Configuration Reference

See Configuration for file locations, precedence, and an annotated example. Full template: shunt.toml.example.

[server]

Key	Default	Meaning
bind	127.0.0.1:3001	Address shunt listens on
default_provider	anthropic	Provider for any model with no matching route
sse_keepalive_seconds	30	Idle seconds before an SSE ping is injected; 0 disables (details)

[server.auth] (optional)

Presence of this table enables inbound client-token auth (details):

Key	Default	Meaning
header	x-shunt-token	Header carrying the client token
tokens_env	SHUNT_CLIENT_TOKENS	Env var holding comma-separated name:token pairs

[providers.<name>]

Each provider is a table under a name of your choosing. Built-ins (anthropic, openai, codex) can be partially overridden — config maps deep-merge.

Key	Values	Meaning
kind	anthropic | responses	Upstream protocol / adapter. anthropic = Messages API (passed through, optionally re-keyed); responses = Anthropic Messages translated to the OpenAI Responses API.
base_url	URL	Upstream base; shunt appends the endpoint path.
auth	passthrough | api_key | chatgpt_oauth	passthrough forwards the client’s own credential; api_key injects a key from api_key_env; chatgpt_oauth reuses ~/.codex/auth.json.
api_key_env	env var name	Where the key is read from, when auth = "api_key".
api_key_header	bearer (default) | x_api_key	Header the injected key is sent in.
effort	low … max	Optional default reasoning effort (responses providers).
count_tokens	tiktoken (default) | estimate	responses providers only: local tiktoken count vs. 404 fallback (details).

[[routes]]

Exact-match routing entries — checked first:

Key	Required	Meaning
model	✅	The exact model id Claude Code sends
provider	✅	Name of a [providers.<name>] table
upstream_model	—	Rewrite the model id forwarded upstream
effort	—	Per-route reasoning-effort override

[[route_prefixes]]

Prefix-match routing entries — checked after exact routes:

Key	Required	Meaning
prefix	✅	Model-id prefix, e.g. gpt-
provider	✅	Name of a [providers.<name>] table

[[models]]

Entries returned by GET /v1/models for model discovery. Ids must begin with claude or anthropic or Claude Code ignores them.

Key	Required	Meaning
id	✅	Model id exposed to Claude Code
display_name	—	Label shown in the /model picker

Routing precedence

Exact [[routes]] match → [[route_prefixes]] prefix match → server.default_provider.