The hardest gaps are not incomplete. They do not exist at all.

When foundational artifacts are missing entirely, the remediation sequence is everything. Fix it in the wrong order and you will rewrite everything.

What was missing in one real DHF assessment: the System Design Document, the DFMEA and the SFMEA.

The remediation sequence

1. System Design Document. The foundation. Everything flows from here.
2. Software Architecture Description.
3. Safety classification, justified per item.
4. DFMEA and SFMEA, built against the real decomposition.
5. Risk Management File, with risk controls traced to architecture.
6. SOUP assessment: versions, anomalies and justification.
7. V&V traceability: requirements through test evidence.

The architects who avoid expensive remediation aren't smarter. They just built the habit of writing things down at the right moment.