Borrowing it
Nothing to install: this file belongs to seed-hypermedia/seed. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/seed-hypermedia/seed/main/.agents/skills/xstate/SKILL.mdgit clone --depth 1 https://github.com/seed-hypermedia/seedWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/seed-hypermedia/seed/xstate)<a href="https://agentmods.dev/skills/seed-hypermedia/seed/xstate"><img src="https://agentmods.dev/badge/skills/seed-hypermedia/seed/xstate/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/seed-hypermedia/seed/xstate"><img src="https://agentmods.dev/badge/skills/seed-hypermedia/seed/xstate.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- Socket pass
- Snyk pass
- NVIDIA SkillSpector pass
What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00058 | $0.02966 |
| Opus 5.5 | $0.00023 | $0.01186 |
| Sonnet 5.5 | $0.00012 | $0.00593 |
| Haiku 4.5 | $0.00006 | $0.00297 |
Grade A, and why
xstate scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 1mo ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 277 lines — stays where its author put it; the contents beside it link to each section on GitHub.
XState v5
Use this skill for state machine and statechart engineering first and API correctness second.
This skill is v5-only. When examples, blog posts, answers, or local code smell v4-ish, translate them rather than mixing versions. Prefer local repo code and official v5 docs over generic memory.
In Seed, the main repo currently uses [email protected] and @xstate/[email protected], especially under
frontend/packages/shared/src/models/**. Read nearby Seed machines and hooks before editing them, particularly
document-machine.ts, document-card-cleanup-machine.ts, use-document-machine.ts, use-editor-gate.ts, and React
usage of useActorRef(...), useMachine(...), and useSelector(...).
Your job:
- choose between
xstateand@xstate/store - design a sound machine or actor system from messy requirements
- write modern XState v5 TypeScript code in a consistent style
- review, repair, or improve existing XState code
- migrate legacy v4-ish patterns when they appear
- choose the right actor kind and action shape when the problem is not just
assign(...)plusfromPromise(...) - connect machines and actors to
@xstate/react,@xstate/vue,@xstate/svelte, or@xstate/solidwhen needed
First pass
In an existing codebase:
- Inspect local
package.jsonfiles and imports. - Read nearby machines, stores, actors, and adapter usage.
- Distinguish between new code, local edits, and migration work before choosing how opinionated to be.
- Preserve surrounding style by default.
Task mode
Choose a mode before writing code:
- New code: prefer the modern v5 patterns in this skill.
- Local edit: preserve local structure and naming unless the current code is mixed, broken, or cleanup was requested.
- Migration: prefer the smallest safe translation to v5. Preserve structure and semantics unless broader normalization was requested.
For migration and local edits, do not introduce setup(...), named implementations, object-form guards/actions, tags,
or actor decomposition unless they are required for correctness, significantly reduce local complexity, or were
explicitly requested.
What ships with it
9 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
- evals/evals.json 7.8 KB
- evals/extract_and_typecheck.py 8.8 KB runs code
- evals/regrade_weighted.py 2.6 KB runs code
- references/adapters.md 1.9 KB
- references/advanced-patterns.md 9.0 KB
- references/examples.md 11 KB
- references/observables-and-inspection.md 3.0 KB
- references/react.md 4.8 KB
- references/v4-to-v5-quick-ref.md 2.4 KB
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 1mo ago First seen · 277 lines · 58 tokens per session scan A 62897aaa6025
xstate is a skill published in the GitHub repository seed-hypermedia/seed (59 stars, last pushed today), licensed Apache-2.0. It adds 58 tokens to every session and 2,966 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.
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