Add git:<url> as a third install source

commands/install.md

@@ -1,7 +1,7 @@
 ---
 name: skill-git:install
-description: Install a skill from SkillHub (skills.sh) or ClawHub (clawhub.ai). Triggers on "install skill", "download skill from", or when called from /skill-git:search after the user confirms an install. Usage: /skill-git:install skillhub:<owner/repo@skill> or /skill-git:install clawhub:<slug>.
-argument-hint: skillhub:<owner/repo@skill> | clawhub:<slug> [-a <agent>]
+description: Install a skill from SkillHub (skills.sh), ClawHub (clawhub.ai), or any git URL (public or private — including your own GitHub/GitLab/self-hosted). Triggers on "install skill", "download skill from", or when called from /skill-git:search after the user confirms an install. Usage:  /skill-git:install skillhub:<owner/repo@skill> | clawhub:<slug> | git:<owner/repo>[@<name>] | git:<full-url>[@<name>].
+argument-hint: skillhub:<owner/repo@skill> | clawhub:<slug> | git:<owner/repo>[@<name>] [-a <agent>]
 allowed-tools: Bash(bash *), AskUserQuestion
 ---
 
@@ -37,6 +37,7 @@ If `$ARGUMENTS` is empty:
 Identifier required.
 Usage: /skill-git:install skillhub:<owner>/<repo>@<skill>
        /skill-git:install clawhub:<slug>
+       /skill-git:install git:<owner>/<repo>[@<name>]      (also accepts a full git URL)
 
 Use /skill-git:search to find skills first.
 ```
@@ -46,7 +47,11 @@ Extract `registry` and `identifier` from the first non-flag token:
 
 - `skillhub:<owner>/<repo>@<skill>` → `registry = "skillhub"`, validate `identifier` contains `/` and `@`
 - `clawhub:<slug>` → `registry = "clawhub"`, validate slug is non-empty with no `/` or spaces
-- Unknown prefix → `Unknown registry. Use "skillhub:" or "clawhub:" as prefix.` Stop.
+- `git:<spec>` → `registry = "git"`. The spec is either:
+  - `<owner>/<repo>` shorthand (expanded to `https://github.com/<owner>/<repo>.git`; HTTPS works with gh's credential helper for private repos), or
+  - a full git URL (`https://...`, `http://...`, `git@host:...`, `ssh://...`)
+  - and may end with `@<install_name>` to override the auto-derived name
+- Unknown prefix → `Unknown registry. Use "skillhub:", "clawhub:", or "git:" as prefix.` Stop.
 
 On validation failure, extract a best-effort search query from all non-flag tokens (e.g. `vercel/agent-browser` → `agent-browser`) and run a registry search to suggest the correct identifier:
 
@@ -74,6 +79,7 @@ When the user selects a result, use that as the new `identifier` and `registry`
 Derive `install_name` immediately:
 - SkillHub: the `<skill>` part after `@`
 - ClawHub: the `<slug>`
+- Git: parse the spec by checking if it ends in `@<name>` where `<name>` matches `[A-Za-z0-9_][A-Za-z0-9._-]*` (the suffix contains no `/` or `:`). If so, that suffix is `install_name` and the prefix is the URL. Otherwise the URL is the whole spec and `install_name` is the URL basename with any `.git` suffix stripped (e.g. `tianyilt/skill-paper-write` → `skill-paper-write`, `git@gitlab.com:foo/bar.git` → `bar`).
 
 Extract optional flags:
 - `-a <value>`: target agent (`claude`, `gemini`, `codex`, `openclaw`). Pass through to prelude.
@@ -181,7 +187,32 @@ Could not write SKILL.md to <install_path>.
 ```
 Stop.
 
-### 3c. Validate
+### 3c. Git URL
+
+For `registry = "git"`, hand the parsed spec to the helper script. It normalizes shorthand to a full URL and clones into `install_path`:
+
+```bash
+bash "${CLAUDE_PLUGIN_ROOT}/scripts/sg-install-git.sh" "<url_or_shorthand>" "<install_path>" 2>&1
+```
+
+`<url_or_shorthand>` is the URL portion derived in Step 0 (i.e. without the optional trailing `@<name>`). The script preserves the cloned `.git` and its history; `sg-init.sh` (Step 5) will detect the existing repo and either reuse its `v*` tags (Case D — already versioned) or add a `v1.0.0` tag at the first commit (Case C). Origin remote is left intact so the user can `git pull` updates later.
+
+If the command succeeds and `<install_path>/SKILL.md` exists:
+- Set `skill_source_dir` = `<install_path>` (files already in place)
+- Read `<install_path>/SKILL.md` as `downloaded_content`
+
+If the command fails or `SKILL.md` is not found:
+```
+Could not download skill from git URL.
+  URL: <url>
+
+  The repository may not exist, you may not have access, or the repo may not contain a SKILL.md at its root.
+  Verify access with: git ls-remote <url>
+  For private GitHub repos, ensure your SSH key or gh auth is configured.
+```
+Stop.
+
+### 3d. Validate
 
 Verify `downloaded_content` is non-empty and starts with `---`. If not:
 ```
@@ -206,7 +237,7 @@ Display the skill preview:
 ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 Install preview
 
-  Source   : <SkillHub — owner/repo@skill | ClawHub — slug>
+  Source   : <SkillHub — owner/repo@skill | ClawHub — slug | Git — <url>>
   Name     : <install_name>
   Install  : <install_path>/
   Desc     : <skill_description or "(no description)">
@@ -248,7 +279,7 @@ Installed ✅
 
   <install_name>  v1.0.0
   Path : <install_path>/SKILL.md
-  From : <SkillHub — owner/repo@skill | ClawHub — slug>
+  From : <SkillHub — owner/repo@skill | ClawHub — slug | Git — <url>>
   Desc : <skill_description or "(no description)">
 
   Next steps:

scripts/sg-install-git.sh

@@ -0,0 +1,52 @@
+#!/usr/bin/env bash
+# sg-install-git.sh — clone a skill from any git URL into the install path.
+#
+# Used by /skill-git:install when registry = "git".
+# Accepts shorthand "owner/repo" (defaults to GitHub SSH) or any full git URL
+# (https://, http://, ssh://, git@host:...). The cloned `.git` and its history
+# are preserved so /skill-git:init (Step 5 of install) can re-tag idempotently
+# (Case C/D in sg-init.sh) and so the user can `git pull` updates from origin
+# later.
+#
+# Usage:
+#   sg-install-git.sh <url-or-shorthand> <install_path>
+
+set -euo pipefail
+
+if [ $# -lt 2 ]; then
+  echo "[skill-git] Error: sg-install-git.sh requires <url> <install_path>" >&2
+  exit 1
+fi
+
+url="$1"
+install_path="$2"
+
+# Shorthand "<owner>/<repo>" → HTTPS GitHub URL by default. HTTPS works for
+# public repos out of the box and for private repos when the user has run
+# `gh auth login` (gh registers a credential helper for git on first auth).
+# Users who prefer SSH can pass the full URL: git:git@github.com:owner/repo.git
+if [[ "$url" =~ ^[A-Za-z0-9_][A-Za-z0-9_.-]*/[A-Za-z0-9_][A-Za-z0-9_.-]*$ ]]; then
+  url="https://github.com/${url}.git"
+fi
+
+# Refuse to clone over a non-empty target — preserves existing skill folders.
+if [ -e "$install_path" ] && [ -n "$(ls -A "$install_path" 2>/dev/null || true)" ]; then
+  echo "[skill-git] Error: install path already exists and is non-empty: $install_path" >&2
+  exit 1
+fi
+
+mkdir -p "$(dirname "$install_path")"
+
+# Clone with full history. Origin remote is set automatically by `git clone`.
+if ! git clone "$url" "$install_path"; then
+  echo "[skill-git] Error: git clone failed for $url" >&2
+  exit 1
+fi
+
+# Sanity check: a skill must have a SKILL.md at the repo root.
+if [ ! -f "$install_path/SKILL.md" ]; then
+  echo "[skill-git] Error: cloned repo has no SKILL.md at root: $install_path" >&2
+  exit 1
+fi
+
+echo "[skill-git] Cloned $url → $install_path"