modern-auth-2026

modern-auth-2026 is a skill for Claude Code from curiositech/some_claude_skills. It costs 134 tokens per session (6,697 once invoked), scanned A, original, MIT.

A guide to implementing passwordless and social sign-in for web and mobile apps. It covers passkeys, which use device-based cryptographic login, along with OAuth, magic links, multi-factor authentication, and account recovery.

In plain words
What is it for?
Adding passkeys/WebAuthn, Google or Apple sign-in, Supabase Auth flows, one-time codes, cross-device login, multi-factor authentication, and email or SMS recovery.
Why use it?
It helps replace or supplement passwords with modern login flows and addresses sign-in across devices, recovery, and app-store requirements.

Skill for Claude Code

Written for Claude Code: allowed-tools in frontmatter.

Good fit Adding passkeys/WebAuthn, Google or Apple sign-in, Supabase Auth flows, one-time codes, cross-device login, multi-factor authentication, and email or SMS recovery.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/curiositech/some_claude_skills/modern-auth-2026
Install

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.

Any agent
npx skills add curiositech/some_claude_skills --skill modern-auth-2026
Clone the repo
git clone --depth 1 https://github.com/curiositech/some_claude_skills

Made for: Claude Code.

Wrote 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.

agentmods badge for modern-auth-2026

README.md
[![agentmods](https://agentmods.dev/badge/skills/curiositech/some_claude_skills/modern-auth-2026/github.svg)](https://agentmods.dev/skills/curiositech/some_claude_skills/modern-auth-2026)
Your own site
<a href="https://agentmods.dev/skills/curiositech/some_claude_skills/modern-auth-2026"><img src="https://agentmods.dev/badge/skills/curiositech/some_claude_skills/modern-auth-2026/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.

agentmods 80×15 button for modern-auth-2026

Your own site · 80×15
<a href="https://agentmods.dev/skills/curiositech/some_claude_skills/modern-auth-2026"><img src="https://agentmods.dev/badge/skills/curiositech/some_claude_skills/modern-auth-2026.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 134 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 6,697 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector warn 7 Sept 2026
SkillSpector: 5 findings, up to high

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

  • high Privilege Escalation · line 739
    Code accesses credential files (SSH keys, AWS credentials, etc.). This could indicate credential theft attempts.
    Fix: Remove references to credential paths. Use environment variables or secrets managers. For docs, use placeholder paths (e.g., /path/to/config). Never load .env or token files in production code paths.
  • high Privilege Escalation · line 750
    Code accesses credential files (SSH keys, AWS credentials, etc.). This could indicate credential theft attempts.
    Fix: Remove references to credential paths. Use environment variables or secrets managers. For docs, use placeholder paths (e.g., /path/to/config). Never load .env or token files in production code paths.
  • high Privilege Escalation · line 889
    Code accesses credential files (SSH keys, AWS credentials, etc.). This could indicate credential theft attempts.
    Fix: Remove references to credential paths. Use environment variables or secrets managers. For docs, use placeholder paths (e.g., /path/to/config). Never load .env or token files in production code paths.
  • high Privilege Escalation · line 882
    Code accesses credential files (SSH keys, AWS credentials, etc.). This could indicate credential theft attempts.
    Fix: Remove references to credential paths. Use environment variables or secrets managers. For docs, use placeholder paths (e.g., /path/to/config). Never load .env or token files in production code paths.
  • high Privilege Escalation · line 884
    Code accesses credential files (SSH keys, AWS credentials, etc.). This could indicate credential theft attempts.
    Fix: Remove references to credential paths. Use environment variables or secrets managers. For docs, use placeholder paths (e.g., /path/to/config). Never load .env or token files in production code paths.
How audits are shown
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00134 $0.06697
Opus 5 $0.00067 $0.03349
Sonnet 5 $0.00027 $0.01339
Haiku 4.5 $0.00013 $0.00670

Measured 7d ago against content hash eab615ec8ba6, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

modern-auth-2026 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 7d 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.

.claude/skills/modern-auth-2026/SKILL.md · 951 lines

How it starts

The opening of the file, as written. The whole thing — 951 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Modern Authentication Expert (2026)

Master passwordless-first authentication with passkeys, OAuth, magic links, and cross-device sync for modern web and mobile applications.

When to Use

USE this skill for:

  • Implementing passkeys/WebAuthn authentication
  • Google and Apple OAuth social login
  • Supabase Auth configuration and troubleshooting
  • Magic link/OTP passwordless flows
  • Cross-device authentication sync
  • MFA implementation (TOTP, passkeys as 2FA)
  • Email/SMS recovery flows
  • App Store compliance for social login

DO NOT use for:

  • Session management without auth context → use standard JWT patterns
  • Authorization/RBAC policies → use security-auditor skill
  • API key management → use api-architect skill
  • Supabase RLS policies → use supabase-admin skill

2026 Authentication Landscape

Industry Adoption Stats

  • Passkeys: 87% of US/UK companies now use passkeys (FIDO Alliance)
  • Google: 800+ million accounts use passkeys
  • Amazon: 175 million users created passkeys in first year
  • Trend: Passwordless is the security baseline, not a luxury

Key Standards

Standard Purpose Status
WebAuthn L2 Browser passkey API Fully supported
FIDO2/CTAP2 Cross-platform passkeys Mature
OAuth 2.1 Simplified OAuth Replacing 2.0
OAuth3 Short-lived tokens Emerging
Passkey Sync iCloud/Google sync Production

Architecture: Passwordless-First Design

Recommended Auth Hierarchy (2026)

Primary Methods (Phishing-Resistant):
├── 1. Passkeys (WebAuthn) ← PREFERRED
│   ├── Platform authenticators (Face ID, Touch ID, Windows Hello)
│   └── Roaming authenticators (YubiKey, security keys)
├── 2. Social OAuth
│   ├── Google Sign-In (synced passkeys)
│   └── Apple Sign-In (privacy-focused)
│
Fallback Methods (Lower Security):
├── 3. Magic Links (email-based)
├── 4. Email OTP (time-limited codes)
└── 5. SMS OTP (deprecated - SIM swap risk)
    ⚠️ SMS should be last resort only

Legacy (Avoid):
└── 6. Password + Email ← DISCOURAGE

Read the full file on GitHub · 951 lines

Changes

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.

  1. 7d ago First seen · 951 lines · 134 tokens per session scan A eab615ec8ba6

Subscribe to this mod's changes

modern-auth-2026 is a skill published in the GitHub repository curiositech/some_claude_skills (219 stars, last pushed 5d ago), licensed MIT. It adds 134 tokens to every session and 6,697 once invoked, about $0.0007 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 2026-09-03.

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