Claude Code setup: Haiku runs, Opus advises, Jev routes micro-forks

Skunzu @skunzuOriginally posted 2026.11.05

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THIS IS ACTUAL F*CKING GOLD Anthropic just documented the cheapest way to get Opus-level decisions in Claude Code. The idea: let Haiku 5.5, the fastest and cheapest model, write the code, and keep Opus 5.5 on call as the advisor for the moments that actually decide the outcome. Anthropic's own docs call it the lowest-cost main model with strong planning. You just start Claude Code like this: claude --model haiku --advisor opus this is how it splits: → Haiku 5.5 drives the session, edits the files and runs the tests → Haiku 5.5 subagents search the repo and pull docs in parallel → Opus 5.5 waits on call and reads the full transcript only when Claude asks for it → you stop paying Sonnet or Opus rates for typing a fast model can do Opus only steps in at three moments: → right before a plan locks → when the same error comes back twice → right before you call it done Haiku builds. Haiku explores. Opus thinks. JEV engineering is the same idea one layer down: the forks that need no thinker (which file, which tool, retry or stop) get settled by JEV in milliseconds, and the big models only see the ones that actually split the full tree > Haiku 5.5 runs the main session and edits the code > search maps the repo on Haiku 5.5, read-only > grep finds call sites on Haiku 5.5 > docs pulls the API reference on Haiku 5.5 > Opus 5.5 on call as advisor, reads the full transcript only when consulted > JEV routes micro-forks in milliseconds one honest note: it costs more than Haiku alone, but less than running the whole session on Sonnet or Opus. needs Claude Code v2.1.293 or later, so run claude update first paste the tree and this prompt into Claude Code ↓ "Set up my Claude Code around this tree: 1. Run the main session on Haiku 5.5 with Opus 5.5 as advisor. 2. Create three read-only Haiku 5.5 subagents: search (maps the repo), grep (finds call sites), docs (pulls the API reference). 3. Add one rule to CLAUDE.md: consult the advisor before a plan locks, after the same error twice, and before a task is marked done. 4. Route fast deterministic forks (tool choice, path selection, retries) through JEV. Show me every change as a diff first. Nothing gets edited until I say go." ↳ http://code.claude.com/docs/en/advisor save it, this is the cheapest Opus you'll ever run.

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