feat: script only components

.github/workflows/main-windows.yml

@@ -102,15 +102,13 @@ jobs:
           name: js-generated-tests
           path: packages/jco-transpile/test/fixtures/generated
 
-      - name: Build jco-transpile
-        run: pnpm --filter '@bytecodealliance/jco-transpile' run build
-
-      - name: Upload jco-transpile vendor
+      - name: Upload jco-transpile build output
         uses: actions/upload-artifact@cf430e030ddbb5b0abf93d22962f4752f3646cd9 # v7.0.2
         with:
-          name: jco-transpile-vendor
+          name: jco-transpile-build
           path: |
             packages/jco-transpile/vendor
+            packages/jco-transpile/dist
 
       - name: Build preview2-shim
         run: pnpm --filter '@bytecodealliance/preview2-shim' run build
@@ -236,11 +234,11 @@ jobs:
           path: packages/preview2-shim/dist
 
       # The runtime integration tests exercise the local transpiler through the API and CLI.
-      - name: Restore jco-transpile vendor
+      - name: Restore jco-transpile build output
         uses: actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c # v8.0.1
         with:
-          name: jco-transpile-vendor
-          path: packages/jco-transpile/vendor
+          name: jco-transpile-build
+          path: packages/jco-transpile
 
       - name: Build workspace jco-transpile
         run: pnpm --filter '@bytecodealliance/jco-transpile' run build:ts
@@ -318,6 +316,12 @@ jobs:
         with:
           name: jco-build-ts
           path: packages/jco/dist
+
+      - name: Restore jco-transpile build output
+        uses: actions/download-artifact@9000827ccba6bdab643e8b6fd33ac0654aef8333 # v8.0.2
+        with:
+          name: jco-transpile-build
+          path: packages/jco-transpile
       - name: Restore Component Model runtime build output
         uses: actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c # v8.0.1
         with:

.github/workflows/main.yml

@@ -95,15 +95,13 @@ jobs:
           name: js-generated-tests
           path: packages/jco-transpile/test/fixtures/generated
 
-      - name: Build jco-transpile
-        run: pnpm --filter '@bytecodealliance/jco-transpile' run build
-
-      - name: Upload jco-transpile vendor
+      - name: Upload jco-transpile build output
         uses: actions/upload-artifact@cf430e030ddbb5b0abf93d22962f4752f3646cd9 # v7.0.2
         with:
-          name: jco-transpile-vendor
+          name: jco-transpile-build
           path: |
             packages/jco-transpile/vendor
+            packages/jco-transpile/dist
 
       - name: Build preview2-shim
         run: pnpm --filter '@bytecodealliance/preview2-shim' run build
@@ -211,11 +209,11 @@ jobs:
           path: packages/preview2-shim/dist
 
       # The runtime integration tests exercise the local transpiler through the API and CLI.
-      - name: Restore jco-transpile vendor
+      - name: Restore jco-transpile build output
         uses: actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c # v8.0.1
         with:
-          name: jco-transpile-vendor
-          path: packages/jco-transpile/vendor
+          name: jco-transpile-build
+          path: packages/jco-transpile
 
       - name: Build workspace jco-transpile
         run: pnpm --filter '@bytecodealliance/jco-transpile' run build:ts
@@ -294,8 +292,8 @@ jobs:
       - name: Restore jco-transpile build output
         uses: actions/download-artifact@9000827ccba6bdab643e8b6fd33ac0654aef8333 # v8.0.2
         with:
-          name: jco-transpile-vendor
-          path: packages/jco-transpile/vendor
+          name: jco-transpile-build
+          path: packages/jco-transpile
       - name: Restore Component Model runtime build output
         uses: actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c # v8.0.1
         with:
@@ -375,6 +373,12 @@ jobs:
         with:
           name: jco-build-ts
           path: packages/jco/dist
+
+      - name: Restore jco-transpile build output
+        uses: actions/download-artifact@9000827ccba6bdab643e8b6fd33ac0654aef8333 # v8.0.2
+        with:
+          name: jco-transpile-build
+          path: packages/jco-transpile
       - name: Restore Component Model runtime build output
         uses: actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c # v8.0.1
         with:
@@ -457,6 +461,12 @@ jobs:
         with:
           name: jco-build-ts
           path: packages/jco/dist
+
+      - name: Restore jco-transpile build output
+        uses: actions/download-artifact@9000827ccba6bdab643e8b6fd33ac0654aef8333 # v8.0.2
+        with:
+          name: jco-transpile-build
+          path: packages/jco-transpile
       - name: Restore Component Model runtime build output
         uses: actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c # v8.0.1
         with:
@@ -623,11 +633,11 @@ jobs:
           name: jco-build-ts
           path: packages/jco/dist
 
-      - name: Restore jco-transpile vendor
+      - name: Restore jco-transpile build output
         uses: actions/download-artifact@9000827ccba6bdab643e8b6fd33ac0654aef8333 # v8.0.2
         with:
-          name: jco-transpile-vendor
-          path: packages/jco-transpile/vendor
+          name: jco-transpile-build
+          path: packages/jco-transpile
 
       - name: Bundle browser entry against packed tarballs
         run: node scripts/build-browser-bundle.mjs
@@ -871,12 +881,11 @@ jobs:
           name: js-generated-tests
           path: packages/jco-transpile/test/fixtures/generated
 
-      - name: Restore jco-transpile vendor
+      - name: Restore jco-transpile build output
         uses: actions/download-artifact@9000827ccba6bdab643e8b6fd33ac0654aef8333 # v8.0.2
         with:
-          name: jco-transpile-vendor
-          path: |
-            packages/jco-transpile/vendor
+          name: jco-transpile-build
+          path: packages/jco-transpile
 
       - name: Install Rust
         if: ${{ matrix.project.uses-webidl2wit }}
@@ -978,6 +987,12 @@ jobs:
           name: jco-build-ts
           path: packages/jco/dist
 
+      - name: Restore jco-transpile build output
+        uses: actions/download-artifact@9000827ccba6bdab643e8b6fd33ac0654aef8333 # v8.0.2
+        with:
+          name: jco-transpile-build
+          path: packages/jco-transpile
+
       - name: Restore jco build transpilation output
         uses: actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c # v8.0.1
         with:
@@ -1125,11 +1140,11 @@ jobs:
           name: jco-cm-runtime-dist
           path: packages/jco-cm-runtime/dist
 
-      - name: Restore jco-transpile vendor
+      - name: Restore jco-transpile build output
         uses: actions/download-artifact@9000827ccba6bdab643e8b6fd33ac0654aef8333 # v8.0.2
         with:
-          name: jco-transpile-vendor
-          path: packages/jco-transpile/vendor
+          name: jco-transpile-build
+          path: packages/jco-transpile
 
       - name: Build extended component tree
         working-directory: test/components

crates/js-component-bindgen-component/src/lib.rs

@@ -43,6 +43,9 @@ mod bindings {
     });
     export!(JsComponentBindgenComponent);
 }
+use bindings::exports::local::js_component_bindgen::scripts::{
+    self, ScriptComponentOpts, ScriptEngineBackend, ScriptEngineWitInput, ScriptEngineWorld,
+};
 use bindings::{
     AsyncImportsExports, AsyncMode, BindingsMode, EnabledFeatureSet, ExportType, GenerateOptions,
     InstantiationMode, PackageMismatch, Transpiled, TypeGenerationOptions, UnpackError, Wit,
@@ -264,6 +267,46 @@ impl bindings::Guest for JsComponentBindgenComponent {
     }
 }
 
+/// Implementation of the `local:js-component-bindgen/scripts` interface
+impl scripts::Guest for JsComponentBindgenComponent {
+    fn script_engine_world_new(
+        inputs: Vec<ScriptEngineWitInput>,
+        backend: ScriptEngineBackend,
+    ) -> Result<ScriptEngineWorld, String> {
+        use js_component_bindgen::script;
+        let inputs: Vec<script::WitInput> = inputs
+            .into_iter()
+            .map(|input| script::WitInput {
+                path: PathBuf::from(input.path),
+                world: input.world,
+            })
+            .collect();
+        let backend = match backend {
+            ScriptEngineBackend::Starlingmonkey => script::Backend::StarlingMonkey,
+            ScriptEngineBackend::Quickjs => script::Backend::QuickJs,
+        };
+        let engine = script::engine_world(&inputs, backend).map_err(|e| format!("{e:#}"))?;
+        Ok(ScriptEngineWorld {
+            wit: engine.wit,
+            world_name: engine.world_name,
+            bootstrap: engine.bootstrap,
+            imports: engine.imports,
+            exports: engine.exports,
+        })
+    }
+
+    fn script_component_new(opts: ScriptComponentOpts) -> Result<Vec<u8>, String> {
+        use js_component_bindgen::script;
+        script::script_component(&script::ScriptComponent {
+            name: opts.name,
+            source: opts.source,
+            engine_world: opts.engine_world,
+            exports: opts.exports,
+        })
+        .map_err(|e| format!("{e:#}"))
+    }
+}
+
 fn parse_package_spec(spec: &str) -> Option<String> {
     let source = format!("package {spec}; world validate {{}}");
     UnresolvedPackageGroup::parse("package-spec.wit", &source)

crates/js-component-bindgen-component/wit/js-component-bindgen.wit

@@ -1,5 +1,62 @@
 package local:js-component-bindgen;
 
+/// Script engines and the script-only components that run on them
+///
+/// A script engine is a JavaScript engine componentized against the union of several WIT
+/// worlds, with an extra `jco:script-engine/script-loader` export through which a host feeds it
+/// scripts at runtime. A script-only component packages one script's source as a component
+/// exporting `jco:script/script`.
+interface scripts {
+  /// A WIT world a script engine must support
+  record script-engine-wit-input {
+    /// Path to a WIT file or directory
+    path: string,
+    /// World to select within the package (the package's only world if omitted)
+    %world: option<string>,
+  }
+
+  /// JavaScript engine a script engine bootstrap will be componentized with
+  enum script-engine-backend {
+    starlingmonkey,
+    quickjs,
+  }
+
+  /// A merged script engine world and the bootstrap module that implements it
+  record script-engine-world {
+    /// Single WIT document (with nested packages) defining the engine world
+    wit: string,
+    /// Name of the engine world within `wit`
+    world-name: string,
+    /// JavaScript module to componentize as the engine
+    bootstrap: string,
+    /// Specifiers scripts may import
+    imports: list<string>,
+    /// JavaScript export names of the engine world, excluding the script loader
+    exports: list<string>,
+  }
+
+  /// A script to package as a script-only component
+  record script-component-opts {
+    /// Name the script is packaged under
+    name: string,
+    /// Script source, a bundled ES module
+    source: string,
+    /// Fully-qualified engine world the script was bundled against
+    engine-world: string,
+    /// JavaScript export names of the script
+    exports: list<string>,
+  }
+
+  /// Merge WIT worlds into a script engine world and generate the engine's bootstrap module
+  script-engine-world-new: func(
+    inputs: list<script-engine-wit-input>,
+    backend: script-engine-backend,
+  ) -> result<script-engine-world, string>;
+
+  /// Package a bundled ES module as a component exporting `jco:script/script`
+  script-component-new: func(opts: script-component-opts) -> result<list<u8>, string>;
+}
+
 world js-component-bindgen {
   type files = list<tuple<string, list<u8>>>;
   type maps = list<tuple<string, string>>;
@@ -221,4 +278,6 @@ world js-component-bindgen {
 
   /// Expand an encoded WIT package into a conventional WIT directory file map.
   export unpack-wit: func(expected: option<package-spec>, binary: list<u8>) -> result<wit-files, unpack-error>;
+
+  export scripts;
 }

crates/js-component-bindgen/Cargo.toml

@@ -32,6 +32,7 @@ heck = { workspace = true }
 log = { workspace = true }
 semver = { workspace = true }
 wasm-encoder = { workspace = true, features = [ "wasmparser" ] }
+wasm-metadata = { workspace = true }
 wasmparser = { workspace = true, features = [ "features", "component-model" ] }
 wasmtime-environ = { workspace = true, features = ['component-model'] }
 wit-bindgen-core = { workspace = true }

crates/js-component-bindgen/src/lib.rs

@@ -18,6 +18,7 @@ mod ts_bindgen;
 pub mod esm_bindgen;
 pub mod function_bindgen;
 pub mod names;
+pub mod script;
 pub mod source;
 
 pub mod intrinsics;