oauth

A feature installer that adds GitHub sign-in to an existing email-and-password login system. GitHub OAuth is a standard way for users to approve sign-in through their GitHub account.

In plain words
What is it for?
Use it in an application that already has user authentication to add GitHub login, account linking, callback handling, routes, and login and registration buttons.
Why use it?
It avoids making users create another password and links GitHub accounts to existing users by email, reducing separate or duplicate accounts.

Skill for Claude CodeCodex

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.

agentmods
npx agentmods add skills/fullstack-phoenix/saas_kit/oauth
Any agent
npx skills add fullstack-phoenix/saas_kit --skill oauth
Clone the repo
git clone --depth 1 https://github.com/fullstack-phoenix/saas_kit

Made for: Claude Code, Codex.

Per session 44 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,363 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00044 $0.01363
Opus 5 $0.00022 $0.00681
Sonnet 5 $0.00009 $0.00273
Haiku 4.5 $0.00004 $0.00136

Measured 2d ago against content hash 013bafa8ea51, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

oauth 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 2d 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.

skills/oauth/SKILL.md · 139 lines

How it starts

The opening of the file, as written. The whole thing — 139 lines — stays where its author put it; the contents beside it link to each section on GitHub.

OAuth Login

Adds GitHub OAuth sign-in on top of the existing authentication feature. Built on Ueberauth, it generates a UserIdentity schema that links OAuth accounts to your users by email, an OauthCallbackController that handles the full request/callback flow, and "Sign in with Github" buttons on the login and registration pages. New OAuth users are auto-created and confirmed; existing users are matched and linked by email.

When to use

  • The app already has email/password auth and you want to add "Sign in with GitHub".
  • You want OAuth users automatically linked to existing accounts by email, with no separate account silo.
  • Don't reach for this if you have no users yet — install authentication first. Don't use it as your only auth: it extends the password flow, not replaces it.

Dependencies

  • Requires: authentication (the User schema, Users context, and login/registration LiveViews must already exist).
  • Recommended: None.

Install

mix saaskit.feature.install oauth

No interactive decisions. The installer adds ueberauth and ueberauth_github to mix.exs, injects Ueberauth config, mounts the /auth routes, generates the user-identity context and controller, and adds the sign-in buttons.

What it generates

  • lib/my_app/user_identities.ex — context. find_or_create_user/1 resolves the four identity/user scenarios (register, log in, link, re-link) and returns {:ok, user} or {:just_created, user}. Also CRUD: list_user_identities/1, create_user_identity/2.
  • lib/my_app/user_identities/user_identity.ex — schema for the user_identities table (provider, uid, belongs_to :user).
  • lib/my_app_web/controllers/oauth_callback_controller.ex — handles GET /auth/:provider and GET /auth/:provider/callback, logs the user in via UserAuth.log_in_user/2.
  • lib/my_app/ecto_helpers/stringable.ex — Ecto type for the provider/uid fields.
  • Migration priv/repo/migrations/*_create_user_identities.exsuser_identities table with a unique index on (uid, provider).
  • Injects Users.confirm_user/1 into lib/my_app/users.ex (used to auto-confirm verified OAuth sign-ins).
  • Adds the /auth scope to lib/my_app_web/router.ex and "Sign in with Github" buttons to the login and registration LiveViews.
  • Tests + fixtures: test/my_app/user_identities_test.exs, test/support/fixtures/user_identities_fixtures.ex.

Read the full file on GitHub · 139 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. 2d ago First seen · 139 lines · 44 tokens per session scan A 013bafa8ea51

Subscribe to this mod's changes

oauth is a skill published in the GitHub repository fullstack-phoenix/saas_kit (2 stars, last pushed 2mo ago), licensed MIT. It adds 44 tokens to every session and 1,363 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 2026-08-31.

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