testing: real-socket scope-close TCP teardown test (comms-4lz5) - #15
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The Tier-3 residue of the hexagonal test-architecture epic: the one assertion that genuinely cannot leave the socket — interrupting an in-flight FetchHttpClient long-poll on scope close actually tears down the underlying TCP connection (AbortSignal -> fetch -> socket). comms-e5vm.2 moved every event-pump LOGIC test (gap-replay, 429 retry, BAD_EVENT_QUEUE_ID reconnect, the Effect fiber-interrupt path of scope close) onto the stub HttpClient + TestClock — deterministic, no socket. The stub proves the fiber unwinds; it cannot prove the socket unwinds. This test closes that gap and is the only surviving Bun.serve long-poll. The assertion is server-side: a real Bun.serve whose long-poll handler parks forever but listens on req.signal, so observing the abort proves the teardown reached the peer rather than just unwinding our fiber. Lifecycle is Effect.acquireRelease/Scope throughout. Also refreshes the realm-hooks doc comment, whose forward-reference to this bead described a teardown-starvation mode that .2 dissolved.
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The Tier-3 residue of the hexagonal test-architecture epic (comms-e5vm): the one assertion in the suite that genuinely cannot leave the socket — that interrupting an in-flight `FetchHttpClient` long-poll on scope close actually tears down the underlying TCP connection (`AbortSignal → fetch → socket`).
Why this is the only surviving socket test
comms-e5vm.2 (#12) moved every event-pump LOGIC test — gap-replay, 429 retry, BAD_EVENT_QUEUE_ID reconnect, and the Effect fiber-interrupt path of scope close — onto the owned-fake stub HttpClient + TestClock: deterministic, no socket. The stub proves the fiber unwinds. It cannot prove the socket unwinds, because there is no socket. This test closes exactly that gap and is the only surviving `Bun.serve` long-poll in the suite.
The assertion is server-side
A real `Bun.serve` whose long-poll handler parks forever but listens on the request's `req.signal`. When the client tears the connection down, Bun fires that abort — observing it is proof the teardown reached the peer, not merely that our Effect fiber unwound (which the stub already covers). The Effect platform client wires this end to end: `httpClient.make` aborts the request's `AbortController` `onInterrupt`, and `FetchHttpClient` passes that `signal` into `fetch`.
Lifecycle is `Effect.acquireRelease`/`Scope` throughout: the server's release is `server.stop(true)`, and the long-poll is forked into an inner `Effect.scoped` whose close is the interruption under test — so release is guaranteed even on the interruption path. The proof is timeout-guarded, so a non-teardown fails loud (verified by a mutation: detaching the fiber from the scope makes the test time out).
Broader-rework question (comms-4lz5's original scope): recommend leave-as-is
The bead also asked whether to migrate the ~170 `realm.`/`fixture.` hook call sites to a per-test `Effect.scoped` wrapper. That rework was motivated by a contention-driven teardown-starvation flake in the infinite-long-poll tests — which .2 dissolved structurally by moving that logic off the socket. Every fixture still wired through `registerRealmHooks` is now a plain request/response realm that starts and stops in a few ms; there is no teardown-starvation mode left to fix, and the `acquireRelease`/`Scope` shape now lives exactly where it is load-bearing (this one socket test). The migration would be churn across ~170 sites for no behavioural payoff — YAGNI. This PR also refreshes the now-stale `realm-hooks.ts` doc comment that still described the dissolved failure mode.
Closes comms-4lz5.