📦 archetype: library

Publish a library without the breaking-change rage.

Building an npm, PyPI, crates.io, or Maven library? GreatCTO auto-detects the library archetype and ships semver enforcement, API stability checks, changelog discipline, and migration guides from day one.

$ npx great-cto init Back to home ↗

What you avoid

The 5 library bugs that destroy adoption.

Without GreatCTO

☐Breaking change shipped as patch — community rage
☐No TypeScript types — JS-only adoption
☐Stale CHANGELOG.md — users blindsided on upgrade
☐Tree-shaking broken — bundle size doubles
☐No migration guide for v1 → v2
☐Stars drop · forks happen · ecosystem fork.

With GreatCTO

✓Semver gate: any public API change → minor or major
✓Types auto-generated · published · checked
✓CHANGELOG.md updated at gate:ship — required
✓Bundle-size budget enforced with size-limit
✓Migration guide template required for major bumps
✓Predictable upgrades · happy users · ecosystem trust.

Auto-applied gates

Detected: `package.json` with `"main"` + `"exports"` →
library archetype.

No regulatory compliance — but TDD, 12-angle review, security audit, and supply-chain hardening still apply:

01 · code-reviewer

API surface diff

Detects breaking changes via api-extractor / pyright / cargo public-api. Forces semver alignment.

02 · qa-engineer

Backward-compat matrix

Tests against last 3 major versions of consumers. Snapshot diff on type definitions. Bundle-size regression checked.

03 · senior-dev

CHANGELOG discipline

Conventional commits → auto-generate CHANGELOG.md · Keep a Changelog format · migration guides for major bumps.

04 · security-officer

Supply-chain audit

npm audit · cargo audit · Dependabot · OpenSSF Scorecard · provenance checks at publish time.

Domain pack overlays

Likely to overlay on library.

Packs auto-attach when CLI detects pack-specific signals (e.g. twilio in deps → voice-pack). Each pack adds its own reviewer agents + human gates on top of the base archetype pipeline.

+ API Platform

OAuth 2.1, webhook signing, idempotency, RFC 8594 Sunset

Real-world examples

Companies operating as library.

2 startups in this space. Click for full pack mapping.

HAPI FHIR

Open-source FHIR Java server

open-sourceCA

ROS / Open Robotics

Robot Operating System (ROS 2)

open-sourceUS

Listed companies operate in this space. Inclusion is based on publicly available product descriptions and does not imply endorsement of or by GreatCTO.