fix: process.export broken when state and parameters not explicitly provided

[Copilot]

process.dump() fails with a Pydantic validation error when state and parameters are omitted at LocalProcess construction.

Root cause: ExportMixin._save_args_wrapper wraps both LocalProcess.__init__ and Process.__init__. When LocalProcess.__init__ calls super().__init__(..., parameters=None, state=None), the parent wrapper captures those explicit None values and merges them into __save_args_init__. The export dict then contains parameters=None and state=None, which fail ProcessArgsSpec validation.

# This was broken:
process = LocalProcess(components=[A(), B()], connectors=[...])
process.dump("out.yaml")  # ValidationError: state=None, parameters=None

Changes

• plugboard-schemas/plugboard_schemas/process.py: Added _coerce_parameters and _coerce_state field_validators to ProcessArgsSpec to coerce None → {} and None → StateBackendSpec() respectively. Consistent with ProcessArgsDict which already typed state as NotRequired[StateBackendSpec | None].
• tests/integration/test_process_builder.py: Added test_process_dump_with_default_state_and_parameters to reproduce and validate the fix.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• astral.sh
  • Triggering command: /usr/bin/curl curl -LsSf REDACTED grep -l state.*None py de/node/bin/grep (dns block)
• releases.astral.sh
  • Triggering command: /home/REDACTED/.local/bin/uv uv venv .venv --python python3.13 state.*None hemas/state.py k/_temp/ghcca-node/node/bin/grep (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

Original prompt

---

This section details on the original issue you should resolve

<issue_title>bug: process.export broken</issue_title>
<issue_description>### Summary

Consider this model:

from plugboard.component import Component, IOController as IO
from plugboard.process import LocalProcess
from plugboard.connector import AsyncioConnector
from plugboard.schemas import ConnectorSpec

class A(Component):
    io = IO(outputs=["out_1"])

    async def step(self) -> None:
        pass

class B(Component):
    io = IO(inputs=["in_1"])

    async def step(self) -> None:
        pass

process.dump("test-export.yaml")

Fails with:

  Input should be a valid dictionary [type=dict_type, input_value=None, input_type=NoneType]
    For further information visit https://errors.pydantic.dev/2.12/v/dict_type
plugboard.process.args.state
  Input should be a valid dictionary or instance of StateBackendSpec [type=model_type, input_value=None, input_type=NoneType]
    For further information visit https://errors.pydantic.dev/2.12/v/model_type

Version Information

Plugboard version: 0.6.0
Platform: Linux-6.6.84.1-microsoft-standard-WSL2-x86_64-with-glibc2.39
Python version: 3.12.11
```</issue_description>

## Comments on the Issue (you are @copilot in this section)

<comments>
</comments>

• Fixes bug: process.export broken #225

---

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[github-actions]

Benchmark comparison for 64adfa9a (base) vs 92eccec1 (PR)

------------------------------------------------------------------------------------------------------------------ benchmark: 2 tests -----------------------------------------------------------------------------------------------------------------
Name (time in ms)                                                                         Min                 Max                Mean            StdDev              Median               IQR            Outliers     OPS            Rounds  Iterations
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
test_benchmark_process_run (pr/.benchmarks/Linux-CPython-3.12-64bit/0001_pr)         363.9104 (1.0)      376.8133 (1.01)     367.8705 (1.0)      5.1566 (4.24)     365.9110 (1.0)      4.8327 (2.49)          1;0  2.7183 (1.0)           5           1
test_benchmark_process_run (main/.benchmarks/Linux-CPython-3.12-64bit/0001_base)     370.3269 (1.02)     373.1919 (1.0)      371.3854 (1.01)     1.2172 (1.0)      370.9975 (1.01)     1.9383 (1.0)           1;0  2.6926 (0.99)          5           1
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Legend:
  Outliers: 1 Standard Deviation from Mean; 1.5 IQR (InterQuartile Range) from 1st Quartile and 3rd Quartile.
  OPS: Operations Per Second, computed as 1 / Mean

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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