All four Oracle Construction and Engineering products overlap on purpose, and three of them hold cost. The damage comes from owning two and never deciding which one is authoritative. A practical comparison by whose record each product holds, plus a decision procedure and the integration constraints nobody scopes.
Most as-planned vs as-built analysis compares the baseline to the last P6 update and calls the result an as-built. It isn't one. This is how to build the data layer underneath a delay analysis: versioned XER ingestion, activity identity across renumbering, a first-appearance table that proves when every actual date entered the record, calendar-safe float, and record linking that proposes candidates instead of asserting cause.
A layer-by-layer architecture for a construction dispute intelligence platform: hashed intake and immutable originals, OCR with page coordinates, a versioned Primavera P6 schedule plane, an event model that joins documents to activities, hybrid retrieval on pgvector, and a generation layer bounded by human confirmation. Written around what each layer prevents.