Document AgentCard checkout origin

[hiroTamada]

Summary

• Add optional checkout_origin to the AgentCard card spec shown in CLI help.
• Document the canonical origin format, autopilot matching behavior, approval fallback, and browser-origin validation limitation.
• Clarify that prepared checkout uses preparation.merchant_origin and that this field does not guarantee payment success.
• Keep raw spec forwarding unchanged and cover the field in forwarding/help tests.

Checks

• go test ./cmd
• make build
• make test (includes go vet ./... and go test ./...)
• git diff main...HEAD --check

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Note

Low Risk
Documentation and test-only updates; card spec JSON is still forwarded unchanged with no new client validation.

Overview
Documents optional checkout_origin on AgentCard card specs in the README AgentCard checkout example, vaults cards CLI help (AgentCardCardSpec), and related prose.

The new field is described as a canonical merchant HTTPS origin (with localhost HTTP for tests) that Kernel forwards to AgentCard for non-prepared autopilot rule matching, with explicit limits: no browser-side validation, autopilot/approval may still apply, no payment guarantee, and prepared checkout should use preparation.merchant_origin instead.

Tests add a raw-spec forwarding case for checkout_origin and assert the help text includes the field and autopilot/approval guidance.

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Cursor Bugbot has reviewed your changes using default effort and found 1 potential issue.

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[cursor]

Checkout origin dropped from JSON

Low Severity

Documented public checkout_origin is still absent from the display-safe spec allowlist, so create/get -o json silently drops the stored origin after the request is forwarded.

 

^{Triggered by learned rule: Filter vault secrets; print action URLs in full}

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[AnnaXWang]

cmd/vaults_help.go:73 — please retain main’s newer warning that card updates replace the whole spec, so omitting checkout_origin from an update removes its existing value.