A set of rules for the core authentication engine, the part of a system that verifies login credentials and creates identity tokens. It defines how different credential providers plug in and how verified users and their attributes are handled.

Use it when adding credential providers, changing token claims, updating the provider registry, or working on authentication federation.

It keeps provider-specific login logic out of shared services and ensures tokens identify the correct user consistently.

How qauth-labs/qauth configures Claude Code

Reuse

Borrowing it

Nothing to install: this file belongs to qauth-labs/qauth. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file

curl -O https://raw.githubusercontent.com/qauth-labs/qauth/main/.claude/skills/auth-engine/SKILL.md

Clone the repo

git clone --depth 1 https://github.com/qauth-labs/qauth

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.

README.md

[![agentmods](https://agentmods.dev/badge/skills/qauth-labs/qauth/auth-engine/github.svg)](https://agentmods.dev/skills/qauth-labs/qauth/auth-engine)

Your own site

<a href="https://agentmods.dev/skills/qauth-labs/qauth/auth-engine"><img src="https://agentmods.dev/badge/skills/qauth-labs/qauth/auth-engine/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.

Your own site · 80×15

<a href="https://agentmods.dev/skills/qauth-labs/qauth/auth-engine"><img src="https://agentmods.dev/badge/skills/qauth-labs/qauth/auth-engine.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 45 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 1,271 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 pass 7 Sept 2026

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.

Model	Per session	Once invoked
Fable 5.1	$0.00045	$0.01271
Opus 5.5	$0.00018	$0.00508
Sonnet 5.5	$0.00009	$0.00254
Haiku 4.5	$0.00005	$0.00127

Measured 7d ago against content hash 80b44703ff25, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

auth-engine 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/auth-engine/SKILL.md · 104 lines

How it starts

The opening of the file, as written. The whole thing — 104 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Auth Engine Rules

You are working in the QAuth authentication core.

CredentialProvider Pattern

Every authentication method implements the CredentialProvider interface:

// libs/server/federation/src/providers/credential-provider.interface.ts
export interface CredentialProvider {
  readonly type: string;
  verify(input: unknown): Promise<VerifiedIdentity>;
  extractAttributes(result: VerifiedIdentity): UserAttribute[];
}

The auth engine:

Looks up the credential from user_credentials by (realm_id, provider_type, external_sub)
Passes credential data to provider.verify()
Receives VerifiedIdentity
Upserts user_attributes from provider.extractAttributes()
Issues tokens with sub = users.id

The engine does not contain provider-specific logic. Switch/case on provider_type belongs only in the provider registry, not in service routes.

Current Providers

PasswordProvider (provider_type: 'password') — Phase 1, COMPLETE
- Located at libs/server/federation/src/providers/password.provider.ts
- externalSub is the normalized email address
- assuranceLevel: 'low' — no acr claim in tokens
WalletProvider (provider_type: 'wallet') — T4, Epic #231 (checked 2026-08-31)
- libs/server/federation/src/providers/wallet.provider.ts
- verify() throws unconditionally and must keep throwing. That is a permanent fail-closed property, not a stage in an implementation — a stub resolving a placeholder VerifiedIdentity would be an authentication-bypass primitive. Never "finish" it, and never wire it into a login path. See AGENTS.md.
- Wallet login itself is merged, flag-gated behind WALLET_FEDERATION_ENABLED (default off). It does not go through this provider: it runs on the dedicated /ui/wallet-login + /oid4vp/response seam (apps/auth-server/src/app/routes/ui/wallet-login.ts, apps/auth-server/src/app/routes/oid4vp/response.ts), validated end-to-end against a mock wallet on the oid4vp-1.0-base profile.
- extractAttributes() is implemented (#235) and is the half of this provider that does real work.

Read the full file on GitHub · 104 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.

7d ago Changed · +2 lines 80b44703ff25
1mo ago Changed · +19 lines a07f7f5c5294
1mo ago First seen · 83 lines · 45 tokens per session scan A b213ef930f0a

Subscribe to this mod's changes

auth-engine is a skill published in the GitHub repository qauth-labs/qauth (26 stars, last pushed today), licensed Apache-2.0. It adds 45 tokens to every session and 1,271 once invoked, about $0.0002 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 2026-08-30.

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qauth: Skill for Claude Code

Borrowing it

Wrote this? Show the measurements

What it costs to keep this loaded

Grade A, and why

Nothing flagged

How it starts

Auth Engine Rules

CredentialProvider Pattern

Current Providers

What this file has done since we first saw it

Other skills, from other repositories

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