feat: auto-generate ~/.mackup/ssr-custom.cfg for uncovered dot-dirs

Before each `ssr sync`, scan $HOME for dot-dirs/files not yet present
in the Mackup backup directory and write them into
~/.mackup/ssr-custom.cfg. This covers tools like .claude, .cursor,
.easymcp, .codex, .factory, and any future dot-dir without requiring
the user to write manual Mackup app definitions.

Curated list handles common developer tools; auto-discovery adds the
rest while skipping caches, credential dirs (.ssh, .gnupg, .aws,
.azure) and other volatile state.

Configurable via:
  SSR_MACKUP_AUTODISCOVER=true   (opt-out with false)
  SSR_MACKUP_EXTRA_PATHS="..."   (space-separated $HOME-relative paths)

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

lib/mackup.sh

@@ -4,6 +4,109 @@
 # remains the simplest way to sync dotfiles for a wide range of apps. The
 # user can swap engines via ~/.mackup.cfg without changing this script.
 
+# ---------------------------------------------------------------------------
+# Custom Mackup app definition auto-generator
+# ---------------------------------------------------------------------------
+
+# Curated dot-paths that matter for developer workflows but are not in
+# Mackup's built-in app definitions. Add your own via SSR_MACKUP_EXTRA_PATHS
+# (space-separated) in ssr.conf.
+_SSR_MACKUP_CURATED=(
+    .claude          # Claude AI CLI config, skills, agents
+    .cursor          # Cursor IDE config + rules
+    .codex           # OpenAI Codex config
+    .easymcp         # EasyMCP config
+    .factory         # Factory AI config
+    .config/claude
+    .config/cursor
+    .config/gh       # GitHub CLI (if not already in mackup)
+    .config/op       # 1Password CLI config
+    bin              # personal ~/bin scripts
+)
+
+# Dot-dirs/files to never auto-include.
+# Covers: caches, generated state, credentials, large build artefacts.
+_SSR_MACKUP_SKIP=(
+    .Trash .localized .DS_Store .CFUserTextEncoding
+    .cache .npm .yarn .pnpm .bun
+    .gradle .m2 .ivy2 .sbt
+    .docker .vagrant .minikube .kube .helm
+    .local          # runtime state, not config
+    .bash_history .zsh_history .zsh_sessions .sh_history
+    .lesshst .wget-hsts .python_history .node_repl_history
+    .ruby_history .irb_history .psql_history .mysql_history
+    .dbshell .viminfo .Xauthority
+    .Spotlight-V100 .fseventsd .DocumentRevisions-V100
+    # Security-sensitive — back up separately with encryption
+    .ssh .gnupg .aws .azure .gcloud .config/gcloud
+)
+
+# Generate (or refresh) ~/.mackup/ssr-custom.cfg with:
+#   1. Curated entries that exist in $HOME and are not yet in the Mackup backup.
+#   2. Any dot-dir discovered in $HOME that is not in the skip list and not
+#      already materialised in the Mackup backup directory.
+#
+# The file is picked up automatically by `mackup backup/restore`.
+# Idempotent: re-running overwrites the previous version.
+ssr::mackup::generate_custom_cfg() {
+    local mackup_dir="$1"   # the cloud Mackup backup directory
+    local cfg_dir="$HOME/.mackup"
+    local cfg_file="$cfg_dir/ssr-custom.cfg"
+
+    mkdir -p "$cfg_dir"
+
+    # Build a fast lookup set from the skip list.
+    local skip_set=" ${_SSR_MACKUP_SKIP[*]} "
+
+    # Helper: is <item> already in the Mackup backup?
+    _in_backup() { [[ -e "$mackup_dir/$1" ]]; }
+
+    local -a items=()
+
+    # 1. Curated entries (exist on disk, not yet backed up).
+    local item
+    for item in "${_SSR_MACKUP_CURATED[@]}" ${SSR_MACKUP_EXTRA_PATHS:-}; do
+        [[ -e "$HOME/$item" ]]     || continue
+        _in_backup "$item"         && continue
+        items+=("$item")
+    done
+
+    # 2. Auto-discover uncovered dot-dirs in $HOME.
+    local name
+    while IFS= read -r dotdir; do
+        name="${dotdir##*/}"
+        # Skip if in the skip set.
+        [[ "$skip_set" == *" $name "* ]] && continue
+        # Skip if already in backup.
+        _in_backup "$name" && continue
+        # Skip if already in the curated list we built above.
+        local dup=false
+        for item in "${items[@]:-}"; do [[ "$item" == "$name" ]] && dup=true && break; done
+        $dup && continue
+        items+=("$name")
+    done < <(find "$HOME" -maxdepth 1 -mindepth 1 -name '.*' -type d 2>/dev/null | sort)
+
+    if [[ ${#items[@]} -eq 0 ]]; then
+        ssr::log "No uncovered dot-dirs to add — ~/.mackup/ssr-custom.cfg not changed."
+        return 0
+    fi
+
+    {
+        printf '# Auto-generated by ssr sync (%s)\n' "$(date '+%Y-%m-%dT%H:%M:%S')"
+        printf '# Do not edit manually — regenerated on every sync.\n'
+        printf '# Add custom paths via SSR_MACKUP_EXTRA_PATHS in ssr.conf.\n\n'
+        printf '[application]\n'
+        printf 'name = ssr-custom\n\n'
+        printf '[configuration_files]\n'
+        local it
+        for it in "${items[@]}"; do
+            printf '%s\n' "$it"
+        done
+    } > "$cfg_file"
+
+    ssr::ok "~/.mackup/ssr-custom.cfg: ${#items[@]} item(s) added → ${items[*]}"
+}
+
 ssr::mackup::ensure_installed() {
     if command -v mackup >/dev/null 2>&1; then
         return 0