ytstack/NOTICE at main · Yesterday-AI/ytstack · GitHub

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ytstack
Copyright 2026 Yesterday

This product includes software and conceptual work from the following sources.

---

## superpowers

Vendored via git subtree at vendor/superpowers/. Source repository:
<https://github.com/obra/superpowers>

License: MIT. See vendor/superpowers/LICENSE.

We vendor superpowers read-only and wrap selected skills with ytstack-namespaced
skills at skills/test-driven-development/, skills/systematic-debugging/,
skills/verification-before-completion/. We do not modify vendored content.

Attribution: Jesse Vincent and the Prime Radiant team are the original authors
of the superpowers methodology and skills. Their maintainer rules (see
vendor/superpowers/CLAUDE.md) explicitly request that skill content NOT be
modified without extensive eval evidence. ytstack respects this constraint.

---

## gstack

Vendored via git subtree at vendor/gstack/. Source repository:
<https://github.com/garrytan/gstack>

License: MIT. See vendor/gstack/LICENSE.

We vendor gstack read-only and wrap three planning skills:
skills/plan-ceo-review/, skills/office-hours/, skills/plan-eng-review/.

Attribution: gstack originates from Garry Tan's work, shaped around YC-style
product and engineering review patterns.

---

## External AI-first methodology

Conceptual influence (not vendored, not attributed by name per ytstack
design direction). We adopted the following concepts and re-implemented them
in our own prose:

- Three-tier context model (core / task / background)
- Component-based system thinking for AI organizations
- Skill-playbook-based skill creation
- Artifact-as-memory with append-only decision register

No source material, prose, or graphics from any external methodology is
included in this repository. All artifact formats, file structures, and
prose are original ytstack work.

---

## Claude Code

ytstack is a plugin for Claude Code. Claude Code is a product of Anthropic.
<https://claude.com/code>

The plugin system, hook event names, skill format, and AskUserQuestion tool
are part of Claude Code's public extension API.

---

## GSD (Get Shit Done)

Referenced for architectural inspiration only. ytstack does NOT vendor, depend
on, or install GSD. See README.md and .ytstack/DECISIONS.md for why we
replicated GSD's artifact discipline via skills + hooks rather than using
the GSD TypeScript runtime directly.

GSD source: <https://github.com/gsd-build/gsd-2>