fusion/.changeset/FN-4958-auto-prerebase.md

@runfusion/fusion

@runfusion/fusion
patch

Add a merger auto-prerebase policy that can rebase task branches onto local main before the existing Stage 1/2 rebase cascade when divergence from task.baseCommitSha crosses a threshold or touches configured shared-infra hot files. This introduces project settings prerebaseAutoEnabled, prerebaseHotFiles, and prerebaseDivergenceThreshold, and emits run-audit events merge:auto-prerebase:applied, merge:auto-prerebase:skipped, and merge:auto-prerebase:failed.