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.
git clone --depth 1 https://github.com/proSamik/starterkit-nextjs-aisdk-betterauth-polarWrote 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/rules/prosamik/starterkit-nextjs-aisdk-betterauth-polar/authentication-system)<a href="https://agentmods.dev/rules/prosamik/starterkit-nextjs-aisdk-betterauth-polar/authentication-system"><img src="https://agentmods.dev/badge/rules/prosamik/starterkit-nextjs-aisdk-betterauth-polar/authentication-system/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/rules/prosamik/starterkit-nextjs-aisdk-betterauth-polar/authentication-system"><img src="https://agentmods.dev/badge/rules/prosamik/starterkit-nextjs-aisdk-betterauth-polar/authentication-system.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 | $0.00000 | $0.01070 |
| Opus 5 | $0.00000 | $0.00535 |
| Sonnet 5 | $0.00000 | $0.00214 |
| Haiku 4.5 | $0.00000 | $0.00107 |
Grade A, and why
authentication-system 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 8d 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 authentication-system — 0 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 — 137 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Authentication System Guide
Overview
This project uses Better Auth with email OTP verification for secure user authentication. The system includes password reset, email verification during signup, and event tracking via Plunk.
Core Configuration
Server Configuration
The main authentication configuration is in src/lib/auth/server.ts:
- Uses Better Auth with emailOTP plugin
- Requires email verification before login (
requireEmailVerification: true) - 6-digit OTP codes with 5-minute expiration
- Maximum 3 attempts per OTP
- Integrated with Polar for subscription management
Client Configuration
Client-side authentication setup in src/lib/auth/client.ts:
- Includes emailOTPClient plugin for OTP functionality
- Error handling with toast notifications
- Polar client integration
Authentication Flows
User Registration Flow
Located in src/app/(auth)/sign-up/page.tsx:
- Step 1: Email validation and existence check
- Step 2: Password and confirmation input
- Step 3: Full name collection
- Step 4: Email verification with 6-digit OTP
- Account creation after successful email verification
Password Reset Flow
Located in src/app/(auth)/forgot-password/page.tsx:
- Step 1: Email input for OTP request
- Step 2: 6-digit OTP verification
- Step 3: New password setup
Sign-In Flow
Located in src/app/(auth)/sign-in/page.tsx:
- Standard email/password authentication
- Redirects to email verification if account not verified
- Social login options (GitHub, Google)
OTP System Features
Resend Cooldown
Custom hook src/hooks/use-resend-cooldown.ts:
- 2-minute (120 seconds) cooldown between resend attempts
- Real-time countdown display in MM:SS format
- State preserved throughout application session
- Prevents spam and abuse
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.
- 8d ago First seen · 137 lines · 0 tokens per session scan A b49d86dade6e
authentication-system is a cursor rule published in the GitHub repository proSamik/starterkit-nextjs-aisdk-betterauth-polar (4 stars, last pushed 1y ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 1,070 tokens. A static security scan graded it A with 0 findings. It is 100% identical to authentication-system, differing in 0 lines, and is treated as a copy.
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