Vocabulary lean loop with focus queue and overload governor

DEC-0070 - Vocabulary lean loop with focus queue and overload governor

Context

Vocabulary is one of three major platform blocks but still risks becoming heavy and fragmented for users who only need one clear next step. To keep the product full but lean, Vocabulary needs a habit-first default entry and overload protection.

Decision

Lean entry and queue contracts:

• Home/Dashboard default CTA for active vocab users is immediate action: Ôn ngay (5 phút).
• Vocabulary session starts from Today Focus queue rather than broad list browsing by default.
• Today Focus priority:
  • due review words from active lists,
  • valid practice-result suggestion payload,
  • program/course recommended words,
  • program trending fallback.

Queue size and quick-start:

• daily focus surface cap: 20 items.
• quick-start subset: 5 items.

Overload governor:

• if due backlog >40, new-word intake is paused from Today Focus and stored in inbox.
• intake resumes when backlog returns to <=30.

Continuity policy:

• unfinished Today Focus does not create forced debt or penalty.
• next day queue rebuilds by same priority policy.

Decision Value

• Gives users one clear action path, reducing cognitive load and first-click friction.
• Prevents overload spikes from turning vocabulary into a churn driver.
• Keeps implementation simple with deterministic thresholds and queue behavior.

Rationale

This approach preserves personalization while avoiding complex branching logic. Users still have full depth via Vocabulary module, but daily behavior is optimized for consistency and momentum.

Implications

• Product/UX impact:
  • Vocabulary block becomes more action-oriented and less navigation-heavy.
  • Practice-to-Vocabulary handoff remains useful without flooding user workload.
• Data/logic impact:
  • queue contracts and backlog thresholds become explicit, measurable, and auditable.
• Operational impact:
  • lower support burden from “too many words” complaints and confusing list states.

Alternatives considered

• Option A: Keep list-first entry and leave load balancing to users.
• Option B: Hard-force mandatory vocabulary completion each day.

Open follow-ups

• No open blocker for baseline lock.