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/nextjsWrote 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/nextjs)<a href="https://agentmods.dev/skills/ericrisco/rsc-harness/nextjs"><img src="https://agentmods.dev/badge/skills/ericrisco/rsc-harness/nextjs.svg" alt="Measured on agentmods" height="20"></a>- NVIDIA SkillSpector warn
SkillSpector: 2 findings, up to medium
- medium Data Exfiltration · line 241 Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.Fix: Verify the destination URL is trusted and necessary. Remove or replace with documented APIs. Ensure no secrets, tokens, or PII are transmitted.
- medium Data Exfiltration · line 244 Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.Fix: Verify the destination URL is trusted and necessary. Remove or replace with documented APIs. Ensure no secrets, tokens, or PII are transmitted.
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 | $0.00090 | $0.05134 |
| Opus 5 | $0.00045 | $0.02567 |
| Sonnet 5 | $0.00018 | $0.01027 |
| Haiku 4.5 | $0.00009 | $0.00513 |
Grade A, and why
nextjs 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 3d 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 — 401 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Next.js App Router — RSC, Server Actions, React 19, TypeScript
Build, review, test, secure and optimize App Router apps, handling both the Next.js 15 (uncached-by-default) and Next.js 16 (
use cache) caching models correctly.
SDD gate — read before writing code. If this fired on a new, non-trivial feature or behaviour change and there is no approved spec + plan under
02-DOCS/wiki/sdd/, STOP and hand off to../specify/SKILL.md(brainstorm → spec → plan → tasks); it routes back here once the plan is approved. Build directly only for a genuinely one-line / low-risk change. Method:../sdd/SKILL.md.
Not this skill: Pages Router (pages/) — note the difference, defer to the Next.js Pages docs.
A pure React SPA (Vite/CRA) → ../react/SKILL.md; React Native / Expo → ../react-native/SKILL.md;
a generic React question with no Next/RSC dimension → keep it brief, from references/react.md.
Non-Next backends → ../fastapi/SKILL.md, ../go/SKILL.md; the data layer behind the DAL →
../postgresdb/SKILL.md; framework-agnostic security → ../secure-coding/SKILL.md, complemented here, never duplicated.
First: detect the project's version & caching model
Run this before prescribing or reviewing any caching, middleware, or React-Compiler behavior. Never mix v15 and v16 advice.
- Read
package.json→ thenextversion. - Read
next.config.{ts,js,mjs}forcacheComponents,ppr,reactCompiler,experimental. proxy.tsat the root ⇒ v16;middleware.ts⇒ v15 (or v16 not yet migrated).cacheComponents: trueOR any"use cache"in the tree ⇒ Cache Components model (opt-in caching). Otherwise ⇒ v15 model (uncachedfetchby default,revalidate/tags).
Do not flag proxy.ts, use cache, or cacheComponents as errors — they are correct on
Next.js 16.
| Signal in repo | Model | Caching API to use |
|---|---|---|
cacheComponents: true or any "use cache" |
Cache Components (v16) | "use cache" + cacheLife() + cacheTag()/updateTag() |
middleware.ts, no cacheComponents |
v15 baseline | fetch(..., { next: { revalidate, tags } }), unstable_cache, revalidateTag |
proxy.ts present |
v16 routing | middleware logic lives in proxy.ts (NOT a security boundary) |
reactCompiler: true |
Compiler on | drop manual useMemo/useCallback/React.memo (review-only) |
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.
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.
- 3d ago First seen · 401 lines · 90 tokens per session scan A 8039b2f7d927
nextjs is a skill published in the GitHub repository ericrisco/rsc-harness (65 stars, last pushed 2d ago), licensed MIT. It adds 90 tokens to every session and 5,134 once invoked, about $0.0005 per session on Opus 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 2026-09-03.
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