Running every subagent on Haiku takes two env vars, not a --subagents flag

Two posts on X, 10,000 likes between them, call this an "official Anthropic tip": claude --advisor opus --subagents haiku. Half of it is real. --advisor opus exists, but --subagents appears nowhere in the Claude Code docs or in the last nine release notes. Type it and you get an error.

To run every subagent on Haiku 5.5, add two lines to the env block of your settings file. The first line alone is only a default, so a subagent definition with its own model still wins. The second line forces it (v2.1.257 or later).

// ~/.claude/settings.json
{
  "env": {
    "CLAUDE_CODE_SUBAGENT_MODEL": "haiku",
    "CLAUDE_CODE_SUBAGENT_MODEL_FORCE": "1"
  }
}

The advisor is one command. Run /advisor opus inside a session, or pass it at launch.

claude --advisor opus

To confirm it took, open /tasks while a subagent is running and each row shows its model. The haiku alias only points at Haiku 5.5 from v2.1.293, so run claude update first.