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Advanced — 0.0.x primitives

You don't need this page for a normal integration. Use the quickstarts and createMythos() instead. These low-level functions remain exported for custom setups.

Errors (Python)

Typed exceptions raised by mythos-sdk.

MythosError​

Base exception class.

python
class MythosError(Exception):
    ...

InsufficientFundsError​

Raised when Mythos /meter returns 402.

python
class InsufficientFundsError(MythosError):
    ...

SessionNotFoundError​

Raised when Mythos /meter returns 404.

python
class SessionNotFoundError(MythosError):
    ...

MythosConfigError​

python
class MythosConfigError(MythosError):
    ...

Exported for parity with the Node SDK and caught explicitly (mapped to a 500) by the require_launch_token dependency. verify_launch_token currently raises a bare RuntimeError for the same missing-listing-config condition instead of MythosConfigError, so via require_launch_token that case actually falls through to the generic handler and returns 503, not 500.

InvalidLaunchTokenError​

python
class InvalidLaunchTokenError(MythosError):
    ...

Raised by verify_launch_token for a structurally invalid token — missing required claims, missing/invalid aud, or a listingId claim that doesn't match a configured listing ID. If you use the require_launch_token dependency instead of calling verify_launch_token directly, this is caught internally (alongside jose JOSE errors) and mapped to a 401 response.

ProducerMismatchError (0.5.0)​

Extends InvalidLaunchTokenError, with code PRODUCER_MISMATCH, HTTP 401 and message This app is bound to a different Mythos Producer. Check MYTHOS_KEY. Raised when a configured key does not match the launch, handshake or callback pkh. Legacy middleware keeps its invalid-token 401; handshake and callback return {"error":"Producer mismatch"}, without invoking the registration callback. See exact response bodies.

InvalidUsageError​

python
class InvalidUsageError(MythosError):
    ...

Raised by report_usage when credits isn't a positive integer — a caller bug, not an API failure.

HTTP mapping in route handlers​

python
from fastapi import HTTPException
from mythos_sdk import MythosError, InsufficientFundsError, SessionNotFoundError

try:
    await report_usage(session_jti, credits=1)
except InsufficientFundsError as e:
    raise HTTPException(status_code=402, detail=str(e)) from e
except SessionNotFoundError as e:
    raise HTTPException(status_code=404, detail=str(e)) from e
except MythosError as e:
    raise HTTPException(status_code=402, detail=str(e)) from e

See also​