release v1.2.0 - `muxr rename` now also moves the on-disk session file at `<harness>/campaigns/<campaign>/sessions/<segment>.md` and triggers the configured runtime relink, so the harness/campaign/session/segment address stays coherent across tmux state, the filesystem, and the AI runtime in one operation. Best-effort: refuses to clobber an existing target file. Six new tests cover missing source, target-already-exists clobber refusal, cross-campaign skip, and same-campaign rename. Total test count went from 74 to 80. - Hero and avatar iconography in the nomograph paper-palette OV-1 style: `hero.svg` shows harness inputs, the multiplexer junction, and three coupled output rows for tmux session / session file / runtime id; `avatar.svg` is four nested rectangles for harness > campaign > session > segment. - `CODEOWNERS`. - README rewritten to lead with the harness-multiplexer scope. The commands table now reflects that `rename` touches tmux state, the session file, and the runtime id together.