Bump version to 3.9.0

CHANGELOG.md

@@ -5,7 +5,39 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
-## [Unreleased]
+## [3.9.0] - 2026-08-10
+
+The 3.9 shim release of the 4.0 API-unification program (`docs/v4-design.md`):
+every new surface ships additively, and every deprecated spelling keeps
+working through 3.9, with a `FutureWarning` on its documented shim path
+(a few windows are deliberately silent and rowed as such in the ledger -
+e.g. the `QDiDResults` export alias, where constructing `QDiD` is what
+warns). Highlights:
+the three estimator merges (TwoWayFixedEffects absorbs MultiPeriodDiD via
+`event_study=True`, TripleDifference absorbs StaggeredTripleDifference,
+ChangesInChanges absorbs QDiD via `method=`), post-fit
+`results.aggregate(type=...)` across the staggered family, the library-wide
+parameter-rename program (uniform `post`/`time`/`unit`/`first_treat`/
+`covariates` vocabulary, `_col` suffixes dropped), the shared `BaseEstimator`
+`get_params`/`set_params` mixin with transactional `set_params`, fail-closed
+inference-selector validation, deprecation of the module-level estimator
+wrapper functions and the `CDiD`/`Stacked`/`Gardner` aliases, and the 4.0
+migration guide (`docs/migration-4.0.md`). Lifecycle authority for every
+deprecation: `docs/v4-deprecations.yaml`. Full detail in the entries below.
+
+### Changed
+- **Version 3.9.0 + the armed 4.0 rename window.** Bumping `__version__` to
+  3.9 arms the naming guard's next enforcement window (section-8 rule-11
+  "Duty C" in `tests/test_naming_guard.py`: a rename's reader inventory is
+  due when its `deprecated_in` enters the next-release horizon), so this
+  release records the previously-uninventoried readers of the 4.0-scheduled
+  old names on their ledger rows' `code_refs`: the `overall_att` field-flip
+  family [M-050]..[M-058] (producer modules, `diagnostic_report.py`'s
+  `getattr` fallback chains, `prep_dgp.py`, the staggered-DDD engine and
+  container, the three bundled AI guides, and the REGISTRY / REPORTING /
+  continuous-did methodology pages) and [M-016] `period_effects`
+  (`llms-full.txt`). No status flips and no behavior changes - the 4.0
+  removal PRs consult these inventories so no reader is missed.
 
 ### Added
 - **4.0 migration guide** (`docs/migration-4.0.md`, v4 program Phase 4; the
@@ -4744,6 +4776,7 @@ for the full feature history leading to this release.
 [2.1.2]: https://github.com/igerber/diff-diff/compare/v2.1.1...v2.1.2
 [2.1.1]: https://github.com/igerber/diff-diff/compare/v2.1.0...v2.1.1
 [2.1.0]: https://github.com/igerber/diff-diff/compare/v2.0.3...v2.1.0
+[3.9.0]: https://github.com/igerber/diff-diff/compare/v3.8.0...v3.9.0
 [3.8.0]: https://github.com/igerber/diff-diff/compare/v3.7.0...v3.8.0
 [3.7.0]: https://github.com/igerber/diff-diff/compare/v3.6.2...v3.7.0
 [3.6.2]: https://github.com/igerber/diff-diff/compare/v3.6.1...v3.6.2

CITATION.cff

@@ -7,8 +7,8 @@ authors:
     family-names: Gerber
     orcid: "https://orcid.org/0009-0009-3275-5591"
 license: MIT
-version: "3.8.0"
-date-released: "2026-07-18"
+version: "3.9.0"
+date-released: "2026-08-10"
 doi: "10.5281/zenodo.19646175"
 url: "https://github.com/igerber/diff-diff"
 repository-code: "https://github.com/igerber/diff-diff"

diff_diff/__init__.py

@@ -361,7 +361,7 @@ def __getattr__(name: str) -> _Any:
     raise AttributeError(f"module 'diff_diff' has no attribute {name!r}")
 
 
-__version__ = "3.8.0"
+__version__ = "3.9.0"
 __all__ = [
     # Estimators
     "DifferenceInDifferences",

diff_diff/guides/llms-full.txt

@@ -2,7 +2,7 @@
 
 > A Python library for Difference-in-Differences causal inference analysis. Provides sklearn-like estimators with statsmodels-style output for econometric analysis.
 
-- Version: 3.8.0
+- Version: 3.9.0
 - Repository: https://github.com/igerber/diff-diff
 - License: MIT
 - Dependencies: numpy, pandas, scipy (no statsmodels dependency)

docs/v4-deprecations.yaml

@@ -212,8 +212,8 @@ rows:
     status: planned
     phase: 5
     warning: FutureWarning
-    code_refs: [diff_diff/results.py, diff_diff/honest_did.py, diff_diff/pretrends.py, diff_diff/visualization/_event_study.py, diff_diff/results_base.py, diff_diff/diagnostic_report.py, diff_diff/estimators.py]
-    notes: "Period-keyed dict becomes a FutureWarning property VIEW over the unified event-study surface on the successor container at 4.0; removed 5.0. Migrate this locator to the successor class when [M-011] flips (cross-row rule, spec section 11)."
+    code_refs: [diff_diff/results.py, diff_diff/honest_did.py, diff_diff/pretrends.py, diff_diff/visualization/_event_study.py, diff_diff/results_base.py, diff_diff/diagnostic_report.py, diff_diff/estimators.py, diff_diff/guides/llms-full.txt]
+    notes: "Period-keyed dict becomes a FutureWarning property VIEW over the unified event-study surface on the successor container at 4.0; removed 5.0. Migrate this locator to the successor class when [M-011] flips (cross-row rule, spec section 11). Reader inventory completed at the 3.9 bump, when the rule-11 Duty C window armed for 4.0-scheduled rows."
 
   # ---- fit(aggregate=) -> results.aggregate(type=) -------------------------
   - id: M-020
@@ -626,8 +626,8 @@ rows:
     phase: 5
     warning: FutureWarning
     test_ref: null
-    code_refs: [diff_diff/staggered_results.py, diff_diff/power.py, diff_diff/practitioner.py, diff_diff/efficient_did.py, diff_diff/wooldridge.py, diff_diff/_reporting_helpers.py]
-    notes: "Pickle migration via __setstate__ per spec section 5."
+    code_refs: [diff_diff/staggered_results.py, diff_diff/staggered.py, diff_diff/staggered_aggregation.py, diff_diff/power.py, diff_diff/practitioner.py, diff_diff/efficient_did.py, diff_diff/wooldridge.py, diff_diff/_reporting_helpers.py, diff_diff/diagnostic_report.py, diff_diff/prep_dgp.py, diff_diff/_staggered_triple_diff_engine.py, diff_diff/staggered_triple_diff_results.py, diff_diff/guides/llms-autonomous.txt, diff_diff/guides/llms-full.txt, diff_diff/guides/llms-practitioner.txt, docs/methodology/REGISTRY.md, docs/methodology/REPORTING.md]
+    notes: "Pickle migration via __setstate__ per spec section 5. This row carries the token family's CROSS-CUTTING consumer inventory (reports, guides, methodology docs, DGP helpers, the un-rowed staggered-DDD engine/container) alongside its own producers; per-class producer files live on their own rows. Inventory completed at the 3.9 bump, when the rule-11 Duty C window armed for 4.0-scheduled rows."
   - id: M-051
     kind: field
     group: field-flip
@@ -652,7 +652,7 @@ rows:
     status: planned
     phase: 5
     warning: FutureWarning
-    code_refs: [diff_diff/imputation_results.py]
+    code_refs: [diff_diff/imputation_results.py, diff_diff/imputation.py]
     notes: ""
   - id: M-053
     kind: field
@@ -665,7 +665,7 @@ rows:
     status: planned
     phase: 5
     warning: FutureWarning
-    code_refs: [diff_diff/two_stage_results.py]
+    code_refs: [diff_diff/two_stage_results.py, diff_diff/two_stage.py]
     notes: ""
   - id: M-054
     kind: field
@@ -678,7 +678,7 @@ rows:
     status: planned
     phase: 5
     warning: FutureWarning
-    code_refs: [diff_diff/stacked_did_results.py]
+    code_refs: [diff_diff/stacked_did_results.py, diff_diff/stacked_did.py]
     notes: ""
   - id: M-055
     kind: field
@@ -691,7 +691,7 @@ rows:
     status: planned
     phase: 5
     warning: FutureWarning
-    code_refs: [diff_diff/efficient_did_results.py]
+    code_refs: [diff_diff/efficient_did_results.py, diff_diff/efficient_did_aggregation.py]
     notes: ""
   - id: M-056
     kind: field
@@ -717,7 +717,7 @@ rows:
     status: planned
     phase: 5
     warning: FutureWarning
-    code_refs: [diff_diff/chaisemartin_dhaultfoeuille_results.py]
+    code_refs: [diff_diff/chaisemartin_dhaultfoeuille_results.py, diff_diff/chaisemartin_dhaultfoeuille.py]
     notes: ""
   - id: M-058
     kind: field
@@ -730,7 +730,7 @@ rows:
     status: planned
     phase: 5
     warning: FutureWarning
-    code_refs: [diff_diff/continuous_did_results.py]
+    code_refs: [diff_diff/continuous_did_results.py, diff_diff/continuous_did.py, docs/methodology/continuous-did.md]
     notes: "Also flips the deviant overall_att_se/overall_att_p_value/overall_att_conf_int/overall_att_t_stat sibling fields (the trap-catalog outlier)."
 
   # ---- Alias table ---------------------------------------------------------

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "maturin"
 
 [project]
 name = "diff-diff"
-version = "3.8.0"
+version = "3.9.0"
 description = "Difference-in-Differences causal inference with sklearn-like API. Callaway-Sant'Anna, Synthetic DiD, Honest DiD, event studies, parallel trends."
 readme = "README.md"
 license = "MIT"

rust/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "diff_diff_rust"
-version = "3.8.0"
+version = "3.9.0"
 edition = "2021"
 rust-version = "1.85"
 description = "Rust backend for diff-diff DiD library"