Fastify is a TypeScript workable choice for browser extension. GreatCTO auto-detects both — adds the browser-extension archetype overlay, wires browser-extension-specific gates, and runs 83 specialist agents around your existing Fastify workflow.
GreatCTO reads your package.json and detects fastify + browser-extension archetype from signals: imports, file structure, env vars, README hints.
Attaches the browser-extension archetype overlay: archetype-specific reviewer + compliance gates. Override if your specifics differ; the defaults are sensible for Fastify-style projects.
qa-engineer runs tsc --strict / eslint / vitest --coverage; security-officer checks for prototype pollution + XSS sinks; performance-engineer reviews bundle size + cold-start times.
Bugs you've hit before in other Fastify projects (connection-pool exhaustion, ORM N+1 queries, retry storms) — the agent's Step 0 includes the prior detection order. MTTR drops 94 % on second occurrence (methodology).
$ cd my-fastify-app && npx great-cto init ✓ scanning manifests… found package.json ✓ stack: fastify (TypeScript) ✓ archetype: browser-extension ⚠ archetype + stack combo is unusual — review overlay manually ✓ 83 agents ready $ /start "add browser-extension feature" ▸ architect drafting ARCH-browser-extension.md… ▸ pm decomposing into beads tasks… ⚐ gate:plan — your approval needed
Approve → 3 senior-devs run in parallel worktrees → 5 reviewers fan out in parallel → gate:ship → deploy. One real run walked stage-by-stage: /proof.
This is the shape of what senior-dev drafts for "browser-extension feature" — auth first, schema validation, and the audit line the browser-extension reviewer requires before gate:ship opens.
// src/routes/browser-extension.ts — drafted by senior-dev, reviewed by 5 agents
export default async function routes(app: FastifyInstance) {
app.post('/browser-extension', {
preHandler: app.requireAuth, // security-officer: auth before handler
schema: { body: browserExtensionSchema }, // qa-engineer: JSON-schema enforced
}, async (req, reply) => {
const result = await handle(req.body, req.user);
await app.audit.log(req.user.id, 'browser-extension feature', result.confidence); // gate:browser-extension
return result;
});
}browser-extension overlay.Productivity extensions with minimal host permissions.
Enterprise extensions passing Chrome Web Store review.
Cross-browser extensions (Chrome / Firefox / Safari).
Fastify (TypeScript) is not a typical fit for browser extension. The archetype overlay still attaches, but you may want to override defaults more aggressively. Check the browser-extension archetype page for the typical stack list and decide if your case is the right tool / right archetype.
No black-box "AI does it all" loop. GreatCTO is a deterministic state machine — 8 stages, 22 nodes, 2 human gates. Every node maps to a real agent on GitHub. Inspect the state machine →
$ npx great-cto init
Free, MIT, runs locally. Built as a Claude Code plugin — install with one command.
Eight stages, two human gates, four memory layers. Why this exact shape, and what I tried that didn't work.
One run, one feature, from prompt to merged PR. Time, cost, and gate-by-gate breakdown — no marketing math.
Regex vs LLM-based archetype detection, the false-positive count, and why I keep rejecting the obvious fix.
The bottleneck in agentic SDLC isn't model quality — it's process governance. Here's the state machine that closes the gap.