Real-Time Content Moderation (SFU) Engineering Cheat Sheet

One-page reference: real-time vs after-the-fact moderation; the SFU as the single tap point for video, audio, and text; the E2EE-vs-server-moderation fork (SFrame, RFC 9605); frame sampling math ($1.80->$0.12/min at 2 fps) and the layered hash-then-classifier-then-audio-then-text pipeline; the confidence->action ladder with the false-positive/false-negative trade-off; the CSAM legal path (PhotoDNA hash match, seal evidence, report to NCMEC under 18 U.S.C. 2258A); and a build-vs-buy checklist.