Skill: Add WASM Export

Wire up a new C++ function for export to JavaScript via the WASM interface. This requires coordination between three layers.

Usage

• •/add-wasm-export — audit mode: check consistency across all three layers
• •/add-wasm-export functionName — add a new export

The Three Layers

1. •

   C++ Implementation (src/bindings/wasm_interface.cpp)

   • •Function must be EMSCRIPTEN_KEEPALIVE inside extern "C" {}
   • •Use REQUIRE_MACHINE() / REQUIRE_MACHINE_OR(default) for null checks
   • •For data returned to JS, use static buffers (not heap allocation per call)
2. •

   CMake Export List (CMakeLists.txt)

   • •Add "_functionName" to the EXPORTED_FUNCTIONS list
   • •Must match the C function name with underscore prefix
3. •

   JavaScript Call Site (src/js/emulator-worker.js)

   • •Call via wasmModule._functionName()
   • •Add message handler if called from main thread via proxy

Adding a New Export

Step 1 — C++ Implementation

Add to src/bindings/wasm_interface.cpp in the appropriate section:

EMSCRIPTEN_KEEPALIVE
ReturnType functionName(ParamType param) {
    REQUIRE_MACHINE_OR(default_value);
    return g_machine->functionName(param);
}

Step 2 — CMake Export

Add "_functionName" to EXPORTED_FUNCTIONS in CMakeLists.txt.

Step 3 — Worker Integration

Add to emulator-worker.js message handler:

case "functionName": {
    const result = wasmModule._functionName(msg.param);
    postMessage({ type: "functionNameResult", result });
    break;
}

Step 4 — Proxy Method (if needed)

Add to emulator-proxy.js:

functionName(param) {
    this.worker.postMessage({ type: "functionName", param });
}

Step 5 — Update Documentation

Update .claude/skills/speccy/docs/bindings.md with the new function signature.

Audit Mode

When invoked without arguments, check consistency:

1. •Find all EMSCRIPTEN_KEEPALIVE functions in wasm_interface.cpp
2. •Find all entries in EXPORTED_FUNCTIONS in CMakeLists.txt
3. •Find all wasmModule._ calls in JavaScript files
4. •Report:
   • •Functions in C++ but missing from CMake (will be stripped — ERROR)
   • •Functions in CMake but not in C++ (phantom exports — WARNING)
   • •JS calls to non-exported functions (ERROR)
   • •Exported functions never called from JS (unused — INFO)