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# DOCS A2A M2M MCP x402 rails docs for testing results of major initiatives of SNTL DePIN Oracle SNTL DePIN Oracle (Helium / Hivemapper / and select DePIN projects) https://github.com/substreambc ## 🛰️ Ecosystem Overview SNTL is a deterministic machine-to-machine intelligence oracle engineered for decentralized physical infrastructure networks (DePIN). It exposes enriched on-chain events, RF physics propagation telemetry, spatial heuristics, and forensic state chronicles over an automated **x402 payment rail** settled in USDC on Solana Mainnet. PRIMARY DISCOVERY OBJECT FOR ALL PROJECTS LOOKS LIKE THIS Main x402 Challenge https://pop-os.tail08831d.ts.net/ Main A2A Agent Card https://pop-os.tail08831d.ts.net/.well-known/agent-card.json #TELEMETRY: The eyes into the complex system A2A is a small microservice in node/typescript #Test Phase A: Free Tier Routes (Verification)Confirm that non-payment routes operate with sub-5ms latencies:Bash# Health check curl -i https://pop-os.tail08831d.ts.net/health # Agent Card Discovery curl -i https://pop-os.tail08831d.ts.net/.well-known/agent-card.json # Telemetry curl -i https://pop-os.tail08831d.ts.net/__telemetry #Test Phase B: Simulated Unpaid Purchase (Assert 402)Verify that paid endpoints block unauthorized calls cleanly with a standard 402 Payment Required challenge: Bashcurl -i -X POST https://pop-os.tail08831d.ts.net/api/v2/query \ -H "Content-Type: application/json" \ -d '{"query": "SELECT * FROM telemetry LIMIT 1"}' Expected Output: HTTP/1.1 402 Payment Required with the required treasury wallet and price spec payload. Test Phase C: Live Signed Payment (Full E2E Settlement)Run a real agent query with attached payment header (X-Payment). Using sol fetch / @faremeter client or native TS test script:Bashcd ~/sentinel/a2a && yarn test:x402-purchase What this tests: Client: Receives 402, builds SPL-USDC transfer payload, signs with buyer keypair. Rail: Intercepts X-Payment header, validates onchain signature on Solana Mainnet. DB & Response: Executes query against Neon PostgreSQL with LIMIT 1 constraint and returns 200 OK with telemetry payload. Testing the x402 Payment Gate Perform an unauthenticated query against the datalake to verify the 402 Payment Required challenge: curl -i -X POST [https://pop-os.tail08831d.ts.net/api/v2/query](https://pop-os.tail08831d.ts.net/api/v2/query) \ -H "Content-Type: application/json" \ -d '{"sql": "SELECT * FROM enriched_events_base LIMIT 1"}' Tier Level,Endpoint Pattern,Price (USDC),Target Use Case Free Surface,"/stats, /ledger/:wallet, /health",$0.00,"System monitoring, wallet audit history" Tier 4 (Base),"/api/v2/query, /api/v2/threats/low",$0.01,"Raw datalake queries, low-severity events" Tier 3 (Medium),"/api/v2/threats/medium, /api/v2/pyramid/*",$0.50,"Scored wallet pools, medium anomaly events" Tier 2 (High),"/api/v2/threats/high, /api/v2/chronicle",$0.75,"High-threat telemetry, dimensional chronicles" Tier 1 (Critical),"/api/v2/rf/violations, /api/v2/threats/critical",$1.00,"RF physics spoofing, phantom device detection" PROPS TO: @TWZRD may integrate, we appreciate their "preflight" agent/wallet protection work and acknowledge it as historical documentation.