fix(wasm): resolve playground "env" module error

.github/workflows/pages.yml

@@ -39,6 +39,7 @@ jobs:
         run: |
           mkdir -p _site/pkg
           cp playground/index.html _site/
+          cp playground/env.js _site/pkg/
           cp crates/truss-wasm/pkg/truss_wasm.js _site/pkg/
           cp crates/truss-wasm/pkg/truss_wasm_bg.wasm _site/pkg/
 

playground/env.js

@@ -0,0 +1,20 @@
+// WASM "env" shim — provides C stdlib stubs required by tree-sitter.
+//
+// tree-sitter compiles C code that references these symbols.  The Rust
+// allocator handles actual memory management via wasm-bindgen exports,
+// so malloc/free/calloc/realloc here are never called at runtime.  The
+// I/O and clock functions are likewise unreachable in the browser
+// context, but must be present for WebAssembly.instantiate to succeed.
+
+export function malloc()    { return 0; }
+export function free()      {}
+export function calloc()    { return 0; }
+export function realloc()   { return 0; }
+export function abort()     { throw new Error("abort"); }
+export function fprintf()   { return 0; }
+export function snprintf()  { return 0; }
+export function vsnprintf() { return 0; }
+export function fclose()    { return 0; }
+export function clock()     { return 0; }
+export function fwrite()    { return 0; }
+export function fputc()     { return 0; }

playground/index.html

@@ -4,6 +4,9 @@
     <meta charset="UTF-8">
     <meta name="viewport" content="width=device-width, initial-scale=1.0">
     <title>Truss Playground - GitHub Actions Workflow Validator</title>
+    <script type="importmap">
+    { "imports": { "env": "./pkg/env.js" } }
+    </script>
     <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/codemirror/5.65.16/codemirror.min.css">
     <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/codemirror/5.65.16/theme/dracula.min.css">
     <style>