"))]
 use crate::assets::user_theme_dir;
 use crate::events::{
     DeleteAccountRequestEvent, InfoToastEvent, ManualSyncRequestEvent, SyncConfigureRequestEvent,
@@ -32,9 +33,9 @@ use crate::events::{
 use crate::font_plugin::FontResource;
 use crate::progress_plugin::ProgressResource;
 use crate::resources::{SettingsScrollPos, SyncStatus, SyncStatusResource};
-use crate::theme::{
+use crate::theme::{ThemeThumbnailCache, ThemeThumbnailPair, refresh_registry};
-    ImportError, ThemeThumbnailCache, ThemeThumbnailPair, import_theme, refresh_registry,
+#[cfg(not(target_arch = "wasm32"))]
-};
+use crate::theme::{ImportError, import_theme};
 use crate::ui_focus::{FocusGroup, FocusRow, Focusable, FocusedButton};
 use crate::ui_modal::{
     ButtonVariant, ModalButton, ModalScrim, spawn_modal, spawn_modal_actions, spawn_modal_button,
@@ -404,6 +405,7 @@ impl Plugin for SettingsPlugin {
                     sync_settings_panel_visibility,
                     handle_settings_buttons,
                     handle_sync_buttons,
+                    #[cfg(not(target_arch = "wasm32"))]
                     handle_scan_themes,
                     update_sync_status_text,
                     update_card_back_text,
@@ -1857,6 +1859,7 @@ fn spawn_settings_panel(
                     font_res,
                 );
             }
+            #[cfg(not(target_arch = "wasm32"))]
             import_themes_row(body, font_res);
 
             // --- Privacy (only shown when a Matomo URL is configured) ---
@@ -2641,6 +2644,7 @@ fn value_text_font(font_res: Option<&FontResource>) -> TextFont {
 /// [`InfoToastEvent`] is fired per imported theme. `IdCollision` errors (theme
 /// already installed) are silently skipped; all other errors produce a warning
 /// toast. A final toast tells the player to reopen Settings to see new themes.
+#[cfg(not(target_arch = "wasm32"))]
 fn handle_scan_themes(
     interaction_query: Query<(&Interaction, &SettingsButton), Changed<Interaction>>,
     mut toast: MessageWriter<InfoToastEvent>,
@@ -2759,6 +2763,7 @@ fn pill_button(
 /// then presses the button. [`handle_scan_themes`] picks them up, validates,
 /// and installs them. Reopen Settings to see newly imported themes in the
 /// card-theme picker.
+#[cfg(not(target_arch = "wasm32"))]
 fn import_themes_row(parent: &mut ChildSpawnerCommands, font_res: Option<&FontResource>) {
     let caption_font = TextFont {
         font: font_res.map(|f| f.0.clone()).unwrap_or_default(),

solitaire_engine/src/theme/mod.rs

@@ -12,6 +12,7 @@
 //! handles directly on card entities, so a theme switch propagates on
 //! the next frame without re-spawning anything.
 
+#[cfg(not(target_arch = "wasm32"))]
 pub mod importer;
 pub mod loader;
 pub mod manifest;
@@ -28,6 +29,7 @@ use thiserror::Error;
 
 use solitaire_core::card::{Rank, Suit};
 
+#[cfg(not(target_arch = "wasm32"))]
 pub use importer::{ImportError, ThemeId, import_theme, import_theme_into};
 pub use loader::{CardThemeLoader, CardThemeLoaderError};
 pub use manifest::ThemeManifest;

solitaire_server/web/play.html

@@ -0,0 +1,20 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+    <meta charset="UTF-8">
+    <meta name="viewport" content="width=device-width, initial-scale=1.0">
+    <title>Ferrous Solitaire</title>
+    <style>
+        * { box-sizing: border-box; margin: 0; padding: 0; }
+        body { background: #000; overflow: hidden; }
+        #bevy-canvas { display: block; width: 100vw; height: 100vh; }
+    </style>
+</head>
+<body>
+    <canvas id="bevy-canvas"></canvas>
+    <script type="module">
+        import init from "/web/pkg/canvas.js";
+        await init();
+    </script>
+</body>
+</html>

solitaire_web/Cargo.toml

@@ -0,0 +1,23 @@
+[package]
+name    = "solitaire_web"
+version.workspace = true
+license.workspace = true
+edition.workspace = true
+
+[lib]
+crate-type = ["cdylib", "rlib"]
+
+[dependencies]
+solitaire_engine         = { path = "../solitaire_engine" }
+solitaire_data           = { path = "../solitaire_data" }
+# Direct dep so `bevy::` resolves in lib.rs; zero extra features so this
+# contributes nothing to unification with the desktop/Android feature set.
+bevy                     = { workspace = true }
+wasm-bindgen             = "0.2"
+getrandom                = { version = "0.3", features = ["wasm_js"] }
+console_error_panic_hook = "0.1"
+
+# webgl2 must only be enabled for the wasm target — it constrains the
+# renderer to WebGL2 compatibility limits, which is wrong for native builds.
+[target.'cfg(target_arch = "wasm32")'.dependencies]
+bevy = { workspace = true, features = ["webgl2"] }

solitaire_web/src/lib.rs

@@ -0,0 +1,42 @@
+//! Browser entry point for the Ferrous Solitaire Bevy WASM build.
+//!
+//! This crate compiles the full `solitaire_engine` to `wasm32-unknown-unknown`
+//! and renders to a `<canvas id="bevy-canvas">` element. It shares the same
+//! ECS code path as the desktop and Android builds; the only differences are:
+//! - Audio, sync, and analytics plugins are cfg-gated out in `CoreGamePlugin`
+//!   on the wasm32 target (see `solitaire_engine/src/core_game_plugin.rs`).
+//! - `LocalOnlyProvider` is passed as the sync provider (sync is disabled).
+//! - Storage is handled automatically by `WasmStorage` (localStorage-backed),
+//!   wired by `CoreGamePlugin` via `default_storage_backend()`.
+
+use bevy::prelude::*;
+use bevy::window::{Window, WindowPlugin};
+use solitaire_data::LocalOnlyProvider;
+use solitaire_engine::CoreGamePlugin;
+use wasm_bindgen::prelude::*;
+
+#[wasm_bindgen(start)]
+pub fn start() {
+    console_error_panic_hook::set_once();
+
+    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,
+                    ..default()
+                }),
+                ..default()
+            }),
+        )
+        // LocalOnlyProvider disables cloud sync — correct for the web build
+        // since SyncPlugin is cfg-gated out on wasm32 anyway.
+        .add_plugins(CoreGamePlugin::new(Box::new(LocalOnlyProvider)))
+        .run();
+}