also copy sibling files

.github/skills/skill-installer/SKILL.md

@@ -22,7 +22,7 @@ Use this skill to install another skill from a local path, a directory, or a Git
 
 - Local `SKILL.md` file
 - Local skill directory
-- GitHub blob URL to a `SKILL.md` file
+- GitHub blob URL to a `SKILL.md` file, including sibling supporting files
 
 ## Install script
 
@@ -50,5 +50,7 @@ The installer prompts for:
 1. Source path or URL
 2. Target scope: repo or global
 3. Skill name if it cannot be inferred
-4. Whether to copy supporting files
+4. Whether to copy supporting files for a local directory source
 5. Whether to overwrite an existing install
+
+For GitHub blob URLs, supporting files in the same skill directory are downloaded automatically.

.github/skills/skill-installer/scripts/install-skill.sh

@@ -35,6 +35,16 @@ rewrite_github_blob_url() {
   fi
 }
 
+parse_github_blob_url() {
+  local url="$1"
+  if [[ "$url" =~ ^https://github\.com/([^/]+)/([^/]+)/blob/([^/]+)/(.*)$ ]]; then
+    printf '%s\t%s\t%s\t%s\n' "${BASH_REMATCH[1]}" "${BASH_REMATCH[2]}" "${BASH_REMATCH[3]}" "${BASH_REMATCH[4]}"
+    return 0
+  fi
+
+  return 1
+}
+
 extract_skill_name() {
   local file="$1"
   sed -n 's/^name:[[:space:]]*//p' "$file" | head -n 1
@@ -46,6 +56,45 @@ download_source() {
   curl -fsSL "$url" -o "$out"
 }
 
+list_github_contents() {
+  local owner="$1"
+  local repo="$2"
+  local ref="$3"
+  local path="$4"
+
+  curl -fsSL -H 'Accept: application/vnd.github+json' \
+    "https://api.github.com/repos/${owner}/${repo}/contents/${path}?ref=${ref}" | \
+    python3 -c $'import json,sys\ndata = json.load(sys.stdin)\nitems = data if isinstance(data, list) else [data]\nfor item in items:\n    print("%s\\t%s\\t%s" % (item.get("type", ""), item.get("path", ""), item.get("download_url", "")))'
+}
+
+download_github_contents() {
+  local owner="$1"
+  local repo="$2"
+  local ref="$3"
+  local path="$4"
+  local target_root="$5"
+
+  while IFS=$'\t' read -r item_type item_path download_url; do
+    [[ -z "$item_type" ]] && continue
+
+    local relative_path="${item_path#${path}/}"
+    local destination_path="$target_root/$relative_path"
+
+    case "$item_type" in
+      dir)
+        download_github_contents "$owner" "$repo" "$ref" "$item_path" "$target_root"
+        ;;
+      file)
+        mkdir -p "$(dirname "$destination_path")"
+        download_source "$download_url" "$destination_path"
+        ;;
+      *)
+        printf 'Skipping unsupported GitHub content type: %s (%s)\n' "$item_type" "$item_path" >&2
+        ;;
+    esac
+  done < <(list_github_contents "$owner" "$repo" "$ref" "$path")
+}
+
 copy_skill_dir() {
   local source_dir="$1"
   local target_dir="$2"
@@ -82,9 +131,16 @@ source_kind=""
 source_path="$source_input"
 
 if [[ "$source_input" =~ ^https?:// ]]; then
-  source_kind="url"
-  source_path="$(rewrite_github_blob_url "$source_input")"
-  download_source "$source_path" "$staging_dir/SKILL.md"
+  if github_blob_parts="$(parse_github_blob_url "$source_input")"; then
+    source_kind="github-blob-url"
+    IFS=$'\t' read -r github_owner github_repo github_ref github_path <<<"$github_blob_parts"
+    github_skill_dir="$(dirname "$github_path")"
+    download_github_contents "$github_owner" "$github_repo" "$github_ref" "$github_skill_dir" "$staging_dir"
+  else
+    source_kind="url"
+    source_path="$(rewrite_github_blob_url "$source_input")"
+    download_source "$source_path" "$staging_dir/SKILL.md"
+  fi
 elif [[ -d "$source_input" ]]; then
   source_kind="directory"
   skill_file="$source_input/SKILL.md"