Why Kitbash exists, derived from what already exists and where it stops.
- Ponytail (~75k stars in weeks, MIT) — injects a "lazy senior dev" ruleset: a ladder of questions the agent must climb before writing code (does this need to exist? does it already exist? …). Measured ~54% less code, ~20% cheaper on real sessions. Ships adapters for a dozen assistants by hand-maintaining a copy per format.
- Caveman — compresses agent output style to cut token spend; hook-based activation, intensity levels, session stats.
What they prove: single-behavior skills go viral; developers will install agent modifiers in huge numbers; measured claims (Ponytail's %) build trust. Where they stop: each is one hardcoded philosophy. Distribution is copy-paste or per-assistant plugin. No shared format, no tests, no versioned trust. Every one of them re-solves the "N assistants, N formats" problem by hand — that is the tell that infrastructure is missing.
- skills.sh (Vercel) —
npx skills add owner/repocopies SKILL.md folders into 70+ agents; open directory with an install-count leaderboard. The strongest prior art on distribution and proof of demand at scale. Where it stops: it distributes the SKILL.md convention as-is. No manifest — no budgets, permissions, artifacts, dependencies, or gate semantics. Installs are unpinned copies: no lockfile, no diff-on-update, no integrity checking, no tests. Ranking is install counts, i.e. popularity. Distribution without engineering. Kitbash's answer is interop, not rivalry: a bare SKILL.md folder is KSF-minus-manifest, sokitbash installaccepts any skills.sh skill directly — flagged as unmanifested, defaults applied. Their catalog is our funnel; our manifest, lock, and evals are the upgrade path.
- Claude Skills / plugins — richest model: progressive disclosure via frontmatter, scripts, hooks, subagents, marketplaces. Claude-only.
- Cursor Rules (
.mdc, glob-scoped, auto/manual attach) — good scoping model. Cursor-only, no scripts, no tests. - Copilot instructions (repo-wide + path-scoped
*.instructions.md) — GitHub-native. Static text only. - Windsurf workflows / Cline rules / Roo modes / Continue blocks / OpenHands microagents — each a partial re-invention: triggers, scoping, sometimes tool constraints, always locked in.
- Codex CLI + AGENTS.md —
AGENTS.mdis the closest thing to a standard: plain markdown read by many agents. Lowest common denominator: no triggers, no scoping, no permissions, no budget, no composition. It's a README for robots, and that's all it can ever be.
What they prove: the capability set skills need is known — lazy loading, scoped triggers, script execution, tool permissions. Where they stop: every capability dies at the platform boundary. A team using three assistants maintains three divergent rule sets that drift apart.
- Aider conventions files, dotfile rule stacks,
CLAUDE.md/AGENTS.mdhierarchies — accreting text files with no ownership, no measurement, and silent context cost on every request.
| Capability | Prompt packs | Platform systems | skills.sh | Kitbash |
|---|---|---|---|---|
| Cross-assistant distribution | manual copies | none | yes — same file copied | compiler + adapters (native idioms, visible degradation) |
| Versioned, pinned installs | git clone at best | marketplace-ish (one platform) | unpinned copies | lockfile + content hashes |
| Behavior testing | none | none | none | eval tiers |
| Trust / injection review | none | partial review | none | install-time diff, permissions manifest, signing |
| Context cost accounting | none | none | none | declared budgets, lint-enforced |
| Skill composition | none | ad-hoc chaining | none | typed artifacts + pipelines |
| Ranking | stars | stars | install counts | measurement badges |
| Durable repo knowledge | none | per-platform memory | none | lore layer |
skills.sh solved distribution. Everything below the first row is still empty — that's the product: skills.sh distributes skills; Kitbash makes them engineering.
Developers don't want "AI skills." They want: fewer review cycles, faster onboarding, fewer bugs, less repetitive work, better architecture decisions, less context switching. A skill is only worth installing if it moves one of those. Two consequences:
- Grounding beats prompting. A generic "write tests" skill is a commodity — the model already does that. Value comes from project-specific grounding (this team's review standards, this repo's invariants) and enforcement (gates that block, evals that measure). Hence lore and gates are core primitives, not add-ons.
- Trust is the adoption ceiling. Teams won't standardize on unreviewable prompt injections into their codebases. Hence lockfiles, diff-on-update, and permission manifests are v0 features, not v2.
- Personalities as a product — cosmetic; output style doesn't change outcomes. Allowed as config flavor, never a pillar.
- Generic single-task skills (test generator, doc writer, commit writer) as standalone offerings — commodity; every frontier model does this unprompted. Only shipped when grounded in lore or enforced as gates.
- A new agent/framework — competing with Claude Code/Cursor is a losing war and betrays the point: portability of the developer's investment.
- "Adaptive prompts" / auto-optimizing magic — unfalsifiable marketing. Replaced by the measurable version: lore-driven context injection with evals.
- Marketplace-first strategy — a store of untested prompts is a race to the bottom and a prompt-injection watering hole. Registry ships after lint + evals + hashing exist.