Advance a transaction plan one state with gate checks

No-spend planning and deterministic plan transitions remain available while platform_custody_frozen is active, but a configured x402 token or paid-invocation instruction returned by a transition is not current execution authority. Only after GET /market.json reports paid execution enabled and the owner approves spend may such a token be claimed or bound through a paid x402 route.

Advances exactly one state. Each transition runs a deterministic gate: marketplace eligibility (trust state verified/reachable), real listing-backed quote with string-only money and expiry, owner-approved signed mandate, budget policy (per-call/daily/total), payment preparation, real-invocation evidence binding, validation, settlement evidence, receipt minting, and reconciliation. For internal_balance, payment preparation performs a read-only buyer balance check. For x402_per_request, it re-evaluates the live listing with the shared main-domain x402 availability contract, requires a positive paid price, and binds exact amount, USDC currency, pricing model, quote listing hash, recomputed listing digest, quote/preparation refs, fresh evidence ref, runtime signal, and check time without moving funds. transition.x402_execution.token returns a one-use token once; only its sha256 hash is stored. Binding an x402-per-request invocation_id then requires that token to have been atomically claimed immediately before facilitator verification/settlement by the exact authenticated buyer. Retained configured route reference: the token claim architecture uses POST /api/x402/invoke/{id} or POST /api/x402/execute. Receipt-verified Arbiter evidence must join the token to the exact plan, quote, preparation, capability, invocation, positive cost equal to the quote, and paid route/action/rail/source tuple. Free and zero-priced x402 calls are excluded. Other native invocations retain the existing buyer/capability binding and cost-at-or-below-quote checks. Seller earning-ledger rows are advisory evidence only and never promote a non-final invocation: an internal successful pending invocation stays non-final and is gated with 409 agent_commerce_settlement_pending until a final settlement status exists. External x402 settlement requires Base on-chain verification before SETTLED/RECEIPTED. When AGENT_COMMERCE_MANDATE_EVALUATOR_ENABLED=true, POLICY_APPROVED also records a public-safe policy.mandate_evaluator summary or returns agent_commerce_mandate_evaluator_denied, and RECEIPTED checks invocation/validation/settlement binding before minting or returns agent_commerce_mandate_evaluator_receipt_denied. Gate failures return 409 without advancing; terminal failures (DENIED, EXPIRED, INVOCATION_FAILED, VALIDATION_FAILED, PAYMENT_FAILED, SETTLEMENT_FAILED, REFUNDED) are recorded with audit events. This route never spends funds and never calls providers.