Extension Builder

Turn a natural-language description into a working Silo extension. The extension is real, publishable TypeScript — not a prototype or a hack. silo install drops it into Silo immediately; silo uninstall removes it cleanly.

Arguments

The skill accepts two optional arguments: id and path.

• id — the extension id (e.g. dave.clock). If not provided, ask the user.
• path — the directory to create the extension in. If not provided, default to /tmp/silo-ext/<id> and confirm with the user.

Parse arguments from the invocation line. Examples:

• /silo-extension-builder id=dave.clock — id given, use default path
• /silo-extension-builder path=~/projects/my-ext — path given, ask for id
• /silo-extension-builder id=dave.clock path=~/projects/my-ext — both given, skip both questions
• /silo-extension-builder — neither given, ask for both before proceeding

Workflow (always in this order)

1. Resolve args — extract id and path from the invocation; ask the user for any that are missing
2. Scaffold — run npx create-silo-extension to create the directory structure and manifest
3. Plan — identify which ctx.* APIs the extension needs (see API Reference below)
4. Write the implementation to <path>/src/index.tsx (overwrites the scaffold placeholder)
5. Compile with esbuild (output to <path>/dist/index.js)
6. Ask — show the user the compiled output path and ask if they want to install it now
7. Install (only if the user says yes) via silo install <path>
8. Tell the user what to look for in Silo

Choosing an extension id

If the user didn't supply one, ask before writing any files. Pick a namespaced id that reflects what the extension does: dave.clock, dave.tasks, dave.git-branch, etc. The user's name or handle makes a natural namespace.

Step 2 — Scaffold

Run create-silo-extension with all known args to avoid interactive prompts. Prefer the local build when inside the Silo repo; fall back to npx otherwise:

# Prefer the local build (works before npm publish); fall back to npx
REPO_ROOT="$(git rev-parse --show-toplevel 2>/dev/null)"
LOCAL_SCAFFOLD="$REPO_ROOT/packages/create-silo-extension/dist/index.js"
if [ -f "$LOCAL_SCAFFOLD" ]; then
  SCAFFOLD_CMD="node $LOCAL_SCAFFOLD"
else
  SCAFFOLD_CMD="npx --yes create-silo-extension"
fi

$SCAFFOLD_CMD \
  --id dave.<slug> \
  --path <path> \
  --name "<Display Name>" \
  --description "<short description>" \
  --publisher "<publisher>"

This creates <path>/src/index.tsx (placeholder) and <path>/package.json. Skip this step if the directory already exists from a previous run.

Step 3 — Source file shape (write over the scaffold placeholder)

// /tmp/silo-ext/<id>/src/index.tsx
import React, { useState, useEffect } from "react";
import type { Extension, SidePanelProps } from "@silo-code/sdk";
import { useServiceState } from "@silo-code/sdk";

export const extension: Extension = {
  id: "dave.<slug>",
  manifest: {
    name: "My Extension",
    description: "What it does.",
    version: "0.1.0",
  },
  activate(ctx) {
    // register contributions here
  },
};

Step 4 — Compile

cd <path> && npm run build

The scaffold's package.json includes build (one-shot) and dev (watch) scripts wired to esbuild with the correct flags. Use npm run dev for interactive iteration.

Step 5 — Tell the user what to look for

There is no programmatic verification — Silo is a production desktop app. Describe what appeared and where:

• Status bar item: "A clock now appears on the left side of the status bar."
• Side panel: "Open the left sidebar and click the Tasks icon to see the panel."
• Command: "Run it via the command palette (⌘K → 'Tasks: Add item')."
• Extensions panel: "It should appear in Settings → Extensions with an Uninstall button."

Iteration

To rebuild: cd <path> && npm run build, ask the user if they want to reinstall, then silo install <path> if they confirm. Silo replaces the installed version.

To remove: silo uninstall <id>

Publishing

When the extension is ready to share:

1. Move source to a proper project directory
2. npm publish
3. Others install it from Silo's Extensions settings page by typing the package name

---

API Reference

Registration — what activate(ctx) can register

Commands — named, invokable actions:

ctx.registerCommand({ id: "dave.foo.bar", label: "Foo: Do Bar", run: () => { ... } });

Status bar items — widgets in the strip at the bottom:

ctx.registerStatusItem({
  id: "dave.foo.status",
  alignment: "left" | "right",
  priority: 0, // lower = further left/right
  tooltip: "optional hover text",
  component: MyStatusWidget, // React component, no props
});

Side panels — left or right column panels:

ctx.registerSidePanel({
  id: "dave.foo.panel",
  location: "left" | "right",
  title: "My Panel",
  component: MyPanel, // receives SidePanelProps
  lazyMount: true, // defer mount until first open (good for async panels)
});

SidePanelProps: { active: boolean, storage: ExtensionStorage, hydrated: boolean }

Settings pages — a page in the Settings dialog:

ctx.registerSettingsPage({
  id: "dave.foo.settings",
  title: "My Settings",
  component: MySettings,
});

Menu items — entry in File/Edit/View/Window menu:

ctx.registerMenuItem({
  id: "dave.foo.item",
  menu: "file",
  command: "dave.foo.bar",
  label: "...",
  group: "9_custom",
});

Keybindings — keyboard shortcut:

ctx.registerKeybinding({
  id: "dave.foo.key",
  key: "cmd+shift+l",
  command: "dave.foo.bar",
});

Avoid registerDockPanelKind — dock kinds can't be cleanly removed without a reload.

---

Services — what ctx.* provides

ctx.process.exec(cmd, args, opts?) — one-shot subprocess:

const { stdout, code } = await ctx.process.exec("git", [
  "branch",
  "--show-current",
]);
// cwd defaults to active workspace folder

ctx.workspaces — reactive workspace state:

const ws = useServiceState(ctx.workspaces); // inside a React component
const activeFolder = ws.open.find((w) => w.id === ws.activeId)?.folder;

ctx.editors — editor/document model:

const es = useServiceState(ctx.editors);
// es.activeEditorId, es.editors (array), etc.

ctx.files — filesystem:

const text = await ctx.files.readText(path);
await ctx.files.writeText(path, content);
const entries = await ctx.files.list(dir);

ctx.ui — toast notifications, file pickers, modals:

ctx.ui.notify("info" | "warn" | "error", "message");
const path = await ctx.ui.pickFile();
const ok = await ctx.ui.confirm({
  title: "...",
  body: "...",
  confirmLabel: "...",
});

SidePanelProps.storage — persisted key/value per panel:

storage.get<T>("key"); // read (returns undefined if missing)
storage.set("key", value); // write (undefined deletes)
storage.subscribe(listener); // re-render when storage changes

---

React patterns

Reactive workspace subscription (get active workspace folder):

function MyStatusWidget() {
  const ws = useServiceState(ctx.workspaces);
  const folder = ws.open.find((w) => w.id === ws.activeId)?.folder ?? null;
  // ...
}

CSS theming — always use design tokens, never hard-code colors/fonts:

color: var(--silo-color-fg);
background: var(--silo-color-surface);
border: 1px solid var(--silo-color-border);
font-family: var(--silo-font-mono);
border-radius: var(--silo-radius-sm);

---

Example Prompts

Git branch status bar:

/silo-extension-builder Create a status bar item on the left that shows the current git branch for the active workspace, with a dot when there are uncommitted changes. Update when the active workspace switches.

Workspace task list:

/silo-extension-builder Create a right-side panel called "Tasks" with a persistent to-do list. Items have a checkbox and a delete button. Persist tasks so they survive app restarts.

GitHub issues panel:

/silo-extension-builder Create a right-side panel called "Issues" that fetches open GitHub issues for the active workspace's repo using gh issue list --json number,title,url. Show a refresh button and make each issue a clickable link. Load lazily on first open.

Open PRs panel:

/silo-extension-builder Same as the Issues panel but for pull requests — call it "Pull Requests", use gh pr list --json number,title,isDraft,url, and dim draft PRs.

Scratch pad:

/silo-extension-builder A right-side panel called "Scratch Pad" with a full-height textarea, persisted via storage so notes survive restarts. Use Silo's theme tokens for colors and the monospace font.

Word count status bar:

/silo-extension-builder A right-aligned status bar item showing the word count of the currently active editor. Update when the active editor changes.