Use this skill when you need to inspect the endy environment of a running task — handoff lineage (who handed work to whom and why), peers in the same and other endy sessions, and per-agent tier headroom (codex 5h/wk, opencode session cost) so you can pick the next agent to hand off to. The same data is auto-prepended to every spawn prompt as a '## endy environment' block, so use this skill when you need it on-demand or in JSON form.
Use this skill — it is the primary one — when you need to drive another coding agent interactively through a tmux pane. Open named windows, send prompts, capture output, manage lifecycle, AND switch models / change auth / use slash commands inside the live CLI (claude, cmd, opencode, hermes, gemini, codex). Includes a per-CLI reference of model-management commands, available models, and the picker-driving recipe you need to do this from outside the terminal.
Use this skill when a task is best handed off to another coding agent in the endy stack — OpenCode (multi-model worker, fast refactors, test writing), CommandCode/cmd (Kimi K2.6 / DeepSeek), Hermes (Nous Research, tool-heavy), Gemini, or Claude. Covers three delivery modes: short blocking calls, long detached tmux spawns, and `endy handoff` — the cross-agent transfer used when one CLI runs out of tier mid-task.