From 68393f5e3bf9c11dedec6c6b7858ade42d56f02a Mon Sep 17 00:00:00 2001
From: Web3RJ <xyzcryp0@gmail.com>
Date: Sat, 31 Oct 2026 13:10:11 +0530
Subject: [PATCH 1/4] Exclude computed fields from Pydantic payload converter
 serialization

Updated to_payload method to use SchemaSerializer for JSON serialization.
---
 temporalio/contrib/pydantic.py | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/temporalio/contrib/pydantic.py b/temporalio/contrib/pydantic.py
index bb8fe0010..78ef6fc80 100644
--- a/temporalio/contrib/pydantic.py
+++ b/temporalio/contrib/pydantic.py
@@ -18,7 +18,7 @@
 from typing import Any
 
 from pydantic import TypeAdapter
-from pydantic_core import SchemaSerializer, to_json
+from pydantic_core import SchemaSerializer
 from pydantic_core.core_schema import any_schema
 
 import temporalio.api.common.v1
@@ -104,17 +104,24 @@ def encoding(self) -> str:
     def to_payload(self, value: Any) -> temporalio.api.common.v1.Payload | None:
         """See base class.
 
-        Uses ``pydantic_core.to_json`` to serialize ``value`` to JSON.
+        Serializes ``value`` to JSON with a ``pydantic_core`` schema
+        serializer configured to match ``pydantic_core.to_json`` defaults.
 
-        See
-        https://docs.pydantic.dev/latest/api/pydantic_core/#pydantic_core.to_json.
+        Computed fields are excluded so payloads always round-trip, even for
+        models with ``extra="forbid"`` which would reject them on read.
         """
         data = (
             self._schema_serializer.to_json(
-                value, by_alias=True, exclude_unset=self._to_json_options.exclude_unset
+                value,
+                by_alias=True,
+                exclude_unset=self._to_json_options.exclude_unset,
+                exclude_computed_fields=True,
             )
             if self._to_json_options
-            else to_json(value)
+            # by_alias=True matches the pydantic_core.to_json default
+            else self._schema_serializer.to_json(
+                value, by_alias=True, exclude_computed_fields=True
+            )
         )
         return temporalio.api.common.v1.Payload(
             metadata={"encoding": self.encoding.encode()}, data=data

From 5439f376552d7d0d6d49aa09c7a0e93221a9ea2c Mon Sep 17 00:00:00 2001
From: Web3RJ <xyzcryp0@gmail.com>
Date: Sat, 31 Oct 2026 13:11:57 +0530
Subject: [PATCH 2/4] Require pydantic>=2.11 for exclude_computed_fields
 support

Updated pydantic dependency version to 2.11.0.
---
 pyproject.toml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pyproject.toml b/pyproject.toml
index a87c0790d..034cfb38c 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -27,7 +27,7 @@ classifiers = [
 [project.optional-dependencies]
 grpc = ["grpcio>=1.48.2,<2"]
 opentelemetry = ["opentelemetry-api>=1.26,<2", "opentelemetry-sdk>=1.26,<2"]
-pydantic = ["pydantic>=2.0.0,<3"]
+pydantic = ["pydantic>=2.11.0,<3"]
 openai-agents = ["temporalio-openai-agents>=1.0.0"]
 google-adk = ["temporalio-google-adk[mcp]>=0.0.1"]
 langgraph = ["temporalio-langgraph>=0.1.0"]

From b0d8381ef91ab97ca21b576078fdf23e9eb80e03 Mon Sep 17 00:00:00 2001
From: Web3RJ <xyzcryp0@gmail.com>
Date: Sat, 31 Oct 2026 13:17:58 +0530
Subject: [PATCH 3/4] Add round-trip regression test for excluded computed
 fields

Added tests for computed fields in Pydantic models, ensuring they are excluded during serialization.
---
 tests/contrib/pydantic/test_pydantic.py | 32 +++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/tests/contrib/pydantic/test_pydantic.py b/tests/contrib/pydantic/test_pydantic.py
index c3ab95f18..8ba6025f7 100644
--- a/tests/contrib/pydantic/test_pydantic.py
+++ b/tests/contrib/pydantic/test_pydantic.py
@@ -128,6 +128,38 @@ def test_to_json_options_exclude_unset_keeps_aliases():
     assert converter.from_payload(payload, AliasModel) == AliasModel(orderId=7)
 
 
+class ComputedFieldModel(BaseModel):
+    model_config = pydantic.ConfigDict(extra="forbid")
+    x: int
+
+    @pydantic.computed_field
+    @property
+    def double(self) -> int:
+        return self.x * 2
+
+
+@pytest.mark.parametrize(
+    "converter",
+    [
+        PydanticJSONPlainPayloadConverter(),
+        PydanticJSONPlainPayloadConverter(
+            temporalio.contrib.pydantic.ToJsonOptions(exclude_unset=True)
+        ),
+    ],
+)
+def test_computed_fields_excluded_for_round_trip(
+    converter: PydanticJSONPlainPayloadConverter,
+):
+    # Computed fields are derived on read, so serializing them breaks models
+    # with extra="forbid" which reject them as unexpected input.
+    payload = converter.to_payload(ComputedFieldModel(x=21))
+    assert payload is not None
+    assert payload.data == b'{"x":21}'
+    assert converter.from_payload(payload, ComputedFieldModel) == ComputedFieldModel(
+        x=21
+    )
+
+
 async def test_pydantic_data_converter_pickle():
     restored = pickle.loads(pickle.dumps(pydantic_data_converter))
     value = {"a": 1}

From 0eec5cb133120e8e18990a3fc9c049c6b65a6e4a Mon Sep 17 00:00:00 2001
From: Web3RJ <xyzcryp0@gmail.com>
Date: Sat, 31 Oct 2026 13:19:10 +0530
Subject: [PATCH 4/4] Add changelog entry for computed fields fix

Exclude computed fields from Pydantic JSON serialization to ensure models round-trip correctly with extra='forbid'. Requires pydantic>=2.11.
---
 changelog/fixed/tidy-computed-teapot.md | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 changelog/fixed/tidy-computed-teapot.md

diff --git a/changelog/fixed/tidy-computed-teapot.md b/changelog/fixed/tidy-computed-teapot.md
new file mode 100644
index 000000000..6509d06a5
--- /dev/null
+++ b/changelog/fixed/tidy-computed-teapot.md
@@ -0,0 +1 @@
+Exclude computed fields when the Pydantic payload converter serializes to JSON, so models using computed fields round-trip even with extra="forbid". Requires pydantic>=2.11.