Teaching it something
without retraining anything.
A skill is a folder with instructions in it. Eshlon ships around thirty, and the interesting engineering is in what they cost when you are not using them.
A skill on disk — the folder, the SKILL.md, the frontmatter — next to it being used in a session.
16/9The economics of knowing things
Only the description is always loaded
Every skill carries a one-line description, and that line is the only part present by default. The body — which can run to thousands of words — loads when the skill is actually chosen. Thirty skills therefore cost thirty lines, not thirty documents, and the model picks from a menu rather than reading the whole cookbook before every meal.
Which makes the description the whole design
If the one line does not say when the skill applies, the skill never gets picked, and a perfectly good skill that is never selected is indistinguishable from one that does not exist. Most skill authoring effort goes into that sentence.
They ship inside the installer
Built-in skills are packed into the application rather than fetched, so they work on a machine that has never seen the repository and works offline. Verifying that on a developer machine is misleading — a local skills folder masks a packaging failure completely, which is why it is checked on a clean install.
FAQ
Can I write my own?
Yes. A folder, a markdown file, and a frontmatter description saying when it applies.
How many ship with Eshlon?
Around thirty, covering document work, research method, data handling and engineering practice.
Do skills slow the model down?
Barely. An unused skill costs one line of context. Only a chosen skill loads its body.