Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add PracticalSwan/agent-skills --skill nextjs-developmentgit clone --depth 1 https://github.com/PracticalSwan/agent-skillsWrote 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/practicalswan/agent-skills/nextjs-development)<a href="https://agentmods.dev/skills/practicalswan/agent-skills/nextjs-development"><img src="https://agentmods.dev/badge/skills/practicalswan/agent-skills/nextjs-development/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/practicalswan/agent-skills/nextjs-development"><img src="https://agentmods.dev/badge/skills/practicalswan/agent-skills/nextjs-development.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector warn
SkillSpector: 8 findings, up to high
These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →
- high Prompt Injection · line 908 Hidden instructions were detected in comments or invisible text. These could contain malicious directives. Manual review is recommended.Fix: Audit all comments and invisible characters. Remove any instructions that direct the agent to perform unauthorized actions. Use plain, reviewable content.
- medium Data Exfiltration · line 331 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 389 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 394 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 MCP Rug Pull · line 110 npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.Fix: Pin the version: npx @scope/[email protected]
- medium MCP Rug Pull · line 846 npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.Fix: Pin the version: npx @scope/[email protected]
- medium MCP Rug Pull · line 852 npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.Fix: Pin the version: npx @scope/[email protected]
- medium MCP Rug Pull · line 853 npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.Fix: Pin the version: npx @scope/[email protected]
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 | $0.00054 | $0.06867 |
| Opus 5.5 | $0.00022 | $0.02747 |
| Sonnet 5.5 | $0.00011 | $0.01373 |
| Haiku 4.5 | $0.00005 | $0.00687 |
Grade A, and why
nextjs-development 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 — 940 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Next.js Development
Optimized for Next.js 16+, React 19+, TypeScript 5.5+, Turbopack, and App Router-first architectures.
Comprehensive reference for Next.js (latest: 16.2.4) with the App Router, TypeScript, and modern patterns. Covers project structure, Server/Client Components, data fetching, caching with the use cache directive, Server Actions, MCP devtools integration, and performance optimization.
- Leverage native parallel subagent dispatch and 200k+ context windows where available.
Component Review Rubric Reference
Apply the shared Component Review Rubric before approving Next.js components, then run the Next.js-specific checks below.
Cross-Client Portability
This skill is written to stay usable across GitHub Copilot, Claude Code, and Codex.
- GitHub Copilot: keep the folder in a Copilot-visible skill path or wrap the workflow in project instructions when folder discovery is unavailable.
- Claude Code: keep the folder in a local skills directory or a compatible plugin source.
- Codex: install or sync the folder into
$CODEX_HOME/skills/nextjs-developmentand restart Codex after major changes.
MCP Availability And Fallback
Preferred MCP Server: Next.js MCP
- Fallback prompt: "Use the Next.js Development skill without MCP. Follow the documented local or manual fallback, show the selected tool surface, and report the verification evidence."
- Use
next dev,next build,next lint, browser console output, and local server logs when live MCP diagnostics are unavailable. - Verify routing, rendering mode, and data-fetching behavior with the bundled examples and a running dev server.
- Do not claim an MCP operation was used when the active host does not expose it.
Anti-Patterns
- Mixing server and client responsibilities: Bundle size, caching, and auth decisions become harder to reason about.
- Using legacy synchronous request APIs: Modern Next.js expects async request surfaces such as
params,headers(), andcookies(). - Skipping route-level loading and error states: Streaming apps feel broken when only the happy path is implemented.
What ships with it
7 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.
- 1mo ago Changed · +1 lines 962fc3b28e2b
- 1mo ago Changed 7e6858c8767d
- 1mo ago First seen · 939 lines · 54 tokens per session scan A e6d72ed4a2ce
nextjs-development is a skill published in the GitHub repository PracticalSwan/agent-skills (21 stars, last pushed 4d ago), licensed MIT. It adds 54 tokens to every session and 6,867 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 2026-09-03.
Other skills, from other repositories
server-side-calls
Call tRPC procedures directly from server code using t.createCallerFactory() and router.createCaller(context) for integration testing, internal server logic, and custom API endpoints. Catch TRPCError and extract HTTP status with getHTTPStatusCodeFromError(). Error handling via onError option.
implement-feature
Implement an approved feature plan with fresh-context slices, TDD, revision-bound evidence, and PR-ready output.
verify-bug
Post-merge UAT verification workflow. Walks JIRA reproduce steps, performs comparative audits (Before/After), attaches evidence to JIRA, and transitions status on PASS.
verify-work
Verify feature, bug, UI, API, mobile, security, or deployment work against acceptance criteria.
test-loop
Plan, generate, and heal an executable E2E test suite from approved acceptance criteria (web and mobile).
common-subagent-driven-development
Execute multi-task implementation plans by dispatching a fresh implementer subagent per task with independent review gates. Use when implementing plans, executing multi-task PRs, or transitioning from planning to implementation.