feat: add sqlite-vec memory search acceleration

scripts/sqlite-vec-smoke.mjs

@@ -0,0 +1,40 @@
+import { DatabaseSync } from "node:sqlite";
+import { load, getLoadablePath } from "sqlite-vec";
+
+function vec(values) {
+  return Buffer.from(new Float32Array(values).buffer);
+}
+
+const db = new DatabaseSync(":memory:", { allowExtension: true });
+
+try {
+  load(db);
+} catch (err) {
+  const message = err instanceof Error ? err.message : String(err);
+  console.error("sqlite-vec load failed:");
+  console.error(message);
+  console.error("expected extension path:", getLoadablePath());
+  process.exit(1);
+}
+
+db.exec(`
+  CREATE VIRTUAL TABLE v USING vec0(
+    id TEXT PRIMARY KEY,
+    embedding FLOAT[4]
+  );
+`);
+
+const insert = db.prepare("INSERT INTO v (id, embedding) VALUES (?, ?)");
+insert.run("a", vec([1, 0, 0, 0]));
+insert.run("b", vec([0, 1, 0, 0]));
+insert.run("c", vec([0.2, 0.2, 0, 0]));
+
+const query = vec([1, 0, 0, 0]);
+const rows = db
+  .prepare(
+    "SELECT id, vec_distance_cosine(embedding, ?) AS dist FROM v ORDER BY dist ASC"
+  )
+  .all(query);
+
+console.log("sqlite-vec ok");
+console.log(rows);