fix: handle WASM OOM for LM head + show error details

LM head matVec is 49152 x 960 = 188MB, which can exceed WASM
linear memory. Fall back to JS for matrices >100MB.

Also: read error body from Aether 500 responses to show
actual error message instead of generic 'Internal Server Error'.

aether-server.mjs

@@ -61,15 +61,25 @@ async function loadSIMD() {
 
     return {
       matVec(matrix, vector, rows, cols) {
-        const saved = wasm.getHeapPtr();
-        const mPtr = wasm.allocate(matrix.byteLength);
-        const vPtr = wasm.allocate(vector.byteLength);
-        const rPtr = wasm.allocate(rows * 4);
-        copyTo(mPtr, matrix); copyTo(vPtr, vector);
-        wasm.matVecSimdBatch4(mPtr, vPtr, rPtr, rows, cols);
-        const result = copyFrom(rPtr, rows);
-        wasm.resetHeap(saved);
-        return result;
+        // Fall back to JS for huge matrices (LM head: 49152 x 960 = 188MB)
+        // that exceed WASM linear memory
+        if (matrix.byteLength > 100_000_000) {
+          return matVecJS(matrix, vector, rows, cols);
+        }
+        try {
+          const saved = wasm.getHeapPtr();
+          const mPtr = wasm.allocate(matrix.byteLength);
+          const vPtr = wasm.allocate(vector.byteLength);
+          const rPtr = wasm.allocate(rows * 4);
+          copyTo(mPtr, matrix); copyTo(vPtr, vector);
+          wasm.matVecSimdBatch4(mPtr, vPtr, rPtr, rows, cols);
+          const result = copyFrom(rPtr, rows);
+          wasm.resetHeap(saved);
+          return result;
+        } catch (e) {
+          // WASM OOM -- fall back to JS
+          return matVecJS(matrix, vector, rows, cols);
+        }
       },
       rmsNorm(x, weight, eps) {
         const saved = wasm.getHeapPtr();

app.py

@@ -96,6 +96,13 @@ def gen_aether(prompt):
             result["tokens"],
             result["avgTokenMs"],
         )
+    except urllib.error.HTTPError as e:
+        body = e.read().decode() if e.fp else str(e)
+        try:
+            detail = json.loads(body).get("error", body[:200])
+        except Exception:
+            detail = body[:200]
+        return f"[Aether error: {detail}]", 0, 0, 0
     except Exception as e:
         return f"[Aether error: {e}]", 0, 0, 0