Positioning

One-line: s402 is the universal HTTP 402 server — it speaks every 402 dialect on the wire, offers six payment schemes no other protocol can express, and enforces every invariant on-chain instead of in server policy.

This page is the canonical positioning document. The landing page, pitch deck, grant applications, and outbound messages all pull from here. If it isn't written here, it isn't official positioning yet.

The Three-Pillar USP

s402's defensibility comes from three pillars that compound. Any one in isolation is commoditizable. Together they are uncopyable without a year of dedicated engineering and a Sui-native settlement layer.

Pillar 1 — Expressiveness

Six payment schemes as first-class protocol primitives.

Scheme	Use case	Competitors
Exact	One-shot per-call pricing	x402, MPP Charge
Upto	Variable-price APIs with ceiling	x402 (upto)
Prepaid	Deposit + batch for high-frequency access	MPP Session (partial)
Escrow	Arbiter-backed disputes	None
Stream	Per-second billing (inference, video)	None
Unlock	Pay-to-decrypt via SEAL + Walrus	None

x402 ships 2 schemes. MPP ships 1 formally registered intent. L402 ships 1. s402 ships 6. Three of the six (Escrow, Stream, Unlock) have no equivalent in any competing protocol — they require on-chain primitives (object ownership, PTB atomic settlement, threshold crypto) that the competitors' trust models don't support.

Pillar 2 — Universal Read

One server speaks every 402 dialect on the wire.

Dialect	Status	Module
x402 V1/V2 (Coinbase)	✅ Production	s402/compat/x402
MPP Charge — crypto rails (Stripe/Tempo)	✅ v0.6	s402/compat/mpp
MPP Accept-Payment	✅ v0.6	s402/compat/mpp
MPP Session	📋 v0.7	s402/compat/mpp
L402 (Lightning Labs)	📋 v0.7	s402/compat/l402
IETF draft-ryan-httpauth-payment	🟡 Partial via MPP	(reference impl path)
Google AP2 (Agent Payments Protocol)	📋 research	s402/compat/ap2
ERC-7824 statechannels	📋 watch	—

Any client speaking any dialect in the "Production" rows can hit an s402 server unchanged. A new dialect becomes a sub-path export (s402/compat/*) with its own conformance vectors — zero core pollution.

Pillar 3 — On-Chain Enforcement

Every scheme's invariants are Move contracts, not server policies.

• Upto ceiling — enforced by the Move contract; a server cannot overcharge even if compromised.
• Stream rate — physically bounded by the on-chain meter; no overdraw.
• Prepaid balance — atomic debit; double-spend impossible.
• Escrow release — arbiter-signed on-chain; no custodian can freeze.
• Unlock threshold — SEAL + Walrus; no single party holds the key.

x402 relies on server honesty + facilitator trust. MPP relies on Tempo's permissioned validator set + Stripe's fiat ledger. s402 relies on a permissionless public chain. This is not a marketing difference — it is a structural difference in what can go wrong and who bears the loss.

Why the Three Compound

• Expressiveness without universal read = a better protocol nobody can reach. Clients stay on what they have.
• Universal read without expressiveness = a translator with nothing to say. Clients use the source protocol directly.
• Neither without on-chain enforcement = a web2 payment rail wearing a crypto costume. Agents gain nothing over Stripe.

The full pitch only works when all three land in the same sentence: "You can pay us with any 402 dialect you already speak, we offer schemes your current protocol structurally cannot express, and every invariant is enforced by a Move contract rather than our server."

The Absorption Principle

s402 absorbs every 402 dialect we discover in production. This is a standing commitment, not a roadmap item.

Rule: when a new 402 dialect is identified in-the-wild, a compat layer plan is opened within two weeks. Each compat layer:

1. Lives in its own sub-path export (s402/compat/{name}) with zero core imports.
2. Implements the read path first (decode, translate to s402 types). Write path is a separate milestone.
3. Passes its own conformance vectors sourced from the dialect's canonical spec.
4. Documents exactly what it does not translate (e.g., processor methods, session intents, bespoke auth).

Explicit non-goals:

• We do not absorb fiat rails (Visa, ACH, card networks) — that requires becoming a card network, not writing code.
• We do not absorb protocols we cannot read structurally (closed-source, undocumented wire formats).
• We do not fork source spec semantics — we translate, never redefine.

What s402 Is Not

Clarity in positioning requires clarity in what we refuse.

• Not a wallet. Wallets sign payments; s402 is the server/resource/facilitator side.
• Not a card network. MPP wins on fiat rails; we coexist via Accept-Payment.
• Not a chain. s402 is chain-agnostic wire format; Sui is where all six schemes land natively today because of object model + PTB + SEAL, not because we are "a Sui protocol."
• Not a subset of x402 or MPP. We translate them; we are strictly larger in surface, enforcement model, and scheme count.
• Not closed. Apache-2.0, community adapters welcome, 161 conformance vectors public.

The Tagline Hierarchy

Use the tightest one that fits the audience.

• One word: Universal.
• One line: The universal HTTP 402 server.
• Two lines: Every 402 dialect on the wire. Six schemes no one else can express. Every invariant enforced on-chain.
• Paragraph: s402 is the universal HTTP 402 protocol for AI agents. It reads x402, MPP, and every other 402 dialect in production, so any agent can pay any s402 endpoint unchanged. It offers six payment schemes — Exact, Upto, Prepaid, Escrow, Stream, Unlock — three of which no other protocol can structurally express. And every scheme's invariants are enforced by Move contracts on a permissionless public chain, not by server policy.

How to Use This Document

• Landing page copy — hero tagline from the one-line, feature grid from the three pillars.
• Pitch deck — one slide per pillar, one slide on absorption, one on non-goals.
• Grant apps — three-pillar USP as the "why" section; absorption principle as the "defensibility" section.
• Outbound messages — tailor the tagline depth to the recipient's technical level; never shorten the three-pillar claim when it fits.
• When positioning drifts — fix it here first, then propagate. Don't let the landing page and pitch deck drift apart.

Change Log

• 2026-04-20 — initial version. Three-pillar USP codified. Absorption principle added. Non-goals locked.