"TLS HANDSHAKE FAILED: ... unexpected EOF" is exactly how the certificate
mismatch presented -- the defect that cost three live gate attempts and was
invisible everywhere else. It is the one line this project has learned to
treat as serious.
A reachability probe forges it for free: TcpStream::connect followed by a
drop opens the connection and closes without sending a byte, and the
acceptor reports that as "unexpected EOF". The launcher's preflight makes
two such probes per run. On 2026-08-12 they produced ten of these lines and
sent a whole session diagnosing a client-side fault that did not exist --
autopatch, ptrace_scope and client_arm.sh were all investigated before the
pairing of the timestamps gave it away.
Classify before the acceptor sees the connection: peek one byte, and treat
EOF-before-any-byte as a probe with its own quiet line. A timeout is
deliberately NOT a probe -- a slow or broken client must still reach the
acceptor and produce a real diagnostic, since misclassifying a fault as
benign would defeat the point.
The counter exists because the test needs it. A probe produces no response
either way, so a test written against client-visible behaviour passes with
the classification deleted; asserting on a count is what makes the mutation
detectable. Verified: all three mutations (drop the classification, treat
undetermined as a probe, treat a speaking client as a probe) are killed.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
funman300
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