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ADR-0043: Rollback window N + process-cap arithmetic (F8-cap)
| field | value |
|---|---|
| Status | Proposed — Proposed (awaiting Mohamed) |
| Date | 2026-08-29 |
| Register | factory (docs/adr, 4-digit ids) |
| Source | docs/adr/0043-ruleset-rollback-window-and-cap-arithmetic.md — permalink at 9c90c0209 (unchanged on master since that commit) |
| Wiki register entry | ADR-0043 (wiki status: Proposed) |
The record
Status: Proposed (awaiting Mohamed) · Date: 2026-08-29
Context
Deliberately split from F8's deny-all-semantics half (still under review). Stable ×7; §3 and the §4.2 table agree on the arithmetic; round-15 findings touch the window conjunct's evaluation, not the ratified number; recommended as a split since round 12.
Decision (proposed)
The rollback window is the last N ratified composition generations per name (N ratified at deploy). The engine-process cap satisfies CAP ≥ 2×max_pins + rollback headroom, checked at ratification time — a composition that could not be rolled back under the cap is refused before activation.
Alternatives rejected
Unbounded rollback (unbounded process residency); post-activation cap discovery (fails at the worst moment).
Consequences
Rollback feasibility is a ratification-time guarantee, not an operational hope.
Provenance
Design v16 §3/§4.2 + §11 F8; rounds 12-15 readiness tables.
Related ADRs
No other ADR is named in this record.
Rulings cited
None.
Specs cited
None (or no spec page exists for the ones named).