fix: use proper phrase decompress algorithm

[deploy]

src/lib/serialization/actions.ts

@@ -1,23 +1,18 @@
 /**
- * Compresses an action list into a Uint8Array of 10-bit integers, supporting values of up to 1023
+ * Compresses an action list into a Uint8Array of variable-length 8/13-bit integers.
+ *
+ * Action codes <32 are invalid.
  */
 export function compressActions(actions: number[]): Uint8Array {
-  const overflow = actions.length % 4
-  const array = new Uint8Array(
-    Math.ceil((actions.length - overflow) * 1.25 + (overflow === 0 ? 0 : overflow + 1)),
-  )
-  let arrayOffset = 0
-  for (let i = 0; i < actions.length; i += 4) {
-    let final = 0
-    for (let j = 0; j < 4 && i + j < actions.length; j++) {
-      const action = actions[i + j]
-      array[arrayOffset++] = (action >>> 2) & 0xff
-      final |= (action & 0x03) << (j * 2)
+  const buffer = new Uint8Array(actions.length * 2)
+  let i = 0
+  for (const action of actions) {
+    if (action > 0xff) {
+      buffer[i++] = action >>> 8
     }
-    array[arrayOffset++] = final
+    buffer[i++] = action & 0xff
   }
-  console.assert(arrayOffset === array.length)
-  return array
+  return buffer.slice(0, i)
 }
 
 /**
@@ -27,12 +22,12 @@ export function compressActions(actions: number[]): Uint8Array {
  */
 export function decompressActions(raw: Uint8Array): number[] {
   const actions: number[] = []
-  for (let i = 0; i < raw.length + 4; i += 5) {
-    const overflow = raw[Math.min(i + 4, raw.length - 1)]
-
-    for (let j = 0; j < 4 && i + j < raw.length - 1; j++) {
-      actions.push((raw[i + j] << 2) | ((overflow >>> (j * 2)) & 0x3))
+  for (let i = 0; i < raw.length; i++) {
+    let action = raw[i]
+    if (action < 32) {
+      action = (action << 8) | raw[++i]
     }
+    actions.push(action)
   }
   return actions
 }