Add --merge-run to rsync and --force to arr_sync for authoritative node compliance

Rsync/rsync.sh

@@ -131,6 +131,13 @@
 # rsync.sh /path/to/share --seed
 #     Skip the empty-remote-share guard. Use for first-time seeding of a new share.
 #
+# rsync.sh /path/to/share --merge-run
+#     Bidirectional merge: pull remote-unique content to local first (--ignore-existing),
+#     then push local → remote with --delete so the remote matches local exactly.
+#     Local is always authoritative — remote loses divergent file versions but keeps
+#     any content the local did not have (pulled in pass 1 before the delete push).
+#     Also auto-triggered when pre-scan detects ≥75% directory overlap with remote.
+#
 # ==============================================================================================
 
 SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
@@ -141,12 +148,14 @@ source "$SCRIPT_DIR/../load_config.sh"
 DIRECTORY=""
 PROFILE_OVERRIDE=""
 SEED=false
+MERGE_RUN=false
 RAW_ARGS=()
 
 for ARG in "$@"; do
     case "$ARG" in
         --profile=*) PROFILE_OVERRIDE="${ARG#--profile=}" ;;
         --seed)      SEED=true ;;
+        --merge-run) MERGE_RUN=true ;;
         --*|*=*)     RAW_ARGS+=("$ARG") ;;
         *)           [[ -z "$DIRECTORY" ]] && DIRECTORY="$ARG" || RAW_ARGS+=("$ARG") ;;
     esac
@@ -260,6 +269,31 @@ check_remote_rootfs
 [[ "$SEED" == false ]] && check_remote_share "$DIRECTORY"
 check_remote_disks "$DIRECTORY"
 
+# ── Merge-run pre-scan ────────────────────────────────────────────────────────────────────────
+# Auto-promote to merge mode when ≥75% of remote's top-level entries exist locally.
+# Skipped when --merge-run is already set or --seed is active (remote was just created).
+if [[ "$MERGE_RUN" == false && "$SEED" == false ]]; then
+    _remote_top=$(ssh -i "$SSH_KEY" -o ConnectTimeout=10 -o BatchMode=yes \
+        root@"$REMOTE_SERVER" "ls -1A '$DIRECTORY' 2>/dev/null | sort" 2>/dev/null)
+    _remote_count=$(echo "$_remote_top" | grep -c . 2>/dev/null || echo 0)
+
+    if [[ "$_remote_count" -gt 0 ]]; then
+        _local_top=$(ls -1A "$DIRECTORY" 2>/dev/null | sort)
+        _overlap=$(comm -12 \
+            <(echo "$_local_top") \
+            <(echo "$_remote_top") | grep -c . 2>/dev/null || echo 0)
+        _overlap_pct=$(( _overlap * 100 / _remote_count ))
+
+        if [[ "$_overlap_pct" -ge 75 ]]; then
+            info "Overlap ${_overlap_pct}% (${_overlap}/${_remote_count} entries) — auto-promoting to merge mode"
+            MERGE_RUN=true
+        else
+            log "Overlap ${_overlap_pct}% (${_overlap}/${_remote_count} entries) — normal sync"
+        fi
+    fi
+    unset _remote_top _remote_count _local_top _overlap _overlap_pct
+fi
+
 # Remote Docker daemon — check before attempting container operations
 if [[ ${#CRITICAL_CONTAINER_NAMES[@]} -gt 0 ]] || [[ ${#REMOTE_RESTART_CONTAINERS[@]} -gt 0 ]]; then
     check_remote_docker_daemon || {
@@ -315,6 +349,29 @@ RSYNC_OPTS+=(--stats)
 
 [[ "$DRY_RUN" == true ]] && RSYNC_OPTS+=("--dry-run")
 
+# ── Merge pass 1: pull remote-unique content to local (--ignore-existing) ────────────────────
+# Runs before the push so anything the remote has that we don't is preserved locally.
+# After this pass, local is the superset — the delete push in pass 2 is then safe.
+if [[ "$MERGE_RUN" == true ]]; then
+    echo "$ICON_SYNC  Merge pass 1 — pulling ${REMOTE_SERVER_NAME}-unique content to local..."
+    _pull_opts=(-av --ignore-existing --stats)
+    [[ "$DRY_RUN" == true ]] && _pull_opts+=(--dry-run)
+    _pull_output=$(rsync "${_pull_opts[@]}" \
+        -e "ssh -i $SSH_KEY -T -o Compression=no -o IPQoS=throughput" \
+        "root@${REMOTE_SERVER}:${DIRECTORY}/" "${DIRECTORY}/" 2>&1)
+    _pull_exit=$?
+    _pull_bytes=$(echo "$_pull_output" | \
+        awk '/Total transferred file size:/{gsub(/,/,"",$NF); gsub(/[^0-9]/,"",$NF); print $NF+0}')
+    if [[ "$_pull_exit" -eq 0 ]]; then
+        echo "$ICON_DONE Merge pass 1 complete — ${_pull_bytes:-0} bytes pulled"
+    else
+        warn "Merge pass 1 failed (exit $_pull_exit) — continuing with push"
+    fi
+    unset _pull_opts _pull_output _pull_exit _pull_bytes
+    # Pass 2: push with --delete — local is now the authoritative superset
+    RSYNC_OPTS+=(--delete)
+fi
+
 START=$(date +%s)
 RSYNC_SUCCESS=false
 BYTES_TRANSFERRED=0