# DecisionDrift 0.1.0

## Initial release

### Core modules
* `dd_build()` — construct a `drift_panel` object from long-format panel data.
* `dd_prevalence()` — detect drift in decision rate; computes Decision Drift Index (DDI).
* `dd_transition()` — detect drift in transition structure; computes Transition Drift Index (TDI).
* `dd_entropy_trend()` — track rolling Shannon entropy and switching rate over time.
* `dd_group_drift()` — detect group-differential drift; computes Group Differential Drift (GDD).
* `dd_changepoint()` — change-point and regime-shift detection via CUSUM, segmented regression, and event alignment.

### Summary indices
* `dd_indices()` — compute all four original drift indices in one call:
  DDI, TDI, GDD (Group Differential Drift), CDB (Cumulative Drift Burden).

### Robustness & sensitivity
* `dd_robustness()` — test stability of drift conclusions across analytic choices
  (balanced panel, leave-one-period-out, leave-one-group-out, min_waves grid, bootstrap CI).
* `dd_sensitivity()` — probe vulnerability to data problems: decision miscoding,
  missing-wave attrition, threshold shifts, and subgroup composition shifts.

### Flagship audit
* `dd_audit()` — integrated three-layer audit (detection → decomposition → stress-testing)
  with a single-call verdict.

### Plotting
* S3 `plot()` methods for all module outputs.
* Multi-panel composite via `plot.dd_audit()` (requires `patchwork`).

### Relationship to `decisionpaths`
* `decisionpaths` asks: *What happened?* (path construction, DRI, entropy, equity)
* `DecisionDrift` asks: *Did the system change?* (drift detection, decomposition, stress-testing)
* These packages form complementary layers of a longitudinal decision audit framework.
