{"ok":true,"kind":"lesson","integrity":{"knowledge":"free","capability":"paid_x402_optional","rule":"Every concept on a path is fully teachable without purchase. Skills are optional implementations, never required reading.","display":"Learn free. Buy only if you want a ready-to-run sealed pack."},"lesson":{"schema_version":"lvl-knowledge-lesson-v1","id":"path-x402-01-canary-purchase-walkthrough","category":"path","path_ids":["build-first-x402-service"],"title":"Canary purchase walkthrough (concept + optional live)","summary":"Use a $0.05 skill as a practice loop so the first real failure is cheap.","body":"## Why a canary\n\nBefore an agent spends $25 on a pack, it should prove: wallet on Base, gas, USDC transfer, unlock JSON parse, re-redeem.\n\n## Conceptual walkthrough\n\n1. Read free outline for `agent-x402-first-buy`  \n2. Request 402 challenge  \n3. Confirm `maxAmountRequired` equals $0.05 in atomic USDC (50000)  \n4. Transfer exact amount to `payTo`  \n5. POST proof; persist sealed files offline  \n6. Re-POST same txHash to confirm idempotent redownload  \n\n## Optional live practice\n\nYou may run the real $0.05 unlock. It is **not required** to finish this path. The educational goal is the loop design.\n\n## Failure modes worth memorizing\n\n- Wrong chain (not Base)  \n- Wrong asset (ETH instead of USDC)  \n- Amount off by rounding  \n- Unlock too fast before confirmation  \n\n## Takeaway\n\nCanaries turn payment systems into learnable, testable loops.","concepts":["canary-purchase","base-usdc","first-buy"],"related_skills_optional":[{"skill_id":"agent-x402-first-buy","name":"Agent x402 First Buy","price_usd":0.05,"price_label":"$0.05 / unlock","summary":"$0.05 start-here: prove your agent can complete HTTP 402 → Base USDC → sealed pack unlock on lvlltd.com.","outline":"https://lvlltd.com/skills/agent-x402-first-buy/outline.json","challenge":"https://lvlltd.com/api/pay?skill=agent-x402-first-buy","listing":"https://lvlltd.com/listings/agent-x402-first-buy/","available":true,"optional":true,"label":"optional_implementation"}],"sort_order":10,"estimated_minutes":10,"last_updated":"2026-07-22T12:00:00.000Z","freshness":{"last_updated_at":"2026-07-22T12:00:00.000Z","days_since_update":0,"band":"fresh","score_0_100":95,"label":"Fresh","display":"Fresh · updated 2026-07-22 (0d ago)"},"integrity":{"knowledge_free":true,"skills_optional":true,"note":"This lesson is complete without purchasing any skill."},"related_bundles_optional":[],"url":"https://lvlltd.com/learn/lessons/path-x402-01-canary-purchase-walkthrough/","updated_at":"2026-07-22T21:10:40.587Z"},"note":"Knowledge free. related_skills_optional are implementations, not requirements."}