[cryptodinn]

Paid tasks could complete while an agent lost the response, then a retry looked like a new payment failure. This PR documents the verified recovery and response contracts across the Base and Solana x402 gateways, including the review follow-ups in BlockRunAI/blockrun#968 and BlockRunAI/blockrun-sol#559.

• Explain original-credential task recovery, fresh wallet ownership proofs and the 24-hour read window. Search remains synchronous by default; Prefer: respond-async opts into 202, and a legacy retry receives 409 with the original pointer.
• Explain Solana image generation/edit recovery before spent/expired-transaction verification, the original payment disposition gate, and unchanged batch/completion billing. A job URL or historical transaction alone does not grant content access.
• Document bounded DeFiLlama pages and uncharged 400 refusals for projections that contain only empty objects, alongside media MIME, pricing, model discovery, request parameters and free message authentication.
• Separate the application read window from 2-day lifecycle eligibility and later soft-delete/version retention. Production lifecycle application remains blocked by the operator's missing bucket-update permission; the code PRs include an explicit preflight and operator runbook.

Validation: checked the changed Markdown and relative links against the companion route/helper implementations and passing regression tests. No application deployment or paid production retest was performed. Scope is the Base/Solana x402 gateways; the separate MPP gateway has its own contract.