Gitea cannot re-run one job and a full run takes ~1h. Add a plan job that turns the optional `only` input (e.g. cac:php85) into one filtered matrix per image family; image jobs take their matrix from it and are skipped when empty. Push events / empty input plan the full set as before. Unknown values fail the plan job. Tests added to multiarch-workflow.test.py. Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_0185ukXjXyosSkunDsdWz3mb