alkstore/tasks/suite-opts-backoff-rows.md

id, name, status, depends_on, scope, risk, impact, level, tags

id	name	status	depends_on	scope	risk	impact	level	tags
suite-opts-backoff-rows	Contract-suite rows — backoff-curve equivalence + the deferred enqueue-opts clock legs	pending		narrow	low	phase	implementation	wave-5 contract-suite queues

Description

Complete the arithmetic-equivalence backlog rows (core-contract.md §Verification backlog): "Backoff-curve and stamp-resolution equivalence across engines" and the two wall-clock-adjacent legs the existing enqueue_opts_resolution row explicitly deferred ("The run_at-alone-literal and neither-field-resolves-to-now legs ... pin with wave 5's equivalence row").

Work:

• Extend enqueue_opts_resolution in place (one owner per property — the row's own doc comment names this wave-5 completion; stamps accumulate per the convention): the run_at-alone literal leg (a future run_at is the row's ready time verbatim; a past run_at resolves to ready-now — the boundary-total rule, ADR-023 §2) and the neither-field leg (ready now — tolerance-bounded proximity, never a tight timing assert).
• Add backoff_curve_equivalence — the equal-jitter exponential curve (ADR-010 §3): delay ∈ [base·2^(a−1)/2, base·2^(a−1)] per attempt, uniform jitter over the lower half — the range, not a jitter label, is the definition. Drive claim → retry(err, None) cycles on a queue with a small backoff_base_s stamp (2 s keeps the integer-second row resolution honest: ranges [1,2], [2,4], [4,8] across the first attempts; the inter-attempt waits stay tolerance-bounded and sequential), reading the computed delay back via get_job's run_at minus now, asserting range membership per attempt on both engines — identical bounds is the equivalence pin (ADR-012 §2: engine-side arithmetic, suite-pinned identical outputs). Include the explicit-delay override leg (retry(err, Some(d)) honored — a Some(0) resolves ready-now per the boundary-total rule). The 1-hour cap leg is not suite-pinnable (reaching capped attempts requires waiting out minute-scale delays); it stays pinned engine-side (both engines' unit tests already pin the curve against the ADR text — the wave-3/4 reviews verified it) — record that disposition in Notes for the review gate.

Acceptance Criteria

• enqueue_opts_resolution extended with both clock legs; its doc comment's deferral note updated (stamps accumulate)
• backoff_curve_equivalence exists, version-stamped (ADR-010 §3, ADR-020 §1–§3, ADR-012 §2, ADR-023 §2)
• Rows wired into both engines' contract_suite.rs targets
• SQLite column green server-less; pg column green against the harness server
• The cap-leg disposition recorded in Notes
• cargo test -p alkstore-sqlite -p alkstore-postgres green (pg rows skip cleanly server-less); clippy -D warnings; fmt clean

References

• docs/architecture/core-contract.md §Verification backlog (backoff-curve and stamp-resolution equivalence; enqueue-opts resolution equivalence)
• docs/architecture/decisions/010-queue-semantics-depth.md §3
• docs/architecture/decisions/020-enqueue-opt-semantics-and-bridges.md §1–§3
• docs/architecture/decisions/012-forked-substrate-design.md §2
• alkstore-contract-suite/src/properties.rs (enqueue_opts_resolution's deferral note)

Notes

To be filled by implementation agent

Summary

To be filled on completion