refactor: ssr-*.cfg files are user-owned after creation

ssr mackup scan now only suggests NEW files — it never overwrites an
existing ssr-*.cfg. Once created, the file belongs to the user who
edits it directly in ~/.mackup/ to customise which paths are backed up.

- _ssr_mackup_write_cfg: returns early if file already exists
- scan: drops UPD logic; only shows NEW suggestions
- _ssr_mackup_resolve_paths: removed SSR_MACKUP_SELECTIVE_PATHS support
  (ssr.conf config variable removed — edit the cfg files instead)
- Scan output: hints to edit files directly after creation

Co-authored-by: Cursor <cursoragent@cursor.com>

lib/mackup.sh

@@ -76,62 +76,46 @@ _ssr_mackup_cfg_name() {
     printf 'ssr-%s' "$name"
 }
 
-# Resolve the list of [configuration_files] entries for an item.
-# If a selective override exists for the item, expand sub-paths that are
-# present on disk.  Falls back to the item itself (whole directory).
+# Resolve the initial [configuration_files] entries for a NEW item.
+# Uses _SSR_MACKUP_SELECTIVE defaults; once a cfg file exists the user owns
+# it and this function is never called for that item again.
 #
 # Outputs one path per line.
 _ssr_mackup_resolve_paths() {
     local item="$1"
-    local -a all_selective=("${_SSR_MACKUP_SELECTIVE[@]}")
-    # Merge user-defined selectives from ssr.conf.
     local entry
-    for entry in ${SSR_MACKUP_SELECTIVE_PATHS:-}; do
-        all_selective+=("$entry")
-    done
-
-    for entry in "${all_selective[@]}"; do
+    for entry in "${_SSR_MACKUP_SELECTIVE[@]}"; do
         local key="${entry%%=*}"
         local val="${entry#*=}"
         if [[ "$key" == "$item" ]]; then
-            # Split comma-separated sub-paths; only include those that exist.
             local sub
             local IFS=','
             for sub in $val; do
                 IFS=' '
-                local full="$item/$sub"
-                # List the path even if it doesn't exist yet — it may be created later.
-                printf '%s\n' "$full"
+                printf '%s\n' "$item/$sub"
             done
             return 0
         fi
     done
-
-    # No selective entry — back up the whole directory.
+    # No selective default — back up the whole directory.
     printf '%s\n' "$item"
 }
 
-# Write a single ~/.mackup/<name>.cfg for one dot-path.
-# Uses selective sub-paths when a matching entry exists in _SSR_MACKUP_SELECTIVE.
-# Skips writing if content is unchanged (idempotent).
+# Write a single ~/.mackup/<name>.cfg for a NEW item.
+# Never called when the file already exists — existing files are user-owned.
 _ssr_mackup_write_cfg() {
     local cfg_dir="$1" item="$2"
     local app_name; app_name="$(_ssr_mackup_cfg_name "$item")"
     local cfg_file="$cfg_dir/${app_name}.cfg"
 
-    # Build [configuration_files] block.
+    # Never overwrite existing files — user may have customised them.
+    [[ -f "$cfg_file" ]] && return 0
+
     local paths_block
     paths_block="$(_ssr_mackup_resolve_paths "$item")"
 
-    local desired
-    desired="$(printf '[application]\nname = %s\n\n[configuration_files]\n%s\n' \
-        "$app_name" "$paths_block")"
-
-    if [[ -f "$cfg_file" ]] && [[ "$(cat "$cfg_file")" == "$desired" ]]; then
-        return 0   # already up-to-date
-    fi
-
-    printf '%s\n' "$desired" > "$cfg_file"
+    printf '[application]\nname = %s\n\n[configuration_files]\n%s\n' \
+        "$app_name" "$paths_block" > "$cfg_file"
 }
 
 # Build a newline-separated list of all paths already declared in Mackup's