Pay attention cause detection mechanics are pretty unforgiving once enemies spot you. The moment someone sees you, they'll instantly signal nearby allies and the whole patrol network switches into this aggressive search mode, where they're really good at coordinating to flush you out. Your best bet is breaking line of sight fast, cause their detection range gets way bigger once alerted. Maybe interesting to know that suppressed weapons are actually vital here, cause regular gunshots just make everything worse by drawing more attention. The AI stays pretty sharp for like 2-3 minutes after spotting you, and they'll methodically sweep the area instead of just forgetting about you. Something to remember is that certain loot spots might lock down permanently if reinforcements show up during major missions, so timing really matters. Tip for you - always mark some backup escape routes and keep armor-piercing rounds handy, since your gear takes extra wear during those intense firefights that happen after stealth fails. Sure you can reload saves, but getting spotted repeatedly makes faction relationships way harder to manage later on, since patrols have this weird memory system that remembers troublemakers.