Claude Code background agent team: Opus leads, Fable plays adversary
Using claude --bg to launch background sessions in isolated worktrees, Opus 5.5 handles architecture and merging, Sonnet 5.5 implements, and Fable 5.1 steps in only at three points such as schema changes, with Jev's 16ms mechanical decision layer cited as the same pattern one level down.
Claude Code tip: stop burning Opus 5.5 context babysitting one terminal on tasks Sonnet 5.5 can swarm in the background, while Fable 5.1 sits idle spin up a background team with --bg claude --bg --name adversary --model fable Opus 5.5 acts as the lead architect, dispatching the team and merging every worktree Sonnet 5.5 teammates run as background sessions in isolated git worktrees and hammer out implementations at medium effort Fable 5.1 runs as its own background session, a dedicated adversary that only steps in at three critical moments: → when a schema changes: does every other teammate's code still match it? → when a test breaks twice: are we patching the bug or just hiding the symptom? → before the lead merges: what edge case did the whole team overlook? Sonnet 5.5 builds. Fable 5.1 challenges. Opus 5.5 merges and ships Jev engineering runs the identical pattern one layer down: mechanical decisions that need no reasoning (which file to open, which tool to invoke, retry or abort) execute in 16ms, so the frontier models only wake up when execution paths actually diverge Plan on high. Delegate on medium. Keep the adversary on peer-to-peer call. - the full team setup > Opus 5.5 on high leads and watches every session from claude agents > api writes the migration and endpoints in its own worktree > ui builds client state in a separate worktree > adversary runs on Fable 5.1 and only reviews the diffs it is sent > teammates message each other by name the moment a contract changes > close the terminal and the whole team keeps running paste the setup and this prompt into Claude Code below: "Configure my Claude Code workspace for a background agent team: 1. Split [describe the feature] into tasks that touch different folders > Print one claude --bg --name <task> --model sonnet command per task > Add claude --bg --name adversary --model fable > Print the commands, run nothing 2. Lock the lead session in ~/.claude/settings.json: > Set model to opus and effortLevel to high > Pin claude-sonnet-5-5 to medium in modelSettings 3. Add to every task prompt: when you change anything another teammate depends on, message it by name, and send every finished diff to adversary before the lead merges 4. Add a team rule to ~/.claude/CLAUDE.md: nothing merges until adversary has replied, and report anything that blocks messaging (crossSessionInbound set to refuse, deny rules on SendMessage) Show every configuration diff first. Do not apply edits until confirmed" save it
This post quotes another post: x.com/eng_khairallah1/status/2107767577963594051