                        Changes in version 0.3.0                        

  - Add trace_impact(), impact analysis for a changed source variable.
    Given a variable that is about to change, it walks the derivation
    graph in reverse and returns every ADaM variable that derives from
    it, directly or through a chain, each with its distance from the
    change and a readable path back to it. This is the question a data
    team asks before editing a source: what breaks downstream. Circular
    references are handled and multi-step chains are followed through
    adam_derivations, the same input trace_chains() uses.

                        Changes in version 0.2.1                        

  - Add trace_problems(), a focused view of just the traceability issues
    worth acting on: variables that are not traced to the required
    level, and, when a derivation table is supplied, chains that never
    reach SDTM, that are circular, or that were cut off at the depth
    limit. On a large submission this is what a team consumes rather
    than the full per-variable coverage table. The engine is verified on
    a 10,000-variable synthetic model.

                        Changes in version 0.2.0                        

  - Add export_traceability_report() and traceability_coverage(), which
    summarize traceability coverage per ADaM dataset (percent traced,
    untraced variables listed) with an overall summary row, and export
    the table as a data.frame, CSV, or Excel file for ADRG appendices.
  - Add trace_chains(), which follows multi-step derivation chains back
    to source (ADaM derived from ADaM derived from SDTM), reports the
    depth and whether each variable is grounded in SDTM, caps the walk
    with trace_depth, and detects circular references. Add
    plot_trace_graph() to draw the derivation graph with igraph.
  - Add vignette: "Case study: tracing ADaM back to SDTM", a worked
    walkthrough building a trace model from the example CDISC pilot
    metadata in r4subdata, finding orphan variables, and reading the
    coverage indicators.
  - Clarified the package DESCRIPTION: "R4SUB" expands to "Ready for
    Submission" (previously "R for Regulatory Submission", inconsistent
    with the rest of the ecosystem).

                        Changes in version 0.1.1                        

  - Add vignette: "Traceability Analysis with r4subtrace" covering
    build_trace_model(), compute_trace_levels(),
    trace_indicator_scores(), and orphan variable detection.

                 Changes in version 0.1.0 (2026-03-03)                  

  - Initial CRAN release.
