added router details to usage endpoint

proxy.mjs

@@ -675,12 +675,21 @@ const server = createServer(async (req, res) => {
     notes.push("Anthropic has no public balance API — check console.anthropic.com");
     notes.push("Z.ai is flat-rate; no balance API available");
 
+    // Build routing summary (the 3 Claude Code / Roo Code tiers)
+    const routing = {
+      sonnet: { provider: "zai", model: "glm-4.7", description: "Daily workhorse (Z.ai flat-rate)" },
+      opus: { provider: "anthropic", model: "claude-opus-4-6", description: "Complex tasks (Anthropic pay-per-token)" },
+      haiku: { provider: "deepseek", model: "deepseek-chat", description: "Trivial/fast tasks (DeepSeek cheap tier)" },
+      default: { provider: "zai", model: "glm-4.7", description: "Unknown models fall back here" },
+    };
+
     res.writeHead(200, { "content-type": "application/json" });
     res.end(
       JSON.stringify({
         service: "ein-ai-proxy",
         generatedAt: new Date().toISOString(),
         currentPeriod,
+        routing,
         providers,
         totals: {
           ...totals,