Skill instrumentation pattern, brain /pass-rate HTTP endpoint, and
optional hyperguild CLI subcommand for shell access. Pilot with tdd
SKILL.md, then roll out to 6 binary-outcome skills (code-review,
debug, feature-spec, session-retrospective, trainer, spec-driven-dev).
Decisions: SKILL.md as source of truth for the logging contract;
on-demand aggregation from JSONL (no materialized counters until
proven necessary); pass|fail|skip vocabulary forward, with
ok|error|skipped accepted by the read-side aggregator for backwards
compat.
Seven success criteria, ten out-of-scope items, six risks.