index: latest_mcpp -> 2026.9.25.1

Author: speak-agent

index.toml

@@ -98,7 +98,12 @@
 # Raising it would cost every client below the floor the WHOLE index (E0006 at
 # the index-open choke point) for a diagnostic note they merely would not have
 # received.
+# ── 2026-09-25: latest_mcpp -> 2026.9.25.1, min_mcpp unchanged ─────────────
+#
+# The pull request that moves validate.yml's pin to 2026.9.25.1 runs every
+# member on every platform with that release, which is what "known good"
+# means for this hint. The release changes no descriptor grammar.
 [index]
 spec        = "1"
 min_mcpp    = "2026.9.18.3"
-latest_mcpp = "2026.9.21.2"
+latest_mcpp = "2026.9.25.1"