Fill the single missing section in three scripts that had everything else

Rsync/media_seed.sh

@@ -35,6 +35,25 @@
 # progress in the UI, and lets it be re-run or cancelled without touching onboard.
 #
 # ==============================================================================================
+# OPERATIONAL MODEL
+# ==============================================================================================
+#
+# One share at a time, in DAILY_SYNC_SHARES order, each handed to Rsync/rsync.sh --seed. The
+# transfer itself, its bandwidth cap and its resume behaviour are all rsync.sh's — this script
+# decides what to seed and in what order, never how.
+#
+# Sequential on purpose. The cap that matters is DEFAULT_RSYNC_OPTS' --bwlimit, which is a limit
+# per rsync rather than per host; running shares in parallel would multiply it by the number of
+# shares and saturate the link the rest of the ecosystem is still using.
+#
+# Refuses before it starts rather than partway. RSYNC_ENABLED must be true and DAILY_SYNC_SHARES
+# must be non-empty, both checked up front — a multi-week transfer is the wrong place to
+# discover that the global gate was off.
+#
+# Nothing waits on this. Phase 3 runs after the partnership is already established, so a seed
+# that is still copying weeks later blocks no flag, no status card and no job record.
+#
+# ==============================================================================================
 # DESIGN PRINCIPLES
 # ==============================================================================================
 #