diff --git a/lectures/life-expectancy-vs-gdp-per-capita.csv.yml b/lectures/life-expectancy-vs-gdp-per-capita.csv.yml
index c9da0d4..030ffd8 100644
--- a/lectures/life-expectancy-vs-gdp-per-capita.csv.yml
+++ b/lectures/life-expectancy-vs-gdp-per-capita.csv.yml
@@ -87,7 +87,11 @@ integrity:
     note: >
       OWID has published a newer vintage under the same grapher slug. Our copy
       is an older export and is what every consuming lecture reads. See `delta`
-      before refreshing — the change is not cosmetic.
+      before refreshing — the change is not cosmetic. Reviewed 2026-09-01 under
+      the register's post-migration review and KEPT: adopting the new vintage is
+      a lecture-content change (a new filename, four repos, five figures) with
+      no reader benefit, since the lecture embeds the live OWID grapher beside
+      the frozen data. Revisit only on an author request in lecture-python-intro.
     delta_kind: upstream-moved
     delta: >
       Fetched 2026-08-12: HTTP 200, 1,414,428 B against our 2,059,709 B.
diff --git a/lectures/mpd2020.xlsx.yml b/lectures/mpd2020.xlsx.yml
index 5dfbf2d..a135f68 100644
--- a/lectures/mpd2020.xlsx.yml
+++ b/lectures/mpd2020.xlsx.yml
@@ -74,7 +74,11 @@ integrity:
     against: https://www.rug.nl/ggdc/historicaldevelopment/maddison/data/mpd2020.xlsx
     note: >
       Checked in full against upstream and found to differ in three header
-      labels; every data value matches. See `delta`.
+      labels; every data value matches. See `delta`. Reviewed 2026-09-01 under
+      the register's post-migration review and KEPT deliberately: the data is
+      the current Maddison release and the three labels are load-bearing for
+      long_run_growth, so restoring the pristine file would change nothing a
+      reader sees while touching all four consuming repos, the canary included.
     delta_kind: local-edit
     delta: >
       Re-fetched from the Maddison release and compared cell by cell across all