Threat model for detecting Invalid Script Purpose vulnerabilities.

An Invalid Script Purpose Attack reuses a spending validator as a minting policy. If the script does not strictly check its purpose, it may validate under MintingScript context even though it was intended to run only under SpendingScript context.

Consequences ==

1. Authorization bypass: Spending-specific checks may be skipped when the same script is executed under minting purpose.
2. Unexpected code paths: Purpose-dependent logic can be triggered in ways that were never intended by contract authors.

Mitigation ==

A secure spending validator should explicitly reject non-spending purposes, for example by matching only on SpendingScript and failing otherwise.

This threat model mutates a valid transaction by adding a mint action that executes the provided Plutus V3 script as a minting policy. If the modified transaction still validates, the script may be vulnerable to purpose confusion.