Claude Model Router

A Claude Code Mod that chooses a model and effort for each main-conversation turn, advised by a prompt classifier: Jev, or Cloudflare's Clef and Clef Flash.

The Mod changes only the model and effort in Claude Code's turn hook. Claude Code sends the request, streams the reply, runs tools, and reports usage. The router does not proxy Anthropic traffic or start a local server. Subagent model choices pass through unchanged.

The band above the prompt shows the tier, model, and reason for each turn. /router opens a pane to pin a tier, edit the model and effort of each tier, and tune the policy. See the user guide.

The router needs Claude Code 2.1.289 or newer. Current savings are not measured. The panel shows Claude's reported usage and configured-price scenarios, not a savings total. See the evaluation.

How it works

sequenceDiagram
  actor Dev as Developer
  participant Code as Claude Code
  participant Mod as Router Mod
  participant Cls as Classifier
  participant API as Anthropic
  Dev->>Code: Prompt
  Code->>Mod: Main or subagent step
  alt Main conversation in Auto
    Mod->>Cls: Bounded prompt and dialogue
    Cls-->>Mod: Tier advice
    Mod-->>Code: Selected model and effort
  else Manual or subagent
    Mod-->>Code: Original model and effort
  end
  Code->>API: Native request and tools
  API-->>Code: Response stream and usage
  Mod-->>Dev: Status band and router pane

The active classifier labels a new logical turn once. Tool continuations keep that choice. A local policy applies vote, context, failure, and cache-cost rules before the Mod changes the next step. Claude Code owns request construction, model credentials, tools, streaming, and the API cost ledger.

These are routing defaults. They do not claim equal model quality.

Install

You need Claude Code 2.1.289 or newer and credentials for one classifier: a Jev API key from typesafe.ai, or a Cloudflare API token and account ID for Clef or Clef Flash on Workers AI.

claude plugin marketplace add alexei-led/claude-router
claude plugin install router@alexei-led-claude-router

Start Claude Code on the full baseline model, for example claude --model claude-sonnet-5-5. Run /plugin configure router and save the key. For Clef or Clef Flash, save the Cloudflare token and account ID, then pick the classifier on the pane's Classifier tab. A session on the baseline model starts in Auto; on another model it starts in Manual, and /router auto turns routing on.

Claude Code updates the plugin at startup when auto-update is on for this marketplace. Otherwise run claude plugin marketplace update alexei-led-claude-router, then claude plugin update router@alexei-led-claude-router.

Upgrading from 0.8? Remove the gateway settings that 0.8 /router:setup wrote before the first 1.0 session, or requests go to a gateway that 1.0 no longer starts. Follow the migration steps.

Run from a checkout

Start Claude Code with this directory as a local plugin and the full Sonnet baseline model:

claude --plugin-dir "$PWD" --model claude-sonnet-5-5

In Claude Code, run /plugin configure router and save your classifier key in the sensitive plugin option. The Mod adds its status band and /router pane. No status-line setup or gateway environment variables are needed.

Run /router to open the pane: route status, per-tier controls, tuning, and usage. Run /model to select a model and enter Manual mode, and /router auto to resume. For controls, metrics, tuning, and troubleshooting, see the user guide.

Before a push, run the same checks as CI. npm run validate and npm run test:plugin need the claude CLI: they load the Mod in the Claude Code engine, which refuses some faults that lint and unit tests miss.

npm run check && npm test && npm run validate && npm run test:plugin

Documentation

• User guide: install, use the controls, read the panel, and troubleshoot.
• Configuration: classifiers and keys, the optional profile router.json, defaults, and migrations.
• Architecture: Mod event flow, state, safeguards, and runtime boundaries.
• Native router details: panel semantics, tuning, and accepted limits.
• Evaluation: historical gateway results and the native shadow replay.
• Changelog: user-visible changes by version.