diff --git a/.changeset/transport-http-requeue.md b/.changeset/transport-http-requeue.md
new file mode 100644
index 0000000..11755f8
--- /dev/null
+++ b/.changeset/transport-http-requeue.md
@@ -0,0 +1,7 @@
+---
+'@smooai/observability': patch
+---
+
+TypeScript: re-queue ingest batches when native `fetch` resolves a non-2xx response.
+
+Native `fetch` resolves normally for HTTP 4xx and 5xx responses. The transport only handled rejected promises, so a non-2xx ingest response removed the batch from the queue permanently instead of retrying it. The transport now treats `response.ok === false` as a failure and pushes the batch back onto the queue for the existing retry path.
diff --git a/packages/core/src/__tests__/transport.test.ts b/packages/core/src/__tests__/transport.test.ts
index f00c4f4..1865015 100644
--- a/packages/core/src/__tests__/transport.test.ts
+++ b/packages/core/src/__tests__/transport.test.ts
@@ -93,4 +93,14 @@ describe('Transport', () => {
         // the queue after the throw rather than being dropped.
         expect(t._queueSize()).toBe(1);
     });
+
+    it('re-queues the batch when native fetch resolves a non-2xx response', async () => {
+        const fetcher = vi.fn().mockResolvedValue({ ok: false, status: 503 });
+        const t = new Transport({ dsn: 'https://example.com', maxBatchSize: 1, flushIntervalMs: 1000 }, { canBeacon: false, fetcher });
+        t.enqueue(evt('a'));
+        await vi.runOnlyPendingTimersAsync();
+        await Promise.resolve();
+        expect(fetcher).toHaveBeenCalled();
+        expect(t._queueSize()).toBe(1);
+    });
 });
diff --git a/packages/core/src/transport.ts b/packages/core/src/transport.ts
index 2032a1c..174dfeb 100644
--- a/packages/core/src/transport.ts
+++ b/packages/core/src/transport.ts
@@ -81,12 +81,13 @@ export class Transport {
             // (`@smooai/fetch`) — it owns retries/timeouts/circuit-breaking.
             // Fall back to global fetch when no fetcher was injected (tests).
             const fetcher = this.adapter.fetcher ?? ((url, init) => fetch(url, init));
-            await fetcher(this.opts.dsn, {
+            const response = await fetcher(this.opts.dsn, {
                 method: 'POST',
                 headers: { 'content-type': 'application/json' },
                 body: JSON.stringify(payload),
                 keepalive: true,
             });
+            if (response.ok === false) throw new Error('ingest request failed');
         } catch {
             // Best-effort: push events back to the front of the queue for next attempt.
             this.queue.unshift(...batch);