python-type-codegen does not generate models from shapes

[nemec]

When I use the python-type-codegen plugin with the echo sample it does not generate any models at all (whereas python-client-codegen seems to work fine for the same model)

smithy-build.json:

{
    "version": "1.0",
    "sources": ["model"],
    "maven": {
        "dependencies": [
            "software.amazon.smithy:smithy-model:[1.54.0,2.0)",
            "software.amazon.smithy:smithy-aws-traits:[1.54.0,2.0)",
            "software.amazon.smithy.python.codegen:core:0.0.1",
            "software.amazon.smithy.python.codegen.plugins:types:0.0.1"
        ]
    },
    "projections": {
        "client": {
            "plugins": {
                "python-client-codegen": {
                    "service": "com.example#EchoService",
                    "module": "echo",
                    "moduleVersion": "0.0.1"
                },
                "python-type-codegen": {
                    "service": "com.example#EchoService",
                    "module": "echo",
                    "moduleVersion": "0.0.1"
                }
            }
        }
    }
}

model/main.smithy:

$version: "2.0"

namespace com.example

use aws.protocols#restJson1

@restJson1
service EchoService {
    version: "2025-09-01"
    operations: [EchoMessage]
}

@http(uri: "/echo", method: "POST")
operation EchoMessage {
    input := {
        message: String
    }
    output := {
        message: String
    }
}

contents of model/build/smithy/client/python-type-codegen/src/echo/models.py:

# Code generated by smithy-python-codegen DO NOT EDIT.

from smithy_core.exceptions import ModeledError


class ServiceError(ModeledError):
    """Base error for all errors in the service.

    Some exceptions do not extend from this class, including
    synthetic, implicit, and shared exception types.
    """

Is there something I'm missing?