Teaching Coding Agent to Write XSLT — Building a Domain Skill

XSLT is unforgiving. Small mistakes — a wrong namespace, a version mismatch, an engine-specific function — produce silent failures. AI assistants make the same mistakes without explicit guidance. The fix isn't a smarter model. It's giving the model a playbook . Claude Code supports custom skills — markdown files that load into context when a task matches. I built one that encodes real XSLT expertise: five work modes, engine detection, version discipline, and structured output you can debug immediately. What is a Claude Code skill? A skill is a markdown file in .claude/skills/<name>/SKILL.md . When Claude detects a matching task, it reads the skill and follows its instructions. Reference files alongside it provide deeper detail on demand. .claude/skills/xslt/ ├── SKILL.md # modes, rules, output spec └── references/ ├── lml.md # Logic Apps Mapping Language ├── logicapps-xslt.md # Logic Apps deployment and artifacts ├── saxoncs-quirks.md # SaxonCS / XSLT 3.0 gotchas ├── biztalk-xslt.md #