Changes in version 0.6.6                        

Bug Fixes

  - cards.due epoch fixes missed by 0.6.5: anki_study_plan(),
    anki_forecast(), anki_simulate_session(), anki_health_check(),
    anki_quick_summary(), anki_due(). All now use
    col_today_days(col$crt). Also removed a duplicate anki_today() in
    recommendations.R that was shadowed at load time by the active
    definition in simulation_enhanced.R.
  - anki_to_obsidian_sr(include_scheduling = TRUE): sr-due computed with
    due_to_date() and gated on queue 2. Sys.Date() + due put dates years
    in the future on non-fresh collections.
  - parse_search_term() and apply_operator() error if today_days is
    missing instead of falling back to as.integer(Sys.Date()).

                        Changes in version 0.6.5                        

Bug Fixes

  - Corrected cards.due interpretation across the package: for queue-2
    cards, due is days since collection creation (col.crt), not days
    since the Unix epoch. Fixes is:due / due_today in anki_search(),
    anki_search_enhanced(), anki_quick_summary(), anki_today(),
    anki_backlog_calculator(), and anki_workload_projection(). On
    long-running collections this could shift counts by hundreds of
    days.
  - anki_retention_rate() gained queue_only = TRUE (default) to restrict
    retention to review-queue reviews (review_type == 1), matching
    Anki's own definition. Same correction applied internally in
    anki_stats_daily() and anki_quick_summary().
  - anki_schema_version(): use the correct connection slot (col$con);
    previously errored on every call.
  - anki_quick_summary(): streak field name (was NA days).
  - anki_today(): filter on review_type, not the non-existent type
    column on revlog tibbles.
  - read_revlog() now projects lastIvl, unblocking anki_ts_learning()
    and anki_ts_maturation().
  - read_cards() now projects ord, factor, flags, card_created_date, and
    data_json, unblocking anki_search_enhanced() operators added:,
    card:N, prop:ease, and flag:N.
  - anki_stats_daily() gained a learned column, fixing the cards_learned
    metric in anki_forecast_enhanced().
  - Forecast helpers (forecast_seasonal, forecast_holt) now guard
    against degenerate series (zero-history weekdays, n < 2).
  - Collection opener now accepts .anki21b files.

Misc

  - Added importFrom(stats, sd/quantile/reorder/var) for R CMD check
    cleanliness; removed function names from globalVariables().
  - Fixed malformed nested \dontrun in fsrs_interval() docs.
  - Vignette: install.packages chunk no longer tries to hit CRAN during
    R CMD check; queue/due value docs expanded.
  - README: anki_quick_summary() example now matches real output.

                 Changes in version 0.6.0 (2026-02-18)                  

Major New Features

Monte Carlo Forecasting (NEW)

  - anki_forecast_monte_carlo() - Forecast using bootstrap simulation
    with 3 methods:
      - weekday: Preserves day-of-week patterns (recommended)
      - block: Preserves temporal sequences
      - simple: Independent sampling
  - anki_plot_monte_carlo() - Visualize forecasts with confidence bands
    and simulation traces
  - anki_compare_forecasts() - Compare Monte Carlo vs statistical
    methods (ARIMA, Holt-Winters)
  - Features: empirical confidence intervals, probability queries
    (prob_above(), prob_below()), handles irregular study habits

Burnout Detection & Review Quality (NEW)

  - anki_burnout_detection() - Detect warning signs: declining
    retention, increasing response time, shorter sessions, more lapses
  - anki_review_quality() - Detect pattern clicking, rushed reviews,
    suspicious timing, review bunching

Cohort Analysis & Learning Velocity (NEW)

  - anki_cohort_analysis() - Compare card performance by when added
    (vintage analysis)
  - anki_learning_velocity() - Track cards/day,
    acceleration/deceleration, retention trends
  - anki_backlog_calculator() - Calculate time to clear backlog, project
    backlog growth if you stop

Gamification (NEW)

  - anki_gamification() - XP system, levels (Novice to Grandmaster), 22
    achievements, weekly goals

Streak Analytics (NEW)

  - anki_streak_analytics() - Best streaks, recovery time after breaks,
    weekend patterns, survival curves

Card Content Analysis (NEW)

  - anki_card_content() - Word count, cloze density, complexity score,
    media usage, complexity vs retention

A/B Comparison (NEW)

  - anki_ab_comparison() - Compare retention by note type, deck, tag, or
    creation period
  - anki_compare_groups() - Statistical comparison of two groups with
    significance testing

Addon Integration (NEW)

  - import_addon_export() - Import JSON exports from ankiR Stats addon
  - analyze_addon_import() - Analyze imported addon data

Learning Efficiency Analysis

  - anki_learning_efficiency() - Calculate learning ROI (successful
    retention per time, efficiency ratio, learning points per minute)
  - anki_retention_by_type() - Break down retention by card
    characteristics (cloze vs basic, with/without media, by length, by
    note type)
  - anki_roi_analysis() - Calculate knowledge half-life extension per
    study minute, cumulative retention value

Forgetting Curve Analysis

  - anki_fit_forgetting_curve() - Fit power law forgetting curve to
    actual review data, compare to FSRS defaults
  - anki_plot_forgetting_curve() - Visualization comparing fitted curve
    to FSRS default with confidence intervals

Optimal Review Timing

  - anki_best_review_times() - Analyze retention/performance by hour and
    weekday, identify best/worst times
  - anki_session_analysis() - Identify discrete study sessions, analyze
    duration/retention/fatigue patterns
  - anki_simulate_session() - Given time budget, predict cards completed
    and expected retention

Sibling & Interference Analysis

  - anki_sibling_analysis() - Analyze how sibling cards affect each
    other's retention, statistical testing
  - anki_interference_analysis() - Detect cards frequently confused
    (co-failure patterns, content similarity)
  - anki_weak_areas() - Identify tags/decks with lowest retention or
    highest lapse rates

Actionable Recommendations

  - anki_card_recommendations() - Generate recommendations for leeches,
    unsuspend candidates, cards to retire
  - anki_health_check() - Comprehensive health check with 0-100 score
    (orphan cards, leech rates, missing FSRS)
  - anki_summary() - One-liner overview (total cards, mature cards, due
    today, streak, retention)
  - anki_today() - Today's activity summary with breakdown by ease
    button

Extended FSRS Analysis

  - fsrs_compare_parameters() - Compare your FSRS parameters against
    defaults, flag significant differences
  - fsrs_decay_distribution() - Analyze FSRS-6 per-card decay parameter
    distribution (requires Anki 24.11+)
  - fsrs_memory_states() - Calculate current FSRS memory state for all
    cards with future projections
  - anki_response_time_outliers() - Find reviews with suspicious times
    (too fast or too slow)

Academic/Exam Preparation Tools

  - anki_exam_readiness() - Project completion and retention before exam
    date, assess risk level
  - anki_coverage_analysis() - Show percentage complete/mature/retained
    by topic
  - anki_study_priorities() - Identify which topics should be
    prioritized
  - anki_study_plan() - Generate daily study plan based on exam date and
    available time

Additional Export Formats

  - anki_to_obsidian_sr() - Export to Obsidian Spaced Repetition plugin
    format
  - anki_to_mochi() - Export to Mochi Cards JSON format
  - anki_to_json() - Full collection as structured JSON for web
    dashboards
  - anki_progress_report() - Generate shareable HTML or Markdown
    progress report

Enhanced Search

  - anki_search_enhanced() - Advanced search with added:, rated:, note:,
    card:, prop:, re: and OR operators
  - anki_find_similar() - Find similar cards using TF-IDF, Jaccard, or
    n-gram similarity

Enhanced Forecasting

  - anki_forecast_enhanced() - ARIMA, seasonal, and Holt-Winters
    forecasting with workload ceilings
  - anki_workload_projection() - Rough workload estimates with scenario
    comparison (for accurate FSRS simulation, use Anki's built-in
    simulator or FSRS Helper add-on)
  - anki_retention_stability() - Analyze how stable your retention is
    over time

Utilities

  - anki_schema_version() - Detect Anki database schema version for
    compatibility debugging
  - anki_quick_summary() - Get a one-liner overview of your collection
  - anki_today() - Detailed breakdown of today's Anki activity

Removed (use r-fsrs instead)

The following algorithm functions were removed - ankiR focuses on
reading/analyzing data, not implementing FSRS. For FSRS algorithm, use
r-fsrs:

  - fsrs_retrievability() - use fsrsr::fsrs_retrievability()
  - fsrs_interval() - use fsrsr::fsrs_next_interval()
  - fsrs_simulate() - use Anki's built-in simulator
  - fsrs_simulate_new_deck() - use Anki's built-in simulator
  - fsrs_time_to_mastery() - use Anki's built-in simulator
  - fsrs_review_burden() - use Anki's built-in simulator
  - fsrs_workload_estimate() - use Anki's built-in simulator
  - fsrs_optimal_new_rate() - use Anki's built-in simulator

                        Changes in version 0.5.0                        

New Features

Visualization Functions

  - anki_plot_heatmap() - Calendar heatmap of review activity
  - anki_plot_retention() - Retention rate over time with rolling
    average
  - anki_plot_forecast() - Workload forecast chart
  - anki_plot_difficulty() - FSRS difficulty distribution histogram
  - anki_plot_intervals() - Card interval distribution
  - anki_plot_stability() - FSRS stability distribution
  - anki_plot_hours() - Reviews by hour of day
  - anki_plot_weekdays() - Reviews by day of week

Comparative Analysis

  - anki_compare_decks() - Side-by-side deck statistics
  - anki_compare_periods() - Compare two time periods
  - anki_compare_by_age() - Retention by card age
  - anki_compare_deck_difficulty() - Rank decks by difficulty
  - anki_benchmark() - Compare your stats to FSRS averages

Time Analysis

  - anki_time_by_hour() - Detailed hourly statistics
  - anki_time_by_weekday() - Statistics by day of week
  - anki_session_stats() - Study session analysis
  - anki_response_time() - Response time by difficulty/interval
  - anki_monthly_summary() - Monthly statistics
  - anki_consistency() - Study consistency metrics

Card Quality Analysis

  - anki_card_complexity() - Measure card complexity
  - anki_similar_cards() - Find potential duplicates
  - anki_tag_analysis() - Tag usage and retention by tag
  - anki_empty_cards() - Find cards with empty fields
  - anki_long_cards() - Find overly long cards
  - anki_quality_report() - Comprehensive quality assessment

Predictive Features

  - fsrs_time_to_mastery() - Estimate when deck will be learned
  - fsrs_forgetting_index() - Percentage of cards below target retention
  - fsrs_review_burden() - Long-term daily review workload estimate
  - fsrs_optimal_new_rate() - Sustainable new card rate recommendation
  - fsrs_simulate_new_deck() - Project workload when adding cards

Interactive Dashboard

  - anki_dashboard() - Launch Shiny dashboard with all analytics

Export Formats

  - anki_to_org() - Export to Emacs Org-mode (org-drill)
  - anki_to_markdown() - Export to Markdown (Obsidian/Logseq/basic)
  - anki_to_supermemo() - Export to SuperMemo Q&A format
  - fsrs_from_csv() - Import review data from other sources
  - anki_export_importable() - Export to Anki-importable format

Time Series Analysis

  - anki_ts_intervals() - Track interval progression over time
  - anki_ts_retention() - Track retention rate changes
  - anki_ts_stability() - FSRS stability trends
  - anki_ts_workload() - Workload trends over time
  - anki_ts_learning() - New cards learned per period
  - anki_ts_maturation() - Card maturation tracking
  - anki_ts_decompose() - Decompose into trend/seasonal/residual
  - anki_ts_anomalies() - Detect unusual study days
  - anki_ts_forecast() - Forecast future reviews
  - anki_ts_autocorrelation() - Find cyclical patterns
  - anki_ts_plot() - Plot any time series with trend

                        Changes in version 0.4.0                        

Features

Analytics & Statistics

  - anki_cards_full() - Cards joined with notes, decks, models
  - anki_tags() - Unique tags with counts
  - anki_field_contents() - Parse note fields into columns
  - anki_stats_deck() - Per-deck statistics
  - anki_stats_daily() - Daily review stats
  - anki_retention_rate() - Actual retention from history
  - anki_learning_curve() - Card progression over time
  - anki_heatmap_data() - Calendar heatmap data
  - anki_streak() - Current/longest streaks

Search & Filter

  - anki_search() - Anki-like search syntax
  - anki_suspended(), anki_buried(), anki_leeches()
  - anki_due(), anki_new(), anki_mature()

Media Management

  - anki_media_list(), anki_media_unused(), anki_media_missing()
  - anki_media_path(), anki_media_stats()

FSRS Advanced

  - fsrs_difficulty_distribution(), fsrs_stability_distribution()
  - fsrs_current_retrievability(), fsrs_simulate()
  - fsrs_workload_estimate(), fsrs_prepare_for_optimizer()
  - fsrs_get_parameters()

Export

  - anki_to_csv(), anki_report(), anki_export_revlog(), anki_forecast()

                        Changes in version 0.3.0                        

  - anki_decks(), anki_models(), fsrs_interval(),
    date_to_anki_timestamp()
  - FSRS-6 per-card decay parameter support
  - Comprehensive test suite

                 Changes in version 0.2.0 (2026-01-19)                  

  - FSRS parameter support via anki_cards_fsrs()
  - fsrs_retrievability() function

                 Changes in version 0.1.0 (2026-01-16)                  

  - Initial release with core functions