Architecture deep-dive
Harbor is the evidence-evaluation runtime behind Kit — between an agent request to spend and a defensible release or refund outcome.
How proof-gated release works under the hood.
Paybond Harbor
Payment APIs can move money.
Harbor records what was agreed, what evidence arrived, and why the outcome was release, refund, or review.
Most teams integrate Paybond Kit and never land here. This page is for partners who need the agreement → evidence → release/refund detail behind the SDK.
Example Harbor record
Hotel sourcing agent booking
- Agreement
- Find refundable hotel under $1,200 by Friday
- Budget
- $1,200 reserved
- Evidence
- Booking receipt and cancellation policy submitted
- Decision
- Release approved
This is what Harbor produces.
Example Harbor record
Hotel sourcing agent booking
A buyer reserved budget for an agent to source a refundable hotel booking under a signed completion rule.
Released after evidence check
- Agreement
Find refundable hotel under $1,200 by Friday
The budget, deadline, parties, and completion criteria are captured before work starts.
- Budget
$1,200 reserved
Budget is authorized through the tenant's approved settlement configuration on customer-owned rails.
- Rail
Stripe Connect, configured for this workspace
The customer can request an allowed rail; Harbor resolves the destination from server-side tenant settings.
- Evidence
Booking receipt and cancellation policy submitted
Evidence stays attached to the transaction with submitter and timing context.
- Decision
Release approved
The record shows whether completion passed, failed, or needed human review.
- Reusable records
Settlement record, dispute case, audit export
Finance, risk, and partners can review the same transaction story outside the live console.
Transaction flow
Agreement to audit record
Harbor decides whether an agent has earned payment — and preserves the evidence behind that decision.
A payment result is not a completion decision
Payment API
Did money move?
Harbor
Should money have moved?
Payment APIs answer whether funds transferred. Harbor keeps the separate question—whether the agent earned release—explicit, reviewable, and tied to the agreement and submitted evidence.
How Kit and Harbor fit together
Kit is what you write against; Harbor is what runs the transaction. You use both — Kit in your agent, Harbor as the runtime behind it.
Kit
SDK you integrate into your application.
Harbor
Runtime that evaluates evidence and records release or refund.
A transaction record with a reason for the outcome.
Four concepts keep the transaction story together for buyers, operators, finance, and reviewers.
Agreement
Parties, budget, deadline, completion criteria, and evidence requirements are captured before work starts.
Intent lifecycle>Evidence
Signed evidence submissions and authenticated operator actions stay attached to the transaction instead of scattered across tools.
Evidence kit>Decision
A reviewable record shows the release, refund, or dispute outcome and the inputs behind it.
How agent settlement works>Audit record
Exportable records support audit, partner review, underwriting, and Signal standing checks.
Ledger and provenance>
Step 1
Define the agreement
Buyer and operator agree on participants, budget, deadline, completion criteria, and required evidence before work starts.
Intent lifecycle>- Parties
- Budget
- Criteria
Step 2
Reserve budget
Budget is authorized through an enabled rail (prefer Stripe Connect or x402) so the transaction has a clear release or refund path.
Configure settlement rails>- Authorize
- Reserve budget
- Rail path
Step 3
Submit evidence
The payee or agent attaches signed evidence showing what happened and who submitted it.
Evidence kit>- Submit
- Sign
- Attach
Step 4
Evaluate evidence
Harbor compares the evidence to the agreed completion criteria and records whether the check passed, failed, or needs review.
Disputes and evidence evaluation>- Agreement
- Evidence
- Check
Step 5
Decide the outcome
Harbor records release, refund, or human review with the inputs behind the decision.
How agent settlement works>- Pass
- Fail
- Review
Step 6
Produce the audit record
Teams receive settlement records and review trails for audit, partner verification, and Signal standing.
Ledger and provenance>- Settlement
- Dispute
- Export
When evidence does not prove completion
Harbor distinguishes the evidence check from the human review path, so automation and escalation stay understandable.
Evidence proves completion
Harbor records the passing check and the transaction can proceed to release through the configured rail.
Evidence fails the agreement
The failed check is preserved in the lifecycle, then the transaction can refund or move into review based on the agreed workflow.
Evidence is unclear or contested
Harbor opens a dispute path so a human reviewer sees the agreement, evidence, timeline, and notes before resolving release/refund through Harbor or recording a non-rail case outcome in Gateway.
Mental model
Think of Harbor as the transaction coordinator for AI systems.
It receives an intent, evaluates policy and evidence, coordinates release or refund on customer-owned rails, and issues a signed receipt.
See Harbor working
Each Harbor claim should point to a working flow, shipped rail, review path, or reusable record a buyer can inspect.
Walkthrough you can inspect
The public walkthrough follows an agent transaction from agreement to evidence, decision, and reviewable record.
Open walkthrough>Choose customer rails without changing your application.
Prefer tenant-configured Stripe Connect and USDC on Base (x402). Other enabled rails remain available where configured; Harbor resolves destinations from approved server-side settings.
Configure settlement rails>Live rails start on paid plans
Free Developer workspaces are for sandbox-only guardrail integration. Production release/refund on live rails requires a paid plan and configured tenant routing.
Review plans>Review path for unclear outcomes
When evidence is incomplete or contested, Harbor moves the transaction into review with the agreement, timeline, evidence, and notes together.
Disputes and evidence evaluation>Records beyond the console
Settlement records, compliance exports, and Signal standing checks give finance, risk, and partner teams proof they can reuse outside the live app.
Ledger and provenance>Harbor API reference
Integrate intent lifecycle, evidence submission, and settlement outcomes through the Harbor API.
Harbor API reference>
Where this architecture shows up
The same evidence-evaluation path applies wherever an agent workflow needs reserved budget, verified completion, and a record people can trust later.
Travel booking agents
Reserve budget for sourcing, release on verified booking evidence, and keep cancellation policy attached to the record.
Marketplace release-or-refund
Authorize tasks up front, release on verified completion, and resolve disputes against evidence instead of screenshots.
Autonomous procurement
Bind agent spend to completion criteria and produce records finance, compliance, and partners can review.
Insurance workflows
Gate release against policy terms, accept signed proof of service, and keep human review for contested claims.
Vendor payments
Reserve budget for B2B services, accept milestone evidence, and preserve the decision trail for AP and audit.
Construction milestones
Stage releases against signed completion evidence and route exceptions to review with the full transaction context.
Controls customers can explain.
A reviewer should be able to answer who agreed, what was funded, what evidence arrived, why money moved, and who intervened.
Controls
- Customer-scoped records are enforced from authenticated credentials, not form fields.
- Release, refund, and dispute decisions are recorded with who/what/when context.
- Receipts and exports give auditors and partners a replayable summary of the decision.
- Paybond records workflow rules around supported rails; payment processors and networks move funds under their own terms unless a written agreement says otherwise.