feat: add JavaScript bindings generation and transpilation for WIT co…

[GordonSmith]

…mponents

• Implemented generateJsBindings and generateJsBindingsFromPath for generating TypeScript bindings from WIT content.
• Added transpileJsHost and transpileJsHostFromPath for transpiling WebAssembly components into JavaScript host modules.
• Introduced interfaces and types for binding options and results.
• Created tests for guest and host bindings generation, including complex WIT definitions and command contributions.
• Ensured backward compatibility with deprecated aliases for guest and host bindings.
• Implemented edge case tests for WitFormatter to ensure proper formatting of various input scenarios.
• Added comprehensive tests for WitSyntaxValidator, covering error parsing and diagnostic creation.
• Introduced file-based tests for WASM detection utilities to validate header reading and component identification.
• Enhanced vitest configuration to include coverage reporting for better test insights.
• Added a new command for running unit tests with coverage.

[Copilot]

Pull request overview

Adds JavaScript/TypeScript bindings generation and host-module transpilation to the vscode-wit extension (via @bytecodealliance/jco), expands command surface (guest/host bindings + docs), and significantly increases unit test coverage across formatting, validation, and WASM utilities.

Changes:

• Add JS bindings generation (types) and host transpilation (transpile) utilities, plus corresponding VS Code commands/menus.
• Refactor/rename binding generation commands into “guest” vs “host” groupings and add Markdown docs generation command wiring.
• Add extensive Vitest coverage configuration and new unit tests (validator, formatter edge cases, wasm detection/utils, JS bindings).

Reviewed changes

Copilot reviewed 28 out of 33 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
wit-bindgen-wasm/Cargo.toml	Bumps wasm-bindgen and web-sys versions for the WASM subproject.
wit-bindgen-wasm/Cargo.lock	Lockfile updates corresponding to Rust dependency bumps.
vitest.config.ts	Enables V8 coverage reporting and configures report outputs.
tests/wasmUtils.test.ts	Adds unit tests for wasmUtils with mocked VS Code + wasm module.
tests/wasmDetection-fs.test.ts	Adds file-based tests for wasm header reading/component detection.
tests/validator-methods.test.ts	Adds tests for WitSyntaxValidator error parsing and diagnostics creation.
tests/test-wit-validator.js	Adds/updates a test helper file (appears empty in provided diff).
tests/js-bindings.test.ts	Adds tests for JS guest/host bindings + host transpilation + command contributions.
tests/formatter-edge.test.ts	Adds formatter edge-case coverage (indentation, comments, aliases, etc.).
tests/bindingsSource.test.ts	Adds tests for deciding between path-based vs in-memory WIT generation.
src/jsBindings.ts	Implements JS bindings generation and component-to-host transpilation wrappers around jco.
src/formatter.ts	Minor formatter refactor (removes unused intermediate variable).
src/extension.ts	Adds JS binding commands, reorganizes guest binding commands, and wires new menus/flows.
src/bindingsSource.ts	Introduces helpers to detect whether path-based generation is safe/possible.
samples/greeter/wit/world.wit	Adds sample WIT world for greeter component.
samples/greeter/src/lib.rs	Adds sample Rust component implementation for greeter.
samples/greeter/Cargo.toml	Adds greeter sample crate manifest.
samples/counter/wit/world.wit	Adds sample WIT world for counter resource component.
samples/counter/src/lib.rs	Adds sample Rust component implementation for counter resource.
samples/counter/Cargo.toml	Adds counter sample crate manifest.
samples/adder/wit/world.wit	Adds sample WIT world for adder component.
samples/adder/src/lib.rs	Adds sample Rust component implementation for adder.
samples/adder/Cargo.toml	Adds adder sample crate manifest.
samples/build.sh	Adds script to build all sample components.
samples/README.md	Documents sample projects, build steps, and inspection workflow.
samples/Cargo.toml	Adds a Cargo workspace for samples.
samples/Cargo.lock	Adds lockfile for samples workspace dependencies.
samples/.gitignore	Ignores sample build artifacts.
package.json	Adds jco + coverage tooling, renames/extends commands/menus, adds build/test scripts.
.vscode/launch.json	Updates launch configs and adds a “samples” launch target.
.prettierignore	Ignores sample build output from formatting.
.gitignore	Ignores sample build output and coverage artifacts.

[github-actions]

🎉 This change has been included in wit-idl-v0.3.28 🎉

The release is available on:

• GitHub releases: wit-idl: v0.3.28
• Visual Studio Marketplace: https://marketplace.visualstudio.com/items?itemName=bytecodealliance.wit-idl
• Open VSX Registry: https://open-vsx.org/extension/bytecodealliance/wit-idl

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