Exception Handling Implementation Standard

Purpose

The Exception Handling Implementation Standard defines how backend failures become safe API errors and auditable operational signals.

Error Categories

Category	API Error Direction
Validation failure	VALIDATION_FAILED.
Authentication failure	AUTHENTICATION_REQUIRED or TOKEN_INVALID.
Authorization denial	AUTHORIZATION_DENIED or MFA_REQUIRED.
Tenant context failure	TENANT_CONTEXT_REQUIRED, ORGANIZATION_CONTEXT_REQUIRED, or TENANT_ACCESS_DENIED.
Entitlement failure	ENTITLEMENT_REQUIRED or USAGE_LIMIT_REACHED.
Idempotency failure	IDEMPOTENCY_KEY_REQUIRED or IDEMPOTENCY_CONFLICT.
Conflict	RESOURCE_CONFLICT.
Integration failure	INTEGRATION_UNAVAILABLE or INTEGRATION_CALLBACK_INVALID.
Unexpected failure	INTERNAL_ERROR.

Rules

• Exceptions must be translated into the standard error envelope.
• Error responses include correlation ID.
• Errors do not expose stack traces, SQL details, secrets, tokens, provider credentials, or internal class names.
• Retryability must be explicit where useful.
• Domain errors use business language and stable codes.
• Security denials must not reveal sensitive resource existence.
• Material failures are logged with safe context and audit metadata where required.

Handling Flow

flowchart LR
    Failure[Failure]
    Classify[Classify]
    Map[Map to Error Code]
    Envelope[Standard Error Envelope]
    Audit[Safe Log and Audit]

    Failure --> Classify --> Map --> Envelope
    Map --> Audit

Testing Expectations

Tests must verify error code mapping, correlation IDs, safe messages, no sensitive leakage, retryable flags, and tenant-safe denial behavior.