diff --git a/scripts/playbook.py b/scripts/playbook.py
index 7166fa6..bc04219 100644
--- a/scripts/playbook.py
+++ b/scripts/playbook.py
@@ -2,7 +2,7 @@
 import sys
 from datetime import datetime, timezone
 from pathlib import Path
-from shutil import copy2, copytree
+from shutil import copy2, copytree, which
 import subprocess
 
 import tomllib
@@ -640,6 +640,115 @@ def sync_standards_action(config: dict, context: dict) -> int:
     return 0
 
 
+def normalize_names(raw: object, label: str) -> list[str]:
+    if raw is None:
+        raise ValueError(f"{label} is required")
+    if isinstance(raw, str):
+        items = [raw]
+    else:
+        items = list(raw)
+    cleaned: list[str] = []
+    for item in items:
+        name = str(item).strip()
+        if not name:
+            continue
+        if "/" in name or "\\" in name or ".." in name:
+            raise ValueError(f"invalid {label}: {name}")
+        cleaned.append(name)
+    if not cleaned:
+        raise ValueError(f"{label} is empty")
+    return cleaned
+
+
+def normalize_globs(raw: object) -> list[str]:
+    if raw is None:
+        return ["**/*.md"]
+    if isinstance(raw, str):
+        items = [raw]
+    else:
+        items = list(raw)
+    cleaned = [str(item).strip() for item in items if str(item).strip()]
+    return cleaned or ["**/*.md"]
+
+
+def install_skills_action(config: dict, context: dict) -> int:
+    mode = str(config.get("mode", "list")).lower()
+    codex_home = Path(config.get("codex_home", "~/.codex")).expanduser()
+    if not codex_home.is_absolute():
+        codex_home = (context["project_root"] / codex_home).resolve()
+
+    skills_src_root = PLAYBOOK_ROOT / "codex/skills"
+    if not skills_src_root.is_dir():
+        print(f"ERROR: skills source not found: {skills_src_root}", file=sys.stderr)
+        return 2
+
+    skills_dst_root = codex_home / "skills"
+    ensure_dir(skills_dst_root)
+
+    if mode == "all":
+        skills = [
+            path.name
+            for path in skills_src_root.iterdir()
+            if path.is_dir() and not path.name.startswith(".")
+        ]
+    elif mode == "list":
+        try:
+            skills = normalize_names(config.get("skills"), "skills")
+        except ValueError as exc:
+            print(f"ERROR: {exc}", file=sys.stderr)
+            return 2
+    else:
+        print("ERROR: mode must be list or all", file=sys.stderr)
+        return 2
+
+    timestamp = datetime.now().strftime("%Y%m%d%H%M%S")
+    for name in skills:
+        src = skills_src_root / name
+        if not src.is_dir():
+            print(f"ERROR: skill not found: {name}", file=sys.stderr)
+            return 2
+        dst = skills_dst_root / name
+        if dst.exists():
+            backup = skills_dst_root / f"{name}.bak.{timestamp}"
+            dst.rename(backup)
+            log(f"Backed up existing skill: {name} -> {backup.name}")
+        copytree(src, dst)
+        log(f"Installed: {name}")
+
+    return 0
+
+
+def format_md_action(config: dict, context: dict) -> int:
+    tool = str(config.get("tool", "prettier")).lower()
+    if tool != "prettier":
+        print("ERROR: format_md.tool only supports prettier", file=sys.stderr)
+        return 2
+
+    project_root: Path = context["project_root"]
+    prettier = project_root / "node_modules/.bin/prettier"
+    if not prettier.is_file():
+        prettier = PLAYBOOK_ROOT / "node_modules/.bin/prettier"
+    if not prettier.is_file():
+        resolved = which("prettier")
+        if resolved:
+            prettier = Path(resolved)
+        else:
+            log("Skip: prettier not found.")
+            return 0
+
+    globs_raw = config.get("globs", ["**/*.md"])
+    globs = normalize_globs(globs_raw)
+    result = subprocess.run(
+        [str(prettier), "-w", *globs],
+        cwd=project_root,
+        capture_output=True,
+        text=True,
+    )
+    if result.returncode != 0:
+        sys.stderr.write(result.stderr)
+    return result.returncode
+
+
 def run_action(name: str, config: dict, context: dict) -> int:
     print(f"[action] {name}")
     if name == "vendor":
@@ -648,6 +757,10 @@ def run_action(name: str, config: dict, context: dict) -> int:
         return sync_templates_action(config, context)
     if name == "sync_standards":
         return sync_standards_action(config, context)
+    if name == "install_skills":
+        return install_skills_action(config, context)
+    if name == "format_md":
+        return format_md_action(config, context)
     return 0
 
 
diff --git a/tests/cli/test_playbook_cli.py b/tests/cli/test_playbook_cli.py
index b7cb3a6..eec82c0 100644
--- a/tests/cli/test_playbook_cli.py
+++ b/tests/cli/test_playbook_cli.py
@@ -101,5 +101,26 @@ langs = ["tsl"]
             self.assertEqual(result.returncode, 0)
             self.assertTrue(agents_index.is_file())
 
+    def test_install_skills(self):
+        with tempfile.TemporaryDirectory() as tmp_dir:
+            target = Path(tmp_dir) / "codex"
+            config_body = f"""
+[playbook]
+project_root = "{tmp_dir}"
+
+[install_skills]
+codex_home = "{target}"
+mode = "list"
+skills = ["brainstorming"]
+"""
+            config_path = Path(tmp_dir) / "playbook.toml"
+            config_path.write_text(config_body, encoding="utf-8")
+
+            result = run_cli("-config", str(config_path))
+
+            skill_file = target / "skills/brainstorming/SKILL.md"
+            self.assertEqual(result.returncode, 0)
+            self.assertTrue(skill_file.is_file())
+
 if __name__ == "__main__":
     unittest.main()