Feature/async signal index

[wakonig]

Description

This PR introduces async signal indices for keeping track of individual updates of async signal events. This will become useful once we have the data api and try to match async and monitored signals.

Related Issues

closes #755

Type of Change

• new endpoint device_async_signal_index
• new message type DeviceAsyncSignalIndexMessage
• bec message handler calculates the index and pushes the data to a list in redis

How to test

• Run unit tests
• Check redis for the new endpoint

[codecov]

Codecov Report

❌ Patch coverage is 97.29730% with 1 line in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
...er/bec_server/device_server/bec_message_handler.py	96.00%	0 Missing and 1 partial ⚠️

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[Copilot]

Pull request overview

This PR adds a companion “async signal index” channel to persist per-update indexing (+ shape metadata) for async device signal updates, enabling downstream services to correlate async updates even after the async stream data has expired.

Changes:

• Add DeviceAsyncSignalIndexMessage and a new Redis LIST endpoint device_async_signal_index.
• Extend the device-server async signal handler to compute per-signal update indices and publish them alongside async signal updates.
• Update tests/mocks to serialize the new message and supply required async metadata in affected tests.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
bec_server/bec_server/device_server/bec_message_handler.py	Computes async indices and publishes index+shape companion messages to a Redis list.
bec_lib/bec_lib/messages.py	Introduces DeviceAsyncSignalIndexMessage message type.
bec_lib/bec_lib/endpoints.py	Adds device_async_signal_index endpoint (LIST op).
bec_lib/tests/test_bec_messages.py	Adds serialization roundtrip test for the new message type.
bec_lib/bec_lib/tests/utils.py	Updates ConnectorMock.rpush to accept expire (and should align better with real connector).
bec_server/tests/tests_device_server/test_device_manager_ds.py	Adjusts fixture and async message test inputs to include async_update metadata.

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