diff --git a/src/ml4t/models/integration/backtest.py b/src/ml4t/models/integration/backtest.py
index 7a048c1..13065e9 100644
--- a/src/ml4t/models/integration/backtest.py
+++ b/src/ml4t/models/integration/backtest.py
@@ -405,11 +405,9 @@ def backtest_inputs_from_weights(
 def _coerce_feed_spec_mapping(schema: Any | None) -> dict[str, Any]:
     feed_spec_cls = _load_feed_spec_class()
     if feed_spec_cls is not None:
-        return {
-            key: value
-            for key, value in asdict(feed_spec_cls.from_any(schema)).items()
-            if value is not None
-        }
+        spec = feed_spec_cls.from_any(schema)
+        data = spec.to_dict() if hasattr(spec, "to_dict") else asdict(spec)
+        return {key: value for key, value in data.items() if value is not None}
     return _fallback_feed_spec_mapping(schema)
 
 
diff --git a/uv.lock b/uv.lock
index 7299efe..940abed 100644
--- a/uv.lock
+++ b/uv.lock
@@ -1152,11 +1152,11 @@ wheels = [
 
 [[package]]
 name = "packaging"
-version = "26.2"
+version = "26.3"
 source = { registry = "https://pypi.org/simple" }
-sdist = { url = "https://files.pythonhosted.org/packages/d7/f1/e7a6dd94a8d4a5626c03e4e99c87f241ba9e350cd9e6d75123f992427270/packaging-26.2.tar.gz", hash = "sha256:ff452ff5a3e828ce110190feff1178bb1f2ea2281fa2075aadb987c2fb221661", size = 228134, upload-time = "2026-04-24T20:15:23.917Z" }
+sdist = { url = "https://files.pythonhosted.org/packages/7d/fa/3944b40b07da9ce895c0e6303a5ab7d53da063554f534556b134a54d6093/packaging-26.3.tar.gz", hash = "sha256:94edc256424af38762eb31306eed28beb9f0efc50a8837492c9d6fd6004aed79", size = 313412, upload-time = "2026-08-04T18:15:28.737Z" }
 wheels = [
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+    { url = "https://files.pythonhosted.org/packages/63/34/ba1c580383c9eada3711951fef0795c80b829a078d72188184bcab9dd527/packaging-26.3-py3-none-any.whl", hash = "sha256:d7193f7c8e4e93f444fde0262bf90af30e16fa0ad0ad44cb553c87339b23cd1c", size = 129956, upload-time = "2026-08-04T18:15:27.159Z" },
 ]
 
 [[package]]
@@ -1314,14 +1314,14 @@ wheels = [
 
 [[package]]
 name = "python-discovery"
-version = "1.5.1"
+version = "1.6.3"
 source = { registry = "https://pypi.org/simple" }
 dependencies = [
     { name = "filelock" },
 ]
-sdist = { url = "https://files.pythonhosted.org/packages/04/b7/1581a8103855c43567776aa34135e5ec3c597346c23bfd10c7eb5e0b10a4/python_discovery-1.5.1.tar.gz", hash = "sha256:e2ea8b884cd1701f386eda8cf327b87743f1dc21b7f784470799537d95635384", size = 77200, upload-time = "2026-07-31T22:06:02.48Z" }
+sdist = { url = "https://files.pythonhosted.org/packages/fc/54/fad125f5c48f7821644ee6f223ebfcedc4e23597c1a16eeb13d33aa4a91a/python_discovery-1.6.3.tar.gz", hash = "sha256:a62b301d96cf5489cb96ab023b32e068421867fdd5df2e42eece877869047fa2", size = 88998, upload-time = "2026-10-16T03:54:29.507Z" }
 wheels = [
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+    { url = "https://files.pythonhosted.org/packages/de/ec/643826e4d69b7bdce4213f221e8f5ed06d0a9dd69fa9b33342578d2cc8c8/python_discovery-1.6.3-py3-none-any.whl", hash = "sha256:cb7654125e3dcb594269a6feb56ac693f1f13b7c654493a93eba72dc22d18034", size = 39386, upload-time = "2026-10-16T03:54:28.237Z" },
 ]
 
 [[package]]
@@ -1632,26 +1632,27 @@ wheels = [
 
 [[package]]
 name = "urllib3"
-version = "2.7.0"
+version = "2.8.0"
 source = { registry = "https://pypi.org/simple" }
-sdist = { url = "https://files.pythonhosted.org/packages/53/0c/06f8b233b8fd13b9e5ee11424ef85419ba0d8ba0b3138bf360be2ff56953/urllib3-2.7.0.tar.gz", hash = "sha256:231e0ec3b63ceb14667c67be60f2f2c40a518cb38b03af60abc813da26505f4c", size = 433602, upload-time = "2026-05-07T16:13:18.596Z" }
+sdist = { url = "https://files.pythonhosted.org/packages/e3/05/b17359e1cefb4f909b5e40b1b90a496d987258916dbbf88e842c729f510e/urllib3-2.8.0.tar.gz", hash = "sha256:63bf2ead4c879426ebf22ef2a781eeb4aa3b4ae798a0435506f8687fd5bb9b63", size = 458972, upload-time = "2026-09-15T19:29:36.253Z" }
 wheels = [
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+    { url = "https://files.pythonhosted.org/packages/92/9d/c4e665119135114480843e7ab388fa94d8480650450e6f8e26b70d323a4c/urllib3-2.8.0-py3-none-any.whl", hash = "sha256:0cf3cae568d36aa9576b28dfb35f11328f1cb974ca7647d9475ebb86c75ac6e3", size = 135717, upload-time = "2026-09-15T19:29:34.577Z" },
 ]
 
 [[package]]
 name = "virtualenv"
-version = "21.7.1"
+version = "21.14.8"
 source = { registry = "https://pypi.org/simple" }
 dependencies = [
     { name = "distlib" },
     { name = "filelock" },
+    { name = "packaging" },
     { name = "platformdirs" },
     { name = "python-discovery" },
 ]
-sdist = { url = "https://files.pythonhosted.org/packages/ea/fa/18004e5cb15541ad2a68ff219c755233b012b12d4ec8663d06a258082bec/virtualenv-21.7.1.tar.gz", hash = "sha256:d0dbfaa5483487baea28d7210ef8d24c9d1bd0f10f449eeb215568825a9b334e", size = 5525237, upload-time = "2026-07-30T15:40:36.36Z" }
+sdist = { url = "https://files.pythonhosted.org/packages/0b/6a/fbdeea5c07d5674139639d42a97a41d26e9b9b8cb2a1265fa936f655ee20/virtualenv-21.14.8.tar.gz", hash = "sha256:394e45ed610ceffb5018e1a179e3a8012c02fd87fe792ab4aae67ce5e7e3afbd", size = 5474561, upload-time = "2026-10-16T00:09:09.672Z" }
 wheels = [
-    { url = "https://files.pythonhosted.org/packages/4b/a7/ded126c19495158a05c7202b3389139839d4cf78d622d453867778e0f7a8/virtualenv-21.7.1-py3-none-any.whl", hash = "sha256:6394973f990536e34c05157179146c020284c42fe01da1dfeb0ba16c345280d9", size = 5504576, upload-time = "2026-07-30T15:40:34.512Z" },
+    { url = "https://files.pythonhosted.org/packages/14/01/cd63b97dd556293e1c74d76053936d9cef11a28eac605c735ae9f0ee324f/virtualenv-21.14.8-py3-none-any.whl", hash = "sha256:d2a347fdbc1a65e33c2c5e84dc767b4a3538a25749536a752744d4fe1f71c37a", size = 5487606, upload-time = "2026-10-16T00:09:07.441Z" },
 ]
 
 [[package]]