BLURT/USD price source research

Status: Research notes (not a design decision) Date: 2026-04-21 Scope: Evaluate five proposed additional price sources beyond the existing Klingex + Coingecko pair. Interacts with: ADR-0011 (fee model consumes price), OPERATIONS.md §13 (stale-price runbook)

Context

The indexer's price path today:

Klingex → Coingecko → static_floor

Composite source with the first live feed winning, TTL cache, and background refresh. priceSource.current() returns the BLURT/USD rate used by order fee verification in apps/indexer/src/indexer/handlers/order.ts.

The revisit list asked for evaluation of five additional sources: Tribaldex, Hive-Engine, CoinMarketCap, Blockchair, Blockchain.com. This document records what I found about each and a recommendation for or against integrating it.

The goal of additional sources is not diversification for its own sake — every new source is another background HTTP request, another failure mode, another API policy to track. Additional sources earn their place only if they narrow a real gap in the existing chain.

Source-by-source findings

CoinMarketCap — FEASIBLE, API KEY REQUIRED

Endpoint: https://pro-api.coinmarketcap.com/v1/cryptocurrency/quotes/latest?slug=blurt&convert=USD
Auth: X-CMC_PRO_API_KEY header. Free tier exists with daily call-credit limit; paid tiers for higher volume.
Response shape: data.<id>.quote.USD.price (number, USD per BLURT). Timestamp in data.<id>.quote.USD.last_updated.
BLURT is listed on CMC (slug: blurt).
CAVEAT (important): the BLURT page on coinmarketcap.com/currencies/blurt shows $0 USD trading volume as of 2026-04-21. This means either (a) CMC isn't aggregating volume from Tribaldex / Hive-Engine sidechain pools (the main BLURT trading venue today), or (b) the listing is stale. A price source that reports $0 volume is a red flag even if it reports a non-zero price — the price may be a frozen historical value, not a live rate. Operator verification required before making this a primary or secondary source.
Policy risk: CMC Terms of Service allow API use for data display, including commercial use on paid tiers. Free-tier limits (typically ~10,000 credits/month) are enough for an operator polling once every 60s (43,200/month) only on the lowest paid tier — free-tier polling must be slower (>5-min interval) to stay under.
Recommendation: FEASIBLE but de-prioritized until an operator confirms the CMC BLURT price is live and actively updating. The $0 volume flag means CMC could be reporting a stuck number. If verified live, slot in as an optional source between Klingex and Coingecko.

Tribaldex — NOT FEASIBLE AS DIRECT SOURCE (sidechain depeg risk)

What it is: Tribaldex is a front-end for Hive-Engine sidechain trading. BLURT on Tribaldex is actually SWAP.BLURT, a wrapped BLURT token bridged via blurt-swap. Not BLURT itself.
Pricing geometry: To derive BLURT/USD from Tribaldex you'd need: SWAP.BLURT/SWAP.HIVE × HIVE/USD (three-hop: cross-chain bridge peg × sidechain pair × mainnet price provider)
Fundamental problem: the SWAP.BLURT ↔ BLURT peg depends on bridge liquidity. Under thin liquidity or a bridge-operator issue, SWAP.BLURT can trade meaningfully below (or above) BLURT's "real" rate. Using this as a primary BLURT/USD feed would produce wrong fees during bridge stress events — exactly when fee accuracy matters most.
Endpoint details (for reference if ever used as a sanity-check): Hive-Engine RPC at https://api.hive-engine.com/rpc/contracts — POST JSON-RPC call to the market contract's metrics table with symbol: "SWAP.BLURT" returns last price against SWAP.HIVE.
Recommendation: DO NOT add as a primary or secondary source. Could serve a niche role as a divergence alarm — if SWAP.BLURT/SWAP.HIVE × HIVE/USD disagrees with the Klingex/Coingecko consensus by >10%, log a warning for operator attention. But even that is nice-to-have; a three-hop derived price isn't worth the infrastructure it requires.

Hive-Engine — SAME AS TRIBALDEX

Same chain, same problem. Tribaldex IS a Hive-Engine front-end; there's no independent Hive-Engine "price" distinct from what Tribaldex surfaces.
API documentation: https://hive-engine.github.io/engine-docs/ (contract tables) and https://hiveengine.readthedocs.io/en/latest/hiveengine.api.html (Python library reference, useful for endpoint shapes).
Recommendation: treat as identical to Tribaldex. Do not integrate.

Blockchair — NOT APPLICABLE

Supported chains: ~48 blockchains as of 2025, covering Bitcoin family (BTC, LTC, BCH, DOGE, DASH, ZEC, ARRR, DCR, SOL, ETH, XRP, DGB, XEC, GRS), Ethereum family, Solana, TRON, Polygon, and similar account-model / UTXO chains.
Graphene-family chains (BLURT, Hive, Steem) are NOT supported. Blockchair's model is built around indexing UTXO and account-model chains; delegated-PoS social chains like BLURT aren't in scope.
Not a BLURT price source at all. Blockchair can't return BLURT/USD because it doesn't index BLURT.
Useful elsewhere? Yes — for BTC/XMR fee-attestation. When an order's fee_method is btc or xmr (ADR-0011 sub-phase 4b), an attestor verifies the claimed payment on the external chain. Blockchair's /bitcoin/dashboards/transaction/{hash} endpoint is a clean way to look up a payment. This is a separate workstream from BLURT/USD pricing — I'm logging it here but it belongs in the attestor-UX design, not in priceSource.
Recommendation: do NOT integrate into priceSource. Revisit in the ADR-0011 sub-phase 4b attestor workstream as an explorer-rotation candidate.

Blockchain.com — NOT APPLICABLE

Explorer APIs are Bitcoin-focused: block data, transaction lookup, charts/stats for BTC. Not a multi-chain indexer.
Exchange API lists pairs they run on exchange.blockchain.com — BTC-USD, ETH-USD, etc. BLURT is not listed.
The exchange_rates_api endpoint returns fiat/BTC conversion rates, not altcoin prices.
Recommendation: do NOT integrate for BLURT price. Same as Blockchair, could be useful in an attestor role for BTC fee verification (as a Blockchair alternate), but that's a separate workstream.

Summary table

Source	BLURT/USD?	Verdict	Priority
Klingex	direct	already integrated (primary)	—
Coingecko	direct	already integrated (fallback)	—
CoinMarketCap	direct (but volume=$0 concern)	FEASIBLE pending operator verification	Medium
Tribaldex	three-hop derived	NOT RECOMMENDED (sidechain depeg risk)	Low (divergence alarm only)
Hive-Engine	same as Tribaldex	NOT RECOMMENDED	Low
Blockchair	does not index BLURT	NOT APPLICABLE	— (reconsider for BTC attestor)
Blockchain.com	does not list BLURT	NOT APPLICABLE	— (reconsider for BTC attestor)

Recommendations

Short term (this audit cycle):

Do NOT add any new primary price sources. The existing Klingex → Coingecko → static_floor chain is working and the proposed additions each have disqualifying issues.
Have an operator verify CMC BLURT price freshness. If the $0 volume flag is just cosmetic (CMC not aggregating sidechain volume, but price feed is live), CMC slots in cleanly as a third provider. Required check: poll https://pro-api.coinmarketcap.com/v1/cryptocurrency/quotes/latest?slug=blurt with a trial API key across a week, compare the returned price against Klingex and Coingecko over the same interval. If CMC tracks within 5% of the consensus and last_updated advances steadily, green- light integration.
Document the decision not to integrate Tribaldex and Hive-Engine in docs/adr/0004-price-feeds.md (the existing price feeds ADR) so the question doesn't come back in a future session.

Medium term (ADR-0011 sub-phase 4b):

Revisit Blockchair and Blockchain.com in the attestor-UX design workstream. For BTC/XMR fee-attestation, a user who's attesting that a payment landed needs to query an explorer to verify the claimed tx. An explorer rotation with Blockchair + Blockchain.com + mempool.space + one or two others is the right shape for that problem, but it's separate from priceSource.

Long term (if BLURT gets listed on a major CEX):

Add direct exchange tickers as primary sources when they become available. Binance, Kraken, Gate.io etc. would all be preferable to aggregators if BLURT ever gets there. Today, no major CEX lists BLURT, so this isn't actionable.

What I'd integrate code-wise (if operator green-lights CMC)

Minimal skeleton (for reference, not shipped this session):

// apps/indexer/src/indexer/priceFetchers/coinmarketcapFetcher.ts
export function createCmcFetcher(
  apiKey: string,
  baseUrl = 'https://pro-api.coinmarketcap.com'
): PriceFetcher {
  return async (): Promise<PriceSample | null> => {
    const url = `${baseUrl}/v1/cryptocurrency/quotes/latest?slug=blurt&convert=USD`;
    const res = await fetch(url, {
      headers: {
        'X-CMC_PRO_API_KEY': apiKey,
        Accept: 'application/json'
      }
    });
    if (!res.ok) return null;
    const body = await res.json();
    // Shape: { data: { <id>: { quote: { USD: { price, last_updated } } } } }
    const entries = Object.values(body.data ?? {});
    const first = entries[0];
    if (!first || typeof first !== 'object') return null;
    const quote = (first as any).quote?.USD;
    if (!quote || typeof quote.price !== 'number') return null;
    return {
      blurtUsd: quote.price,
      source: 'coinmarketcap',
      fetchedAt: new Date(),
      observedAt: new Date(quote.last_updated)
    };
  };
}

Order in composite: Klingex → CMC → Coingecko → static_floor. CMC slots in between Klingex and Coingecko because it's the most authoritative aggregator; Coingecko remains the backstop because it's free-tier-friendly.

Config additions needed:

MORPHIT_INDEXER_CMC_API_KEY (secret, env-only, never in logs)
MORPHIT_INDEXER_CMC_BASE_URL (default https://pro-api.coinmarketcap.com, override for testing)
MORPHIT_INDEXER_PRICE_MODE gains cmc as a valid value, mostly for test scenarios.

Files that would change if we ship CMC

apps/indexer/src/indexer/priceFetchers/coinmarketcapFetcher.ts (new)
apps/indexer/src/indexer/priceFactory.ts (wire cmc into composite)
apps/indexer/src/config/index.ts (+ 2 config fields)
OPERATIONS.md §13 (how to acquire a CMC API key, what happens if CMC rate-limits)
docs/adr/0004-price-feeds.md (document the third source)

No schema changes. No migration. Pure additive.

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