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Include a description, reproduction steps, potential impact, affected release or commit, and any suggested remediation.

Epitelesis enforces subprocess lifecycle policy; it is not a security sandbox. On a supported Unix backend the supervisor kills the process group before reaping so ordinary descendants are cleaned up. Captured pipes are nonblocking and share the supervisor event loop; a noisy stream receives only a bounded turn before deadline and cancellation checks resume. A hostile child can call setsid, escape the group, and survive. Use a purpose-built OS sandbox or container when executing hostile code.

The v1 defaults reduce accidental exposure and resource exhaustion:

• Clean uses real environment clearing;
• environment allowlisting is explicit;
• inheriting the full environment requires a recorded reason;
• stdout and stderr are each limited to 10 MiB by default and limits fail closed; and
• deadlines are mandatory unless explicitly waived with a reason.

Explicit unbounded execution or capture is an exceptional policy choice, not a safety guarantee. The caller owns the justification and the resulting resource risk.

Captured stdout and stderr are untrusted bytes and may contain secrets. The library transports them; callers own redaction, storage, retention, and safe rendering. Tracing must not record argument values, inherited environment values, or captured output by default.

Lifecycle errors retain one aggregate evidence object containing typed signal and reap outcomes, both capture reports, recoverable elapsed time, and the typed cleanup outcome. Incomplete capture means EOF was not observed, whether because reading failed or the cleanup deadline expired. A CleanupOutcome::Incomplete value specifically means that deadline expired without proof of full settlement; Unknown means an adapter could not recover the evidence. Security-sensitive callers should inspect the whole typed result instead of treating timeout or cancellation as proof that every descendant was contained.

• policy bypasses that allow execution without a declared deadline;
• environment clearing or allowlist failures;
• capture-limit, drain, cancellation, kill, or reap failures;
• evidence loss that masks incomplete cleanup; and
• dependency or build behavior that creates a practical vulnerability for consumers.

Misuse by a caller—such as executing an untrusted program without a sandbox, passing unvalidated arguments, or publishing raw captured output—is outside the library's security boundary unless Epitelesis makes the outcome worse.

After a fix ships, maintainers may publish a GitHub Security Advisory with the affected releases, impact, remediation, and reporter credit.