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)
weichen