fix: move rate limiting into adapters, make requests sequential

Each adapter now owns its own RateLimiter and gates every individual
HTTP request. The two internal fetches (normal + token txs) run
sequentially instead of in parallel. Without an API key, Tronscan
is limited to 1 req/s and Etherscan to 2 req/s to avoid 429 errors
from browser cross-origin requests.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: Blackman99

packages/core/src/adapters/etherscan/index.ts

@@ -4,6 +4,7 @@ import type {
   FetchTxOptions,
   RawTransaction,
 } from '../../adapter/types'
+import { RateLimiter } from '../../utils/rate-limiter'
 
 export interface EtherscanAdapterConfig {
   apiKey?: string
@@ -20,15 +21,17 @@ export class EtherscanAdapter implements DataSource {
     hasAddressTags: false,
     returnsPrebuiltGraph: false,
     supportedChains: ['Ethereum'],
-    rateLimit: 5,
+    rateLimit: 2,
   }
 
   private apiKey: string
   private baseUrl: string
+  private limiter: RateLimiter
 
   constructor(config: EtherscanAdapterConfig = {}) {
     this.apiKey = config.apiKey || ''
     this.baseUrl = config.baseUrl || DEFAULT_BASE_URL
+    this.limiter = new RateLimiter(config.apiKey ? 5 : 2)
   }
 
   async fetchTransactions(
@@ -37,11 +40,12 @@ export class EtherscanAdapter implements DataSource {
     const page = opts.page ?? 1
     const pageSize = opts.pageSize ?? 100
 
-    // Fetch normal transactions and token transfers in parallel
-    const [normalTxs, tokenTxs] = await Promise.all([
-      this.fetchNormalTxs(opts.address, page, pageSize),
-      this.fetchTokenTxs(opts.address, page, pageSize),
-    ])
+    // Sequential to respect rate limits
+    await this.limiter.acquire()
+    const normalTxs = await this.fetchNormalTxs(opts.address, page, pageSize)
+
+    await this.limiter.acquire()
+    const tokenTxs = await this.fetchTokenTxs(opts.address, page, pageSize)
 
     let allTxs = [...normalTxs, ...tokenTxs]
 

packages/core/src/adapters/tronscan/index.ts

@@ -4,6 +4,7 @@ import type {
   FetchTxOptions,
   RawTransaction,
 } from '../../adapter/types'
+import { RateLimiter } from '../../utils/rate-limiter'
 
 export interface TronscanAdapterConfig {
   apiKey?: string
@@ -19,15 +20,18 @@ export class TronscanAdapter implements DataSource {
     hasAddressTags: false,
     returnsPrebuiltGraph: false,
     supportedChains: ['Tron'],
-    rateLimit: 3,
+    rateLimit: 1,
   }
 
   private apiKey: string
   private baseUrl: string
+  private limiter: RateLimiter
 
   constructor(config: TronscanAdapterConfig = {}) {
     this.apiKey = config.apiKey || ''
     this.baseUrl = config.baseUrl || DEFAULT_BASE_URL
+    // Tronscan free tier is very restrictive from browser cross-origin
+    this.limiter = new RateLimiter(config.apiKey ? 3 : 1)
   }
 
   async fetchTransactions(
@@ -36,11 +40,12 @@ export class TronscanAdapter implements DataSource {
     const pageSize = opts.pageSize ?? 50
     const start = ((opts.page ?? 1) - 1) * pageSize
 
-    // Fetch TRX transfers and TRC20 transfers in parallel
-    const [trxTxs, trc20Txs] = await Promise.all([
-      this.fetchTrxTransfers(opts.address, start, pageSize),
-      this.fetchTrc20Transfers(opts.address, start, pageSize),
-    ])
+    // Sequential to respect rate limits
+    await this.limiter.acquire()
+    const trxTxs = await this.fetchTrxTransfers(opts.address, start, pageSize)
+
+    await this.limiter.acquire()
+    const trc20Txs = await this.fetchTrc20Transfers(opts.address, start, pageSize)
 
     let allTxs = [...trxTxs, ...trc20Txs]
 

packages/core/src/graph/builder.ts

@@ -1,7 +1,6 @@
 import type { TxGraph, TxNode, TxEdge } from '../types'
 import type { DataSource } from '../adapter/types'
 import { aggregateTransactions } from './aggregator'
-import { RateLimiter } from '../utils/rate-limiter'
 
 export interface BuilderOptions {
   maxDepth?: number
@@ -74,7 +73,6 @@ export class GraphBuilder {
     const nodes = new Map<string, TxNode>()
     const allEdges: TxEdge[] = []
     const visited = new Set<string>()
-    const rateLimiter = new RateLimiter(this.adapter.capabilities.rateLimit)
 
     const rootNode: TxNode = {
       address: rootAddress,
@@ -105,8 +103,6 @@ export class GraphBuilder {
           totalNodes: nodes.size,
         })
 
-        await rateLimiter.acquire()
-
         let page = 1
         let hasMore = true
         const allTxs = []
@@ -123,10 +119,6 @@ export class GraphBuilder {
           allTxs.push(...result.transactions)
           hasMore = result.hasMore
           page++
-
-          if (hasMore) {
-            await rateLimiter.acquire()
-          }
         }
 
         const edges = aggregateTransactions(allTxs, this.options.direction)
@@ -203,9 +195,6 @@ export class GraphBuilder {
     chain: string,
     existing: TxGraph
   ): Promise<TxGraph> {
-    const rateLimiter = new RateLimiter(this.adapter.capabilities.rateLimit)
-    await rateLimiter.acquire()
-
     let page = 1
     let hasMore = true
     const allTxs = []
@@ -222,7 +211,6 @@ export class GraphBuilder {
       allTxs.push(...result.transactions)
       hasMore = result.hasMore
       page++
-      if (hasMore) await rateLimiter.acquire()
     }
 
     const edges = aggregateTransactions(allTxs, this.options.direction)