Clipping (moderation/report clips) and the `combine` CLI no longer demux+remux through GStreamer's ConcatBin. Canonical .m4s segments are blindly concatenatable, so a clip is just their bytes fed to `muxl wrap --format flat`: muxl unwraps every segment, aggregates the catalogs, and synthesizes one ftyp+moov over the lot. Each segment's C2PA signature passes through verbatim, so no re-signing. - ClipUser: read the canonical .m4s archive (was reading .mp4, which drifted when the archive moved to .m4s) and MultiReader → RunMuxlWrap. - cmd/combine: same path; drops the signer + the "Livestream Clip" wrapper manifest (segments are already individually signed). - Delete CombineSegments/CombineSegmentsUnsigned (segment_combine.go) and MediaSigner.SignConcatMP4 — their only users are gone. ConcatBin now has a single remaining caller (RTMPPush). Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>