[aksharprabhudesai]

Category (Required)

• Core Protocol: Changes to the base communication layer, global context, or breaking refactors. (Requires Technical Council approval)
• Governance/Contributing: Updates to GOVERNANCE.md, CONTRIBUTING.md, or CODEOWNERS. (Requires Governance Council approval)
• Capability: New schemas (Discovery, Cart, etc.) or extensions. (Requires Maintainer approval)
• Documentation: Updates to README, or documentations regarding schema or capabilities. (Requires Maintainer approval)
• Infrastructure: CI/CD, Linters, or build scripts. (Requires DevOps Maintainer approval)
• Maintenance: Version bumps, lockfile updates, or minor bug fixes. (Requires DevOps Maintainer approval)
• SDK: Language-specific SDK updates and releases. (Requires DevOps Maintainer approval)
• Samples / Conformance: Maintaining samples and the conformance suite. (Requires Maintainer approval)
• UCP Schema: Changes to the ucp-schema tool (resolver, linter, validator). (Requires Maintainer approval)
• Community Health (.github): Updates to templates, workflows, or org-level configs. (Requires DevOps Maintainer approval)

Description

The Python REST sample server was unconditionally setting checkout.status = CheckoutStatus.READY_FOR_COMPLETE at creation, even without buyer or fulfillment selection, but would reject complete_checkout with 400 until fulfillment address and option were selected (as noted in Universal-Commerce-Protocol/ucp#949).

This aligns the status assignment with the completion gate:

• Extracts fulfillment selection validation into _has_fulfillment_selection
• Sets ready_for_complete on create/update only when fulfillment requirements are satisfied; otherwise leaves status as incomplete
• Updates README example responses that lacked fulfillment to show incomplete
• Adds test_checkout_readiness_lifecycle covering the state transition from create (incomplete) -> update with fulfillment (ready_for_complete) -> complete (completed)

[google-cla]

Thanks for your pull request! It looks like this may be your first contribution to a Google open source project. Before we can look at your pull request, you'll need to sign a Contributor License Agreement (CLA).

View this failed invocation of the CLA check for more information.

For the most up to date status, view the checks section at the bottom of the pull request.