diff --git a/docs/fdroid-official/de.jeanlucmakiola.calendula.yml b/docs/fdroid-official/de.jeanlucmakiola.calendula.yml
index 45a7a3e..29f9b66 100644
--- a/docs/fdroid-official/de.jeanlucmakiola.calendula.yml
+++ b/docs/fdroid-official/de.jeanlucmakiola.calendula.yml
@@ -48,6 +48,19 @@ Builds:
     # No NDK / no flavors. The release buildType applies a signingConfig only
     # when key.properties exists; on the buildserver it does not, so this
     # produces the unsigned APK F-Droid compares against our binary.
+    #
+    # DO NOT add `submodules: true` here ahead of need. fdroidserver's
+    # initsubmodules() RAISES NoSubmodulesException ("No git submodules
+    # available") on any build entry whose commit has no `.gitmodules`, so
+    # `submodules: true` is a HARD BUILD FAILURE — not a no-op — on every
+    # release before the floret-kit submodule lands. (Verified 2026-06-28: it
+    # broke the fdroid build / checkupdates / check-source-code jobs on
+    # fdroiddata MR !41553; confirmed locally with the fdroidserver-master
+    # fetchsrclibs path.) Add `submodules: true` ONLY in the recipe entry that
+    # targets the FIRST release actually shipping the `floret-kit` git submodule
+    # (composite build via `includeBuild("floret-kit")`, core-time refactor on
+    # branch `chore/floret-kit-core-time`) — and only there. From that entry on
+    # it becomes the AutoUpdateMode template and propagates to future builds.
 
 # SHA-256 of our app signing certificate (public; embedded in every published
 # APK). Locks F-Droid to publish only binaries signed with our key.