feat: add webui-wasm crate for WebAssembly playground

Introduce a new webui-wasm crate that compiles the full WebUI
parse → protocol → render pipeline to WebAssembly, enabling an
interactive browser-based playground with zero server dependencies.

WebAssembly crate (crates/webui-wasm):
- Exposes build_and_render(), build_protocol(), and render() via
  wasm-bindgen for JavaScript consumption
- Uses the real webui-parser with CssStrategy::Inline so component
  styles work in-memory without external CSS files
- Feature-gates walkdir/filesystem behind 'fs' feature so
  webui-parser compiles cleanly for wasm32-unknown-unknown
- Removes 6 unused deps from webui-parser (tokio, anyhow,
  tree-sitter-typescript, lazy_static, nom, streaming-iterator)
- Bumps tree-sitter-language to 0.1.7 for bundled WASM C headers

Build tooling:
- Cross-platform cargo xtask build-wasm command with auto-detection
  of LLVM clang, wasi-libc, and WASM headers per OS
- Friendly colored error messages with platform-specific install
  hints using the console crate (matches webui-cli style)
- JS glue patching to replace tree-sitter env imports with inline
  C stdlib stubs for browser compatibility
- Reusable GitHub Actions composite action (.github/actions/setup-wasm)
  shared by PR checks and docs deployment workflows
- Refactored xtask into modules: main.rs, build_wasm.rs, build_apps.rs, util.rs

Author: mohamedmansour

.github/actions/setup-wasm/action.yml

@@ -0,0 +1,45 @@
+name: 'Setup and Build WASM'
+description: 'Install WASM toolchain, build webui-wasm, and verify output'
+
+runs:
+  using: 'composite'
+  steps:
+    - name: Setup Rust
+      uses: dtolnay/rust-toolchain@stable
+      with:
+        toolchain: 1.93
+        targets: wasm32-unknown-unknown
+
+    - name: Rust Cache
+      uses: Swatinem/rust-cache@v2
+
+    - name: Install wasm-pack
+      shell: bash
+      run: cargo install wasm-pack
+
+    - name: Install LLVM
+      shell: bash
+      run: sudo apt-get update && sudo apt-get install -y clang llvm lld
+
+    - name: Setup WASM headers
+      shell: bash
+      run: |
+        cargo fetch
+        WASM_HEADERS=$(find $HOME/.cargo/registry/src -path "*/tree-sitter-language-*/wasm/include" -type d | head -1)
+        if [ -n "$WASM_HEADERS" ]; then
+          echo "WASI_INCLUDE=$WASM_HEADERS" >> $GITHUB_ENV
+        else
+          echo "::error::Could not find tree-sitter-language WASM headers"
+          exit 1
+        fi
+
+    - name: Build WASM
+      shell: bash
+      run: cargo xtask build-wasm
+
+    - name: Verify WASM output
+      shell: bash
+      run: |
+        test -f docs/public/wasm/webui_wasm_bg.wasm
+        test -f docs/public/wasm/webui_wasm.js
+        ! grep -q "from 'env'" docs/public/wasm/webui_wasm.js

.github/workflows/docs.yml

@@ -8,39 +8,40 @@ on:
     branches: [ "main" ]
     paths:
       - 'docs/**'
+      - 'crates/webui-wasm/**'
+      - 'crates/webui-parser/**'
+      - 'crates/webui-handler/**'
+      - 'crates/webui-protocol/**'
   workflow_dispatch:
 
 jobs:
   build-and-deploy:
     runs-on: ubuntu-latest
 
     steps:
-      # Step 1: Checkout the repository
       - name: Checkout Repository
         uses: actions/checkout@v4
 
-      # Step 2: Setup Node.js environment
+      - name: Build WASM playground
+        uses: ./.github/actions/setup-wasm
+
       - name: Setup Node.js
         uses: actions/setup-node@v3
         with:
           node-version: '22'
-          
-      # Step 3: Setup pnpm
+
       - name: Setup pnpm
         uses: pnpm/action-setup@v2
         with:
           version: latest
           run_install: false
 
-      # Step 4: Install dependencies
       - name: Install Dependencies
         run: cd docs && pnpm install
 
-      # Step 5: Build the Vitepress site
       - name: Build Site
         run: cd docs && pnpm build
 
-      # Step 6: Deploy to GitHub Pages
       - name: Deploy to GitHub Pages
         uses: peaceiris/actions-gh-pages@v3
         with:

.github/workflows/pr.yml

@@ -54,3 +54,14 @@ jobs:
 
       - name: Build docs
         run: pnpm --filter @webui/docs build
+
+  wasm:
+    name: WASM Build
+    runs-on: ubuntu-latest
+    # Only run when WASM-relevant files change
+    if: |
+      contains(github.event.pull_request.labels.*.name, 'wasm') ||
+      github.event_name == 'workflow_dispatch'
+    steps:
+      - uses: actions/checkout@v3
+      - uses: ./.github/actions/setup-wasm

Cargo.lock

@@ -7,6 +7,7 @@ members = [
     "crates/webui-parser",
     "crates/webui-protocol",
     "crates/webui-state",
+    "crates/webui-wasm",
     "xtask",
 ]
 resolver = "2"
@@ -30,6 +31,8 @@ tokio = { version = "1.49.0", features = ["full"] }
 clap = { version = "4", features = ["derive"] }
 console = "0.15"
 prost = "0.13"
+wasm-bindgen = "0.2"
+serde-wasm-bindgen = "0.6"
 
 # Test dependencies
 criterion = "0.8.2"

Cargo.toml

@@ -9,27 +9,21 @@ repository.workspace = true
 
 [features]
 default = ["fs"]
-fs = []
+fs = ["walkdir"]
 
 [dependencies]
 webui-expressions = { path = "../webui-expressions" }
 webui-protocol = { path = "../webui-protocol" }
 serde = { workspace = true }
 serde_json = { workspace = true }
 thiserror = { workspace = true }
-anyhow = { workspace = true }
-tokio = { workspace = true }
 tree-sitter = "0.26.5"
+tree-sitter-language = "0.1.7"
 tree-sitter-html = "0.23.2"
 tree-sitter-css = "0.25.0"
-tree-sitter-typescript = "0.23.2"
-walkdir = "2.5.0"
-lazy_static = "1.5.0"
-nom = "8.0.0"
-streaming-iterator = "0.1.9"
+walkdir = { version = "2.5.0", optional = true }
 
 [dev-dependencies]
 mockall = { workspace = true }
-tokio-test = { workspace = true }
 tempfile = { workspace = true }
 webui-test-utils = { path = "../webui-test-utils" }

crates/webui-parser/Cargo.toml

@@ -0,0 +1,26 @@
+[package]
+name = "webui-wasm"
+description = "WebAssembly bindings for WebUI framework — powers the online playground"
+version.workspace = true
+edition.workspace = true
+authors.workspace = true
+license.workspace = true
+repository.workspace = true
+
+[package.metadata.wasm-pack.profile.release]
+wasm-opt = false
+
+[lib]
+crate-type = ["cdylib", "rlib"]
+
+[dependencies]
+webui-parser = { path = "../webui-parser", default-features = false }
+webui-handler = { path = "../webui-handler" }
+webui-protocol = { path = "../webui-protocol" }
+serde = { workspace = true }
+serde_json = { workspace = true }
+wasm-bindgen = { workspace = true }
+serde-wasm-bindgen = { workspace = true }
+
+[dev-dependencies]
+webui-test-utils = { path = "../webui-test-utils" }