Zingolib fails to sync with zainod

[idky137]

when running either zingo-cli, or zingo-pc, with Zainod sync stalls indefinitely, but completes successfully when running with Lightwalletd.

Steps to reproduce:

• Run Zebrad on Testnet.
• Run Zainod, configured to connect to the local Zebrad using the "fetch" backend.
• Load an adequately old (currently unknown) wallet into zingo-cli (or zingo-pc) and try to sync the wallet.

[idky137]

Initial observation: zingolib seams to spam get_mempool_stream calls to zainod and never start the sync process, this does not happen with lightwalletd, zainod's get mempool stream passes all tests and works on inspection with grpcurl. There are subtle differences in the responses from zainod and lightwalletd but none that obviously look like they would cause an error:

Zainod:

$ grpcurl -v -plaintext -import-path ../zaino/zaino-proto/proto -proto service.proto 127.0.0.1:8137 cash.z.wallet.sdk.rpc.CompactTxStreamer/GetLightdInfo

Resolved method descriptor:
// Return information about this lightwalletd instance and the blockchain
rpc GetLightdInfo ( .cash.z.wallet.sdk.rpc.Empty ) returns ( .cash.z.wallet.sdk.rpc.LightdInfo );

Request metadata to send:
(empty)

Response headers received:
content-type: application/grpc
date: Tue, 10 Mar 2026 14:38:15 GMT

Response contents:
{
  "version": "0.1.2",
  "vendor": "ZingoLabs ZainoD",
  "taddrSupport": true,
  "chainName": "test",
  "saplingActivationHeight": "280000",
  "consensusBranchId": "4dec4df0",
  "blockHeight": "3892641",
  "gitCommit": "02e7c21a219d0b8e36bfa738269d433391f2546c",
  "branch": "fix_slow_get_block_range_init",
  "buildDate": "1773073072",
  "buildUser": "idky137",
  "estimatedHeight": "3892641",
  "zcashdBuild": "v3.1.0",
  "zcashdSubversion": "/Zebra:3.1.0/",
  "upgradeName": "Nu6_1",
  "upgradeHeight": "3536500",
  "lightwalletProtocolVersion": "v0.4.0"
}

Response trailers received:
(empty)
Sent 0 requests and received 1 response

$ grpcurl -v -plaintext -import-path ../zaino/zaino-proto/proto -proto service.proto 127.0.0.1:8137 cash.z.wallet.sdk.rpc.CompactTxStreamer/GetMempoolStream

Resolved method descriptor:
// Return a stream of current Mempool transactions. This will keep the output stream open while
// there are mempool transactions. It will close the returned stream when a new block is mined.
rpc GetMempoolStream ( .cash.z.wallet.sdk.rpc.Empty ) returns ( stream .cash.z.wallet.sdk.rpc.RawTransaction );

Request metadata to send:
(empty)

Response headers received:
content-type: application/grpc
date: Tue, 10 Mar 2026 14:36:28 GMT

Response trailers received:
(empty)
Sent 0 requests and received 0 responses

Local Lightwalletd:

$ grpcurl -v -plaintext -import-path ../zaino/zaino-proto/proto -proto service.proto 127.0.0.1:9067 cash.z.wallet.sdk.rpc.CompactTxStreamer/GetLightdInfo

Resolved method descriptor:
// Return information about this lightwalletd instance and the blockchain
rpc GetLightdInfo ( .cash.z.wallet.sdk.rpc.Empty ) returns ( .cash.z.wallet.sdk.rpc.LightdInfo );

Request metadata to send:
(empty)

Response headers received:
content-type: application/grpc

Response contents:
{
  "version": "v0.4.18",
  "vendor": "ECC LightWalletD",
  "taddrSupport": true,
  "chainName": "test",
  "saplingActivationHeight": "280000",
  "consensusBranchId": "4dec4df0",
  "blockHeight": "3892641",
  "gitCommit": "8c4c83aa8d9727c9669fe8e8b80b4ff62d6c95f0",
  "buildDate": "2026-03-06",
  "buildUser": "idky137",
  "estimatedHeight": "3892641",
  "zcashdBuild": "v3.1.0",
  "zcashdSubversion": "/Zebra:3.1.0/"
}

Response trailers received:
(empty)
Sent 0 requests and received 1 response

$ grpcurl -v -plaintext -import-path ../zaino/zaino-proto/proto -proto service.proto 127.0.0.1:9067 cash.z.wallet.sdk.rpc.CompactTxStreamer/GetMempoolStream

Resolved method descriptor:
// Return a stream of current Mempool transactions. This will keep the output stream open while
// there are mempool transactions. It will close the returned stream when a new block is mined.
rpc GetMempoolStream ( .cash.z.wallet.sdk.rpc.Empty ) returns ( stream .cash.z.wallet.sdk.rpc.RawTransaction );

Request metadata to send:
(empty)

Response headers received:
(empty)

Response trailers received:
content-type: application/grpc
Sent 0 requests and received 0 responses

ZecRocks Testnet LightwalletdEndpoint:

$ grpcurl -v -import-path ../zaino/zaino-proto/proto -proto service.proto testnet.zec.rocks:443 cash.z.wallet.sdk.rpc.CompactTxStreamer/GetLightdInfo

Resolved method descriptor:
// Return information about this lightwalletd instance and the blockchain
rpc GetLightdInfo ( .cash.z.wallet.sdk.rpc.Empty ) returns ( .cash.z.wallet.sdk.rpc.LightdInfo );

Request metadata to send:
(empty)

Response headers received:
content-type: application/grpc
date: Tue, 10 Mar 2026 14:38:25 GMT
fly-request-id: 01KKC2YKXKBV9XV203CH0G4HF1-cdg
server: Fly/352a645a (2026-03-10)
via: 2 fly.io, 2 fly.io
x-region-edge: ams

Response contents:
{
  "version": "v0.4.18",
  "vendor": "ECC LightWalletD",
  "taddrSupport": true,
  "chainName": "test",
  "saplingActivationHeight": "280000",
  "consensusBranchId": "4dec4df0",
  "blockHeight": "3892642",
  "gitCommit": "8c4c83aa8d9727c9669fe8e8b80b4ff62d6c95f0",
  "buildDate": "2025-06-01",
  "buildUser": "root",
  "estimatedHeight": "3892642",
  "zcashdBuild": "v4.0.0",
  "zcashdSubversion": "/Zebra:4.0.0/",
  "donationAddress": "u157q45z9fwy7349t5r7w4d0tpmdzhw6xvuwm4ucqq80ysftk9wxryrru0l7puxpdlujnkmj5d9ewzaxz5x6slfg3xys4egayx7vry57wd"
}

Response trailers received:
(empty)
Sent 0 requests and received 1 response

$ grpcurl -v -import-path ../zaino/zaino-proto/proto -proto service.proto testnet.zec.rocks:443 cash.z.wallet.sdk.rpc.CompactTxStreamer/GetMempoolStream

Resolved method descriptor:
// Return a stream of current Mempool transactions. This will keep the output stream open while
// there are mempool transactions. It will close the returned stream when a new block is mined.
rpc GetMempoolStream ( .cash.z.wallet.sdk.rpc.Empty ) returns ( stream .cash.z.wallet.sdk.rpc.RawTransaction );

Request metadata to send:
(empty)

Response headers received:
(empty)

Response trailers received:
content-type: application/grpc
date: Tue, 10 Mar 2026 14:37:09 GMT
fly-request-id: 01KKC2W4YMMR50BFKA91NKFTD6-cdg
server: Fly/352a645a (2026-03-10)
via: 2 fly.io, 2 fly.io
x-region-edge: ams
Sent 0 requests and received 0 responses