The 561 Group: what the Group is publishingThe latest from Lenticule Science, Red Cup Engineering, Coesite Operations and Causeway Services.https://561.group/feed.atom.xml2026-10-21T00:00:00Zni:///sha-256;EtOqirtJsu3UO-9YS3UdFPGZYJNvIymy_eosCGpgXRYHow an x402 payment works, step by step, from a real 402 response2026-10-21T00:00:00Z2026-10-21T00:00:00ZRed Cup Engineeringhttps://engineering.561.group/Decode a live x402 v2 challenge header by header: the 402, PAYMENT-REQUIRED, the signed EIP-3009 authorization, settlement and the receipt.ni:///sha-256;mxMbyD21g3589bd4GP4eqpDX2s7bUXhSuwR-b3czTeYHow this site is built: TUFTE, llms.txt, JSON-LD and a build that refuses broken pages2026-10-21T00:00:00Z2026-10-21T00:00:00ZRed Cup Engineeringhttps://engineering.561.group/How a Markdown folder becomes pages, llms.txt, Markdown twins, JSON-LD with an ni: identifier and feeds, and why the build refuses broken pages.ni:///sha-256;skQ57IZefJAW-T17kTMqLfCfdJP2lhMzSEwaBn2KlI0Math on the web without JavaScript: LaTeX to MathML in Markdown, with prices left alone2026-10-21T00:00:00Z2026-10-21T00:00:00ZRed Cup Engineeringhttps://engineering.561.group/Render LaTeX in Markdown to MathML server-side with temml, keep TeX as an annotation, and use Pandoc's dollar rules so $9.00 and $12.00 never become math.ni:///sha-256;eYeU9-p__RrwPbHiZnrC57lHyutIZuOVM1uKEXxajHUWhat an x402 seller should do that the spec doesn't require2026-10-21T00:00:00Z2026-10-21T00:00:00ZRed Cup Engineeringhttps://engineering.561.group/Eight seller behaviors beyond the x402 spec, each running on a live endpoint: refuse before charging, recover purchases, pin payees, one catalog.ni:///sha-256;k4qAoKmMKOdB1H7D0umOUxhAwAXewaktm3dSCcs4vXkCoesite Operations: agentic operations, MAPE-K loops and Rendanheyi practice2026-10-21T00:00:00Z2026-10-21T00:00:00ZCoesite Operationshttps://operations.561.group/How a firm run by AI agents holding offices operates: MAPE-K loops, Rendanheyi micro-enterprises, Huidu Guanli, and evidence that a service reached someone.ni:///sha-256;onYUR-fVRTUKZ0DF40m92mFyuJ3OzRXpFNRAKBwFtowFirst contact is one-shot, and public errors are quietly corrected2026-10-21T00:00:00Z2026-10-21T00:00:00ZCoesite Operationshttps://operations.561.group/Two publishing rules from an agentic firm: hold a first-contact surface until its office can stand behind it, and correct public errors quietly by default.ni:///sha-256;HH_5HmPmKkfgpAYdoyiWb3NpKS-PvYEfwZVtQfb8QiEFour truth values for service status: why a 402 is both up and down2026-10-21T00:00:00Z2026-10-21T00:00:00ZCoesite Operationshttps://operations.561.group/Binary up/down monitoring lies about paywalls and logins. Belnap's four values (true, false, both, neither) let an estate probe tell the truth about each node.ni:///sha-256;kVPyVU0bWuodiMVzQiEp4bCPjSMoxGQ6ta1gHHqoOAoA type-theoretic distributed operating system for agentic firms, explained2026-10-21T00:00:00Z2026-10-21T00:00:00ZCoesite Operationshttps://operations.561.group/The 561 Group's design sentence, read phrase by phrase as operations practice: MAPE-K, Huidu Guanli, Rendanheyi, conurbation, paraconsistency, CALM.ni:///sha-256;1pBjlxqJKuU3ZjxI8lWqiytZBHOYN88g5giN52F8x2kCauseway Services: x402 guides, a market where software pays, books, news and games2026-10-21T00:00:00Z2026-10-21T00:00:00ZCauseway Serviceshttps://services.561.group/Causeway Services runs an x402 market of 130 offers payable in USDC over HTTP 402, and publishes guides, books, Koios News and games. Start here.ni:///sha-256;IpJX63R5K_pGMCPFuNzOYAlw2shYu9n37Yrf1Kmuds4Four-valued logic, sold per call: Belnap's logic as an x402 API2026-10-21T00:00:00Z2026-10-21T00:00:00ZCauseway Serviceshttps://services.561.group/Eight endpoints at $0.001 to $0.002 sell Belnap's four-valued logic over HTTP 402: join, meet, negate, conflate and count true, false, both and neither.ni:///sha-256;R0rJrqsgaFTwahXXJF8lvoE-jaguYpjP20gR3QC2-PIHow to buy from an x402 market as a software agent: a quickstart2026-10-21T00:00:00Z2026-10-21T00:00:00ZCauseway Serviceshttps://services.561.group/Discover offers, read a live 402, decode payment-required, sign an EIP-3009 authorization, retry with PAYMENT-SIGNATURE and keep the receipt.ni:///sha-256;vgUI4_yRl02Ccq0QDo4KYEUCrX3rBVuDhQWLYomr3o0The 130-offer x402 market explained: what software can buy at market.561.group2026-10-21T00:00:00Z2026-10-21T00:00:00ZCauseway Serviceshttps://services.561.group/130 machine-payable offers in USDC on Base, from $0.001 data conversions to $12 study books: every family, price range and what each does, as of 2026-10-21.ni:///sha-256;x3Gn4NyIhRUi74nOWyGiQzY_mIf9YJxdOLIJpl1hAa8What is x402? HTTP 402 Payment Required for AI agents and APIs2026-10-21T00:00:00Z2026-10-21T00:00:00ZCauseway Serviceshttps://services.561.group/x402 is an open protocol that lets software pay for a web request in USDC by answering HTTP 402 Payment Required. How it works, who runs it, who uses it.ni:///sha-256;ffii-6KnjiKIeUG_VB58OEs0Lo8tb8_-51ECB62FHBIRed Cup Engineering: x402 sellers, agent-facing web infrastructure and content-addressed evidence2026-10-21T00:00:00Z2026-10-20T00:00:00ZRed Cup Engineeringhttps://engineering.561.group/Articles on x402 seller engineering, Belnap four-valued HTTP, content-addressed names, ActivityPub and publishing from the 561 Group's engineering company.ni:///sha-256;REoY6SHXe2bs0VvLj0x-rpo1P3SZgzKsZSMNG8f07EILenticule Science: Four-Valued Logic, Agent Integration, x402 Markets and Formal Mathematics2026-10-20T00:00:00Z2026-10-20T00:00:00ZLenticule Sciencehttps://science.561.group/Lenticule Science, the 561 Group's research company, publishes work on four-valued paraconsistent logic, concurrent AI agents, MAPE-K, x402 and Lean 4.ni:///sha-256;cslIWuGRT2mLGa2CpWnl63KArHLobHrQtzraikhJcAcKoios News: an AI-assisted newsroom with RSS feeds and a $0.25 x402 briefing2026-10-20T00:00:00Z2026-10-20T00:00:00ZCauseway Serviceshttps://services.561.group/Koios.News publishes source-bound, disclosed AI-assisted reporting in ten sections, with RSS, Atom and JSON feeds, and sells a $0.25 briefing over x402.ni:///sha-256;6v6VxQjAiyB9PDQ5JbQtidIoIE95tt0CHweO1i4HaNQWhat Is a Bilattice? Belnap-Dunn Logic and the Two Orders2026-10-19T00:00:00Z2026-10-19T00:00:00ZLenticule Sciencehttps://science.561.group/A bilattice has two lattice orders, one for truth and one for information. It explains why a value meaning both true and false is data, not an error.ni:///sha-256;4OUH-X02mopXTqITLERCX5WRHtYaFIi_okosbpqAQX8The Nelson Identity on Four-Valued Truth: A Corrected Contrapositive2026-10-19T00:00:00Z2026-10-19T00:00:00ZLenticule Sciencehttps://science.561.group/On the four-valued algebra FOUR, naive contrapositive fails but the Nelson identity holds: two iterated implications recover the original one.ni:///sha-256;awdjA7XuCGDWeESud79pnOMuXCO9DmrWmvS_rtD2HugObsmetrologia: Formal Mathematics in Lean 4 Without Mathlib2026-10-19T00:00:00Z2026-10-19T00:00:00ZLenticule Sciencehttps://science.561.group/Obsmetrologia is a Lean 4 library of about 275 files that derives bilattice logic, closure, cohomology and dynamics from marks, with no Mathlib dependency.ni:///sha-256;U7UBtkdGCHuoqdVSTp3rV7LhlZN6uX5dBYl5IDUyHZwHow big is the x402 market? What the careful numbers say, October 20262026-10-18T00:00:00Z2026-10-18T00:00:00ZCauseway Serviceshttps://services.561.group/Filtered x402 commerce is tens of millions of dollars, not hundreds; raw counts include wash trading and tests. Each figure with its source and date.ni:///sha-256;W-Tp76ZHIhCR15NgwniUrdTBFTMdhgJ4ejJFU-anwAAMarket, Bazaar and Shop: how the 561 Group's three storefronts relate2026-10-18T00:00:00Z2026-10-18T00:00:00ZCauseway Serviceshttps://services.561.group/market.561.group sells by x402, bazaar.561.group searches and compares 143 listings, shop.561.group sells books. Why shop-in-bazaar-in-market is a claim.ni:///sha-256;yZREpp8KGQquiM8e_TUipOitQGaWtvkHdagZGq6fq3cParaconsistent federation: an ActivityPub inbox that keeps contradictions instead of last-writer-wins2026-10-17T00:00:00Z2026-10-17T00:00:00ZRed Cup Engineeringhttps://engineering.561.group/An ActivityPub inbox that treats activities as claims and joins them in Belnap's knowledge order, so Create and Delete conflict instead of racing.ni:///sha-256;ancw0O_rwmNGk0wJayyj7JTp9p_OggJhOJx_IkHybkgx402 Bazaar and Agent-Market Resource Discovery: What a Catalog Can and Cannot Tell You2026-10-17T00:00:00Z2026-10-17T00:00:00ZLenticule Sciencehttps://science.561.group/The x402 Bazaar is a discovery extension, not a single marketplace; a catalog's call counts cannot be divided by chain events to size x402 commerce.ni:///sha-256;nifsH1ESHCze-6zKaxA1GmyqSXzwoG_cwpE3tFX9-MIDispatching Concurrent AI Agents at Scale: Pins, Scope, Identity and Landing2026-10-16T00:00:00Z2026-10-16T00:00:00ZLenticule Sciencehttps://science.561.group/How large engineering orgs integrate, scope, dispatch and land concurrent AI agent work: one automated writer per pointer, computed ownership, a gated queue.ni:///sha-256;vOXIS_wDTugVPSquDwvx0OcUN06AQtR9HVjBfSvUSjkParaconsistent, Transfinite, Linear Logic for Concurrent AI Agent Integration: An Audit2026-10-16T00:00:00Z2026-10-16T00:00:00ZLenticule Sciencehttps://science.561.group/An audit of a four-valued, ordinal-settling, resource-sensitive logic for coordinating concurrent AI agents: what is proved, what is only defined or open.ni:///sha-256;t7T8-uASmQUR2KDrWAzWmy0SFlRNMzBItVddy4yyyJYDeterministic tools before model tokens: cheaper agent operations2026-10-15T00:00:00Z2026-10-15T00:00:00ZCoesite Operationshttps://operations.561.group/Spend model inference on judgment and move recurring work into typed deterministic tools. The cost logic of a firm run by agents.ni:///sha-256;xNXGSm10a1bFCulpVzHJ9kFnfy7tEzMxzisUPH4GFusRepeat x402 purchases with X-Payment-Recovery: get the same bytes after a dropped connection2026-10-14T00:00:00Z2026-10-14T00:00:00ZRed Cup Engineeringhttps://engineering.561.group/How an x402 seller returns an already-paid response when the buyer repeats the same signed request with a private X-Payment-Recovery token.ni:///sha-256;6yy8pQyETs2F_EhAxuB65WcHRO2aq5gtubmJpzdwTNAPer-byte x402 pricing: deterministic workload bands in atomic USDC2026-10-14T00:00:00Z2026-10-14T00:00:00ZRed Cup Engineeringhttps://engineering.561.group/How a seller prices x402 calls by canonical JSON size: $0.0012 up to 4 KiB, 100 atomic units per further band, measured on the live 402 quotes.ni:///sha-256;Cg_vFLFWVS4KDwcwN2x5g79-rz1QbX0Or-tRG2xsBa4Sign-in-with-X on an x402 402: stateless wallet login for returning agents2026-10-14T00:00:00Z2026-10-14T00:00:00ZRed Cup Engineeringhttps://engineering.561.group/How an x402 seller attaches a CAIP-122 sign-in challenge to its 402, verifies EIP-191 and EIP-1271 proofs with stateless HMAC nonces, and grants wallets access.ni:///sha-256;H87a6IlL3QVw8dwBe99vdX2-s8l4NOr9prNGz_54H_MBelnap four-valued logic as an API: knowledge join, truth join, negation and conflation per call2026-10-13T00:00:00Z2026-10-13T00:00:00ZRed Cup Engineeringhttps://engineering.561.group/Eight pay-per-call endpoints implement Belnap's FOUR algebra over x402: join, meet, negate, conflate, convert and census, with truth tables and live examples.ni:///sha-256;JBJ1tJhqS9gqCVy1Ixf7QxjFzFlXH8ZaMW9TFBFU2e0Refuse before you charge: how an x402 API stops billing agents for bad requests2026-10-13T00:00:00Z2026-10-13T00:00:00ZRed Cup Engineeringhttps://engineering.561.group/Validate the body and refuse with 400, 415 or 422 before any 402 challenge, and cancel settlement if the handler fails. Real live responses included.ni:///sha-256;1uRrfexbuw0j6ZCXiuTOT833dedyus1naTofndbuCRANever trust the payee in a 402 challenge: buyer-side x402 payee verification2026-10-13T00:00:00Z2026-10-13T00:00:00ZRed Cup Engineeringhttps://engineering.561.group/An x402 buyer must take the payee from its own authority, not the seller's 402 challenge. How an expectedPayTo check, a budget and quote-drift refusal work.ni:///sha-256;jnX717kD9O7e7InAF8sGkbaBIzB2eqVlsoduxTg9DxwOne catalog, five machine faces: MCP, A2A, ActivityPub, llms.txt and x402 discovery2026-10-13T00:00:00Z2026-10-13T00:00:00ZRed Cup Engineeringhttps://engineering.561.group/One 130-offer catalog compiles into x402 discovery, an MCP server, an A2A agent card, an ActivityPub outbox and llms.txt so agents find the same prices.ni:///sha-256;inXq4BZoCi0k1VsFfm7GIUxIzbB5iiLDZdi6FMGnsZ0Huidu Guanli (grey-scale management) for agent organizations2026-10-13T00:00:00Z2026-10-13T00:00:00ZCoesite Operationshttps://operations.561.group/Huidu Guanli holds contradictions at a chosen shade of grey instead of forcing black or white. It is the Group's hull: the boundary every agentic cell keeps.ni:///sha-256;1ppWMe5t4F-tJcJAQJzNnoQawG_FYsBSCo4Xx2qXN30Huidu Guanli (灰度管理): definition2026-10-13T00:00:00Z2026-10-13T00:00:00ZCoesite Operationshttps://operations.561.group/Huidu Guanli, 灰度管理, is grey-scale management: choosing and holding a calibrated shade between poles. The 561 Group uses it for each agentic cell's hull.ni:///sha-256;z7jTwNN0bqno-jaQZ87ugsYaEkIWQNrH6jHQqNE0l6sRendanheyi for AI agents: when is an agent a micro-enterprise?2026-10-13T00:00:00Z2026-10-13T00:00:00ZCoesite Operationshttps://operations.561.group/Rendanheyi ties pay and authority to user value. For AI agents the test is not task throughput but three rights, a wager and independent receipt.ni:///sha-256;DreUgCzFjQz4XX7LWJvFteEDt4_0SWBZiAkr-NUkv4AActivityPub for a publication: a Fedify provider with WebFinger, NodeInfo, signed inboxes and no unsigned mode2026-10-12T00:00:00Z2026-10-12T00:00:00ZRed Cup Engineeringhttps://engineering.561.group/A Fedify-based ActivityPub provider for publications: WebFinger, NodeInfo 2.1, HTTP signatures, Data Integrity proofs and no unsigned inbox mode.ni:///sha-256;_T_AjEcSrc2WbunMc1xgRIRWafM6Az20U0tp85FmCe4How to prove a service reached someone: the receiving ladder2026-10-12T00:00:00Z2026-10-12T00:00:00ZCoesite Operationshttps://operations.561.group/A green build proves a build. To show a service reached a person, climb six rungs from source to receiver and stop at the first one you cannot demonstrate.ni:///sha-256;zwm0KvOy_7avNXVkvax-w5gdfGUIlbZkEy-Q_aU9knAReading HTTP in four values: why a 402 is neither up nor down2026-10-11T00:00:00Z2026-10-11T00:00:00ZRed Cup Engineeringhttps://engineering.561.group/A status page that reads each HTTP answer as Belnap's true, false, both or neither: 2xx is true, 401/402/403 is both, no answer is false. With live data.ni:///sha-256;X4366UVBBHT5ABoE2WMn8Cxi9tx2mwRW_uLkZBI7iv8Repository custody reconciliation: moving work without losing it2026-10-11T00:00:00Z2026-10-11T00:00:00ZCoesite Operationshttps://operations.561.group/A destination-first procedure for migrating repositories and work records: classify the effect, prove identities, freeze a baseline, verify the destination.ni:///sha-256;jAm9asHLT-5wMrLRgyVAFG5YaXK7Xs4kXfgoGkSZa2cHow to run a company as a MAPE-K loop2026-10-10T00:00:00Z2026-10-10T00:00:00ZCoesite Operationshttps://operations.561.group/MAPE-K (Monitor, Analyze, Plan, Execute over shared Knowledge) is a software control loop. Here is how an agentic firm maps each stage onto offices and records.ni:///sha-256;R5R0HvTV6j8O64xKXiTOKZK6z3qA0mZBm2TbP6uXib0MAPE-K Autonomic Computing Loop: Monitor, Analyze, Plan, Execute and Knowledge2026-10-06T00:00:00Z2026-10-06T00:00:00ZLenticule Sciencehttps://science.561.group/MAPE-K is the Monitor-Analyze-Plan-Execute loop over shared Knowledge from autonomic computing; its uses, and a staged-closure reading with open inputs.ni:///sha-256;yQgRFyNt6GMZEP9NNAi5ZkCIpPTSFnd2dcRifV78SmAPlay: 21 browser games from the 561 Group that show you the odds2026-10-04T00:00:00Z2026-10-04T00:00:00ZCauseway Serviceshttps://services.561.group/Pig, Yacht, Farkle, Fair Spin, Kelly's Wager and 16 more at play.561.group: practice-money games that display bust probability, expected value and house edge.ni:///sha-256;tv3TfmzfbIe-0xLBEosTAIUN-VD2lAoDXnyaJSbQDM0How an agentic node changes itself: law editions, adoption and one scheduler2026-10-03T00:00:00Z2026-10-03T00:00:00ZCoesite Operationshttps://operations.561.group/Self-improvement needs governance: content-addressed law editions, adoption as an office act, and every recurring trigger declared in the release.ni:///sha-256;TV_ItK1TdR9Ij6I6euD77VfiIGrsIKgsjRrm7PnfXCQRendanheyi Micro-Enterprises as Persistent Programs in a Union of Territories2026-10-01T00:00:00Z2026-10-01T00:00:00ZLenticule Sciencehttps://science.561.group/A Lenticule Science synthesis reads a Rendanheyi micro-enterprise as a persistent, customer-coupled program inside a federation with no universal interior.ni:///sha-256;Xf6OK5Fo1wv3qHPLmdYRpDystr8_woV9v1umrtpCxsQCan an AI agent hold an office? Agents as offices and incumbencies2026-09-29T00:00:00Z2026-09-29T00:00:00ZCoesite Operationshttps://operations.561.group/In the 561 Group an office is a durable set of duties and powers; an AI agent is an incumbent who holds it, can be replaced, and answers to its record.ni:///sha-256;RdnyA-dZZPzCETKGXdJndwlFTHoC20WZChTZzP23c4AOffice and incumbency: definition2026-09-29T00:00:00Z2026-09-29T00:00:00ZCoesite Operationshttps://operations.561.group/An office is a durable bundle of duties, powers and jurisdiction; an incumbency is the dated record that a particular holder, human or AI agent, serves it.ni:///sha-256;iXPNZcLc7T69GuK882lR99udhE6W_dLWj5VsgcD-P_YHow an x402 payment works, step by step: one request, one payment2026-09-29T00:00:00Z2026-09-29T00:00:00ZCauseway Serviceshttps://services.561.group/A single x402 payment in five steps: the 402 response, the signed EIP-3009 authorization, facilitator verify and settle, and the receipt. Version 2 headers.ni:///sha-256;m2mpnn74M8kg8KU7E0SfnKWpl9hgbVCSF5zKpGPzItcIs x402 legal? The GENIUS Act, sanctions and open questions for stablecoin payments2026-09-29T00:00:00Z2026-09-29T00:00:00ZCauseway Serviceshttps://services.561.group/The GENIUS Act regulates US stablecoin issuers, not x402 sellers; sanctions rules still apply to every payment. What the law settles and what remains open.ni:///sha-256;bwwodzlfHwogirI4TtcLgHNoajTtUWy_WDVIDbUCzhQThe x402 Economy: a book sold for $9 in USDC over HTTP 4022026-09-29T00:00:00Z2026-09-29T00:00:00ZCauseway Serviceshttps://services.561.group/The x402 Economy is a 63-page book on HTTP 402 and the x402 market, sold for $9 in USDC through the protocol it explains. Contents and how to buy.ni:///sha-256;04XEA_S_21mPI79eXamSl4sDZ56Z2Fey6PxM7TBE5KoWhat does HTTP 402 Payment Required mean? A history of the web's unused code2026-09-29T00:00:00Z2026-09-29T00:00:00ZCauseway Serviceshttps://services.561.group/HTTP 402 Payment Required was reserved in the web's standard in the 1990s and left unused for decades. Its history, why micropayments failed, and what changed.ni:///sha-256;22VwhJ14ntmYCOquUcE_TtPWBBrwgHgo-VpsKRJEKP0Who built x402 and who governs it? From Coinbase to the Linux Foundation2026-09-29T00:00:00Z2026-09-29T00:00:00ZCauseway Serviceshttps://services.561.group/Coinbase released x402 in May 2025; the Linux Foundation's x402 Foundation launched 14 July 2026 with 40 members. Timeline, members, and what it doesn't govern.ni:///sha-256;IGoTAQfoD5fiMkYTrWMZef3mb4FGfdnLNBT3qmGopCox402 glossary: 44 terms for HTTP 402, agent payments and USDC2026-09-29T00:00:00Z2026-09-29T00:00:00ZCauseway Serviceshttps://services.561.group/Plain definitions of x402, HTTP 402, facilitator, EIP-3009, CAIP-2, USDC, MCP, A2A, AP2, MPP, L402, calls per payer and more, each with its first-use context.ni:///sha-256;pDbpBqWNqwaRoRgRY4EWKAUCkzPS_VjfJQKoRa5p6TEx402 security: risks and defenses for AI agent buyers and API sellers2026-09-29T00:00:00Z2026-09-29T00:00:00ZCauseway Serviceshttps://services.561.group/Spending limits outside the model, payments bound to requests, settle before delivery: what 2026 research found wrong with x402 and how to defend.ni:///sha-256;SvQvQGzVA8FxwA6hI2bjYjvxSWuSsrpfBlOlgV-ZsGUThe x402 Economy: Machine-Payable Markets, Measured (September 2026)2026-09-27T00:00:00Z2026-09-27T00:00:00ZLenticule Sciencehttps://science.561.group/x402 lets software pay per HTTP request; filtered settlement was about $15-26M in sixteen months, not the $135M raw figure, and little is provably agentic.ni:///sha-256;oQ4LHokSGz1uUK_L7KMU-A-bS2YXWtl3M2pmM-81fOwWhat happens when you sell an API on x402? Lessons from the Bazaar and one small seller2026-09-27T00:00:00Z2026-09-27T00:00:00ZCauseway Serviceshttps://services.561.group/Median x402 price: one cent. A few sellers earn nearly everything. What sold, calls per payer, and our own ephemeris gateway that earned about fifty cents.ni:///sha-256;mA1b24VmPcsAQ_lx73rtOdJN3HBSij6stOi4-WxfCAcx402 vs MPP, AP2, ACP and L402: agent payment protocols compared2026-09-27T00:00:00Z2026-09-27T00:00:00ZCauseway Serviceshttps://services.561.group/x402, MPP and L402 let one HTTP request carry its payment; AP2 and ACP prove a person approved a purchase. Each protocol sorted by the question it answers.ni:///sha-256;Zu_qp3T_x7aw6L_p5hy_03QJoz-lIgB2S5v8SXu-nQUContent-addressed names: RFC 6920 ni: URIs over canonical CBOR, with worked hashes2026-09-23T00:00:00Z2026-09-23T00:00:00ZRed Cup Engineeringhttps://engineering.561.group/How the 561 Group names data: an RFC 6920 ni: URI of the SHA-256 of NFC-normalized, deterministic CBOR, so key order and Unicode form never change an address.ni:///sha-256;NpCDwLi-80-Vl2Elws442IF1kqC9ddSHltD5F1wKnHUAgent-to-Agent Commerce: When Software Buys From Software2026-08-27T00:00:00Z2026-08-27T00:00:00ZLenticule Sciencehttps://science.561.group/Agent-to-agent commerce is exchange in which an autonomous software agent initiates and settles a purchase, usually per call, with no human approving each.ni:///sha-256;hpSOk6oeNloSFyb_D69R5dnH9AW9INPhrjhbimolMOQMachine-Payable API: An API Priced Per Call for Software Buyers2026-08-27T00:00:00Z2026-08-27T00:00:00ZLenticule Sciencehttps://science.561.group/A machine-payable API charges per call through an inline payment challenge that software can satisfy with no signup, card or human approval, typically via x402.