feat: support skills

agent/skills/formatter.py

@@ -0,0 +1,62 @@
+"""
+Skill formatter for generating prompts from skills.
+"""
+
+from typing import List
+from agent.skills.types import Skill, SkillEntry
+
+
+def format_skills_for_prompt(skills: List[Skill]) -> str:
+    """
+    Format skills for inclusion in a system prompt.
+    
+    Uses XML format per Agent Skills standard.
+    Skills with disable_model_invocation=True are excluded.
+    
+    :param skills: List of skills to format
+    :return: Formatted prompt text
+    """
+    # Filter out skills that should not be invoked by the model
+    visible_skills = [s for s in skills if not s.disable_model_invocation]
+    
+    if not visible_skills:
+        return ""
+    
+    lines = [
+        "\n\nThe following skills provide specialized instructions for specific tasks.",
+        "Use the read tool to load a skill's file when the task matches its description.",
+        "",
+        "<available_skills>",
+    ]
+    
+    for skill in visible_skills:
+        lines.append("  <skill>")
+        lines.append(f"    <name>{_escape_xml(skill.name)}</name>")
+        lines.append(f"    <description>{_escape_xml(skill.description)}</description>")
+        lines.append(f"    <location>{_escape_xml(skill.file_path)}</location>")
+        lines.append("  </skill>")
+    
+    lines.append("</available_skills>")
+    
+    return "\n".join(lines)
+
+
+def format_skill_entries_for_prompt(entries: List[SkillEntry]) -> str:
+    """
+    Format skill entries for inclusion in a system prompt.
+    
+    :param entries: List of skill entries to format
+    :return: Formatted prompt text
+    """
+    skills = [entry.skill for entry in entries]
+    return format_skills_for_prompt(skills)
+
+
+def _escape_xml(text: str) -> str:
+    """Escape XML special characters."""
+    return (text
+            .replace('&', '&amp;')
+            .replace('<', '&lt;')
+            .replace('>', '&gt;')
+            .replace('"', '&quot;')
+            .replace("'", '&apos;'))