@draht/router

Role-based model routing with direct API calls, automatic fallback, and cost tracking.

Overview

The router maps task roles to LLM provider/model combinations with ordered fallback chains. No OpenRouter — direct API calls only for minimal latency.

Configuration

Config is loaded from (in priority order):

1. .draht/router.json (project-level)
2. ~/.draht/router.json (global)
3. Built-in defaults

Example .draht/router.json

{
  "architect": {
    "primary": { "provider": "anthropic", "model": "claude-opus-4-6" },
    "fallbacks": [{ "provider": "google", "model": "gemini-2.5-pro" }]
  },
  "implement": {
    "primary": { "provider": "anthropic", "model": "claude-sonnet-4-6" },
    "fallbacks": [
      { "provider": "openai", "model": "gpt-5.2" },
      { "provider": "deepseek", "model": "deepseek-v3" }
    ]
  }
}

Default Role Mapping

| Role | Primary | Fallbacks | |------|---------|-----------| | architect | anthropic/claude-opus-4-6 | google/gemini-2.5-pro | | implement | anthropic/claude-sonnet-4-6 | openai/gpt-5.2 → deepseek/deepseek-v3 | | boilerplate | deepseek/deepseek-v3 | google/gemini-2.5-flash | | quick | google/gemini-2.5-flash | deepseek/deepseek-v3 | | review | anthropic/claude-sonnet-4-6 | — | | docs | openai/gpt-5.2 | anthropic/claude-sonnet-4-6 |

CLI Usage

# Show current configuration
draht router show

# Set model for a role
draht router set implement anthropic/claude-sonnet-4-6 --fallback openai/gpt-5.2,deepseek/deepseek-v3

# Test resolution (dry-run)
draht router test
draht router test architect

# View cost summary
draht router cost

Fallback Behavior

When the primary model fails with a retryable error (429, 5xx, timeout), the router automatically tries the next model in the fallback chain. Non-retryable errors (401, 400) are thrown immediately.

Cost Tracking

Every API call is logged to .draht/cost-log.jsonl with:

• Timestamp, role, provider/model
• Input/output token counts
• Estimated cost in USD
• Session ID

Coding Agent Extension

import { createRouterExtension } from "@draht/router/extension";

const ext = createRouterExtension();
const model = ext.selectModel("implementation"); // → anthropic/claude-sonnet-4-6
const chain = ext.selectModelWithFallbacks("architecture"); // → full fallback chain

Task types are automatically mapped to roles:

• planning, architecture → architect
• implementation, coding → implement
• scaffold, boilerplate → boilerplate
• question, quick → quick
• review, pr-review → review
• documentation, readme → docs