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 agentmods add skills/ihatesea69/kiro-kit/better-authnpx skills add ihatesea69/kiro-kit --skill better-authgit clone --depth 1 https://github.com/ihatesea69/kiro-kitWrote 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/ihatesea69/kiro-kit/better-auth)<a href="https://agentmods.dev/skills/ihatesea69/kiro-kit/better-auth"><img src="https://agentmods.dev/badge/skills/ihatesea69/kiro-kit/better-auth.svg" alt="Measured on agentmods" 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 | $0.00035 | $0.00429 |
| Opus 5 | $0.00017 | $0.00215 |
| Sonnet 5 | $0.00007 | $0.00086 |
| Haiku 4.5 | $0.00003 | $0.00043 |
Grade A, and why
better-auth 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 4d 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.
What it actually says
Better Auth
Activate this skill when implementing authentication or authorization systems.
When to Use
- Adding authentication to an application
- Implementing OAuth flows (Google, GitHub, Discord)
- Setting up JWT or session-based auth
- Implementing role-based access control (RBAC)
- Adding multi-factor authentication (TOTP, SMS)
- Managing user sessions and token refresh
- Implementing passkeys/WebAuthn
Authentication Patterns
JWT (Stateless)
- Short-lived access tokens (15-60 minutes)
- Long-lived refresh tokens (7-30 days, stored securely)
- Rotate refresh tokens on use (detect token theft)
- Include minimal claims (user ID, roles)
- Validate signature, expiry, and issuer on every request
Session-Based (Stateful)
- Store sessions server-side (Redis for distributed)
- Use httpOnly, secure, sameSite cookies
- Implement session rotation on privilege escalation
- Set absolute and idle timeouts
- Invalidate all sessions on password change
OAuth 2.1
- Use PKCE for all flows (including server-side)
- Validate state parameter to prevent CSRF
- Store tokens encrypted at rest
- Implement token refresh before expiry
- Handle provider-specific scopes and claims
Authorization Patterns
- RBAC: roles with permission sets
- ABAC: attribute-based policies for complex rules
- Resource-based: check ownership before access
- Always check authorization server-side (never trust client)
Security Rules
- Hash passwords with bcrypt (cost 12+) or argon2id
- Use constant-time comparison for tokens
- Implement account lockout after failed attempts
- Log all auth events for audit trail
- Never store plain-text passwords or tokens
- Validate redirect URIs strictly (no open redirects)
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.
- 4d ago First seen · 63 lines · 35 tokens per session scan A 7d38cc1b324a
better-auth is a skill published in the GitHub repository ihatesea69/kiro-kit (18 stars, last pushed 15d ago), licensed MIT. It adds 35 tokens to every session and 429 once invoked, about $0.0002 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 2026-08-30.
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