Switching models

The model menu lives in routes.toml under [models]: friendly aliases → "<upstream>:<slug>". Everything below is a way to change that mapping or which alias an agent uses. The proxy hot-reloads routes.toml on save (and keeps the previous config if an edit is invalid), so most changes need no restart.

The mux CLI

bin/mux models                              # list aliases → upstream:slug
bin/mux set flagship openrouter:z-ai/glm-6  # point an alias at a new model
bin/mux use glm-researcher reasoner         # retarget an agent's <<route:>> tag
bin/mux check-latest                        # verify configured slugs exist on OpenRouter

• set <alias> <upstream:slug> rewrites just that alias's value in routes.toml, validating the spec first (anthropic: or openrouter:).
• use <agent> <alias> rewrites the <<route:alias>> tag inside .claude/agents/<agent>.md, so that agent now routes to a different alias.

Runtime override (no file edit)

Override any alias for a single proxy run with an env var named MUX_MODEL_<ALIAS> (uppercase; hyphens become underscores):

MUX_MODEL_FLAGSHIP=openrouter:qwen/qwen3.7-max bun run proxy
MUX_MODEL_CLAUDE_REVIEW=anthropic:claude-opus-4-8 bun run proxy

Handy for trying a model without touching tracked files.

How an agent chooses its model

An agent's model comes from the <<route:alias>> tag on the first content line of its .claude/agents/<name>.md. The tag → alias → upstream:slug. To change it, either edit the tag, bin/mux use, or repoint the alias with bin/mux set.

Adding a new model or route

1. Add an alias under [models] in routes.toml (myalias = "openrouter:vendor/slug").
2. Optionally add a routes entry (e.g. { when = { tag = "myalias" }, use = "myalias" }) — remember it's first-match, most-specific-first.
3. bin/mux models to confirm it loaded; the loader fails loud if an alias is unknown.

After changing anything

Give it a quick real check:

bin/mux check-latest          # slugs still exist?
bun run test:live                # real end-to-end call (needs OPENROUTER_API_KEY)