feat(mcp): add ponytail-mcp, an MCP server for the ruleset (#91)

* feat(mcp): add ponytail-mcp server (prompt + tool) * test(mcp): cover mode resolution and instruction text * Report resolved MCP mode
2026-06-19 00:24:40 +02:00
parent 15749f7ffc
commit 0ac987f995
5 changed files with 155 additions and 0 deletions
@@ -0,0 +1,48 @@
+#!/usr/bin/env node
+// Ponytail MCP server: serves the lazy-senior-dev ruleset over stdio as a
+// prompt (user-invoked) and a tool (for hosts that pull context via tools).
+// It does NOT replace the always-on adapters; it's the clean option for hosts
+// whose only injection point is the prompt menu (see #70).
+import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
+import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js";
+import { z } from "zod";
+
+import { MODES, buildInstructions, resolveMode } from "./instructions.js";
+
+const server = new McpServer({ name: "ponytail", version: "0.1.0" });
+
+const modeArg = z
+  .enum(MODES)
+  .optional()
+  .describe("Ponytail intensity: lite, full, or ultra. Omit for the configured default.");
+
+server.registerPrompt(
+  "ponytail",
+  {
+    title: "Ponytail mode",
+    description: "Lazy senior dev instructions: YAGNI, stdlib first, the smallest correct change.",
+    argsSchema: { mode: modeArg },
+  },
+  ({ mode }) => ({
+    messages: [{ role: "user", content: { type: "text", text: buildInstructions(mode) } }],
+  }),
+);
+
+server.registerTool(
+  "ponytail_instructions",
+  {
+    title: "Ponytail instructions",
+    description: "Return the Ponytail ruleset for the given intensity (lite, full, or ultra).",
+    inputSchema: { mode: modeArg },
+    outputSchema: { mode: z.string(), instructions: z.string() },
+    annotations: { readOnlyHint: true, openWorldHint: false },
+  },
+  ({ mode }) => {
+    const resolvedMode = resolveMode(mode);
+    const instructions = buildInstructions(resolvedMode);
+    const structuredContent = { mode: resolvedMode, instructions };
+    return { content: [{ type: "text", text: instructions }], structuredContent };
+  },
+);
+
+await server.connect(new StdioServerTransport());