feat: add plugin marketplace and skills install

.claude-plugin/marketplace.json

@@ -0,0 +1,20 @@
+{
+  "$schema": "https://anthropic.com/claude-code/marketplace.schema.json",
+  "name": "unsloppify",
+  "description": "Strip AI writing patterns from prose. CLI + Claude Code skill.",
+  "owner": {
+    "name": "Peter Souter",
+    "email": "peter.souter@datadoghq.com"
+  },
+  "plugins": [
+    {
+      "name": "unsloppify",
+      "source": "./",
+      "description": "Anti-slop prose linter — punctuation, banned phrases, structural cliches.",
+      "category": "productivity",
+      "keywords": ["writing", "prose", "linter", "ai-slop", "markdown"],
+      "homepage": "https://github.com/petems/unsloppify",
+      "license": "MIT"
+    }
+  ]
+}

.claude-plugin/plugin.json

@@ -0,0 +1,14 @@
+{
+  "$schema": "https://anthropic.com/claude-code/plugin.schema.json",
+  "name": "unsloppify",
+  "description": "Anti-slop prose linter — Claude skill + Python CLI for stripping AI writing patterns from markdown.",
+  "version": "0.1.0",
+  "author": {
+    "name": "Peter Souter",
+    "email": "peter.souter@datadoghq.com"
+  },
+  "homepage": "https://github.com/petems/unsloppify",
+  "repository": "https://github.com/petems/unsloppify",
+  "license": "MIT",
+  "keywords": ["writing", "prose", "linter", "ai-slop", "markdown"]
+}

.github/workflows/skill-validate.yml

@@ -0,0 +1,76 @@
+name: Skill validate
+
+on:
+  push:
+    branches: [master]
+  pull_request:
+
+permissions:
+  contents: read
+
+jobs:
+  metadata-tests:
+    name: Static metadata tests (pytest)
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v6
+      - uses: astral-sh/setup-uv@v7
+        with:
+          enable-cache: true
+      - name: Set up Python
+        run: uv python install 3.13
+      - run: uv sync --extra dev
+      - run: uv run pytest tests/test_skill_metadata.py -v
+
+  skill-install-smoke:
+    name: npx skills add (codex agent) smoke test
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v6
+      - uses: actions/setup-node@v5
+        with:
+          node-version: "22"
+      - name: Install skill into isolated $HOME
+        env:
+          FAKE_HOME: ${{ runner.temp }}/fakehome
+        run: |
+          set -euxo pipefail
+          mkdir -p "$FAKE_HOME"
+          # Use codex as the target agent: Claude Code users will install via
+          # /plugin marketplace add (validated separately), so npx skills add
+          # is exercised against a non-Claude agent to broaden coverage.
+          # --global writes into $HOME (so source tree isn't mutated); avoid
+          # --all because it expands to --agent '*' and overrides --agent codex.
+          HOME="$FAKE_HOME" npx --yes skills add ./ --global --agent codex --skill '*' --yes
+      - name: Verify installed skill files
+        env:
+          FAKE_HOME: ${{ runner.temp }}/fakehome
+        run: |
+          set -euxo pipefail
+          # Codex is a "universal" agent in the skills CLI — global installs
+          # land in ~/.agents/skills/<name>/SKILL.md, not ~/.codex/skills/.
+          find "$FAKE_HOME" -name SKILL.md -print
+          test -s "$FAKE_HOME/.agents/skills/unsloppify/SKILL.md"
+      - name: Verify skills list shows unsloppify
+        env:
+          FAKE_HOME: ${{ runner.temp }}/fakehome
+        run: |
+          set -euxo pipefail
+          HOME="$FAKE_HOME" npx --yes skills list --global | tee /tmp/skills-list.txt
+          grep -q "unsloppify" /tmp/skills-list.txt
+
+  claude-plugin-validate:
+    name: claude plugin validate (canonical validator)
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v6
+      - uses: actions/setup-node@v5
+        with:
+          node-version: "22"
+      - name: Run the Claude Code plugin validator
+        run: |
+          set -euxo pipefail
+          # Validates marketplace.json, plugin.json, and skill frontmatter using
+          # the canonical CLI. metadata-tests is the redundant guardrail; this
+          # job blocks merges so manifest regressions can't slip through.
+          npx --yes @anthropic-ai/claude-code plugin validate .

README.md

@@ -17,7 +17,7 @@
 | Tier | Examples | Handled by |
 |------|----------|------------|
 | 1. Punctuation | em dashes, smart quotes, ellipsis chars | CLI, auto-fixed |
 | 2. Banned phrases | `delve into`, `tapestry`, `In today's fast-paced world` | CLI, flagged or auto-fixed |
 | 3. Structures | binary contrasts, false agency, parataxis | Skill (LLM judgment) |
 
 Run the CLI first to nuke the obvious stuff. Let the skill handle the rest.
@@ -63,7 +63,22 @@
 
 ### Claude Code skill
 
-Drop `skills/unsloppify/` into `~/.claude/skills/`, or install via the plugin marketplace once published. Then ask Claude to "unsloppify this draft" and it will invoke the CLI first for the deterministic catches, then do a judgment pass on structures.
+Two ways to install:
+
+**Plugin marketplace** (recommended for Claude Code):
+
+```text
+/plugin marketplace add petems/unsloppify
+/plugin install unsloppify@unsloppify
+```
+
+**Skills CLI** (works with Claude Code, Codex, Cursor, and other agents):
+
+```bash
+npx skills add petems/unsloppify
+```
+
+Then ask the agent to "unsloppify this draft" and it will invoke the CLI first for the deterministic catches, then do a judgment pass on structures.
 
 ### Claude Code output style
 

pyproject.toml

@@ -56,6 +56,7 @@ include = [
     "tests/",
     "skills/",
     "output-styles/",
+    ".claude-plugin/",
     "README.md",
     "LICENSE",
     "THIRD_PARTY_NOTICES.md",

tests/test_skill_metadata.py

@@ -0,0 +1,156 @@
+"""Validate skill + plugin metadata files.
+
+These tests guard the install-experience contracts:
+- SKILL.md frontmatter must parse and stay within the Anthropic-allowed key set
+  (otherwise the Claude app refuses to load the skill).
+- .claude-plugin/marketplace.json + plugin.json must satisfy the Claude Code
+  plugin marketplace schema enough to load via `/plugin marketplace add` and
+  `/plugin install`.
+- plugin.json version must stay in sync with pyproject.toml.
+"""
+
+from __future__ import annotations
+
+import json
+import re
+import sys
+import tomllib
+from pathlib import Path
+from typing import Any, cast
+
+import pytest
+import yaml
+
+REPO_ROOT = Path(__file__).resolve().parent.parent
+SKILL_MD = REPO_ROOT / "skills" / "unsloppify" / "SKILL.md"
+MARKETPLACE_JSON = REPO_ROOT / ".claude-plugin" / "marketplace.json"
+PLUGIN_JSON = REPO_ROOT / ".claude-plugin" / "plugin.json"
+PYPROJECT_TOML = REPO_ROOT / "pyproject.toml"
+
+ALLOWED_SKILL_FRONTMATTER_KEYS = {
+    "name",
+    "description",
+    "license",
+    "allowed-tools",
+    "metadata",
+}
+
+KEBAB_CASE = re.compile(r"^[a-z0-9]+(-[a-z0-9]+)*$")
+SEMVER_LIKE = re.compile(r"^\d+\.\d+\.\d+(?:[-+].+)?$")
+
+
+def _parse_frontmatter(path: Path) -> dict[str, Any]:
+    text = path.read_text(encoding="utf-8")
+    if not text.startswith("---"):
+        raise AssertionError(f"{path} does not start with YAML frontmatter")
+    parts = text.split("---", 2)
+    if len(parts) < 3:
+        raise AssertionError(f"{path} frontmatter is not closed by a second '---'")
+    parsed = yaml.safe_load(parts[1])
+    assert isinstance(parsed, dict), f"{path} frontmatter is not a mapping"
+    return cast(dict[str, Any], parsed)
+
+
+@pytest.fixture(scope="module")
+def skill_frontmatter() -> dict[str, Any]:
+    return _parse_frontmatter(SKILL_MD)
+
+
+@pytest.fixture(scope="module")
+def marketplace() -> dict[str, Any]:
+    return cast(dict[str, Any], json.loads(MARKETPLACE_JSON.read_text(encoding="utf-8")))
+
+
+@pytest.fixture(scope="module")
+def plugin() -> dict[str, Any]:
+    return cast(dict[str, Any], json.loads(PLUGIN_JSON.read_text(encoding="utf-8")))
+
+
+def test_skill_md_required_fields(skill_frontmatter: dict[str, Any]) -> None:
+    assert "name" in skill_frontmatter, "SKILL.md must declare a name"
+    assert "description" in skill_frontmatter, "SKILL.md must declare a description"
+    name = skill_frontmatter["name"]
+    assert isinstance(name, str) and KEBAB_CASE.match(name), (
+        f"name must be kebab-case, got {name!r}"
+    )
+    description = skill_frontmatter["description"]
+    assert isinstance(description, str) and description.strip(), (
+        "description must be a non-empty string"
+    )
+
+
+def test_skill_md_only_allowed_keys(skill_frontmatter: dict[str, Any]) -> None:
+    extra = set(skill_frontmatter.keys()) - ALLOWED_SKILL_FRONTMATTER_KEYS
+    assert not extra, (
+        f"SKILL.md has frontmatter keys outside the Anthropic-allowed set "
+        f"{sorted(ALLOWED_SKILL_FRONTMATTER_KEYS)}: {sorted(extra)}. "
+        "The Claude app rejects skills with unexpected top-level keys "
+        "(use metadata: for free-form extras)."
+    )
+
+
+def test_marketplace_json_required_fields(marketplace: dict[str, Any]) -> None:
+    assert marketplace.get("name"), "marketplace.json must declare a name"
+    owner = marketplace.get("owner")
+    assert isinstance(owner, dict) and owner.get("name"), (
+        "marketplace.json must declare owner.name"
+    )
+    plugins = marketplace.get("plugins")
+    assert isinstance(plugins, list) and plugins, (
+        "marketplace.json must list at least one plugin"
+    )
+    for entry in plugins:
+        assert isinstance(entry, dict)
+        assert entry.get("name"), "every plugin entry needs a name"
+        source = entry.get("source")
+        assert isinstance(source, str) and source, (
+            "every plugin entry needs a non-empty string source"
+        )
+        assert source.startswith("./"), (
+            f"local plugin source must start with './' (got {source!r})"
+        )
+
+
+def test_plugin_json_required_fields(plugin: dict[str, Any]) -> None:
+    assert plugin.get("name"), "plugin.json must declare a name"
+    assert plugin.get("description"), "plugin.json must declare a description"
+    version = plugin.get("version")
+    assert isinstance(version, str) and SEMVER_LIKE.match(version), (
+        f"plugin.json version must be semver-like, got {version!r}"
+    )
+
+
+def test_marketplace_plugin_matches_plugin_manifest(
+    marketplace: dict[str, Any],
+    plugin: dict[str, Any],
+) -> None:
+    names = [p.get("name") for p in marketplace["plugins"]]
+    assert plugin["name"] in names, (
+        f"plugin.json name {plugin['name']!r} not listed in marketplace.json plugins"
+    )
+
+
+def test_plugin_version_matches_pyproject(plugin: dict[str, Any]) -> None:
+    pyproject = tomllib.loads(PYPROJECT_TOML.read_text(encoding="utf-8"))
+    py_version = pyproject["project"]["version"]
+    assert plugin["version"] == py_version, (
+        f"plugin.json version ({plugin['version']!r}) must match "
+        f"pyproject.toml version ({py_version!r}). Bump both together."
+    )
+
+
+def test_skill_directory_matches_plugin_skill_name(
+    skill_frontmatter: dict[str, Any],
+) -> None:
+    # The skill directory name should match the SKILL.md `name` so Claude Code's
+    # auto-discovery (which looks at <skill-dir>/SKILL.md) doesn't surface
+    # mismatched identifiers.
+    assert SKILL_MD.parent.name == skill_frontmatter["name"], (
+        f"skill directory {SKILL_MD.parent.name!r} must match SKILL.md name "
+        f"{skill_frontmatter['name']!r}"
+    )
+
+
+def test_python_version_is_modern_enough() -> None:
+    # tomllib requires 3.11+; pyproject pins >=3.11 already. Belt + braces.
+    assert sys.version_info >= (3, 11), "tests require Python 3.11+ for tomllib"