Codex orchestrates multi-agent work by routing Claude for architectural reasoning and Codex for deterministic execution, reducing wasted agent PRs from ~50% to 0% in documented cases. Record & Replay converts demonstrated workflows into inspectable, editable skills without manual scripting. Self-managing threads create, organize, pin, and spawn worktrees autonomously, enabling Chief-of-Staff topologies where one persistent thread holds cross-context knowledge and routes work to child threads. The four-gate self-packaging filter prevents over-engineering: occurrence ≥2 or clearly recurrent; stable inputs, repeatable procedure, clear stopping condition; material speed/quality/consistency gains; not redundant. Durable pinned threads act as persistent workspaces. Multi-device setups require Tailscale as a hard dependency; a single always-on desktop serves as the sole code-writing node. Codex can replace SaaS with agent-native alternatives—Superhuman→Gmail CLI demonstrates the pattern of replicating well-understood UX conventions via agent-built CLI while eliminating vendor lock-in.