Comparison Model

Comparison Model

Baseline

The first populated environment in fixed Dev, QA, Prod order is the baseline.

Inputs	Baseline	Targets
Dev, QA	Dev	QA
Dev, Prod	Dev	Prod
QA, Prod	QA	Prod
Dev, QA, Prod	Dev	QA and Prod

Blank environments are inactive and cannot create false removals.

Paths and values

Objects use dot paths (user.profile.name) and arrays use indexed paths (orders[0].items[2].price). Arrays compare by index, not identifier or set membership, so reordering can create many changes. Empty arrays and objects stay comparable; object property order does not affect flattened path comparison.

Type	Baseline	Target
ADDED	Absent	Present
REMOVED	Present	Absent
CHANGED	Present	Present, same JSON type, unequal value
TYPE_CHANGE	Present	Present, different JSON type

null changing to or from another value is CHANGED. Equality uses JSON serialization after parsing.

Multiple targets

Rows with the same path and type combine. Different outcomes stay separate.

Dev: 100     QA: "100"     Prod: 200

amount | TYPE_CHANGE | 100 | "100" | -
amount | CHANGED     | 100 | -     | 200

Result contract

interface DiffEntry {
  path: string;
  type: 'ADDED' | 'REMOVED' | 'CHANGED' | 'TYPE_CHANGE';
  devValue?: unknown;
  qaValue?: unknown;
  prodValue?: unknown;
}

Output is sorted by path. Value properties appear only where a value exists. ADDED, REMOVED, and TYPE_CHANGE trigger a possible contract-change warning; that warning is a review signal, not a schema-compatibility proof.