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/charlietlamb/ferix/create-auth-skillnpx skills add charlietlamb/ferix --skill create-auth-skillgit clone --depth 1 https://github.com/charlietlamb/ferixWrote 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/charlietlamb/ferix/create-auth-skill)<a href="https://agentmods.dev/skills/charlietlamb/ferix/create-auth-skill"><img src="https://agentmods.dev/badge/skills/charlietlamb/ferix/create-auth-skill.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 5.1 | $0.00021 | $0.01713 |
| Opus 5 | $0.00010 | $0.00856 |
| Sonnet 5 | $0.00004 | $0.00343 |
| Haiku 4.5 | $0.00002 | $0.00171 |
Grade A, and why
create-auth-skill 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 5d 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 — 214 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Create Auth Skill
Guide for adding authentication to TypeScript/JavaScript applications using Better Auth.
For code examples and syntax, see better-auth.com/docs.
Decision Tree
Is this a new/empty project?
├─ YES → New project setup
│ 1. Identify framework
│ 2. Choose database
│ 3. Install better-auth
│ 4. Create auth.ts + auth-client.ts
│ 5. Set up route handler
│ 6. Run CLI migrate/generate
│ 7. Add features via plugins
│
└─ NO → Does project have existing auth?
├─ YES → Migration/enhancement
│ • Audit current auth for gaps
│ • Plan incremental migration
│ • See migration guides in docs
│
└─ NO → Add auth to existing project
1. Analyze project structure
2. Install better-auth
3. Create auth config
4. Add route handler
5. Run schema migrations
6. Integrate into existing pages
Installation
Core: npm install better-auth
Scoped packages (as needed):
| Package | Use case |
|---|---|
@better-auth/passkey |
WebAuthn/Passkey auth |
@better-auth/sso |
SAML/OIDC enterprise SSO |
@better-auth/stripe |
Stripe payments |
@better-auth/scim |
SCIM user provisioning |
@better-auth/expo |
React Native/Expo |
Environment Variables
BETTER_AUTH_SECRET=<32+ chars, generate with: openssl rand -base64 32>
BETTER_AUTH_URL=http://localhost:3000
DATABASE_URL=<your database connection string>
Add OAuth secrets as needed: GITHUB_CLIENT_ID, GITHUB_CLIENT_SECRET, GOOGLE_CLIENT_ID, etc.
Server Config (auth.ts)
Location: lib/auth.ts or src/lib/auth.ts
Minimal config needs:
database- Connection or adapteremailAndPassword: { enabled: true }- For email/password auth
Standard config adds:
socialProviders- OAuth providers (google, github, etc.)emailVerification.sendVerificationEmail- Email verification handleremailAndPassword.sendResetPassword- Password reset handler
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.
- 5d ago First seen · 214 lines · 21 tokens per session scan A 7334700b51f3
create-auth-skill is a skill published in the GitHub repository charlietlamb/ferix (10 stars, last pushed 6mo ago), licensed MIT. It adds 21 tokens to every session and 1,713 once invoked, about $0.0001 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 2026-08-31.
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