Changes in version 0.2.0                        

Major release: the package is rewritten from S4 to S7 and gains a second
estimator (IPW). It is now a thin orchestration layer — fitting is
delegated to medfit and inference to RMediation.

New S7 pipeline

Four verbs over three S7 classes:

set_md_mediation()  ->  run()  ->  pool()  ->  infer()
   MDMediationData      MDMediationFit  MDMediationResult   CI / MBCO

  - set_md_mediation() — entry point; records the data + a medfit-style
    mediation spec (outcome/mediator formulas + treatment/mediator
    roles).
  - run() — fits each imputation via medfit::fit_mediation(), yielding a
    list of named medfit::MediationData.
  - pool() — Rubin's-rules pooling of the named (estimates, vcov) into a
    single named pooled medfit::MediationData, valid input to
    RMediation::ci_mediation_data().
  - infer(type = c("mc", "mbco")) — Monte-Carlo /
    distribution-of-the-product CI (mc), or D4-stacked MBCO
    likelihood-ratio test (mbco).
  - per_imputation_list() — exposes the per-imputation fits for MBCO
    (which does not commute with Rubin's rules).

New S7 classes: MDMediationData, MDMediationFit, MDMediationResult.

Estimators

  - Multiple imputation (method = "mi") — the default; pools m
    imputed-data fits with Rubin's rules.
  - Inverse-probability weighting (method = "ipw") — new. Reweights the
    complete cases by inverse missingness probability and fits once.
    Supports a joint complete-case weight model (default) or
    per-variable formulas, stabilized weights, quantile trimming, and HC
    sandwich SEs (se_type = "sandwich").

MBCO under multiple imputation

  - infer(type = "mbco") implements D4-stacked MBCO, which respects the
    union-null geometry of H0: ab = 0 (branch switching) — exact-match
    parity with the research prototype. See vignette("mbco-mi").

Documentation

  - New vignettes: missingmed (getting started), mbco-mi, and technical
    (design, ecosystem contracts, and methodology).
  - pkgdown site at https://data-wise.github.io/missingmed/.

Deprecations

  - The S4 API (set_sem(), run_sem(), pool_sem(), and the SemImputedData
    / SemResults / PooledSEMResults classes) is deprecated in favour of
    the S7 pipeline above. The shims emit a .Deprecated() warning and
    will be removed in a future release.

Dependencies

  - New Imports: S7, medfit (>= 0.3.1), RMediation (>= 1.4.0). medfit
    and RMediation are available from the Data-Wise R-universe.

                        Changes in version 0.1.0                        

  - Initial S4 implementation: SEM-based mediation across multiply
    imputed datasets (mice + lavaan/OpenMx) with Rubin's-rules pooling.