Switch relays, upstreams or models without restarting Claude Code or Codex#

ThinkWatch Lite points Claude Code and Codex at a gateway on the local machine once; from then on, the gateway decides which upstream and model each request goes to. Switching a relay, an upstream or a model is a change to a routing rule or to a manually selected group in the app. The gateway applies it to the requests that follow without restarting, and neither client is restarted or has its configuration file edited again.

Before you start#

• ThinkWatch Lite, installed. This guide follows version 2026.10.4.
• Claude Code or Codex connected with Connect… on the Clients page. Claude Code uses the new configuration from its next request; Codex needs its terminal reopened once. This is the last change on the client side.
• At least two upstreams on the Upstreams page, such as two relays, or one upstream that offers several models.

Steps#

With a routing rule:

1. On the Routing page, open the route that the client’s key follows under Routes. When there are no other routes, it is the one marked Default.
2. In its rule list, choose Edit… on the rule to change, usually the one shown as All requests (catch-all).
3. Under On match, keep Forward and choose the new upstream or group in Forward to.
4. To change the model as well, open Parameter rewrites and enter a model name in Change model to.
5. Choose Save in the rule dialog, then Save in the route dialog.

With a manually selected group:

1. On the Routing page, choose New group under Groups, enter a Name, set Strategy to Manual, tick the upstreams under Members, choose Set as preferred on one of them, then choose Create.
2. Select the group in a rule’s Forward to, as in the steps above.
3. To switch later, open the group’s menu on the Routing page and choose a member under Preferred upstream. The same switch is in the menu bar menu on macOS and in the tray menu on Windows and Linux: each manually selected group is listed with its current upstream, and its submenu lists the members.

Notes#

• Why no restart is needed. A connected client holds only the gateway’s address and a key of its own: ANTHROPIC_BASE_URL and ANTHROPIC_AUTH_TOKEN in ~/.claude/settings.json for Claude Code, a provider named thinkwatch in ~/.codex/config.toml for Codex. Upstream addresses, keys and models live in the gateway’s configuration, which the gateway reloads in place. A request already in progress finishes on the configuration it started with.
• Codex sessions stay in one list. Codex lists only the sessions of its current provider. While connected, it always uses the thinkwatch provider, so every session started through the gateway stays in the same list, whichever upstream answers it. Sessions from before connecting remain under their original provider and are listed separately; codex resume <session ID> -c model_provider=thinkwatch continues one of them through the gateway.
• Conversations in progress. Inside a group, a conversation stays with the upstream that answered it until the current turn ends, and across turns while that upstream’s prompt cache is warm: an answer within the last five minutes that read or wrote at least 1,024 cached tokens. After the preferred upstream of a manual group changes, new conversations move at once, while one in progress may stay until its cache cools or that upstream fails. A rule pointed at another upstream or group applies to every conversation from the next request.
• Model names. An upstream whose model list lacks the requested model is skipped. When the new upstream uses other model names, such as GLM in place of Claude, set Change model to on the rule. A changed model no longer hits the cached prompt, and the request is priced by the name sent.
• One client only. Each connected client has its own key. To switch one client and leave the others as they are, create a route with New route and add that client’s key under Keys using this route.

Related: Features, Fail over and balance load across relays and API keys, Install and update.