Three process learnings from parallel B1 work, rolled into meta.md: - Cross-spec contracts: shared identifiers/interfaces between systems must be stated as an explicit contract in one spec and referenced via Depends-on, not left as unwritten assumptions. Earned by the observer-id vs person-id drift that schedules.md surfaced (recruit/LookAway hit the wrong observer) — found independently by two parallel sessions. - Depends-on is the audit scope: implementing/changing a spec includes re-verifying the contracts of everything it depends on. - Specs must not silently contradict siblings; a modeling choice touching a depended-on spec's model is recorded (e.g. located witnessing as eyewitnessing vs detection's pooled signals), not made silently. - As-built specs: a spec documenting already-shipped code may start at IMPLEMENTED as the acceptance record (aggregate-observer.md). - Two new meta acceptance criteria + one for the check.sh completeness gate. Defense: meta-spec's own spec-change rule — 'meta-spec changes update this file'; these are process clarifications that narrow agent interpretation without changing game behavior, so they live in spec/ with this defense and need no DESIGN.md amendment.