diff --git a/tests/migrations_test.ts b/tests/migrations_test.ts
new file mode 100644
index 0000000..e624cbe
--- /dev/null
+++ b/tests/migrations_test.ts
@@ -0,0 +1,115 @@
+import { assertEquals } from "@std/assert";
+import { Database } from "@db/sqlite";
+import { applyMigrations } from "../src/migrations/apply.ts";
+
+type TableInfoRow = { name: string };
+type ColumnInfoRow = { name: string };
+
+const tableNames = (db: Database): string[] =>
+  db.prepare(
+    "SELECT name FROM sqlite_master WHERE type = 'table' ORDER BY name",
+  ).all<TableInfoRow>().map((r) => r.name);
+
+const columnNames = (db: Database, table: string): string[] =>
+  db.prepare(`PRAGMA table_info(${table})`)
+    .all<ColumnInfoRow>()
+    .map((r) => r.name)
+    .sort();
+
+const indexNames = (db: Database): string[] =>
+  db.prepare(
+    "SELECT name FROM sqlite_master WHERE type = 'index' AND name NOT LIKE 'sqlite_%' ORDER BY name",
+  ).all<TableInfoRow>().map((r) => r.name);
+
+Deno.test("applyMigrations creates expected tables, columns, and indices", () => {
+  const db = new Database(":memory:");
+  try {
+    applyMigrations(db);
+
+    const tables = tableNames(db);
+    assertEquals(
+      tables.includes("note") &&
+        tables.includes("state") &&
+        tables.includes("webhook_subscription"),
+      true,
+    );
+
+    const noteCols = columnNames(db, "note");
+    for (
+      const col of [
+        "title",
+        "publishedAt",
+        "createdAt",
+        "did",
+        "rkey",
+        "discoverable",
+        "language",
+      ]
+    ) {
+      assertEquals(noteCols.includes(col), true, `note.${col} missing`);
+    }
+
+    const webhookCols = columnNames(db, "webhook_subscription");
+    for (const col of ["id", "did", "method", "url", "token", "verb"]) {
+      assertEquals(
+        webhookCols.includes(col),
+        true,
+        `webhook_subscription.${col} missing`,
+      );
+    }
+
+    const indices = indexNames(db);
+    assertEquals(indices.includes("idx_webhook_subscription_did"), true);
+    assertEquals(indices.includes("idx_webhook_subscription_did_verb"), true);
+  } finally {
+    db.close();
+  }
+});
+
+Deno.test("applyMigrations is idempotent", () => {
+  const db = new Database(":memory:");
+  try {
+    applyMigrations(db);
+    db.exec(
+      "INSERT INTO webhook_subscription (did, method, url, verb) VALUES ('did:plc:x', 'POST', 'https://e.com', 'create')",
+    );
+    applyMigrations(db);
+    applyMigrations(db);
+
+    const [{ count }] = db.prepare(
+      "SELECT COUNT(*) AS count FROM webhook_subscription WHERE did = 'did:plc:x' AND verb = 'create'",
+    ).all<{ count: number }>();
+    assertEquals(count, 1);
+  } finally {
+    db.close();
+  }
+});
+
+Deno.test(
+  "applyMigrations upgrades a legacy schema missing language and discoverable",
+  () => {
+    const db = new Database(":memory:");
+    try {
+      db.exec(`
+        CREATE TABLE note (
+          title TEXT NOT NULL,
+          publishedAt DATETIME,
+          createdAt DATETIME NOT NULL,
+          did TEXT NOT NULL,
+          rkey TEXT NOT NULL,
+          listed INTEGER NOT NULL DEFAULT 1,
+          PRIMARY KEY (did, rkey)
+        );
+      `);
+
+      applyMigrations(db);
+
+      const cols = columnNames(db, "note");
+      assertEquals(cols.includes("discoverable"), true);
+      assertEquals(cols.includes("language"), true);
+      assertEquals(cols.includes("listed"), false);
+    } finally {
+      db.close();
+    }
+  },
+);