pi-config/extensions/smart-router/index.ts

import type {
  ExtensionAPI,
  ExtensionContext,
  BeforeAgentStartEvent,
  BeforeAgentStartEventResult,
  ExtensionCommandContext,
} from "@earendil-works/pi-coding-agent";

// Global state for manual model lock
let isLocked = false;
let lockedModel: any = null;

// Model ID mappings for routing
const MODELS: Record<string, { provider: string; id: string }> = {
  "free-core":          { provider: "openrouter", id: "openrouter/owl-alpha" },
  "router-eval":        { provider: "openrouter", id: "openrouter/owl-alpha" },
  "economy-devops":     { provider: "openrouter", id: "qwen/qwen3.6-flash" },
  "economy-code":       { provider: "openrouter", id: "deepseek/deepseek-v4-flash" },
  "precision-devops":   { provider: "openrouter", id: "qwen/qwen-2.5-72b-instruct" },
  "precision-code-high":{ provider: "openrouter", id: "deepseek/deepseek-v4-pro" },
  "precision-react":    { provider: "openrouter", id: "qwen/qwen3-coder-plus" },
  "context-heavy":      { provider: "openrouter", id: "moonshotai/kimi-k2.6" },
};

function getModel(ctx: ExtensionContext, key: string): any {
  const mapping = MODELS[key];
  if (!mapping) return undefined;
  return ctx.modelRegistry.find(mapping.provider, mapping.id);
}

function modelLabel(key: string): string {
  const m = MODELS[key];
  if (!m) return key;
  // Model IDs already include provider prefix (e.g. "openrouter/owl-alpha")
  // so just use the ID directly to avoid double-prefixing
  return m.id.includes("/") ? m.id : `${m.provider}/${m.id}`;
}

export default function (pi: ExtensionAPI) {

  // 1. Register /lock-model command
  pi.registerCommand("lock-model", {
    description: "Lock to a specific model. Disables dynamic routing until /unlock-model.",
    handler: async (args: string, ctx: ExtensionCommandContext) => {
      const modelId = (args || "").trim();
      if (!modelId) {
        ctx.ui.notify(
          "Usage: /lock-model <provider/model-id>\nExample: /lock-model openrouter/anthropic/claude-3.5-sonnet",
          "error"
        );
        return;
      }
      const slashIdx = modelId.indexOf("/");
      if (slashIdx < 0) {
        ctx.ui.notify("Invalid model ID format. Use: provider/model-id", "error");
        return;
      }
      const provider = modelId.substring(0, slashIdx);
      const id = modelId.substring(slashIdx + 1);
      const model = ctx.modelRegistry.find(provider, id);
      if (!model) {
        ctx.ui.notify(`Model not found: ${modelId}`, "error");
        return;
      }
      isLocked = true;
      lockedModel = model;
      pi.setModel(model);
      ctx.ui.notify(`🔒 Router disabled. Model locked to: ${modelId}`, "info");
    },
  });

  // 2. Register /unlock-model command
  pi.registerCommand("unlock-model", {
    description: "Re-enable dynamic prompt routing.",
    handler: async (_args: string, ctx: ExtensionCommandContext) => {
      isLocked = false;
      lockedModel = null;
      ctx.ui.notify("🔓 Router enabled. Prompts will be dynamically analyzed and routed.", "info");
    },
  });

  // 3. Intercept prompts before agent starts
  pi.on("before_agent_start", async (event: BeforeAgentStartEvent, ctx: ExtensionContext): Promise<BeforeAgentStartEventResult | undefined> => {
    const prompt = event.prompt;

    // Pass-through if user locked the model manually
    if (isLocked && lockedModel) {
      pi.setModel(lockedModel);
      pi.sendMessage({
        customType: "router-status",
        content: `🔒 Locked → ${lockedModel.id || "unknown"}`,
        display: false,
      });
      return;
    }

    // Skip routing for short prompts / simple greetings
    if (prompt.trim().length < 15) {
      const model = getModel(ctx, "router-eval");
      if (model) pi.setModel(model);
      pi.sendMessage({
        customType: "router-status",
        content: `⚡ Short prompt → ${modelLabel("router-eval")}`,
        display: false,
      });
      return;
    }

    // Show analyzing indicator
    pi.sendMessage({
      customType: "router-status",
      content: "🤔 Analyzing prompt intent...",
      display: false,
    });

    try {
      const OPENROUTER_API_KEY = process.env["OPENROUTER_API_KEY"] || "";

      const response = await fetch("https://openrouter.ai/api/v1/chat/completions", {
        method: "POST",
        headers: {
          "Authorization": `Bearer ${OPENROUTER_API_KEY}`,
          "Content-Type": "application/json",
        },
        body: JSON.stringify({
          model: "openrouter/owl-alpha",
          messages: [
            {
              role: "system",
              content:
                'You are a minimal command interceptor router. Analyze the prompt and output ONLY a minified JSON object containing the tag and language. No markdown, no conversation.\n\nValid Tags:\n- "read" (reading/ingesting logs, docs, read-only code)\n- "discuss" (general chat, architectural concepts)\n- "search" (requires web search/external lookups)\n- "devops-low" (editing yaml, single dockerfile, basic bash, env adjustments)\n- "devops-high" (complex multi-container network layers, server crashes)\n- "code-analysis-low" (finding a bug in a short file)\n- "code-analysis-high" (refactoring multiple complex files, tracking syntax errors)\n- "codewrite-low" (generating simple syntax boilerplate or standard functions)\n- "codewrite-high" (complex features, heavy React state, complex PHP architectures)\n\nRespond exactly like this: {"tag":"tag-name","lang":"react|php|python|rust|bash|none"}',
            },
            { role: "user", content: prompt },
          ],
          max_tokens: 35,
          temperature: 0,
        }),
      });

      const payload = await response.json();
      const content = payload?.choices?.[0]?.message?.content?.trim();
      if (!content) {
        const fallback = getModel(ctx, "free-core");
        if (fallback) pi.setModel(fallback);
        pi.sendMessage({
          customType: "router-status",
          content: `⚠️ Analysis failed → fallback ${modelLabel("free-core")}`,
          display: false,
        });
        return;
      }

      const decision = JSON.parse(content);
      const tag: string = decision.tag || "read";
      const lang: string = decision.lang || "none";

      // Deterministic routing tree
      let modelKey: string;
      switch (tag) {
        case "read":
        case "discuss":
        case "search":
          modelKey = "free-core";
          break;
        case "devops-low":
          modelKey = "economy-devops";
          break;
        case "devops-high":
          modelKey = "precision-devops";
          break;
        case "code-analysis-low":
          modelKey = "free-core";
          break;
        case "code-analysis-high":
          modelKey = "context-heavy";
          break;
        case "codewrite-low":
          modelKey = "economy-code";
          break;
        case "codewrite-high":
          modelKey = lang === "react" ? "precision-react" : "precision-code-high";
          break;
        default:
          modelKey = "free-core";
      }

      const model = getModel(ctx, modelKey);
      if (model) {
        pi.setModel(model);
      }

      // Show routing decision
      pi.sendMessage({
        customType: "router-status",
        content: `🎯 ${tag} (${lang}) → ${modelLabel(modelKey)}`,
        display: false,
      });

    } catch (_error) {
      // Fallback gracefully on network drops
      const fallback = getModel(ctx, "free-core");
      if (fallback) pi.setModel(fallback);
      pi.sendMessage({
        customType: "router-status",
        content: `⚠️ Error → fallback ${modelLabel("free-core")}`,
        display: false,
      });
    }
  });
}