Document OAuth 2.0 token behavior: multiple tokens are standard, not a bug

[Copilot]

Issue reports that multiple logins create multiple access tokens without revoking old ones. After investigating OAuth 2.0 RFC 6749 and major provider implementations (Auth0, Okta, Keycloak), this is correct and expected behavior.

Investigation

Attempted automatic token revocation on reauthorization but discovered it breaks refresh token flow:

• RefreshToken.access_token references AccessToken for scope validation
• Deleting access tokens makes get_original_scopes() fail with "invalid_scope"
• All major OAuth providers allow multiple concurrent tokens by default

Changes

Added test suite (test_token_revocation_on_reauth.py):

• Documents that multiple tokens are standard OAuth 2.0 behavior per RFC 6749
• Tests authorization with auto/force approval and different scopes
• All 94 authorization and token tests pass

Added documentation:

• Why multiple tokens exist (multiple devices, token rotation, refresh flows)
• Proper token management using existing tools:
  • python manage.py cleartokens - removes expired tokens
  • Token revocation endpoint - explicit cleanup
  • ACCESS_TOKEN_EXPIRE_SECONDS - configurable expiration (default 10h)

Root Cause

The test app (RP) requests new tokens on each login instead of reusing valid ones. This is a client implementation issue, not an authorization server bug. Standard OAuth 2.0 clients should check for existing valid tokens before initiating new authorization flows.

Example

# Current test app behavior (creates proliferation):
def login():
    return redirect(authorization_url)  # Always creates new token

# Correct OAuth 2.0 client behavior:
def login():
    if current_token and not current_token.is_expired():
        return use_existing_token()
    return redirect(authorization_url)  # Only when needed

Warning

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Original prompt

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This section details on the original issue you should resolve

<issue_title>bug: logging in multiple times creates many access tokens</issue_title>
<issue_description>Describe the bug
If I login multiple times multiple access tokens are created in the admin, it seems like if i have an existing session on the l client my old token should be revoked.

To Reproduce
start the tests/app/idp and rp. Hit login multiple times, look at the accessTokens in the admin.

Expected behavior
A new token is not created when I login and have an existing sessions.

need to confirm what should be happening with the specs.

Version
3.1

</issue_description>

<agent_instructions>Research and verify the correct behavior using the various OAuth and OIDC RFCs and speifications as a primary resource and documentation from okta, auth0, and keycloak as secondary resources. </agent_instructions>

Comments on the Issue (you are @copilot in this section)

• Fixes bug: logging in multiple times creates many access tokens #1605

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