The ping only grepped stdout for two connection strings — a missing
claude binary, a 30s timeout kill, or command-not-found all returned
'ok', and the fleet then burned ~30 shard timeouts discovering the
outage one child at a time. Cross-model finding (testing specialist +
codex adversarial). Other non-zero exits stay deliberately fail-open:
a flaky preflight must not block a runnable suite; pinned both ways.
The Anthropic fail-fast ping ran at module load in every paid test file
importing e2e-helpers — ~30 paid claude -p calls (30s timeout each) per
full sharded run for one bit of information. The parent now pings once
before spawning shards and sets EVALS_PREFLIGHT_OK=1; the module-load
path honors the flag. Extracted to test/helpers/anthropic-preflight.ts
(injectable spawn seam) with regression pins in both directions: the
flag must skip, its absence must ping exactly once, dead API must throw.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Garry Tan