Getting it into your agent
It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.
git clone --depth 1 https://github.com/ericrisco/rsc-harnessnpx agentmods add skills/ericrisco/rsc-harness/animate-expoWrote 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/ericrisco/rsc-harness/animate-expo)<a href="https://agentmods.dev/skills/ericrisco/rsc-harness/animate-expo"><img src="https://agentmods.dev/badge/skills/ericrisco/rsc-harness/animate-expo/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/ericrisco/rsc-harness/animate-expo"><img src="https://agentmods.dev/badge/skills/ericrisco/rsc-harness/animate-expo.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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 | $0.00070 | $0.04655 |
| Opus 5 | $0.00035 | $0.02328 |
| Sonnet 5 | $0.00014 | $0.00931 |
| Haiku 4.5 | $0.00007 | $0.00466 |
Grade A, and why
animate-expo 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 10d 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.
This is a copy
91% identical to animate-expo — 30 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
How it starts
The opening of the file, as written. The whole thing — 282 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Building Animations in Expo
SDD gate. If this fired on a new, non-trivial feature or behaviour change and there is no approved spec + plan under
02-DOCS/wiki/sdd/, hand off to../specify/SKILL.mdfirst — it runs brainstorm → spec → plan → tasks before any code, then routes back here once the plan is approved. Build straight from here only for a genuinely one-line / low-risk change, or a bug fix restoring intended behaviour. Method:../sdd/SKILL.md.
Hand-offs. Web motion is ../animate/SKILL.md's — this file exists because mobile changes the
three things listed above. The Expo platform itself (router, config plugins, EAS, native modules,
store builds) is ../expo/SKILL.md's, and bare React Native app structure is
../react-native/SKILL.md's: both own the app, this one owns its motion. Gesture physics as a
discipline — momentum projection, rubber-banding, velocity handoff — is ../apple-design/SKILL.md's.
A construction skill for React Native. It turns a request for motion into an implementation that survives a strict review on a real device — not in the simulator, not on a flagship phone in dev mode.
Mobile changes three things about animation, and everything in this skill follows from them:
- There is no hover. Every affordance the web puts in hover has to live in press, position, or nothing.
- There are two runtimes. Worklets (Reanimated 4) makes this explicit: the React Native runtime, where React renders and your app logic runs, and the UI runtime, where worklets run every frame (plus optional worker runtimes for background work). An animation that touches the RN runtime stutters the moment the app does anything else. The whole craft is keeping motion on the UI runtime.
- The user's finger is on the element. Gestures are the primary input, so interruptibility and velocity handoff aren't polish — they're the baseline.
Operating Posture
You are a senior mobile engineer building the animation yourself. Make the call, state the reasoning in one line, write the code. Never present motion options as a menu.
What ships with it
2 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.
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.
- 10d ago First seen · 282 lines · 70 tokens per session scan A 6143ffbe3325
animate-expo is a skill published in the GitHub repository ericrisco/rsc-harness (78 stars, last pushed today), licensed MIT. It adds 70 tokens to every session and 4,655 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. It is 91% identical to animate-expo, differing in 30 lines, and is treated as a copy.
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