When Should Control Move? Phase-Scoped Leadership for Embodied LLM Teams

Embodied LLM teams must coordinate task dependencies while their members retain different observations and procedural memories. A task graph specifies what should happen, but not which agent should construct the next plan. We introduce phase-scoped dynamic leadership: agents exchange compact evidence, jointly select a coordinator and phase objective, execute a phase DAG, and replicate progress across coordination rounds. A locked-leader control preserves the same normal phase-planning loop. We formalize the distinction between sharing sufficient advice and accessing local context by transferring planning authority. We evaluate three-agent teams in Minecraft through an eleven-task, 330-run comparison and a 40-run leadership-trace evaluation. Free-form coordination is economical on simple collection, while locked leadership is the stronger structured default. On three tasks with asymmetric memories, Dynamic achieves 9/30 terminal successes versus Static's 1/30, at 1.55 times the mean LLM-call count. The trace evaluation records 4/20 versus 0/20 successes and directly observes leader changes in 8/20 Dynamic runs. Re-election often retains the same agent, and rotation alone does not ensure success. These findings support phase-scoped authority as a targeted coordination mechanism, while separating observed protocol behavior from causal claims about expertise alignment.