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 JustineDevs/premortem --skill next-best-practicesgit clone --depth 1 https://github.com/JustineDevs/premortemWrote 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/justinedevs/premortem/next-best-practices)<a href="https://agentmods.dev/skills/justinedevs/premortem/next-best-practices"><img src="https://agentmods.dev/badge/skills/justinedevs/premortem/next-best-practices/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/justinedevs/premortem/next-best-practices"><img src="https://agentmods.dev/badge/skills/justinedevs/premortem/next-best-practices.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 | $0.00038 | $0.01017 |
| Opus 5 | $0.00019 | $0.00508 |
| Sonnet 5 | $0.00008 | $0.00203 |
| Haiku 4.5 | $0.00004 | $0.00102 |
Grade A, and why
next-best-practices 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 9d 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
100% identical to next-best-practices — 20 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 — 154 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Next.js Best Practices
Apply these rules when writing or reviewing Next.js code.
File Conventions
See file-conventions.md for:
- Project structure and special files
- Route segments (dynamic, catch-all, groups)
- Parallel and intercepting routes
- Middleware rename in v16 (middleware → proxy)
RSC Boundaries
Detect invalid React Server Component patterns.
See rsc-boundaries.md for:
- Async client component detection (invalid)
- Non-serializable props detection
- Server Action exceptions
Async Patterns
Next.js 15+ async API changes.
See async-patterns.md for:
- Async
paramsandsearchParams - Async
cookies()andheaders() - Migration codemod
Runtime Selection
See runtime-selection.md for:
- Default to Node.js runtime
- When Edge runtime is appropriate
Directives
See directives.md for:
'use client','use server'(React)'use cache'(Next.js)
Functions
See functions.md for:
- Navigation hooks:
useRouter,usePathname,useSearchParams,useParams - Server functions:
cookies,headers,draftMode,after - Generate functions:
generateStaticParams,generateMetadata
Error Handling
See error-handling.md for:
error.tsx,global-error.tsx,not-found.tsxredirect,permanentRedirect,notFoundforbidden,unauthorized(auth errors)unstable_rethrowfor catch blocks
Data Patterns
See data-patterns.md for:
- Server Components vs Server Actions vs Route Handlers
- Avoiding data waterfalls (
Promise.all, Suspense, preload) - Client component data fetching
Route Handlers
See route-handlers.md for:
route.tsbasics- GET handler conflicts with
page.tsx - Environment behavior (no React DOM)
- When to use vs Server Actions
Metadata & OG Images
See metadata.md for:
- Static and dynamic metadata
generateMetadatafunction- OG image generation with
next/og - File-based metadata conventions
What ships with it
19 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.
- async-patterns.md 1.6 KB
- bundling.md 4.4 KB
- data-patterns.md 6.5 KB
- debug-tricks.md 2.9 KB
- directives.md 1.4 KB
- error-handling.md 4.6 KB
- file-conventions.md 3.4 KB
- font.md 5.1 KB
- functions.md 4.3 KB
- hydration-error.md 1.8 KB
- image.md 3.8 KB
- metadata.md 7.0 KB
- parallel-routes.md 7.0 KB
- route-handlers.md 3.2 KB
- rsc-boundaries.md 4.2 KB
- runtime-selection.md 985 B
- scripts.md 3.2 KB
- self-hosting.md 8.1 KB
- suspense-boundaries.md 1.3 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.
- 9d ago First seen · 154 lines · 38 tokens per session scan A c78f952d4e98
next-best-practices is a skill published in the GitHub repository JustineDevs/premortem (2 stars, last pushed 1mo ago), licensed Apache-2.0. It adds 38 tokens to every session and 1,017 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 100% identical to next-best-practices, differing in 20 lines, and is treated as a copy.
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