Given a batch of work items, map which block which. Look past the dependencies items declare outright — the ones that bite are implicit.

Blocking edges

Item B is blocked by item A when B's text says so, and also when

B needs something A produces — code, infrastructure, or data,
B and A touch overlapping files or modules — a collision, not an order; pick one to go first and treat the other as blocked by it, or
B's requirements hinge on a decision or interface A will establish.

The frontier

The frontier is the set of still-open items with zero blockers — they can start now.

Recompute the frontier whenever an item completes.

Done when: every item is classified as frontier or blocked, and each blocked item names every item it waits on.