Function min_hold 

pub(crate) fn min_hold() -> Duration

Minimum on-screen time before the splash is allowed to dismiss, so a fast cold start can’t produce a sub-perceptible flash (worse than no splash). Overridable via AGENTMUX_SPLASH_HOLD_MS — also handy for eyeballing the splash during testing (e.g. AGENTMUX_SPLASH_HOLD_MS=3000).