chore: address static-analysis cleanup review

Author: shawcharles

CHANGELOG.md

@@ -5,6 +5,13 @@ 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]
+
+### Changed
+- **Internal: cleaned package-source Ruff static-analysis findings** across forward-reference,
+  stale f-string, invalid `noqa`, and audited unused-local sites. No public API or numerical
+  behavior change.
+
 ## [3.7.0] - 2026-07-08
 
 ### Added
@@ -954,9 +961,6 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   county event studies -12%/-13% (rust/python), with no scenario regressing. Rust outputs
   move only at the cross-backend parity tolerances (REGISTRY-documented; never
   bit-identical across backends).
-- **Internal: cleaned package-source Ruff static-analysis findings** across forward-reference,
-  stale f-string, invalid `noqa`, and audited unused-local sites. No public API or numerical
-  behavior change.
 - **FE-absorption demeaning rewritten: factorize-once + `np.bincount` method of alternating
   projections** (`demean_by_groups` / `within_transform`). Each absorbed dimension is factorized
   once and group means are formed via `np.bincount` instead of re-hashing the group keys with

diff_diff/staggered.py

@@ -4612,7 +4612,8 @@ def _doubly_robust_rc(
         ps_ct = pscore[n_gt + n_gs : n_gt + n_gs + n_ct]
         ps_cs = pscore[n_gt + n_gs + n_ct :]
         # The symmetric treated slices ps_gt and ps_gs are intentionally not
-        # materialized: only control propensity slices feed IPW control weights.
+        # materialized: only control propensity slices feed IPW control weights
+        # (the propensity-estimation IF correction consumes the full pscore array directly).
 
         # =====================================================================
         # 3. Group weights and R-convention means