lunaroute

LunaRoute Claude Code Plugin

What LunaRoute Does

LunaRoute is a Claude Code plugin for mid-session model routing. Users type #!sonnet (or any model name) to set a sticky route tag for the current session. Every subsequent API request — including requests made by subagents — carries a [LUNAROUTE:sonnet] marker injected into the conversation context. An external proxy reads this marker and routes the request to the appropriate LLM backend. Use #!clear to remove the tag and return to default routing.

Installation

Via plugin install:

claude plugin install github.com/<owner>/lunaroute-cc-plugin

Via ~/.claude/settings.json:

{
  "extraKnownMarketplaces": {
    "lunaroute-marketplace": {
      "source": {
        "source": "github",
        "repo": "<owner>/lunaroute-cc-plugin"
      }
    }
  }
}

Usage

Command	Effect
#!sonnet	Set route to sonnet
#!gpt-4o	Set route to gpt-4o
#!claude-3-haiku	Set route to claude-3-haiku
#!clear	Clear the active route

The tag can be standalone or inline with a message:

#!sonnet rewrite this function

Confirmation is shown after each command:

[Route set: sonnet]
[Route cleared]

Subagent Routing

Subagents automatically inherit the session's active route tag. To override routing for a specific subagent, include a #!model tag in the subagent's prompt directly.

#!sonnet                              → main session → sonnet
  ├── subagent A (no override)        → inherits sonnet
  ├── subagent B (prompt has #!haiku) → routes to haiku
  └── subagent C (no override)        → inherits sonnet

Proxy Integration

Critical: The proxy receives the full conversation history, not just the latest message. When a user changes routes mid-session, earlier messages carry stale markers. The proxy must extract the route from the last user message only.

function extractRoute(requestBody) {
  const messages = requestBody.messages || [];

  // Find the last user message
  for (let i = messages.length - 1; i >= 0; i--) {
    if (messages[i].role !== 'user') continue;

    const content = messages[i].content;
    const text = typeof content === 'string'
      ? content
      : content.map(b => b.text || '').join('\n');

    const match = text.match(/\[LUNAROUTE:([a-zA-Z0-9._-]+)\]/);
    if (match) return match[1];

    break; // Only check the last user message
  }

  return null; // No route — use default model
}

How It Works

• UserPromptSubmit hook — detects #! tags in user input, persists state to /tmp/lunaroute-{session_id}, and injects [LUNAROUTE:model] into subsequent requests via additionalContext.
• PreToolUse hook (Agent matcher) — injects the active route marker into subagent prompts via updatedInput, enabling inherited routing without user intervention.

Known Limitations

• The #!model tag remains visible in the prompt text. Hooks can add context but cannot modify the prompt text itself.
• Route state is session-scoped. There is no cross-session persistence — the route resets when the session ends.
• Shebangs like #!/usr/bin/env node are correctly ignored. The regex requires whitespace before #! to distinguish route commands from shell shebangs.