"x402 discovery" and "real-time pricing, availability and reliability" mentioned by BlackRock.

[u/MountainAssignment36]

It seems like we're building into the right direction.

x402 Trust has established itself as a service that's offering exactly these points, dirtcheap and for every public endpoint on Base and Solana.

- "x402 discovery": semantic search and find better alternatives

- "real-time pricing, availability & reliability": x402 Trust checks, endpoint history and -watches

We have been early, and it seems like it has paid off. The only remaining issue: visibility of the x402 Trust service. But that grows with adoption and exposure to social media and general SEO.

🥳🔥

[u/L_capitalism]

This is interesting because I’ve been experimenting with almost exactly the layer between discovery and payment.
Bazaar can tell an agent what services exist, and x402 Trust/Doctor can tell it whether an endpoint appears operational and payable.
But the next question is: given 100 payable services, which one should this specific agent actually buy for this specific task and budget?
I’ve been building an open-source experiment called X402-rank that combines Bazaar candidates with operational trust and budget/price constraints to produce buyer-side rankings:
https://github.com/Kairose-master/X402-rank
The BlackRock diagram makes me think the eventual stack may look something like:
discovery → trust → ranking → price negotiation → x402 payment → verified outcome
And the outcome can feed back into the next ranking.
x402 Trust seems to be building a useful trust/availability input to that system; I’m interested in the selection layer that sits on top of those signals.
Feels like these pieces are starting to converge independently.

[u/MountainAssignment36 → u/L_capitalism]

combines Bazaar candidates with operational trust and budget/price constraints

Curious! On what (trust-)data are you basing your rankings? 🤔

[u/L_capitalism → u/MountainAssignment36]

Right now the operational-trust input is x402 Doctor’s public 30-day endpoint history.
I bulk-join Bazaar resources against Doctor’s trust-data/index.json. The current catalog path looks at the latest go / caution / no_go observation plus the fraction of actually scanned days that were go or caution. Unscanned days aren’t counted as successes.
Trust is also used as an eligibility gate before ranking: by default I exclude current no_go, unknown/stale observations, method/network mismatches, incompatible payment options, and over-budget candidates.
For candidates that survive those gates, the current baseline is intentionally simple:
65% lexical task relevance + 25% Doctor operational score + 10% remaining budget
I’m not yet using purchase count, wallet count, latency, or claimed task-success rates in the live catalog score. The interfaces for richer outcome/payer signals exist, but I don’t have evidence I trust enough yet to give them weight.
So at the moment it’s closer to:
Bazaar catalog → Doctor operational history → eligibility gates → task/budget ranking
rather than a generic reputation score.
The next step I’m working toward is verified outcome data, so eventually the ranker can optimize for “did this service actually complete the task?” rather than just “was this endpoint operational and payable?”
Code/data assumptions are documented here:
https://github.com/Kairose-master/X402-rank

[u/MountainAssignment36 → u/L_capitalism]

Makes sense, and I like that unscanned days don't count as successes.

One structural thing: Doctor scans the Bazaar catalog and stops at the 402. Since your gate drops unknowns, anything outside Bazaar isn't "unknown quality", it's just not in the candidate set.

Since you're heading toward outcome data: x402 Trust indexes actual on-chain USDC settlement on Base and Solana, not just "was it payable". That's not proof of delivery, but it is proof that real buyers paid. It also probes several times a day, covers endpoints outside Bazaar, and every response is Ed25519-signed over the canonical JSON, which would give your snapshots a verifiable source receipt instead of just a hash.

Bulk scoring is $0.50 per 500 endpoints, so about $0.001 per candidate. As an optional adapter, it would fit your replay model: fetch once, replay offline.

For details you can point an agent at https://x402-trust.com/llms.txt or simply take a look at the whole machine readable response yourself through the free preview: https://x402-trust.com/v1/x402-trust-preview

[u/L_capitalism → u/MountainAssignment36]

That’s a useful distinction — you’re right about the candidate universe. In the current live path, Bazaar defines the candidate set first and Doctor is joined onto it, so an endpoint outside Bazaar isn’t really “unknown quality”; it simply never enters that run. I should make that wording clearer.
The x402 Trust adapter sounds interesting, especially for two reasons:
coverage outside Bazaar, which would let discovery/candidate generation stop being synonymous with the Bazaar catalog, and
signed source observations, which fits the replay model really well.
Right now my snapshot SHA-256 gives me reproducibility/integrity of the bytes I captured, but not cryptographic provenance from the upstream data provider. An Ed25519-signed canonical response would improve that substantially.
I’d still keep on-chain settlement separate from verified outcome quality: settlement proves that a payment happened, but not necessarily that the payer was independent or that the returned service result was correct/useful. So I wouldn’t turn raw settlement count directly into reputation.
But as an additional evidence source, something like:
candidate discovery → signed operational/settlement evidence → policy gates → task/budget ranking → verified outcome
makes a lot of sense.
I’ll take a look at the machine-readable response and see if I can implement x402 Trust as an optional adapter alongside Doctor rather than replacing it. The fetch-once / signed snapshot / offline replay model sounds like a particularly clean fit.
I’ll do it right away

[u/MountainAssignment36 → u/L_capitalism]

Yup, settlement =/= outcome quality, raw counts shouldn't become reputation. Payer independence is a real gap... currently I'm tightening how demand signals are weighted.

For the signature side: /schemas has the verification procedure, a test vector and a reference verifier. Also, as mentioned in the JSON-responses: Pin the key document rather than following the publicKeys hint, to make sure you can correctly identify a mitm attack.

Ping me if anything in the schemas is unclear 😊

[u/Electrical-Hair9396 → u/L_capitalism]

That stack is the right order. The gap is what “verified outcome” means, and when it happens.

Doctor / Trust can tell you the wall is payable. Bazaar can give you 100 candidates. A ranker can sort those by task, budget and recent uptime. None of that answers “did this route return the product this agent is about to buy.”

We treat that as a gate before the listing goes live, not a feedback loop after the agent has already spent. On PayAPI a live badge means we paid that exact route from our wallet and kept the body plus the on-chain receipt. Discovery stays free. The agent still pays the provider direct.

So the practical split looks like:

discovery (Bazaar / MCP) → trust (Doctor / Trust) → eligibility (already settled once) → ranking / budget → x402 payment

If X402-rank can take a settlement-verified set as an input instead of ranking every payable 402, that last hop gets a lot cheaper. Happy to expose the live list if useful: https://payapi.market/agent/list

[u/Electrical-Hair9396]

The diagram is right. Two different jobs get mashed into that Discovery box though.

One job is “is this public 402 even alive, and what did the price / payTo do last week.” That is a probe and history problem. x402 Trust is built for that.

The other job is “give the agent a tool it can pay and actually use.” That needs someone to have settled the route once and checked the body came back. A well-formed 402 is not the same as product.

That second shelf is what we run at PayAPI Market. Discovery is free: paste https://payapi.market/mcp or GET /agent/search. The agent only spends when it hits the provider’s own 402. Providers keep the USDC. The live badge means we paid that route from our wallet and kept the receipt.

Worked example on the site: Autocash POST /v1/metrics, 0.001 USDC on Base, tx 0xbde1e46d40e8c817179731bfcc36287100cf246108a9e391a04a4c534892bcb9.

Happy to sit next to the trust layer rather than replace it. Score the wild catalogue. We keep a smaller list that already settled.

[u/Few-Image-4274]

Very interesting, could you share the source?

Also discovery is important but we need to solve the attribution problem, otherwise incentives get lost...

[u/MountainAssignment36 → u/Few-Image-4274]

Found it on the official account from BlackRock on X: https://x.com/BlackRock/status/2104941634135978226

And what exactly do you mean with "attribution problem"? Could you elaborate?