* docs(code-execution): document HERMES_* env narrowing + passthrough workaround
The execute_code sandbox-child env scrub (108397726, #27303) deliberately
dropped the broad HERMES_ prefix passthrough, keeping only an operational
4-var allowlist (HERMES_HOME/PROFILE/CONFIG/ENV). A script that relied on a
non-secret HERMES_* var (HERMES_BASE_URL, HERMES_KANBAN_DB, HERMES_*_WEBHOOK,
or a plugin-defined one) now sees it unset in the child.
Document the behavior change and the two recovery routes (terminal.env_passthrough
in config.yaml, or required_environment_variables in skill frontmatter), plus
the debug log line that surfaces the drop for diagnosis.
* fix: drain thread no longer crashes on fd-less stdout streams
The _wait_for_process drain thread called proc.stdout.fileno()
unconditionally. ProcessHandle implementations whose stdout is not
backed by a real OS fd (iterator-style in-memory streams, mock procs)
raised 'list_iterator' object has no attribute 'fileno' (or
'fileno() returned a non-integer' from select.select), killing the
daemon thread and silently losing all process output.
Resolve the fd defensively at the top of _drain; when stdout has no
usable integer fileno, fall back to draining it as an iterable (the
legacy 'for line in proc.stdout' contract). The real subprocess /
os.pipe-backed select() fast path is unchanged.
90b3c54de9