SRS Engine Analytics Documentation

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System Overview

• Character SRS drives Morse Machine due-first scheduling.
• Word/item SRS drives CW Words and Callsign Training due decks.
• Confusable pairs come from substitution errors across modules.
• Adaptive carrier modes prioritize weakness targets with bounded fallback.
• All SRS state is per-user and derived from session-authenticated username.

Latency-aware Grading

Every attempt is converted into grade 0..5.

Character thresholds

dot_ms = 1200 / exact_wpm
T_fast = max(200, 4 * dot_ms)
T_slow = max(600, 10 * dot_ms)

incorrect => 0
correct && latency <= T_fast => 5
correct && latency <= T_slow => 4
correct && latency > T_slow => 3

Item thresholds

T_fast_item = max(400, 6 * dot_ms)
T_slow_item = max(1200, 18 * dot_ms)
(mapping unchanged)

Scheduling Model (SM-2 inspired)

• Grade < 3: increment lapses, reset reps to 0, set interval_days=0.25 (6h).
• Grade 3..5: reps increment with intervals 1d, 3d, then interval *= ef.
• EF updates with classic SM-2 delta and lower clamp at 1.3.
• due_at is recalculated from interval every scored attempt.

Confusables Engine

• Reads substitution errors from callsign and sentence error tables.
• Aggregates directional errors into symmetric pairs: A↔B.
• Supports timeframe filters: 30d, 90d, all.
• Exposes top pairs for Morse Machine drills and carrier selection.

API Endpoints

• GET /api/srs-due.php - due characters/items and overdue summary.
• POST /api/srs-attempts.php - batch attempts, server-side grading, schedule updates.
• POST /api/srs-item-actions.php - hard/suspend/unsuspend/reset/promote actions.
• GET /api/srs-focus-set.php - due chars + confusable pairs (+ optional items).
• GET /api/srs-plan.php - daily session recommendations and launch URLs.
• POST /api/srs-clear.php - full SRS state reset with DELETE confirmation.

Analytics Metrics

• Backlog health: due counts + overdue 7d/30d.
• Retention: relearn rate (grade < 3), average grade, attempts per module.
• Interval distribution: characters and items bucketed by interval length.
• Confusables trends: top pairs over 30d and 90d windows.
• Daily activity: 14-day attempts series for consistency monitoring.