Verdicts
The six outcomes ForkReason can reach, and what each means.
VerdictMeans
INDEPENDENTSimilarity is consistent with two projects implementing the same specification, with no shared history found.
SHARED_UPSTREAMBoth repositories descend from a common ancestor, which explains the overlap better than derivation does.
DECLARED_FORKOne repository declares the other as its upstream. This is a recorded, legitimate relationship.
LIKELY_DERIVEDChronology and historical evidence support one repository developing from the other.
HEAVILY_DERIVEDA real lineage, but the implementation has since diverged substantially.
INSUFFICIENT_EVIDENCEThe available evidence does not support a conclusion either way.
Direction
A directional verdict names which repository came from which. INDEPENDENT, SHARED_UPSTREAM, DECLARED_FORK and INSUFFICIENT_EVIDENCE have no direction, and the report says so rather than inventing one.
Why insufficient evidence is a real answer
Most repository pairs that look similar are not related, and most pairs with real relationship have evidence that supports it. The honest middle is large. ForkReason returns INSUFFICIENT_EVIDENCE rather than picking the least-bad explanation, because a forced verdict is worse than no verdict.