pact

PACT

PACT is a transaction and authority protocol for AI agents performing consequential actions inside web applications.

Most agent systems give an AI broad access to application tools and rely on instructions such as “only change these resources” or “do not touch billing.” PACT treats that model as insufficient for high-impact operations.

Instead, PACT turns every consequential task into an explicitly scoped transaction.

The workflow is:

Intent → semantic preview → exact-plan approval → scoped authority → commit → canonical verification → receipt.

Before any mutation occurs, PACT determines the exact effects required by the task. The human sees precisely what will change and what will not change. Approval is bound to the specific plan, its hash, and the canonical state on which it was created.

If the underlying state changes after approval, the plan becomes stale and commit authority disappears. The agent must re-plan and obtain approval for the new state instead of silently executing an outdated operation.

PACT includes protections for stale state, duplicate commits, idempotency, version conflicts, approval expiry, negative invariants, post-condition verification, audit integrity, rollback conditions, and transaction recovery.

Its key WebMCP contribution is that agent capability is not equivalent to permanent administrative access. Mutation capabilities can appear only after an exact transaction has been approved and disappear when the authorization is no longer valid.

The reference implementation demonstrates this through operations such as contractor offboarding, ownership transfer, access revocation, and protected resources such as billing or deletion.

The broader thesis is that agents should not receive permanent authority. They should receive narrowly scoped, temporary, verifiable authority for a specific approved transaction.

Accomplishments that we're proud of

What we learned

What's next for pact

Built With

• audit-receipts
• deterministic-verification
• exact-plan-hashing
• javascript
• optimistic-concurrency
• persistence
• scoped-capability-leases
• transaction-state-machines
• vercel
• webmcp