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 oborchers/fractional-cto --skill authenticationgit clone --depth 1 https://github.com/oborchers/fractional-ctoWrote 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/oborchers/fractional-cto/authentication)<a href="https://agentmods.dev/skills/oborchers/fractional-cto/authentication"><img src="https://agentmods.dev/badge/skills/oborchers/fractional-cto/authentication/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/oborchers/fractional-cto/authentication"><img src="https://agentmods.dev/badge/skills/oborchers/fractional-cto/authentication.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 | $0.00067 | $0.00850 |
| Opus 5.5 | $0.00027 | $0.00340 |
| Sonnet 5.5 | $0.00013 | $0.00170 |
| Haiku 4.5 | $0.00007 | $0.00085 |
Grade A, and why
authentication 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 — 82 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Authentication Should Be Invisible
10% of active SaaS users get stuck in password reset flows monthly, and 75% of those quit. That is a potential 7.5% monthly user base loss from authentication friction alone.
The Modern Auth Stack
Support three methods, in order of preference:
1. Magic Links (Frictionless Default)
The lowest-friction option. Airtable found 94% of enterprise users preferred them. Send a one-time link to the user's email — no password to remember.
2. SSO via SAML/OIDC (Enterprise)
Non-negotiable for enterprise customers and SOC 2 compliance. Integrate with identity providers like Okta, Azure AD, Google Workspace.
3. Password + MFA (Fallback)
For high-security contexts or users who prefer passwords. Always pair with multi-factor authentication.
MFA UX Details
The implementation details matter enormously:
OTP input fields:
- Use
input type="text" inputmode="numeric"— NOTtype="number"(which allows scroll-wheel changes and scientific notation) - Set
autocomplete="one-time-code"for iOS/macOS autofill - Auto-submit the form once the user enters a valid-length code
Preventing MFA fatigue:
- Use number matching (display a number, user confirms in their authenticator app) rather than simple approve/deny push notifications
- Verizon's DBIR shows MFA fatigue prompt-bombing succeeds at 3.5x the rate of technical MFA bypasses
- Apply adaptive MFA: stronger verification on untrusted devices, unexpected geolocations, or unusual hours
Session Management
- Warn before expiration with a modal countdown timer offering "Continue Session" and "Log Out" options
- After auto-logout, show an inline notification on the login page explaining what happened
- Most critically: clearly communicate what was saved and what was lost
Password Reset
Never let the reset flow become a dead end:
- Confirmation page should be clear and immediate
- Include a "Resend" option
- Show estimated delivery time for the reset email
- After reset, redirect to login with a success message
What ships with it
2 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.
- 5d ago First seen · 82 lines · 67 tokens per session scan A 71180e1fc892
authentication is a skill published in the GitHub repository oborchers/fractional-cto (32 stars, last pushed 5d ago), licensed MIT. It adds 67 tokens to every session and 850 once invoked, about $0.0003 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 2026-10-13.
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