Why: I1 WP6 - eval needs per-turn command expectations to carry the SetSlot+Start acceptance case, and corpora must reproduce standalone in intentctl (the guard case has been red there since before I1 because the guard spec only existed as a test builtin). Evidence: go vet clean; go test ./... all ok; intentctl eval passes 11/11 on the v1 corpus (guard case fixed via self-declaration) and 1/1 on the new two-turn SetSlot+Start corpus. Impact: new intent/corpus.go (CorpusCase/CorpusTurn/CommandExpect, RunCorpusCase with chained expectations); intentctl eval consumes turns and corpus-declared builtin_specs and domains; report.generate spec and corpus_multiturn.json fixtures added. v1 corpus format and conformance unchanged. Refs: Documents proposal 2026-10-07-agent-stack-n1q1i1-plans.md I1 WP6