Changes in version 0.2.1                        

Bug fixes

  - Report and drift filename slugs now use UTC consistently, matching
    the UTC timestamps stored in the snapshot DB.
  - Removed redundant @importFrom declarations for template-only
    packages.
  - Removed dead read_pass_rate_trend() function from drift.R.
  - CP-07 type-change comparison now uses a single guard so it only runs
    the non-numeric rate comparison when both snapshots classify the
    column as numeric — eliminates spurious WARNs on type-changed
    columns.
  - read_dataset() now forwards the col_names config key to
    readr::read_delim(), so headerless CSVs are read correctly.
  - read_dataset() now forwards the quote_char config key to
    readr::read_delim() as quote =.

Internal

  - All rlang::abort() calls (27 sites) now carry a typed, two-level
    class hierarchy (c("<specific>", "dqcheckr_error")), letting callers
    catch errors broadly or precisely.
  - Consolidated shared test fixtures into helper.R.

                 Changes in version 0.2.0 (2026-06-01)                  

New features

  - New compare_snapshots() and list_snapshots() functions for drift
    analysis. Compares any two historical snapshots and optionally
    renders an HTML drift report with per-column statistical drift,
    schema changes, and trend charts.
  - New resolve_col_type() function: returns the effective type for a
    column, respecting per-column type overrides set in the column_types
    config key.
  - New QC-15 outlier detection check (check_outliers()). Configured via
    max_z_score and/or iqr_fence_multiplier; skipped silently when
    neither is set.
  - check_key_uniqueness() (QC-12) now supports composite keys: set
    key_columns to a character vector in the dataset YAML.
  - check_min_row_count() (QC-14) gains max_row_count and
    max_file_size_mb thresholds.
  - col_threshold() and table_threshold() added as internal helpers;
    column_rules per-column threshold overrides are now correctly stored
    in column_snapshots.threshold (G-01).

Behaviour changes

  - Reports migrated from rmarkdown to Quarto. render_report() uses
    quarto::quarto_render() and returns NULL with a warning when Quarto
    CLI is not installed.
  - compare_schema() (CP-02) split into three separate result objects:
    CP-02a (new columns), CP-02b (dropped columns), CP-02c (type
    changes).
  - compare_non_numeric_rate() (CP-07) now always emits a result for
    every eligible column, including PASS for columns where the rate did
    not increase (G-02).
  - run_timestamp is now stored in ISO-8601 UTC format
    (2026-01-01T12:00:00Z) rather than local time (RC-07).
  - snapshots table gains three columns on first use: comparison_mode,
    render_status, and type_changed_cols_vs_previous. Existing 0.1.x
    databases are auto-migrated on the first 0.2.0 run.
  - SQLite foreign key enforcement is now explicitly enabled on every
    connection (PRAGMA foreign_keys = ON).
  - detect_files() uses filename as a secondary sort when two files
    share the same modification time, making folder-mode ordering
    deterministic (RC-01).
  - check_allowed_values() (QC-09), compare_new_values() (CP-05), and
    compare_dropped_values() (CP-06) cap observed at 20 values with an
    "... and N more" suffix (RC-04, RC-05).
  - check_non_numeric() (QC-11) gains a warn_non_numeric_rate config key
    for a separate WARN threshold (C-01).
  - compare_missing_rate() (CP-03) gains a missing_rate_change_severity
    config key (warn / fail) (B-07).
  - compare_column_order() (CP-08) gains a column_order_severity config
    key that overrides the format-based default (C-02).
  - compute_col_stats() stores the numeric mean under the key
    numeric_parseable_mean (renamed from numeric_mean) to clarify that
    non-parseable values are excluded from the calculation (C-04).
  - Comparison summary in the HTML report now lists all FAIL/WARN
    messages as a bullet list rather than picking the single worst
    result (C-05).
  - compare_snapshots() uses the full merged per-dataset config for
    drift threshold comparisons, so *** markers match the original check
    run for datasets with rule_overrides (G-05/G-06).
  - compute_col_stats() unused qc_results parameter removed (D-01).

                        Changes in version 0.1.1                        

  - flag_new_columns, flag_dropped_columns, flag_type_changes (in CP-02)
    and flag_column_order_change (CP-08) are now honoured. Setting any
    flag to false suppresses the corresponding check from the report.
    Schema changes are still tracked in the SQLite snapshot regardless
    of flags.
  - type_inference_threshold is now configurable per dataset via
    rule_overrides in the dataset YAML (or default_rules in the global
    config). Previously fixed at 90%, it now defaults to 90% if not set.
    Affects QC-06, QC-07, QC-08, QC-11, CP-02, CP-04, CP-05, CP-06, and
    CP-07.

                        Changes in version 0.1.0                        

Initial release.

  - Single-snapshot quality checks: QC-01 to QC-14 (missing rate, empty
    columns, duplicate rows, row/column counts, inferred types, numeric
    stats, distinct counts, allowed values, numeric bounds, non-numeric
    rate, key uniqueness, regex pattern, minimum row count) and
    SC-01/SC-02 (schema contract).
  - Version comparison checks: CP-01 to CP-08 (row count change, schema
    diff, missing rate change, numeric mean shift, new/dropped distinct
    values, non-numeric rate change, column order).
  - Custom organisation-specific checks via a plain R file.
  - Self-contained HTML report with check tables, historical trend
    charts, and column statistics appendix.
  - SQLite snapshot database for long-term trend tracking.
  - Supports CSV and fixed-width (FWF) file formats.
  - Configuration via global dqcheckr.yml and per-dataset YAML files.