Recover disk space safely and complete metadata-only backup updates

etc/app-backup/app-backup.conf

@@ -17,6 +17,10 @@ LOG_RETENTION_DAYS=30
 LOCAL_RETENTION_DAYS=7
 REMOTE_RETENTION_DAYS=30
 RETENTION_KEEP_LAST=3
+# Under disk pressure only: keep at least this many uploaded local sets.
+# Other local copies require a fresh offsite check before removal; never zero.
+# Set equal to RETENTION_KEEP_LAST to retain the former emergency floor.
+SPACE_KEEP_LOCAL=1
 # Enable deliberately after a successful restore rehearsal. v1 runs are retained.
 ENABLE_REMOTE_RETENTION="false"
 
@@ -31,9 +35,9 @@ RCLONE_TIMEOUT="1h"
 RCLONE_CONTIMEOUT="30s"
 # Periodic transfer/check statistics in journald, including otherwise quiet uploads.
 RCLONE_STATS_INTERVAL="1m"
-# Readback policy: full comparisons and individual monthly restore-test reads.
+# Retry policy: metadata checks and individual monthly restore-test downloads.
 # Independent of upload retries. All times are seconds.
-# Deadline includes backend waits; raise it for larger/slower full comparisons.
+# Deadline includes backend waits and applies per attempt.
 RCLONE_CHECK_ATTEMPTS=3
 RCLONE_CHECK_RETRY_DELAY=30
 RCLONE_CHECK_TIMEOUT=300
@@ -125,6 +129,8 @@ MAIL_HOME_EXCLUDES=("OneDrive/" ".cache/" ".ccache/" ".local/share/Trash/")
 
 # Additional directories; only files, no automatic DB/container snapshot semantics.
 # Keep ordering stable: entries become extra-0, extra-1, ...
+# Gemini updater --enable-ai-rem appends /srv/ai-rem and /etc/ai-rem here,
+# and adds ai-rem plus its maintenance timers/services to QUIESCE_SERVICES.
 EXTRA_PATHS=()
 # Restore target directories must already exist. Deletion is off by default.
 RESTORE_STRICT_DELETE="false"