From 8317f23a43197867f3c909db6c05038a7c133770 Mon Sep 17 00:00:00 2001
From: Tung Lam <lamphamabtung96@gmail.com>
Date: Mon, 17 Aug 2026 03:14:54 +0000
Subject: [PATCH] fix redirect background tasks

---
 fasthtml/core.py      |  7 ++++++-
 nbs/api/00_core.ipynb | 20 ++++++++++++++++++--
 2 files changed, 24 insertions(+), 3 deletions(-)

diff --git a/fasthtml/core.py b/fasthtml/core.py
index 46b4d1b9..42b17940 100644
--- a/fasthtml/core.py
+++ b/fasthtml/core.py
@@ -429,6 +429,7 @@ def is_full_page(req, resp):
 def _part_resp(req, resp):
     "Partition response into HTTP headers, background tasks, and content"
     resp = flat_tuple(resp)
+    resp = flat_tuple(o.__response__(req) if hasattr(o, '__response__') else o for o in resp)
     resp = resp + tuple(getattr(req, 'injects', ()))
     http_hdrs,resp = partition(resp, risinstance(HttpHeader))
     tasks,resp = partition(resp, risinstance(BackgroundTask))
@@ -471,7 +472,11 @@ def _resp(req, resp, cls=empty, status_code=200):
     if not (isinstance(cls, type) and issubclass(cls, Response)): cls=empty
     if isinstance(resp, FileResponse) and not os.path.exists(resp.path): raise HTTPException(404, resp.path)
     resp,kw = _part_resp(req, resp)
-    if isinstance(resp, Response): return resp
+    if isinstance(resp, Response):
+        if tasks := kw.get('background'):
+            if resp.background: tasks.tasks.insert(0, resp.background)
+            resp.background = tasks
+        return resp
     if cls is not empty: return cls(resp, status_code=status_code, **kw)
     if _is_ft_resp(resp):
         cts = _xt_cts(req, resp)
diff --git a/nbs/api/00_core.ipynb b/nbs/api/00_core.ipynb
index d8827e07..1046fde1 100644
--- a/nbs/api/00_core.ipynb
+++ b/nbs/api/00_core.ipynb
@@ -1480,6 +1480,7 @@
     "def _part_resp(req, resp):\n",
     "    \"Partition response into HTTP headers, background tasks, and content\"\n",
     "    resp = flat_tuple(resp)\n",
+    "    resp = flat_tuple(o.__response__(req) if hasattr(o, '__response__') else o for o in resp)\n",
     "    resp = resp + tuple(getattr(req, 'injects', ()))\n",
     "    http_hdrs,resp = partition(resp, risinstance(HttpHeader))\n",
     "    tasks,resp = partition(resp, risinstance(BackgroundTask))\n",
@@ -1546,7 +1547,11 @@
     "    if not (isinstance(cls, type) and issubclass(cls, Response)): cls=empty\n",
     "    if isinstance(resp, FileResponse) and not os.path.exists(resp.path): raise HTTPException(404, resp.path)\n",
     "    resp,kw = _part_resp(req, resp)\n",
-    "    if isinstance(resp, Response): return resp\n",
+    "    if isinstance(resp, Response):\n",
+    "        if tasks := kw.get('background'):\n",
+    "            if resp.background: tasks.tasks.insert(0, resp.background)\n",
+    "            resp.background = tasks\n",
+    "        return resp\n",
     "    if cls is not empty: return cls(resp, status_code=status_code, **kw)\n",
     "    if _is_ft_resp(resp):\n",
     "        cts = _xt_cts(req, resp)\n",
@@ -2970,7 +2975,18 @@
     "        print(\"Background task completed!\")\n",
     "    return P(\"Task started\"), BackgroundTask(long_running_task)\n",
     "\n",
-    "response = cli.get(\"/background\")"
+    "response = cli.get(\"/background\")\n",
+    "\n",
+    "task_runs = []\n",
+    "\n",
+    "@app.get(\"/background-redirect\")\n",
+    "def background_redirect():\n",
+    "    return Redirect(\"/\"), BackgroundTask(task_runs.append, True)\n",
+    "\n",
+    "response = cli.get(\"/background-redirect\", follow_redirects=False)\n",
+    "test_eq(response.status_code, 303)\n",
+    "test_eq(response.headers[\"location\"], \"/\")\n",
+    "test_eq(task_runs, [True])"
    ]
   },
   {