Set a Persistent Default Model and Lock Available Models in settings.json

Instead of passing --model on every command, set a persistent default in your settings.json and forget about it:

{
  "model": "claude-sonnet-4-6"
}

This lives at ~/.claude/settings.json for a user-level default. Drop a .claude/settings.json into a project directory to override it project-wide — the project setting always wins.

For teams, the availableModels key restricts which models anyone can select during a session. This prevents a team member from accidentally spinning up an expensive Opus run on a task that only needs Haiku:

{
  "model": "claude-sonnet-4-6",
  "availableModels": ["claude-sonnet-4-6", "claude-haiku-4-5-20251001"]
}

With this config, the /model picker only shows the listed models. Commit this to your repo and the whole team gets consistent, cost-controlled model access.

For CI pipelines where you don't want to commit a config file, use the environment variable instead:

ANTHROPIC_MODEL=claude-haiku-4-5-20251001 claude -p "Quick summary of today's commits"

The full precedence order, from highest to lowest priority:

--model flag > ANTHROPIC_MODEL env var > project settings.json > user settings.json

If you want to switch models mid-session without changing your defaults, use the /model command — it applies only to the current conversation and leaves settings.json untouched.

Set it once in settings.json and stop specifying the model on every command — save --model for the exceptions.