Social Auth

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⚠️ READ FIRST: AGENT_EXECUTION_SPEC.md - Security contract and execution order

• Providers: Google | GitHub | LinkedIn | Apple | Twitter/X
• Patterns: OAuth Flow | Golden Path | Token Management | Refresh Token Lifecycle | Sessions | Data Models
• Adapters: Next.js | Express | Vanilla Node | Pseudocode | Laravel | Django | Flask | Rails | Vue
• Governance (mandatory): Env Contract | Error Handling | Account Linking | Testing

Mandatory Start (No Code)

1. Produce a Discovery Report before any code or config changes.
2. Read mandatory references: references/AGENT_EXECUTION_SPEC.md and all governance references in references/governance/.
3. Confirm provider(s), framework, language, deployment environment, and session strategy. If any are missing or ambiguous, stop and ask.
4. Verify current provider documentation and security guidance (RFC 9700, RFC 7636, RFC 8252, OIDC Core) before implementation.

Multi-Part Implementation Note

OAuth/OIDC requires coordination between frontend and backend. This skill assumes full-stack access. If implementing in parts:

Scenario 1: Backend-only access

• Implement login start and callback routes.
• Document the route URLs for the frontend team.
• Provide success and error redirect URLs.
• See "Role Selection and Multi-Part Implementation" in references/AGENT_EXECUTION_SPEC.md.

Scenario 2: Frontend-only access

• Implement a login button that calls an existing backend route.
• Do not implement OAuth flow logic client-side.
• Use the Frontend-Only Discovery Report in AGENT_EXECUTION_SPEC.md.
• If the backend uses cookie-based sessions, configure API calls with credentials included and derive auth state from the server.
• Do not modify existing auth logic unrelated to the social login being added.

Scenario 3: Full-stack access (recommended)

• Implement backend first (routes, handlers, validation).
• Then add frontend integration (button, redirects).
• Test end-to-end before deploying.

Discovery Report Requirements (Required First Output)

Include these items, even if the user did not ask:

• Detected framework and runtime (or ambiguity that blocks detection).
• Existing auth stack, session store, user model, and account linking rules.
• Current OAuth providers already integrated and any existing callback routes.
• Deployment constraints (domains, redirect URIs, environment variable system, secrets manager).
• Security middleware already present (CSRF, rate limiting, logging redaction).

If any required item is unknown and cannot be inferred from the repo, stop and ask.

Routing Logic

Provider routing:

• If provider is Google, read references/providers/google.md.
• If provider is GitHub, read references/providers/github.md.
• If provider is LinkedIn, read references/providers/linkedin.md.
• If provider is Apple, read references/providers/apple.md.
• If provider is Twitter/X, read references/providers/twitter.md.
• If provider not supported, create a new provider file under references/providers/ before proceeding.
• [All require CREDENTIALS.md first] Google | GitHub | LinkedIn | Apple | Twitter/X

Pattern routing:

• Always read references/patterns/oauth-flow-core.md.
• If you need a canonical end-to-end example, read references/patterns/golden-path.md.
• If tokens are stored, refreshed, or revoked, read references/patterns/token-management.md.
• If refresh tokens are issued or rotated, read references/patterns/refresh-token-lifecycle.md.
• If sessions or cookies are used, read references/patterns/session-handling.md.
• If the project has existing authentication, read references/patterns/existing-auth-integration.md.
• If cookies are used across different domains, read references/patterns/samesite-decision-tree.md.
• If OIDC ID token validation is needed without heavy dependencies, read references/patterns/jwks-validation-helper.md.
• If database changes are needed, read references/patterns/data-models.md.

Adapter routing:

• If framework is Express, read references/adapters/express-patterns.md.
• If framework is Next.js, read references/adapters/nextjs-patterns.md.
• If framework is vanilla Node or custom server, read references/adapters/vanilla-node-patterns.md.
• If framework is Laravel, read references/adapters/laravel-patterns.md.
• If framework is Django, read references/adapters/django-patterns.md.
• If framework is Flask, read references/adapters/flask-patterns.md.
• If framework is Rails, read references/adapters/rails-patterns.md.
• If framework is Vue, read references/adapters/vue-patterns.md and select a backend adapter for server routes.
• If framework is unknown or not covered, read references/adapters/pseudocode-patterns.md and create a new adapter file.

Governance routing (mandatory in every task):

• references/governance/env-contract.md
• references/governance/error-edge-cases.md
• references/governance/account-linking.md
• references/governance/testing-validation.md

Quick Architecture Router (Use After Discovery)

Once you've completed the Discovery Report and confirmed the provider, use this router to find relevant documentation quickly:

Backend Architecture:

• Separate API + frontend → Section 4.2 (JWT) or 4.3 (Sessions)
• Monolithic (Next.js, Rails, Django) → Section 4.3 + framework adapter
• Serverless → Section 4.4 (not yet implemented, use pseudocode patterns)

Provider Documentation:

• Confirmed provider → references/providers/{provider}/CREDENTIALS.md then references/providers/{provider}.md
• Multiple providers → Read multi-provider patterns first

Account Linking:

• Have auth_identities table → Section 5.1
• Only users table → Section 5.2

This router does NOT replace discovery. Always complete the Discovery Report first.

Forbidden Practices (Explicitly Prohibited)

• Implicit flow or token response in front-channel redirects.
• Skipping state or nonce validation.
• Wildcard or open redirect URI matching.
• Storing access, refresh, or ID tokens in localStorage or client-side cookies.
• Logging auth codes, tokens, client secrets, or full provider responses.
• Using unverified email claims as proof of identity.
• Reusing sessions across login (no session rotation).
• Committing .env files or hardcoding secrets in logic.
• Using the sub (subject) claim as a display name (it is an ID, not a name).

Stop Conditions (Must Ask Clarifying Questions)

Stop and ask before any implementation if any of these are missing:

• Provider client credentials and allowed redirect URIs.
• The app framework and runtime are ambiguous or conflicting.
• Session strategy is unclear (cookie vs server session store).
• Account linking rules are unknown (merge by email or provider id).
• The environment variable system or secrets manager is not defined.
• Secrets Rotation Strategy is undefined (e.g., how to handle old vs new client secrets during a key roll).

Required Output Structure (Required)

See references/AGENT_EXECUTION_SPEC.md for the required output structure (source of truth). Summary:

1. Discovery Report
2. Provider Docs Verification
3. Required Environment Variables
4. Planned File Changes
5. Security Checklist Compliance
6. Implementation Plan
7. Testing Checklist

In Required Environment Variables, always separate backend/server-only vs frontend/public and state who must provide them.

If you cannot comply with the required order, stop and ask for clarification.

Multi-Provider Invariant

Assume multiple providers will coexist. Design routes, database models, and session logic so adding a second provider does not break the first.

Documentation Freshness

Provider files are guidance only. You must verify the latest provider docs before coding. If docs conflict, stop and ask.