-All public-inbox-specific files are contained within the
-C<$GIT_DIR/public-inbox/> directory. All files are expected to
-grow in size as more messages are archived, so using compaction
-commands (e.g. L<xapian-compact(1)>) is not recommended unless
-the list is no longer active.
+=over
+
+=item --compact / -c
+
+Compacts the Xapian DBs after indexing. This is recommended
+when using C<--reindex> to avoid running out of disk space
+while indexing multiple inboxes.
+
+While option takes a negligible amount of time compared to
+C<--reindex>, it requires temporarily duplicating the entire
+contents of the Xapian DB.
+
+This switch may be specified twice, in which case compaction
+happens both before and after indexing to minimize the temporal
+footprint of the (re)indexing operation.
+
+=item --reindex
+
+Forces a re-index of all messages in the inbox.
+This can be used for in-place upgrades and bugfixes while
+NNTP/HTTP server processes are utilizing the index. Keep in
+mind this roughly doubles the size of the already-large
+Xapian database. Using this with C<--compact> or running
+L<public-inbox-compact(1)> afterwards is recommended to
+release free space.
+
+This does not touch the NNTP article number database or
+affect threading.
+
+=item --prune
+
+Run L<git-gc(1)> to prune and expire reflogs if discontiguous history
+is detected. This is intended to be used in mirrors after running
+L<public-inbox-edit(1)> or L<public-inbox-purge(1)> to ensure data
+is expunged from mirrors.
+
+=item --max-size SIZE