EVT 2026-02-24 - Cross-stage Recommendation Hardening Candidate Lock (Draft Only)

Session scope

Continue autonomous refinement to prepare a DEC-ready candidate package for recommendation hardening, while preserving the product principle: best UX, full enough, but lean and scalable.

Working assumptions

1. Product lane: DOL English V2.
2. Existing baseline DEC remains valid (DEC-0075, DEC-0077, DEC-0078, DEC-0079, DEC-0080).
3. This cycle remains draft-only; no DEC promotion without explicit confirmation.

Candidate lock decisions (draft)

1) Mixed-program tie-breaker threshold

• Candidate value: 60% (last 5 submitted attempts) instead of 70%.
• Recommended order:
  1. session explicit preference,
  2. recent-consistency >=60%,
  3. goal program,
  4. most recent program.

Why 60%:

• More responsive to behavior drift than 70%.
• Still strong enough to avoid random oscillation.
• Better fit for users switching 1-2 times/week.

2) Inactivity degradation window

• Candidate value: 45 days (warm-start fallback) instead of 30 days.

Why 45 days:

• 30 days is too sensitive for irregular learners and can reset personalization too early.
• 45 days preserves useful context while still preventing stale ranking.

3) Rollout promotion gate threshold

• Candidate value: +5% relative lift in recommendation_start_rate (vs +4%).

Why +5%:

• Reduces false-positive rollouts from noisy uplift.
• Better long-term safety when paired with automatic rollback guardrails.

Trade-off summary

• Lower threshold (60%) increases adaptiveness but can add slight volatility.
• Longer inactivity window (45d) improves continuity but needs freshness safeguards.
• Higher gate (+5%) slows promotions slightly but protects retention and trust.

Guardrails retained (draft)

1. Set size target 3..7, actionable floor >=2.
2. Max one low-confidence item per set, placed near end.
3. Rollout ladder 10% -> 50% -> 100%, 7-day minimum each phase.
4. Auto rollback if breach persists 2 consecutive days.

Minimal telemetry contract (draft)

• recommendation_program_resolution_source
• recommendation_actionable_count
• recommendation_low_confidence_item_count
• recommendation_start_rate
• recommendation_bounce_rate
• day7_active_rate
• support_complaint_tag_recommendation

Promotion readiness check (draft score)

• Clarity: 5/5
• Simplicity: 4/5
• Feasibility: 5/5
• Risk coverage: 4/5
• Testability: 5/5

Status: DEC-ready candidate after confirming 3 numeric knobs (60%, 45d, +5%).