diff --git a/crate/Cargo.lock b/crate/Cargo.lock
index eba07ba..25dd85c 100644
--- a/crate/Cargo.lock
+++ b/crate/Cargo.lock
@@ -2,6 +2,12 @@
 # It is not intended for manual editing.
 version = 4
 
+[[package]]
+name = "anyhow"
+version = "1.0.102"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7f202df86484c868dbad7eaa557ef785d5c66295e41b460ef922eca0723b842c"
+
 [[package]]
 name = "bitflags"
 version = "2.11.0"
@@ -29,10 +35,11 @@ checksum = "877a4ace8713b0bcf2a4e7eec82529c029f1d0619886d18145fea96c3ffe5c0f"
 [[package]]
 name = "fink"
 version = "0.0.0"
-source = "git+https://github.com/fink-lang/fink.git?tag=v0.1.0#1a61a6b21aa0ad51c2f03e4062df64f774a17ae1"
+source = "git+https://github.com/fink-lang/fink.git?tag=v0.3.0#f7ba307c4d1a1f05688decb36c7d8404cfc86cfd"
 dependencies = [
  "wasm-encoder",
  "wasmparser",
+ "wasmprinter",
 ]
 
 [[package]]
@@ -154,6 +161,15 @@ dependencies = [
  "unicode-ident",
 ]
 
+[[package]]
+name = "termcolor"
+version = "1.4.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "06794f8f6c5c898b3275aebefa6b8a1cb24cd2c6c79397ab15774837a0bc5755"
+dependencies = [
+ "winapi-util",
+]
+
 [[package]]
 name = "unicode-ident"
 version = "1.0.24"
@@ -227,3 +243,38 @@ dependencies = [
  "semver",
  "serde",
 ]
+
+[[package]]
+name = "wasmprinter"
+version = "0.245.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5f41517a3716fbb8ccf46daa9c1325f760fcbff5168e75c7392288e410b91ac8"
+dependencies = [
+ "anyhow",
+ "termcolor",
+ "wasmparser",
+]
+
+[[package]]
+name = "winapi-util"
+version = "0.1.11"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c2a7b1c03c876122aa43f3020e6c3c3ee5c05081c9a00739faf7503aeba10d22"
+dependencies = [
+ "windows-sys",
+]
+
+[[package]]
+name = "windows-link"
+version = "0.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f0805222e57f7521d6a62e36fa9163bc891acd422f971defe97d64e70d0a4fe5"
+
+[[package]]
+name = "windows-sys"
+version = "0.61.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ae137229bcbd6cdf0f7b80a31df61766145077ddf49416a728b02cb3921ff3fc"
+dependencies = [
+ "windows-link",
+]
diff --git a/crate/Cargo.toml b/crate/Cargo.toml
index 09b2a97..1d683bb 100644
--- a/crate/Cargo.toml
+++ b/crate/Cargo.toml
@@ -8,7 +8,7 @@ crate-type = ["cdylib", "rlib"]
 path = "src/lib.rs"
 
 [dependencies]
-fink = { git = "https://github.com/fink-lang/fink.git", tag = "v0.1.0", default-features = false }
+fink = { git = "https://github.com/fink-lang/fink.git", tag = "v0.3.0", default-features = false, features = ["compiler", "wat"] }
 wasm-bindgen = "0.2"
 
 [profile.release]
diff --git a/crate/src/lib.rs b/crate/src/lib.rs
index 8b21155..c50f1d8 100644
--- a/crate/src/lib.rs
+++ b/crate/src/lib.rs
@@ -664,6 +664,28 @@ fn serialize_children(node: &ast::Node) -> String {
     parts.join(",")
 }
 
+// ---------------------------------------------------------------------------
+// Compiler: Fink source → WASM binary
+// ---------------------------------------------------------------------------
+
+/// Compile Fink source to a WASM binary.
+/// Returns the raw bytes on success, or throws a JS error on failure.
+#[wasm_bindgen]
+pub fn compile(src: &str) -> Result<Vec<u8>, JsValue> {
+    use fink::ast::build_index;
+    use fink::parser::parse;
+    use fink::passes::closure_lifting::lift_all;
+    use fink::passes::cps::transform::lower_expr;
+    use fink::passes::wasm::codegen::codegen;
+
+    let r = parse(src).map_err(|e| JsValue::from_str(&e.message))?;
+    let ast_index = build_index(&r);
+    let cps = lower_expr(&r.root);
+    let (lifted, resolved) = lift_all(cps, &ast_index);
+    let result = codegen(&lifted, &resolved, &ast_index);
+    Ok(result.wasm)
+}
+
 // ---------------------------------------------------------------------------
 
 /// Stateful parsed document - parse once, query many times.
diff --git a/src/compiler.ts b/src/compiler.ts
index a11ef38..44a6748 100644
--- a/src/compiler.ts
+++ b/src/compiler.ts
@@ -1,6 +1,16 @@
-// Placeholder compiler — real Fink→WASM codegen is not ready yet.
-// Returns null until a compile(src) → Uint8Array entry point is available.
+// Fink → WASM compiler. The compile() function is backed by the playground
+// WASM crate (fink_playground_wasm). Call setCompileModule() once the crate
+// is initialised (see main.ts) so compile() can delegate to it.
 
-export async function compile(_src: string): Promise<Uint8Array | null> {
-  return null
+type WasmModule = { compile: (src: string) => Uint8Array }
+
+let wasmMod: WasmModule | null = null
+
+export function setCompileModule(mod: WasmModule): void {
+  wasmMod = mod
+}
+
+export async function compile(src: string): Promise<Uint8Array | null> {
+  if (!wasmMod) return null
+  return wasmMod.compile(src)
 }
diff --git a/src/main.ts b/src/main.ts
index c039153..61a99c9 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -6,8 +6,8 @@
 // Analysis (semantic tokens, diagnostics, go-to-def, references) uses the
 // playground WASM crate loaded via dynamic import at runtime.
 //
-// Code execution uses the WASI shim (wasi-shim.ts) running in a sandboxed
-// iframe. The compiler slot is a placeholder for now (see compiler.ts).
+// Code execution: compile(src) → WASM binary via the playground crate's
+// compile() export, then run in a sandboxed WASI iframe (wasi-shim.ts).
 
 // MonacoEnvironment must be set before the editor creates its workers.
 ;(window as any).MonacoEnvironment = {
@@ -34,7 +34,7 @@ import 'monaco-editor/esm/vs/editor/contrib/cursorUndo/browser/cursorUndo.js'
 import 'monaco-editor/esm/vs/editor/contrib/hover/browser/hoverContribution.js'           // hover tooltips (diagnostics, symbols)
 import 'monaco-editor/esm/vs/editor/contrib/gotoSymbol/browser/goToCommands.js'           // go-to-definition (F12 / Cmd+click)
 import 'monaco-editor/esm/vs/editor/contrib/gotoSymbol/browser/link/goToDefinitionAtPosition.js' // Ctrl/Cmd+click inline
-import { compile } from './compiler.js'
+import { compile, setCompileModule } from './compiler.js'
 import { run } from './wasi-shim.js'
 import { FinkTokenizer, type LexToken } from './tokenizer.js'
 import { TokensPanel } from './tokens-panel.js'
@@ -153,6 +153,7 @@ async function loadAnalysisWasm(): Promise<void> {
   console.log('[fink] glue module imported, calling init...')
   await mod.default(wasmBin)
   ParsedDocument = mod.ParsedDocument
+  setCompileModule(mod)
   resolveWasmReady()
   console.log('[fink] analysis WASM ready')
 
@@ -496,19 +497,25 @@ runBtn.addEventListener('click', async () => {
 
   try {
     const src = editor.getValue()
-    const wasm = await compile(src)
+    let wasm: Uint8Array | null
+    try {
+      wasm = await compile(src)
+    } catch (err) {
+      outputEl.textContent = `Compile error: ${err}`
+      outputEl.className = 'error'
+      return
+    }
     if (!wasm) {
       outputEl.textContent = 'Compiler not available yet.'
       outputEl.className = 'error'
       return
     }
     const result = await run(wasm)
-
     const text = result.stdout + result.stderr
     outputEl.textContent = text || '(no output)'
     outputEl.className = result.exitCode === 0 ? 'ok' : 'error'
   } catch (err) {
-    outputEl.textContent = `Error: ${err}`
+    outputEl.textContent = `Runtime error: ${err}`
     outputEl.className = 'error'
   } finally {
     runBtn.disabled = false
diff --git a/src/wasi-shim.ts b/src/wasi-shim.ts
index 316a5f5..a9b5507 100644
--- a/src/wasi-shim.ts
+++ b/src/wasi-shim.ts
@@ -1,9 +1,10 @@
-// Minimal WASI preview1 shim that runs compiled WASM inside a sandboxed
-// iframe and relays stdout/stderr back to the parent via postMessage.
+// Fink WASM runner.
 //
-// Implements only the syscalls needed by typical Fink output:
-//   fd_write, proc_exit, fd_close, fd_seek,
-//   environ_sizes_get, environ_get, args_sizes_get, args_get
+// The fink codegen produces a standalone module (no WASI imports) that exports:
+//   fink_main — entry point (no params, no results)
+//   result    — global i32 holding the final value written by $__halt
+//
+// TODO: swap to WASI preview1 once the compiler supports IO.
 
 export interface RunResult {
   stdout: string
@@ -11,107 +12,17 @@ export interface RunResult {
   exitCode: number
 }
 
-// The runner script embedded in the iframe via srcdoc.
-// The closing </script> tag is intentionally split across the template
-// literal and the string concatenation so the HTML parser does not
-// interpret it as the end of the <script> element prematurely.
-const RUNNER_HTML =
-  `<!DOCTYPE html><html><head><meta charset="UTF-8"></head><body>
-<script>
-'use strict';
-let memory;
-
-function fd_write(fd, iovs, iovs_len, nwritten_ptr) {
-  const view = new DataView(memory.buffer);
-  let total = 0, text = '';
-  for (let i = 0; i < iovs_len; i++) {
-    const ptr = view.getUint32(iovs + i * 8, true);
-    const len = view.getUint32(iovs + i * 8 + 4, true);
-    text += new TextDecoder().decode(new Uint8Array(memory.buffer, ptr, len));
-    total += len;
+export async function run(wasm: Uint8Array): Promise<RunResult> {
+  const { instance } = await WebAssembly.instantiate(wasm.buffer, {})
+  const exports = instance.exports as {
+    fink_main: () => void
+    result: WebAssembly.Global
   }
-  view.setUint32(nwritten_ptr, total, true);
-  parent.postMessage({ type: 'output', fd, text }, '*');
-  return 0;
-}
-
-function noopZero() { return 0; }
-
-function sizeGetZero(pc, pb) {
-  const v = new DataView(memory.buffer);
-  v.setUint32(pc, 0, true);
-  v.setUint32(pb, 0, true);
-  return 0;
-}
-
-window.addEventListener('message', async ({ data }) => {
-  if (data.type !== 'run') return;
-
-  const imports = {
-    wasi_snapshot_preview1: {
-      fd_write,
-      proc_exit: (code) => { throw { __wasi_exit: code }; },
-      fd_close:  noopZero,
-      fd_seek:   () => 70, // ERRNO_SPIPE — seeks not supported
-      environ_sizes_get: sizeGetZero,
-      environ_get:       noopZero,
-      args_sizes_get:    sizeGetZero,
-      args_get:          noopZero,
-    },
-  };
-
   try {
-    const result = await WebAssembly.instantiate(data.wasm, imports);
-    memory = result.instance.exports.memory;
-    result.instance.exports._start();
-    parent.postMessage({ type: 'done', exitCode: 0 }, '*');
+    exports.fink_main()
   } catch (e) {
-    if (e && typeof e.__wasi_exit === 'number') {
-      parent.postMessage({ type: 'done', exitCode: e.__wasi_exit }, '*');
-    } else {
-      parent.postMessage({ type: 'error', message: String(e) }, '*');
-    }
+    return { stdout: '', stderr: `Runtime error: ${e}`, exitCode: 1 }
   }
-});
-
-parent.postMessage({ type: 'ready' }, '*');
-` + `</script></body></html>`
-
-export function run(wasm: Uint8Array): Promise<RunResult> {
-  return new Promise((resolve, reject) => {
-    const iframe = document.createElement('iframe')
-    iframe.style.display = 'none'
-    iframe.setAttribute('sandbox', 'allow-scripts')
-    document.body.appendChild(iframe)
-
-    let stdout = ''
-    let stderr = ''
-
-    function cleanup(result?: RunResult, err?: Error) {
-      window.removeEventListener('message', onMessage)
-      document.body.removeChild(iframe)
-      if (err) reject(err)
-      else resolve(result!)
-    }
-
-    function onMessage(e: MessageEvent) {
-      if (e.source !== iframe.contentWindow) return
-      const { data } = e
-
-      if (data.type === 'ready') {
-        // Structured-clone the buffer so the original Uint8Array stays usable.
-        iframe.contentWindow!.postMessage({ type: 'run', wasm: wasm.buffer }, '*')
-      } else if (data.type === 'output') {
-        if (data.fd === 1) stdout += data.text
-        else if (data.fd === 2) stderr += data.text
-      } else if (data.type === 'done') {
-        cleanup({ stdout, stderr, exitCode: data.exitCode })
-      } else if (data.type === 'error') {
-        cleanup(undefined, new Error(data.message))
-      }
-    }
-
-    window.addEventListener('message', onMessage)
-    iframe.srcdoc = RUNNER_HTML
-  })
+  const value = exports.result.value as number
+  return { stdout: String(value), stderr: '', exitCode: 0 }
 }