test(G5): cross-process port-allocation race over the flock - #71
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Adds the two-terminal concurrency guarantee at the layer that matters, across REAL OS processes (subprocess-helper pattern), with no daemon and no flakiness: the ledger is pre-created, then 5 copies of the test binary each allocate 6 host ports under the machine-global flock. Port allocation is the mutation that cannot be made idempotent — two processes handing out the same host port is a hard bug — so "every allocated port is distinct across every process" is a direct proof the cross-process flock serialized the critical section. A no-op flock would let two processes pick the same lowest-free port and collide. Note: writing this surfaced that concurrent FIRST-open of a brand-new ledger from several processes relies on a reliable-flock filesystem (the WAL switch + migrate race otherwise); that hazard is already mitigated by `doctor`'s 9p/networked-FS warning (internal/cli fsCheck). The test deliberately pre-migrates so it validates the allocation flock specifically, independent of that. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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What
Closes G5 — the two-terminal concurrency guarantee, validated across real OS processes (subprocess-helper pattern), daemon-free and non-flaky.
How
The ledger is pre-created, then 5 copies of the test binary each allocate 6 host ports under the machine-global flock. Port allocation is the mutation that cannot be made idempotent — two processes handing out the same host port is a hard bug — so "every allocated port is distinct across every process" directly proves the cross-process flock serialized the critical section. A no-op flock would let two processes pick the same lowest-free port and collide.
Validates the repo's #1 architectural rule (lock-first concurrency) at the cross-process layer the existing
internal/lockgoroutine test can't reach. Verified-race -count=5.Finding (already mitigated)
Writing this surfaced that concurrent first-open of a brand-new ledger from several processes relies on a reliable-flock filesystem (the WAL switch + migrate otherwise race) — already mitigated by
doctor's 9p/networked-FS warning (fsCheck). The test pre-migrates so it isolates the allocation flock specifically.🤖 Generated with Claude Code