Why: I2 acceptance - the evaluator must emit metrics over a multiturn fixture no smaller than the existing corpus, not just print branch names. Evidence: go vet clean; full suite ok; intentctl eval prints precision=1.000 recall=1.000 (TP=12 FP=0 FN=0) over the 11-case multiturn fixture; MetricsOf unit test pins TP/FP/FN counting including wrong-match counting as both. Impact: CorpusMetrics + MetricsOf (expectation_hit counts as a hit); intentctl eval prints the metrics line after the summary; corpus_multiturn.json expanded to 11 cases (chained expectation, tie-break, ambiguous, fallback, handler action, clarify paths). Refs: Documents proposal 2026-10-07-agent-stack-n1q1i1-plans.md I2