skill-authoring

name	skill-authoring
description	Use this when the user wants to write a new skill, edit an existing one, or understand SLICC's skill system. Covers SKILL.md frontmatter (name, description, allowed-tools), how to write a description that triggers reliably, native `/workspace/skills/` vs compatibility `.agents/` / `.claude/skills/` discovery, and when to ship companion files like `.jsh` scripts or `.bsh` browser hooks.
allowed-tools	bash, read_file, write_file, edit_file

Skill authoring

A skill is a folder with a SKILL.md (and optional companion files) that loads into the agent's system prompt when the description matches the user's intent. This skill is about authoring those folders well.

Discovery

SLICC discovers four kinds of skill roots:

Root	Source	Mutability
/workspace/skills/<name>/SKILL.md	Bundled or installed via upskill	Install-managed; you can edit them
.agents/skills/<name>/SKILL.md (anywhere)	Compatibility (Cursor / SuperClaude)	Read-only (discovered, not managed)
.claude/skills/<name>/SKILL.md (anywhere)	Compatibility (Claude Code)	Read-only (discovered, not managed)
<mount>/.claude-plugin/marketplace.json → plugin skills/	Claude Code marketplace (mounted repos)	Read-only (discovered, not managed)

The marketplace root is auto-discovered: when a mounted directory contains .claude-plugin/marketplace.json, SLICC reads the manifest, resolves each plugin's source path, and discovers skills at <plugin-source>/skills/<name>/SKILL.md. No install step needed — mount the repo and the skills are live immediately. Precedence: native > agents > claude > marketplace.

When you create a new skill for SLICC, put it in /workspace/skills/<name>/. The .agents/, .claude/, and marketplace paths exist so SLICC can pick up skills authored for other agents without modification — don't create new skills there.

SKILL.md structure

---
name: <slug>
description: |
  Use this when ...
  ... (1–3 sentences explaining trigger conditions, what's covered, and what's
  NOT covered if there's a sibling skill that handles related topics.)
allowed-tools: bash, read_file, write_file, edit_file
---

# Title (matches `name`)

... body ...

Frontmatter fields

• name — lowercase, kebab-case. Must match the folder name. This is what skill list shows.
• description — the trigger string. The agent uses this to decide whether to load the skill. Get this right; everything else is secondary.
• allowed-tools — comma-separated list of tools the skill needs. Without this, the agent may load the skill but find it can't execute the steps. Common values:
  • bash — almost every skill.
  • read_file, write_file, edit_file — for skills that author files (sprinkles, config edits, three-way merges).
  • Omit only for purely informational skills.

Writing a good description

The description is a trigger, not a summary. It runs through the agent at every turn — too vague and the skill loads when irrelevant; too narrow and it doesn't load when needed.

Pattern that works: "Use this when <user-facing trigger>. Covers <topics>. [For <adjacent topic> use <sibling skill>.]"

Compare:

• ❌ description: Licks, webhooks, cron tasks, viewing pages/images, screencapture, onboarding Keyword soup. The agent has to guess what "licks" or "screencapture" mean for this user.
• ✅ description: Use this when setting up event-driven automation in SLICC — webhooks, cron tasks, or filesystem watchers that route events to scoops. Covers webhook, crontask, and fswatch. Read this BEFORE wiring anything that should fire on a schedule, an HTTP call, or a VFS change. Names the user intent ("setting up event-driven automation"), names the commands the agent will reach for, and tells the agent when to load it.

Rules of thumb:

• Lead with "Use this when..." or "Use this whenever...".
• Name the user-facing trigger (what the user said), not just the implementation.
• If there's a closely-named sibling skill (dips vs sprinkles, mount vs other storage), say which is which inside the description so the agent doesn't load both.
• Multi-line YAML scalars are fine for longer descriptions — use the | block style.

Body conventions

• Lead with one sentence stating what the skill is. No preamble.
• Use tables for option matrices (commands × flags, tradeoffs, etc.).
• Code blocks are bash unless otherwise needed.
• Include a "Don't" or "Common errors" section near the end if the skill is failure-prone — the agent will read it before acting.
• If the skill is large (> ~150 lines), split a reference table or example gallery into a companion <topic>.md and have the SKILL.md read_file it on demand. The sprinkles/ skill (style-guide.md) and dips/ skill (patterns.md) follow this pattern.

Companion files

.jsh — JavaScript shell scripts

.jsh files are auto-discovered as shell commands anywhere on the VFS. Full reference: ./jsh-runtime-extensions.md.

• Auto-discovery: registered as callable commands by filename (without the extension). A skill can ship its own commands by including a .jsh next to SKILL.md. Priority root /workspace/skills/ wins on basename collisions.
• Dual-mode: works in both the CLI server and the Chrome extension (sandbox iframe). Don't rely on CLI-only Node modules.
• Top-level await: scripts are wrapped in AsyncFunction. Always await fs/exec/fetch. Don't use .then().

Runtime surface (use these — don't reinvent)

Node-standard bare globals:

Global	Use for
process	argv, env, cwd(), exit(code), stdout.write, stderr.write, stdin.read()
console	log/info → stdout, warn/error → stderr
fetch	Standard fetch routed through SLICC's proxied transport (cookies + CORS handled).
require(p)	Synchronous CJS require. Use require('sliccy:<name>') for capability bridges and require('fs') for the VFS bridge (see below).
__dirname / __filename	CJS scope vars — the script's own directory and absolute path.

Capability bridges via require('sliccy:<name>') (full reference: ./jsh-runtime-extensions.md):

require('sliccy:<name>')	Use for
sliccy:exec	Callable exec(cmd) + .spawn(argv[]). Composes with any supplemental command or .jsh script.
sliccy:skill	dir / refs / assets / config() / token(providerId) — script-relative paths and provider tokens.
sliccy:http	http.client({ baseUrl, token, headers, retry, timeoutMs }) — standard API-client builder.
sliccy:browser	findTab, ensureTab, eval, evalAsync, cookie, localStorage, fetch, websocket.on(...).
sliccy:usb / sliccy:serial / sliccy:hid	list() / request() + device methods. Chromium-only.
sliccy:cli	die(msg, opts?), out(value), warn(msg, opts?), help(text).
sliccy:color	ANSI helpers (green, red, bold, dim, …) auto-disabled on non-TTY / NO_COLOR.
sliccy:time	parseDuration, ago, range, future, gmailDate.
sliccy:fmt	trunc, col, table, date.
sliccy:pool	pool(n, items, fn) — bounded concurrency runner.

VFS bridge:

require('fs') / require('node:fs')	readFile, writeFile, readFileBinary, writeFileBinary, readDir, exists, stat, mkdir, rm, fetchToFile — all paths are VFS, async. There is no bare fs global.

Runtime extensions (live — prefer these over hand-rolled equivalents)

Reach these via require('sliccy:<name>'). Full reference: ./jsh-runtime-extensions.md. Use them instead of reimplementing the cross-skill patterns they replace.

• process.argv.parseFlags() — returns { positional, flags, subcommand }. Replaces the per-skill --flag=val / --flag val parsing loop.
• require('sliccy:browser') — findTab({ domain | urlMatch }), ensureTab(url), eval(tab, fn), evalAsync(tab, fn), cookie(tab, name), localStorage(tab, key). Replaces shelling out to playwright-cli tab-list and regex-parsing its output.
• browser.fetch(tab, url, opts) — page-context fetch (runs inside the tab's origin, so cookies + same-origin headers are automatic). Replaces the eval-file temp-file + double-JSON-unwrap dance.
• browser.websocket.on(tab, …).filter({…}).forward({ sink }) — declarative WebSocket observer with a closed sink set (webhook / scoop / vfs / log). Required for any new WS-watch use case; do not author page-context WebSocket.prototype patches in skill code.
• require('sliccy:http').client({ baseUrl, token, headers, retry }) — get/post/put/delete with merged headers, lazy token resolution, and Retry-After-aware backoff for retry.on statuses.
• require('sliccy:skill') — dir / refs / assets / config() / token(providerId): replace the per-skill process.argv[1] dirname math, ad-hoc .config JSON readers, and bespoke oauth-token shell-outs.

Ship a .jsh when the skill needs deterministic, parameterizable behavior the agent shouldn't have to re-derive each time (e.g. a slicc-handoff helper, a custom diff formatter, a domain-specific lint).

.bsh — browser shell scripts

.bsh files auto-execute when the browser navigates to a matching URL:

• Filename = hostname pattern: -.okta.com.bsh matches *.okta.com.
• // @match directive: restrict to specific URL patterns in the first 10 lines.
• Same execution engine as .jsh.

Use .bsh for site-specific automations — auto-fillers, lick-emitters, or page transforms that should run whenever the user lands on a particular host.

Filesystem at a glance

The VFS is stored in IndexedDB; it survives tab closes and refreshes. The mount shell command bridges remote storage (local folders, S3-compatible, Adobe DA) into VFS paths — see /workspace/skills/mount/SKILL.md.

The VFS supports symbolic links transparently:

ln -s /workspace/skills /workspace/skill-link    # Create symlink
readlink /workspace/skill-link                    # Read link target
ls -la /workspace/                                # Shows symlinks with -> target

cat, read_file, write_file etc. follow symlinks automatically.

Mount points must be empty. Mounting over existing files is blocked so built-in skills and scripts stay discoverable. ln -s mounted files into the place where you need them.

Don't

• Don't ship a skill without a description that starts with "Use this when..." — the trigger field IS the skill from the agent's perspective.
• Don't put name: in Title Case. Lowercase kebab-case. Match the folder.
• Don't dump shell-command catalogs into a SKILL.md just because they're related — commands already lists them. Skills are for patterns and policy, not reference material.
• Don't author skills under .agents/skills/ or .claude/skills/. Those roots are for compatibility discovery from other agents.