feat: emit Go transfer type converters for proto-backed models

CHANGELOG.md

@@ -18,10 +18,20 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Changed
 
+- Go proto-backed operation models now use SDK transfer-type converters instead
+  of eager conversion at the operation call site. Conversion errors surface on
+  the returned future. Generated converters use
+  `converter.NewContextualTransferTypeConverter`. The Go samples pin the
+  squash-merged experimental SDK API from temporalio/sdk-go#2703.
+
 ### Deprecated
 
 ### Breaking Changes
 
+- Go models with generated transfer-type converters require workflow context and
+  cannot be used as top-level workflow return values or activity arguments.
+- Go generation rejects `@nexus.omit` fields used as resource constructor
+  arguments.
 - .NET generic type parameters now use the C# `T` prefix. For example, the
   authored `output-t` alias generates `TOutput` instead of `OutputT`.
 

GUIDE.md

@@ -619,6 +619,20 @@ code that converts between the public model and its protobuf transfer type.
 Generated callers continue to accept and return the public model; conversion is
 performed by the target SDK or generated operation helpers.
 
+For Go, generated proto-backed operation inputs and outputs implement
+`converter.ValueWithTransferTypeConverter`. The SDK converts these models during
+payload conversion using `converter.NewContextualTransferTypeConverter`; the generated
+method returns both the converter and its construction error. Models and transfer
+types use non-pointer type arguments, with a value receiver on the model.
+
+Go conversion requires a `workflow.Context` to access the workflow's data
+converter. Using these models outside a workflow, including as a workflow's
+top-level return value or an activity argument, fails with `can only be converted
+inside a workflow`. Override-converter types and resource-return or
+output-transform results continue to use generated operation helpers instead of
+model transfer-type converters. Nexus conversion errors surface on the returned
+future. An `@nexus.omit` field cannot supply a Go resource constructor argument.
+
 ### Transfer-Type Conversion
 
 ```wit

advanced/samples/go/go.mod

@@ -6,7 +6,7 @@ require (
 	github.com/nexus-rpc/sdk-go v0.7.0
 	github.com/stretchr/testify v1.10.0
 	go.temporal.io/api v1.63.5
-	go.temporal.io/sdk v1.48.1-0.20260828193328-cfdc74a4e624
+	go.temporal.io/sdk v1.49.1-0.20261006234944-b7c855cd3699
 	google.golang.org/protobuf v1.36.11
 )
 

advanced/samples/go/go.sum

@@ -59,8 +59,8 @@ go.opentelemetry.io/otel/trace v1.44.0 h1:jxF5CsGYCe74MCRx2X4g7WsY/VBKRqqpNvXlX/
 go.opentelemetry.io/otel/trace v1.44.0/go.mod h1:oLl1jrMQAVo6v3GAggN+1VH9VIz9iUSvW53sW1Q8PIE=
 go.temporal.io/api v1.63.5 h1:c11+kPYHkXXL3UiShPdbMD+xtvqGsbTibUA9ypmiCa4=
 go.temporal.io/api v1.63.5/go.mod h1:SrlW2JMwVlDP4nRWSNznUFqnSHd+YeMDS1BkYo63HCQ=
-go.temporal.io/sdk v1.48.1-0.20260828193328-cfdc74a4e624 h1:OOTiDG3gJhzPhqn1YebEGqU5ic1rH/Am5uvOmEk1jL4=
-go.temporal.io/sdk v1.48.1-0.20260828193328-cfdc74a4e624/go.mod h1:tr/G47tBsjORurCbixYoMDy2Lqiks6lIKS5+kI9jd40=
+go.temporal.io/sdk v1.49.1-0.20261006234944-b7c855cd3699 h1:H0lzIOKvMyITmdudf0Aon4wcMGbDBPQw3YyVsZABU2I=
+go.temporal.io/sdk v1.49.1-0.20261006234944-b7c855cd3699/go.mod h1:xP0FulN5JJSfisESUP60LlWsrKz2tLSStGjVdk8r5cc=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
 golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=