[Phase 5] Credits, orders, entitlements and paid launch

[mrgoonie]

Depends on

• Epic [Epic] SkillX Marketplace & Agent-Native Platform Roadmap #31

• Phase 4 [Phase 4] Hook packs and AgentKit reference publishing #36

Objective

Attach commerce to an already-proven package delivery and entitlement system.

Delivery/security depends on Phase 4. Payment-provider approval work may run earlier, in parallel with Phases 2-4.

Scope

• Append-only buyer credit ledger.
• Top-up with verified provider events.
• Quotes/orders.
• Atomic debit + entitlement grant.
• Refund/chargeback.
• Agent-safe transaction confirmation.
• Provider/business-model approval gate.

Implementation tasks

• Add credit ledger entries and balance projection.
• Add top-up records.
• Add webhook inbox/dedup.
• Verify provider signatures and paid-state semantics.
• Add quote model + expiry.
• Add orders/order items.
• Add idempotent purchase command/API.
• Atomically debit + order + entitlement grant.
• Add already-owned handling.
• Add refund compensating entries.
• Add chargeback account/entitlement policy.
• Add seller payable placeholder accounting separate from credits.
• Add quote via CLI/MCP.
• Add transaction-specific confirmation contract.
• Test duplicate webhooks.
• Test duplicate purchase retries.
• Test concurrent debit/overspend.
• Document approved payment architecture.

Acceptance criteria

• No double-mint/double-debit.
• Concurrent purchase cannot create negative usable balance.
• Entitlement is traceable to grant/order.
• Every public representation still protects paid payload.
• Payment provider has approved the actual business model.

Milestone: paid launch.