Issue an AP2 Open Intent Mandate so an AI agent can autonomously search and purchase within user-defined budget and merchant constraints

Steps

1. At session start, the user defines an IntentMandate specifying constraints: maximum budget, allowed payment instruments, permitted merchant categories, and expiry time; use the AP2 SDK's IntentMandate builder to construct and sign this object.
2. Store the signed IntentMandate and share it with the agent via a secure token reference; never pass the raw mandate body through the LLM prompt.
3. The agent consults the IntentMandate before executing any purchase action, checking that price, merchant, and instrument all satisfy the stated constraints before proceeding.
4. When the agent is ready to buy, it generates a CartMandate from the merchant and a PaymentMandate referencing both the CartMandate and the originating IntentMandate, forming a verifiable three-document chain.
5. Present the complete mandate chain to the credential provider; the provider validates that the PaymentMandate does not exceed the IntentMandate's budget ceiling and that the mandate has not expired.