ADR 015: Renewal-by-Default Pacts and a Four-State Machine

Date: 2026-07-29 Status: Accepted

Context

Two problems compounded each other:

  1. The pact set was contracting. The game-theory review (Issue 1) and protocol-design review (Issue 8) found net-negative pact churn in every simulated topology: pacts dissolved quickly (on volume drift, on transient failures) but formed slowly, so the cooperative equilibrium was a "slow-motion collapse."
  2. The state machine was too large. The complexity review flagged the seven-state pact FSM (with standby promotion, renegotiation, partition handling) as more machinery than the mechanism warrants.

Decision

Renewal by default. A healthy pact at its 90-day mark auto-renews via a lightweight handshake. Dissolution requires sustained failure (ADR 014: Failed ≥14 days) or an explicit exit by either party. Pacts persist like real relationships — maintained unless actively broken — instead of requiring continuous requalification.

Four-state FSM. Collapse the pact lifecycle to:

Forming → Active → Failing → Ended
  • Forming — offer sent/accepted, initial checkpoint exchange.
  • Active — challenges passing (Healthy/Degraded); auto-renews at 90 days.
  • Failing — reliability Unreliable/Failed; replacement being sought.
  • Ended — dropped (sustained Failed) or explicit exit.

Standby and archival pacts are deferred (removed from the core). Instant failover is no longer needed once renewal-by-default keeps the ~20-pact set stable. The Guardian pact lifecycle is one paragraph: it expires at 90 days or when the Seedling reaches Hybrid phase (5+ pacts) — the newcomer has grown roots.

Consequences

Positive:

  • Turns the slow-motion collapse into a ratchet toward stability — the single most important game-theory fix.
  • Four states instead of seven; no standby-promotion logic, no separate renegotiation path.
  • Matches the human story: friendships are renewed by default, not re-earned every quarter.

Negative:

  • Loses instant standby failover; a failed partner is replaced over the challenge window rather than swapped atomically. Acceptable given the redundancy target.
  • Auto-renewal must be cheap and abuse-resistant (lightweight signed handshake, not a full renegotiation).

Neutral:

  • The formation state machine from the old equilibrium model is dissolved into the three-phase adoption arc (ADR 016), leaving exactly two lifecycles: the user arc (Bootstrap→Hybrid→Sovereign) and this pact FSM.