feat: update compound calculation

feat: add "will my compound break" page

src/lib/serial/chord.ts

@@ -69,5 +69,8 @@ export function hashChord(actions: number[]) {
   for (let i = 0; i < 16; i++) {
     hash = Math.imul(hash ^ view.getUint8(i), 16777619);
   }
+  if ((hash & 0xff) === 0xff) {
+    hash ^= 0xff;
+  }
   return hash & 0x3fff_ffff;
 }

src/routes/(app)/config/chords/will-my-compound-break/+page.svelte

@@ -0,0 +1,66 @@
+<script lang="ts">
+  import { serializeActions } from "$lib/serial/chord";
+  import { chords } from "$lib/undo-redo";
+  import ChordEdit from "../ChordEdit.svelte";
+
+  export function hashChord(actions: number[]) {
+    const chord = new Uint8Array(16);
+    const view = new DataView(chord.buffer);
+    const serialized = serializeActions(actions);
+    view.setBigUint64(0, serialized & 0xffff_ffff_ffff_ffffn, true);
+    view.setBigUint64(8, serialized >> 64n, true);
+    let hash = 2166136261;
+    for (let i = 0; i < 16; i++) {
+      hash = Math.imul(hash ^ view.getUint8(i), 16777619);
+    }
+    return hash & 0x3fff_ffff;
+  }
+
+  const broken = $derived(
+    $chords.filter((it) => (hashChord(it.actions) & 0xff) === 0xff),
+  );
+</script>
+
+<h1>Will my compound break</h1>
+<p>
+  Pre-2.2.0 there was a bug where creating a compound with specific chords as a
+  base could corrupt your library.
+</p>
+
+{#if broken.length > 0}
+  <p class="warning">Chords have been detected.</p>
+  <p>
+    If you have ever tried to create a compound chord with <b class="warning"
+      >any of these as a base</b
+    >, your library might have been corrupted.
+  </p>
+  {#each broken as chord}
+    <ChordEdit {chord} onduplicate={() => {}} />
+  {/each}
+{:else}
+  <p>No problematic chords found</p>
+{/if}
+
+<style lang="scss">
+  .warning {
+    color: var(--md-sys-color-error);
+    font-weight: bold;
+  }
+
+  .chord {
+    display: flex;
+    gap: 0.5rem;
+    margin-bottom: 0.5rem;
+  }
+
+  .compound {
+    display: flex;
+    flex-direction: column;
+    gap: 0.5rem;
+    margin-bottom: 1rem;
+  }
+
+  p {
+    max-width: 600px;
+  }
+</style>