Function tool_input_escalation_action 

pub fn tool_input_escalation_action(fresh: bool) -> EscalationAction

TR-10’s freshness-matrix decision, given whether probe_tool_input_fresh found the file still matching: fresh -> EscalationAction::KeepStub, !fresh -> EscalationAction::RehydrateFromSidecar. Split from the probe itself (which does the actual disk I/O) so this half stays a pure, trivially-testable function — the same purity discipline A8’s probe_read_freshness/project_messages split follows.