fix: support reusing field-input components in event-driven flows

[Copilot]

Summary

Components like FileWriter could not be reused in event-driven models by subclassing and adding event handlers, because process validation still required connector-backed field inputs and shutdown could replay the last event-populated value. This change allows inherited field inputs to be satisfied by events and closes the event-driven path cleanly once producers are exhausted.

Changes

• Validation

  • Allow components with non-system input_events to have unconnected field inputs.
  • This enables subclasses that populate inherited fields from event handlers instead of field connectors.

• Runtime behavior

  • Treat components with no connected field-input channels as event-driven for producer-graph exhaustion.
  • Exit the wrapped step before rebinding inputs when IO closes, preventing stale event-populated values from being replayed on shutdown.

• API surface

  • Expose IOController.has_connected_field_inputs and use it for the runtime check instead of reaching into internal channel state.

• Coverage

  • Add a focused integration test showing a FileWriter subclass consuming events to populate message.
  • Add a validation test covering the same reuse pattern.

class EventReaderFileWriter(FileWriter):
    io = IO(input_events=[MessageEvent])

    @MessageEvent.handler
    async def handle_message(self, event: MessageEvent) -> None:
        self.message = event.data.message

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:

• metadata.google.internal
  • Triggering command: /home/REDACTED/work/plugboard/plugboard/.venv/bin/python3 /home/REDACTED/work/plugboard/plugboard/.venv/bin/python3 /home/REDACTED/work/plugboard/plugboard/.venv/lib/python3.13/site-packages/ray/dashboard/dashboard.py --host=127.0.0.1 --port=8265 --port-retries=50 --temp-dir=/tmp/ray --log-dir=/tmp/ray/session_2026-04-08_20-39-05_496118_4173/logs --session-dir=/tmp/ray/session_2026-04-08_20-39-05_496118_4173 --logging-rotate-bytes=536870912 --logging-rotate-backup-count=5 --gcs-address=127.0.0.1:37769 --cluster-id-hex=12135458e388ceb3b846ca782e5dd938de9648ae360cbb7d94ee0423 --node-ip-address=127.0.0.1 --stdout-filepath=/tmp/ray/session_2026-04-08_20-39-05_496118_4173/logs/dashboard.out --stderr-filepath=/tmp/ray/session_2026-04-08_20-39-05_496118_4173/logs/dashboard.err cal/bin/git (dns block)
  • Triggering command: /home/REDACTED/work/plugboard/plugboard/.venv/bin/python3 /home/REDACTED/work/plugboard/plugboard/.venv/bin/python3 /home/REDACTED/work/plugboard/plugboard/.venv/lib/python3.13/site-packages/ray/dashboard/dashboard.py --host=127.0.0.1 --port=8265 --port-retries=50 --temp-dir=/tmp/ray --log-dir=/tmp/ray/session_2026-04-08_20-42-25_298805_5295/logs --session-dir=/tmp/ray/session_2026-04-08_20-42-25_298805_5295 --logging-rotate-bytes=536870912 --logging-rotate-backup-count=5 --gcs-address=127.0.0.1:46503 --cluster-id-hex=7cdaee0fa9731bdb3741caecaaa16ea30c42dd0e00066412731da5bb --node-ip-address=127.0.0.1 --stdout-filepath=/tmp/ray/session_2026-04-08_20-42-25_298805_5295/logs/dashboard.out --stderr-filepath=/tmp/ray/session_2026-04-08_20-42-25_298805_5295/logs/dashboard.err p/bin/git r (dns block)
  • Triggering command: /home/REDACTED/work/plugboard/plugboard/.venv/bin/python3 /home/REDACTED/work/plugboard/plugboard/.venv/bin/python3 /home/REDACTED/work/plugboard/plugboard/.venv/lib/python3.13/site-packages/ray/dashboard/dashboard.py --host=127.0.0.1 --port=8265 --port-retries=50 --temp-dir=/tmp/ray --log-dir=/tmp/ray/session_2026-04-08_20-50-35_693193_6522/logs --session-dir=/tmp/ray/session_2026-04-08_20-50-35_693193_6522 --logging-rotate-bytes=536870912 --logging-rotate-backup-count=5 --gcs-address=127.0.0.1:43549 --cluster-id-hex=7a8906b6756dbfd8332941da89ea5d811afa31c7de1ee6047d690f01 --node-ip-address=127.0.0.1 --stdout-filepath=/tmp/ray/session_2026-04-08_20-50-35_693193_6522/logs/dashboard.out --stderr-filepath=/tmp/ray/session_2026-04-08_20-50-35_693193_6522/logs/dashboard.err k/_temp/ghcca-node/node/bin/git 3 /home/REDACTED/wfile (dns block)
• releases.astral.sh
  • Triggering command: /home/REDACTED/.local/bin/uv uv venv .venv --python python3.13 (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)