Why Power Automate
The intake did not need a backend service. It needed structure on top of what M365 already provided. Power Automate moved fastest because it sat on the same identity and permission model the legal team already used, with no new vendor review or sign-off cycle.
Where the leverage came from
The "one ID, three doorways" pattern. The list item, the notification thread, and the attachment folder all share an ID. If a requester replies to the email, the legal team can find the folder. If legal opens the folder, they know which list item to update. If they update the list item, the requester gets pinged.
Where it broke
Parallel branches in Power Automate look concurrent on the canvas but can race on shared state. The first version updated the list item from both the notification branch and the folder-provision branch; whichever finished last won, and sometimes the folder URL was missing from the notification. Fixed by sequencing the folder creation before any notification, and reading the canonical URL from the list item rather than from the local branch state.