Why: a kill between persist(assistant) and commitToolIntent left an unpaired tail that no recovery path repaired (acceptance clause 1's library gap), and Stop.Replacement mutated the in-memory assistant while the transcript kept the original (audit N6 residual). Evidence: GOWORK=off go vet + go test -count=1 ./... green; TestResumePairsOrphanTailAfterCrashWindow (no-intent window pairs with crashInterrupted, run continues), TestResumeMixedIntentAndOrphanTail (intent path and tail repair never double-pair), TestRepairOrphanTailNoopOnHealthyTranscript; the harness assertion now pins replacement-as-user-note (forged=4, notes=3). Impact: every next Run repairs the trailing assistant's resultless calls before the first request; replacement text now appears only as a user message in both memory and transcript (intentional, recorded in the N3 card). Refs: Agent-System-Documents#43 (N3 plan WP1)