Fix up attach filtering

[false200]

What I did

Fixed docker compose up --attach ... so Compose only follows logs for explicitly attached services when containers start or restart during up.

Added a regression test covering the --attach service filter behavior.

Related issue

Fixes #13660

[false200]

Hi maintainers,

I worked on #13660 and fixed the docker compose up --attach ... behavior so Compose now respects the explicit attach filter when containers start or restart during up.

The root cause was that the start event follow path could begin following logs for services that were being monitored but were not part of the requested --attach selection. I updated that logic to check the attach filter before following logs for started containers.

I also added a regression test to cover this case and verified the fix locally with a real two-service reproduction using --attach validator, where only the selected service logs were attached.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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