Phase B3 (part 2): C++<->TS interop — a C++ node joins a TS-driven DHT

[ptesavol]

Summary

Completes the milestone B exit criterion against the real TypeScript implementation: a C++ DhtNode joins a layer-0 DHT whose entry point is @streamr/dht@103.8.0-rc.3 (exactly the TS pin) installed from npm and run in a child node process, over real websockets on 127.0.0.1. Mutual visibility is asserted from both sides.

How the harness works

• test/ts-interop/entryPoint.js — node driver that starts a TS DhtNode entry point (constructed exactly like the TS Layer0.test.ts entry point at the pin), joins its own DHT, then speaks a line protocol on stdout: DESCRIPTOR <hex> (the protobuf-binary PeerDescriptor — exact wire fidelity, no field mapping) followed by NEIGHBORS <id,...> every 500 ms. region is passed explicitly because TS start() otherwise does a GeoIP/CDN lookup over the real network.

• test/ts-interop/package.json + lockfile — per the granular-packages direction: the harness depends only on the published npm package at the pin; the TS monorepo checkout is never built. npm ci runs on demand from the test itself when node_modules is absent.

• test/ts-interop/TsInteropTest.cpp (new streamr-dht-test-ts-interop target) — spawns the driver, reads the descriptor, starts a serverless C++ node with the TS node as entry point, and joins. The serverless start also exercises the B1 connectivity request/response protocol against the TS websocket server for real. Asserts:

  • C++ -> TS: the TS entry point is the C++ node's closest contact and has a live connection,
  • TS -> C++: the TS node reports the C++ node id among its DHT neighbors.

  Node runtime discovery: $STREAMR_TS_INTEROP_NODE, then PATH node if >= 20 (required by the pinned package's dependencies), then the newest ~/.nvm install. Only a missing runtime skips the test; every other failure (npm ci, driver crash, join failure) is a hard failure.

• CI: actions/setup-node (node 22) added to the validate workflow so all three legs run the interop test.

• lint: npm-vendored third-party C++ under node_modules excluded from the sweep; TsInteropTest.cpp joins the documented std-type-unification exclusion list (the compiler builds and runs it; clang-format still checks it).

Test results (local, arm64 mac)

Suite	Result
ts-interop	6/6 consecutive runs, ~1.7 s each
unit	181/181
integration	43/43 (including SingleLayer1Dht this run)
end-to-end	7/7
lint.sh	rc=0

With this, milestone B is complete: C++ nodes interoperate over websocket + WebRTC with each other (part 1, #77) and over websocket with the pinned TS implementation (this PR). Known follow-up (pre-existing, documented in #77): the occasional Layer1ScaleTest.SingleLayer1Dht neighbor-count flake.

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