P2 codex comment on 9a09c4d7: the public `action_timeout` parameter on
tools.act() skipped the same defensive validation that the env-var path
already had. Passing nan made every action time out instantly; inf /
<=0 disabled the guard entirely. Either mode silently defeats the safety
this module exists to provide, especially for callers sourcing timeouts
from runtime config.
Extracted _coerce_valid_action_timeout() (pairs with _parse_env_action_
timeout) and routed the override through it. None / nan / inf /
non-positive all fall back to the env-derived default with a warning.
New test_act_rejects_invalid_action_timeout_override asserts the
fallback by passing bad values and verifying the fast handler actually
executes to completion (which wouldn't happen if nan → immediate
timeout or if inf → hang would leak through).
32416bb48c