diff --git a/.github/workflows/lint.yml b/.github/workflows/lint.yml
new file mode 100644
index 0000000..5934500
--- /dev/null
+++ b/.github/workflows/lint.yml
@@ -0,0 +1,34 @@
+name: Lint
+
+on:
+  pull_request:
+  push:
+    branches: [main]
+
+jobs:
+  validate:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: actions/setup-python@v5
+        with:
+          python-version: "3.11"
+
+      - name: Validate harness skill
+        run: python scripts/validate_skills.py
+
+      - uses: actions/setup-node@v4
+        with:
+          node-version: "20"
+
+      - name: Markdown lint (scoped)
+        run: |
+          npx --yes markdownlint-cli@0.43.0 \
+            'README*.md' \
+            'docs/**/*.md' \
+            'skills/**/*.md' \
+            'CONTRIBUTING.md' \
+            'CHANGELOG.md' \
+            '.github/**/*.md' \
+            --ignore node_modules
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1be8060..ffc4fb5 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,8 @@
 ## [Unreleased]
 
 ### Added
+- `scripts/validate_skills.py` — SKILL frontmatter + reference link validation
+- `.github/workflows/lint.yml` — CI: validate_skills + scoped markdownlint
 - 신규 에이전트/스킬 생성 전 중복 검토 단계 (Phase 3-0, Phase 4-0)
 - `references/agent-design-patterns.md` "에이전트 재사용 설계" 섹션
 - `references/skill-writing-guide.md` §9 "스킬 재사용 설계"
diff --git a/scripts/validate_skills.py b/scripts/validate_skills.py
new file mode 100644
index 0000000..cd539cd
--- /dev/null
+++ b/scripts/validate_skills.py
@@ -0,0 +1,65 @@
+#!/usr/bin/env python3
+"""Validate harness skill metadata and reference links."""
+
+from __future__ import annotations
+
+import re
+import sys
+from pathlib import Path
+
+ROOT = Path(__file__).resolve().parent.parent
+SKILL = ROOT / "skills" / "harness" / "SKILL.md"
+REFS = ROOT / "skills" / "harness" / "references"
+
+
+def validate_frontmatter(text: str) -> list[str]:
+    errors: list[str] = []
+    if not text.startswith("---"):
+        return ["SKILL.md missing YAML frontmatter"]
+    match = re.match(r"---\n(.*?)\n---", text, re.DOTALL)
+    if not match:
+        return ["SKILL.md has invalid frontmatter block"]
+    frontmatter = match.group(1)
+    if "name:" not in frontmatter:
+        errors.append("frontmatter missing name")
+    if "description:" not in frontmatter:
+        errors.append("frontmatter missing description")
+    return errors
+
+
+def validate_references(text: str) -> list[str]:
+    errors: list[str] = []
+    for ref in re.findall(r"`(references/[^`]+)`", text):
+        path = ROOT / "skills" / "harness" / ref
+        if not path.exists():
+            errors.append(f"broken reference link: {ref}")
+    return errors
+
+
+def main() -> int:
+    errors: list[str] = []
+    if not SKILL.exists():
+        errors.append(f"missing {SKILL}")
+    else:
+        text = SKILL.read_text(encoding="utf-8")
+        errors.extend(validate_frontmatter(text))
+        errors.extend(validate_references(text))
+        if len(text.splitlines()) > 520:
+            errors.append("SKILL.md exceeds 520 lines (target <500)")
+
+    if REFS.is_dir():
+        for md in REFS.glob("*.md"):
+            if len(md.read_text(encoding="utf-8").splitlines()) > 650:
+                errors.append(f"{md.name} exceeds 650 lines")
+
+    if errors:
+        for err in errors:
+            print(f"ERROR: {err}", file=sys.stderr)
+        return 1
+
+    print("validate_skills: OK")
+    return 0
+
+
+if __name__ == "__main__":
+    sys.exit(main())