fix(test): survive the MAC-Telnet relay peer exiting mid-stream - #300
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…follow-up)
terminal-mac-telnet.test.ts failed the long-term QA leg twice, including the
retry, with an uncaught dgram error and no assertion involved:
error: ECONNREFUSED: connection refused, recv
at error (node:dgram:176:22)
Not a version split and not a device fact. The same test on the same 7.21.5
passed in the previous long-term run (40.2s) and passes on stable, testing
and development in the run that failed; the failures are FASTER than the
pass (31.9s, 29.9s), i.e. it errored early rather than timing out.
Root cause is in the bridge, not the device. Its UDP relay's peer is a CLI
SUBPROCESS that exits when its command completes, while the guest keeps
sending MAC-Telnet frames. Relaying to the departed port draws an ICMP
port-unreachable, which Linux queues onto the socket and libuv surfaces as
ECONNREFUSED on the next recv. Nothing durably handled it: the only `error`
listener was the stale `once(reject)` left over from bind, which fires
`reject` on an already-settled promise — a no-op that absorbs the FIRST such
error and leaves the SECOND unhandled, crashing the process.
Proven deterministically, not inferred: replicating the bind pattern and
emitting two errors shows listenerCount 1 -> 0 after the first, and the
second throws.
Fix, all three parts:
- a durable `error` handler that counts ECONNREFUSED/ECONNRESET as
`stats.relayPeerGone` and rethrows everything else, so this is a narrow
known-condition tolerance, not a blanket socket-error swallow;
- `udp.send` gets a callback, so a failed send stops escalating to the
socket's `error` event;
- both bind/listen one-shot handlers are removed on success, closing the
stale-listener leak on the TCP server too.
The swallow is counted rather than silent, so "the relay peer went away"
stays visible in `stats()`.
Note on verification: this is structurally unreproducible on the maintainer's
Darwin host — measured, not assumed. An unconnected UDP socket there never
receives the ICMP error (send callbacks succeed, no `error` event fires), so
the race is Linux-only. `bun test terminal-mac-telnet` on 7.21.5 passes
locally (35s), but that is a regression check; the long-term CI leg is the
confirmation.
Refs #299
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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📝 WalkthroughWalkthroughThe bridge now counts expected UDP relay disconnects, handles asynchronous forwarding errors, and manages TCP and UDP error listeners across socket binding. ChangesRelay error handling
Estimated code review effort: 3 (Moderate) | ~20 minutes Merge Risk: 🟡 Moderate · up to The change improves relay error handling, but startup can still leave a TCP listener and connection behind when UDP binding fails, causing resource or port leakage and disrupting subsequent runs. Merge should wait for that cleanup path to be fixed or explicitly accepted. 🚥 Pre-merge checks | ✅ 5✅ Passed checks (5 passed)
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Pull request overview
This PR hardens the MAC-Telnet L2 bridge used by integration tests so the process doesn’t crash when the UDP relay peer (a short-lived CLI subprocess) exits while the guest continues sending MAC-Telnet traffic—addressing an uncaught ECONNREFUSED/ECONNRESET failure seen on the CHR • long-term QA leg.
Changes:
- Adds a durable UDP
errorhandler that tolerates (and counts)ECONNREFUSED/ECONNRESETas an expected “relay peer gone” condition while still failing fast on other errors. - Supplies a callback to
udp.send(...)so send failures are handled deterministically rather than escalating via the socket’serrorevent. - Removes one-shot
bind/listenerror listeners on success to avoid stale listeners absorbing the first post-startup error and letting subsequent ones crash.
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Actionable comments posted: 1
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Inline comments:
In `@test/integration/mactelnet-l2-bridge.ts`:
- Around line 267-274: Update startMacTelnetL2Bridge startup to wrap TCP listen
and UDP bind in try/catch; on failure, close both sockets, destroy conn, remove
temporary UDP error listeners, and rethrow the original bind error while
preserving successful startup behavior.
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test/integration/mactelnet-l2-bridge.ts
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**/*.{ts,tsx}
📄 CodeRabbit inference engine (AGENTS.md)
**/*.{ts,tsx}: Transport or RouterOS-touching code is not done untilbun run test:integrationpasses.
Do not silently fall back to another protocol when the caller pinned--via.
Do not make generated output the hand-edited source of truth.
Do not disable validation to make a test pass; validation is part of the product.
Files:
test/integration/mactelnet-l2-bridge.ts
🔇 Additional comments (3)
test/integration/mactelnet-l2-bridge.ts (3)
111-116: LGTM!Also applies to: 165-165
187-210: 🩺 Stability & AvailabilityRun the required integration verification.
The PR context records local regression tests and
bun run ci, but it does not establishbun run test:integrationor the required Linux long-term QA result. Runbun run test:integrationand complete the Linux QA leg before merging. Verify both expected relay errors and fatal handling for unrelated errors.As per coding guidelines, transport or RouterOS-touching code is not done until
bun run test:integrationpasses.Source: Coding guidelines
239-245: LGTM!Also applies to: 256-264
#300 review) Both review items were real; both are fixed. CodeRabbit — if `udp.bind` rejects after `server.listen` already succeeded, startup threw without closing the TCP server, and since the caller never got a bridge it never got a `close()` either. Demonstrated by forcing a bind failure and checking the captured server directly: without: tcp server still listening: true {"port":52640} => LEAKED with: tcp server still listening: false => no leak (First two attempts measured this with `_getActiveHandles`, which is inert under Bun and reported "no leak" for both arms — a broken detector, not a clean result. Capturing the net.Server and reading `.listening` is what actually discriminates.) Startup now closes the udp socket, destroys any connection, closes the TCP server, and rethrows the ORIGINAL bind error. Copilot — `udpClient` stayed set after the peer was gone, so every later guest frame kept sending to a closed port. Now cleared when a send to it fails, so the relay stops talking to a peer that is provably gone. Deliberately in the send callback, not the socket-level handler: only the send path knows which destination failed. The socket `error` path (the recv side, which is where Linux actually surfaces the queued ICMP error) carries no destination, so clearing there could unhook a client that registered in the meantime. Three tests share this bridge, so a late error unhooking a live client is a real hazard, not a hypothetical — hence the identity check that only clears when the failed target is still the registered one. Verified: bun run ci clean (2814 tests); terminal-mac-telnet + mac-telnet on 7.21.5 both pass (73s). Local runs remain a regression check only — Darwin never delivers the ICMP error that triggers this path. Refs #300 Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
…term (#297) (#301) Records the decision #297 was waiting on, and writes it where a cold agent reads it before writing an integration test rather than only in the issue. Adopted: convention (option 1) plus a LOCAL, scoped long-term run in the done definition. Not a pre-merge CI leg — the cost estimate in the issue measures the wrong run. A full leg is ~18 minutes (measured: stable 17m, long-term 18m, testing 18m, development 16m), but what finds this drift is the TOUCHED file against the OLDEST device, and that is ~22s for one file, 73-120s for two: CENTRS_CHR_CHANNEL=long-term CENTRS_RUN_FAST_INTEGRATION=1 \ bun test test/integration/<touched>.test.ts Verified that command resolves long-term (-> 7.21.5) and passes, rather than documenting an unrun recipe. Every version-drift instance in #297 would have been caught by it before the PR was opened. Three surfaces, one canonical statement plus pointers: - test/AGENTS.md (test/CLAUDE.md symlinks to it, so both harnesses get it) — the rule, with a table mapping each existing contract to when it fits, and the two standing traps: gate on the running VERSION not the channel name, and never relax an assertion to make a version pass. - .github/instructions/done-definition.instructions.md — the long-term run as step 3 of the existing procedure, pointing at the rule. - test/integration/chr.ts — a section header over the contracts naming the two shapes (accepted set vs version boundary) and why they are not interchangeable, so the surface is discoverable from the code. Scope stated explicitly: this prevents VERSION DRIFT. A harness that mishandles normal teardown (#300's unhandled socket error when the relay peer exits) is a different failure that only shows up by running the thing, and saying so keeps the next reader from reading this as flake prevention too. The issue's "used exactly once" premise is already stale: routerOsAtLeast now has three integration call sites and VALIDATION_REJECT_CODES five, with PARSE_REJECTED/PARSE_REJECTED_HINT added in the same shape. The mechanism gets reached for once someone knows it exists — discovery was the gap. Fixes #297 Co-authored-by: Claude Opus 5 <noreply@anthropic.com>
The last failure standing on the
long-termQA leg after #298 and #299. QA run 31849014893 onmain@56ac288: Windows, macOS, stable, testing and development are all green —CHR • long-termis the only red job, andterminal-mac-telnet.test.tsis the only test in it.No assertion is involved — an uncaught socket error killed the process.
Why this is not a version split
The three facts that rule the device out:
Nothing in #299 touches mac-telnet (
git diff df94bdf..56ac288is the catalog parser plus two reject-code assertions).Root cause — in the bridge, not the device
The UDP relay's peer is a CLI subprocess that exits when its command completes, while the guest keeps sending MAC-Telnet frames. Relaying to the departed port draws an ICMP port-unreachable; Linux queues it onto the socket and libuv surfaces it as
ECONNREFUSEDon the next recv.Nothing durably handled it. The only
errorlistener was the staleonce(reject)left over frombind:After bind resolves that one-shot is still attached, so it fires
rejecton an already-settled promise — a no-op that absorbs the first such error, leaving the second unhandled and fatal.Proven deterministically rather than inferred — replicating the pattern and emitting two errors:
That also explains the timing sensitivity: how many frames the guest sends after the subprocess exits decides whether one or two errors land, so a faster or slower leg flips the outcome. It is the long-term leg's timing, not its RouterOS version.
The fix
errorhandler that countsECONNREFUSED/ECONNRESETasstats.relayPeerGoneand rethrows everything else — a narrow tolerance for one known condition, not a blanket socket-error swallow.udp.sendgets a callback, so a failed send no longer escalates to the socket'serrorevent.bind/listenone-shot handlers are removed on success, closing the same stale-listener leak on the TCP server before it can bite.The tolerated case is counted, not silenced — "the relay peer went away" stays visible in
stats()rather than becoming an invisible swallow.Verification, and its honest limit
This is structurally unreproducible on the maintainer's Darwin host — measured, not assumed:
Sending repeatedly to a closed loopback port on macOS produces no
errorevent and no send-callback error, so the race is Linux-only and no amount of local re-running would have surfaced it.bun test terminal-mac-telneton 7.21.5 → 1 pass (35s). A regression check only, for the reason above.bun run ci(lint:ci + 2854 tests + build) clean.The
long-termCI leg is the actual confirmation, and it only runs post-merge, sinceqa.yamldoes not trigger on pull requests.I did not add a unit test for this. On macOS and on the Linux unit runners there is no CHR and no ICMP path, so any such test would pass whether or not the bug were present — decorative by construction. The deterministic listener-lifecycle repro above is recorded in the commit message instead.
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