SETTLED
x402 confirmed
→Credits = 0
→return result
AI Agent Payments Infrastructure
AI Agent Payment Safety Pack
Safe pay-per-call payments for AI Agents.
Credits + x402 + safe fallback + settlement protection + idempotency + double-charge prevention.
For MCP · APIs · SDKs · AI Agents
One-time purchase
Failure mode
The Double-Charge Problem
A successful tool call can still enter a dangerous payment retry loop.
- 01Tool succeeds
- 02settlement request
- 03network timeout
- 04payment may already have moved
- 05unsafe retry
- 06Agent pays again
- 07DOUBLE CHARGE
Implementation edition
AI Agent Payment Safety Engineering Kit
The complete $99 architecture pack, plus an installable Python reference implementation, durable SQLite ledger, deterministic adapters, JSON Schemas, runnable examples, executable safety tests, reconciliation, and incident runbooks.
One-time purchase
Settlement classifier
Three States. One Safe Decision.
FAILED
explicit proof payment did not settle
→safe Credits fallback / safe retry
PAYMENT MAY HAVE MOVED
UNKNOWN
STOP- No Credits fallback
- No new accepts
- Do not pay again
Reference architecture
Payment Decisions Stay Explicit
01Agent / SDK
02Commerce Orchestrator
03Credits / x402
04Tool
05Settlement
06Ledger / Reconciliation
The orchestrator owns funding policy; settlement evidence controls the next safe action.
Non-negotiable rules
Safety Invariants
One Tool call → one final funding source.
x402 SETTLED → Credits charged = 0.
Credits fallback must be explicit.
UNKNOWN → never fallback.
UNKNOWN → never return new accepts.
Unknown payment state → stop instead of charging another rail.
Inside the pack
What’s Included
24chapters
01Credits billing
02x402 pay-per-call payments
03Credits ↔ x402 fallback
04Settlement state management
05Payment retry safety
06MCP / API / SDK payment integration
07SETTLED / FAILED / UNKNOWN classifier
08Reserve / Capture / Release
09Payment claim & replay protection
10Idempotency architecture
11Error → Conversion decision table
12Register / Upgrade / x402 conversion
13Agent / SDK PaymentPolicy
14Security & data minimization
15Reconciliation
16Observability
17Fault-injection testing
18Mutation testing
19Production rollout
20Incident rules
21Reference interfaces
22Orchestrator pseudocode
23Definition of Done
ArchitectureState MachinesError ContractsTest MatrixProduction Checklist
Built for production teams
Who It’s For
x402 API builders
MCP server developers
AI Agent infrastructure teams
API monetization platforms
Pay-per-call Tool providers
Teams combining Credits or subscriptions with wallet payments
ImportantThis is not a “how to send an x402 payment” tutorial.
Before you buy
FAQ
What do I receive?+
A structured architecture pack covering payment states, funding decisions, replay protection, reconciliation, test strategy, rollout, and incident rules.
Is this only for x402?+
x402 is the primary payment rail in the model, but the settlement and fallback principles apply to systems that combine an external payment rail with internal Credits.
Does it include implementation code?+
It includes reference interfaces and orchestrator pseudocode. It is an architecture and engineering pack, not a drop-in payment integration or hosted service.
Who is this for?+
Engineering teams building paid agent tools, MCP servers, API monetization, and mixed Credits plus wallet payment flows.
Why does settlement UNKNOWN matter?+
Because the payment may already have moved. Treating uncertainty as failure can trigger a second funding rail and charge the agent twice.
Can my team use it internally?+
The intended use is internal product and engineering work by the purchasing team. Final purchase terms will be shown when checkout becomes available.
AI Agent Payment Safety Pack
Make uncertainty a stop condition.
Not a second charge.
One-time purchase