update-a-user-skill

name	Update a user skill
description	Find an existing user skill and apply the requested change to its SKILL.md.
appliesTo	["operate"]
userInvokable	true

Update a user skill

You were called because the user typed /update-skill <target-and-change> in the chat input. Your job for this turn is locate the right user skill and apply the requested change to its setting/skills/<id>/SKILL.md. Reuse fs_write — no other writes.

Inputs you have

• The free-text after /update-skill in the most recent user message — usually mixes a target hint ("the warm-healing skill") with the actual change ("add a frame-spacing rule for vertical layouts"). Parse out both.
• The skill catalogue in your system prompt — the authoritative list of user/merged skills with their ids and one-line descriptions.

Resolve the target

1. Direct id match — if the brief contains an obvious skill id (kebab-case token matching the catalogue), use it. Done.
2. Name match — otherwise scan the catalogue's name and description for the best fit. If exactly one matches, use it. Done.
3. Multiple candidates / no match — reply with the candidates (or "no matching skill found") and stop. Do not guess.

Constraints:

• Only user / merged skills can be updated. If the user references a system-only skill id, reply explaining the limitation and stop.
• Never create a new file in this flow. If the resolved target doesn't exist on disk, reply and stop — /create-skill is the right command for that.

Read before you write

Always read("skills/<id>/SKILL.md") first to see the current content. Do not rely on the catalogue blurb or your memory of the file.

Pick the mode

• replace_string — default. Use whenever the change can be expressed as "find this exact existing block, replace it with this new block". Safer: nothing else in the file is touched. Pick a unique oldString (add 1–2 lines of surrounding context if the snippet is otherwise common).
• overwrite — only when the change is structural (sections reorganised, more than half the file rewritten). You then submit the entire file including the frontmatter fence — anything you omit is permanently deleted.

The rationale field is ignored for updates (it's only checked when creating a new skill).

Write it

For a targeted edit:

{
  "path": "skills/<id>/SKILL.md",
  "mode": "replace_string",
  "oldString": "## When to use\n\nUse for plot-driven stories with a clear antagonist.",
  "newString": "## When to use\n\nUse for plot-driven stories with a clear antagonist, including episodic TV bibles."
}

For a structural rewrite:

{
  "path": "skills/<id>/SKILL.md",
  "mode": "overwrite",
  "body": "---\nname: \"…\"\ndescription: \"…\"\nappliesTo: [\"ask\", \"operate\"]\n---\n\n# …\n\n## When to use\n\n…\n"
}

After writing

• Briefly confirm to the user: skill id, mode used (replace_string / overwrite), and a one-line summary of what changed.
• Do not make Space changes in the same turn.