feat: fetch only the root block

lib/spark.js

@@ -140,6 +140,9 @@ export default class Spark {
       statusCode: null
     }
     const searchParams = new URLSearchParams({
+      // See https://github.com/filecoin-project/lassie/blob/main/docs/HTTP_SPEC.md#dag-scope-request-query-parameter
+      // Only the root block at the end of the path is returned after blocks required to verify the specified path segments.
+      'dag-scope': 'block',
       protocols: retrieval.protocol,
       providers: retrieval.providerAddress
     })

test/spark.js

@@ -3,7 +3,7 @@
 import Spark from '../lib/spark.js'
 import { test } from 'zinnia:test'
 import { assertInstanceOf, assertEquals, assertArrayIncludes } from 'zinnia:assert'
-import { SPARK_VERSION, MAX_CAR_SIZE } from '../lib/constants.js'
+import { SPARK_VERSION } from '../lib/constants.js'
 
 test('getRetrieval', async () => {
   const round = {
@@ -82,6 +82,7 @@ test('fetchCAR', async () => {
   assertEquals(requests, [{ url: URL }])
 })
 
+/* Disabled as long as we are fetching the top-level block only
 test('fetchCAR exceeding MAX_CAR_SIZE', async () => {
   const URL = 'url'
   const fetch = async url => {
@@ -110,6 +111,7 @@ test('fetchCAR exceeding MAX_CAR_SIZE', async () => {
   assertEquals(stats.carChecksum, null)
   assertEquals(stats.statusCode, 200)
 })
+*/
 
 test('submitRetrieval', async () => {
   const requests = []