2.2: Create cheddahbot/skills.py — markdown skill registry

New module (not package) that discovers .md files with YAML frontmatter
in the skills/ directory. Provides:
- SkillDef dataclass: name, description, content, tools, agents, file_path
- SkillRegistry: discovers skills, filters by agent, builds prompt sections
- _parse_frontmatter(): splits YAML frontmatter from markdown body
- get_prompt_section(agent_name): builds system prompt injection
- get_body(name): returns skill content without frontmatter

Files without frontmatter (data files) are automatically skipped.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

cheddahbot/skills.py

@@ -0,0 +1,132 @@
+"""Markdown skill registry.
+
+Skills are .md files in the skills/ directory with YAML frontmatter:
+
+    ---
+    name: press-release-writer
+    description: Write professional press releases
+    tools: [write_press_releases, submit_press_release]
+    agents: [writer, default]
+    ---
+    # Press Release Workflow
+    ...
+
+Files without frontmatter (like companies.md, headlines.md) are data
+files and get skipped.
+"""
+
+from __future__ import annotations
+
+import logging
+from dataclasses import dataclass, field
+from pathlib import Path
+
+import yaml
+
+log = logging.getLogger(__name__)
+
+
+@dataclass
+class SkillDef:
+    name: str
+    description: str
+    content: str
+    file_path: Path
+    tools: list[str] = field(default_factory=list)
+    agents: list[str] = field(default_factory=list)
+
+
+def _parse_frontmatter(text: str) -> tuple[dict, str]:
+    """Split YAML frontmatter from markdown content.
+
+    Returns (frontmatter_dict, body) or ({}, full_text) if no frontmatter.
+    """
+    if not text.startswith("---"):
+        return {}, text
+
+    end = text.find("---", 3)
+    if end == -1:
+        return {}, text
+
+    yaml_block = text[3:end].strip()
+    body = text[end + 3 :].strip()
+
+    try:
+        meta = yaml.safe_load(yaml_block) or {}
+    except yaml.YAMLError as e:
+        log.warning("Failed to parse YAML frontmatter: %s", e)
+        return {}, text
+
+    if not isinstance(meta, dict):
+        return {}, text
+
+    return meta, body
+
+
+class SkillRegistry:
+    """Discovers and holds markdown skill definitions."""
+
+    def __init__(self, skills_dir: Path):
+        self._skills: dict[str, SkillDef] = {}
+        self._skills_dir = skills_dir
+        self._discover()
+
+    def _discover(self):
+        """Load all .md files with valid frontmatter from the skills directory."""
+        if not self._skills_dir.exists():
+            log.warning("Skills directory not found: %s", self._skills_dir)
+            return
+
+        for path in sorted(self._skills_dir.glob("*.md")):
+            try:
+                text = path.read_text(encoding="utf-8")
+            except Exception as e:
+                log.warning("Failed to read skill file %s: %s", path.name, e)
+                continue
+
+            meta, body = _parse_frontmatter(text)
+            if not meta.get("name"):
+                # No frontmatter or no name — skip (data file)
+                continue
+
+            skill = SkillDef(
+                name=meta["name"],
+                description=meta.get("description", ""),
+                content=body,
+                file_path=path,
+                tools=meta.get("tools", []),
+                agents=meta.get("agents", []),
+            )
+            self._skills[skill.name] = skill
+            log.info("Loaded skill: %s (%s)", skill.name, path.name)
+
+    def get(self, name: str) -> SkillDef | None:
+        return self._skills.get(name)
+
+    def list_skills(self) -> list[SkillDef]:
+        return list(self._skills.values())
+
+    def get_prompt_section(self, agent_name: str = "default") -> str:
+        """Build a prompt section with skills relevant to an agent.
+
+        If a skill's agents list is empty, it's available to all agents.
+        Otherwise, only agents listed in the skill's agents list get it.
+        """
+        parts = []
+        for skill in self._skills.values():
+            if skill.agents and agent_name not in skill.agents:
+                continue
+            parts.append(
+                f"### Skill: {skill.name}\n"
+                f"{skill.description}\n"
+            )
+
+        if not parts:
+            return ""
+
+        return "# Available Skills\n" + "\n".join(parts)
+
+    def get_body(self, name: str) -> str:
+        """Get the body content of a skill (without frontmatter)."""
+        skill = self._skills.get(name)
+        return skill.content if skill else ""