From 7e88fbc347debac57da3b8c45060776db139243b Mon Sep 17 00:00:00 2001
From: Mats Bosson <mats.bosson@gmail.com>
Date: Sun, 29 Mar 2026 23:49:53 +0700
Subject: [PATCH] MCP discover tool

---
 packages/mcp/src/server.ts                | 17 +++++++---
 packages/mcp/src/tools/add.ts             | 30 +++++++++++++++++
 packages/mcp/src/tools/discover.ts        | 13 +++++++
 packages/mcp/src/tools/validate.ts        | 41 +++++++++++++++++++++++
 packages/mcp/tests/tools/add.test.ts      | 30 +++++++++++++++++
 packages/mcp/tests/tools/discover.test.ts | 29 ++++++++++++++++
 6 files changed, 156 insertions(+), 4 deletions(-)
 create mode 100644 packages/mcp/src/tools/add.ts
 create mode 100644 packages/mcp/src/tools/discover.ts
 create mode 100644 packages/mcp/src/tools/validate.ts
 create mode 100644 packages/mcp/tests/tools/add.test.ts
 create mode 100644 packages/mcp/tests/tools/discover.test.ts

diff --git a/packages/mcp/src/server.ts b/packages/mcp/src/server.ts
index ccdccd2..dbcf78e 100644
--- a/packages/mcp/src/server.ts
+++ b/packages/mcp/src/server.ts
@@ -1,10 +1,19 @@
 import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
+import { z } from "zod/v4";
+import { ComponentRegistry } from "./registry.js";
+import { handleDiscover } from "./tools/discover.js";
 
 /** Creates and configures the PettyUI MCP server. */
 export function createPettyUIServer(): McpServer {
-  const server = new McpServer({
-    name: "pettyui",
-    version: "0.1.0",
-  });
+  const server = new McpServer({ name: "pettyui", version: "0.1.0" });
+  const registry = new ComponentRegistry();
+  server.tool(
+    "pettyui.discover",
+    "Search for components by describing what you need",
+    { intent: z.string().describe("What you need"), maxResults: z.number().optional().describe("Max results") },
+    async ({ intent, maxResults }) => ({
+      content: [{ type: "text", text: JSON.stringify(handleDiscover(registry, { intent, maxResults }), null, 2) }],
+    }),
+  );
   return server;
 }
diff --git a/packages/mcp/src/tools/add.ts b/packages/mcp/src/tools/add.ts
new file mode 100644
index 0000000..04da962
--- /dev/null
+++ b/packages/mcp/src/tools/add.ts
@@ -0,0 +1,30 @@
+import { readFileSync, accessSync } from "node:fs";
+import { resolve, join } from "node:path";
+import type { ComponentRegistry } from "../registry.js";
+
+interface AddInput { component: string; targetDir?: string; }
+interface AddResult { files: Array<{ path: string; content: string }>; dependencies: string[]; }
+
+function toKebab(str: string): string {
+  return str.replace(/([a-z])([A-Z])/g, "$1-$2").toLowerCase();
+}
+
+/** Copies a styled component from the registry to the user's project. */
+export function handleAdd(registry: ComponentRegistry, input: AddInput): AddResult | null {
+  const comp = registry.getComponent(input.component);
+  if (!comp || !comp.hasStyledVersion) return null;
+
+  const kebab = toKebab(comp.meta.name);
+  const registryDir = resolve(import.meta.dirname, "../../registry/src/components");
+  const sourcePath = join(registryDir, `${kebab}.tsx`);
+
+  try { accessSync(sourcePath); } catch { return null; }
+
+  const content = readFileSync(sourcePath, "utf-8");
+  const targetDir = input.targetDir ?? "src/components/ui";
+
+  return {
+    files: [{ path: join(targetDir, `${kebab}.tsx`), content }],
+    dependencies: [comp.exportPath],
+  };
+}
diff --git a/packages/mcp/src/tools/discover.ts b/packages/mcp/src/tools/discover.ts
new file mode 100644
index 0000000..97e05f6
--- /dev/null
+++ b/packages/mcp/src/tools/discover.ts
@@ -0,0 +1,13 @@
+import type { ComponentRegistry } from "../registry.js";
+
+interface DiscoverInput { intent: string; maxResults?: number; }
+interface DiscoverResult { name: string; description: string; exportPath: string; parts: readonly string[]; hasStyledVersion: boolean; score: number; }
+
+/** Searches components by natural language intent description. */
+export function handleDiscover(registry: ComponentRegistry, input: DiscoverInput): DiscoverResult[] {
+  const max = input.maxResults ?? 10;
+  return registry.search(input.intent).slice(0, max).map((r) => ({
+    name: r.meta.name, description: r.meta.description, exportPath: r.exportPath,
+    parts: r.meta.parts, hasStyledVersion: r.hasStyledVersion, score: r.score,
+  }));
+}
diff --git a/packages/mcp/src/tools/validate.ts b/packages/mcp/src/tools/validate.ts
new file mode 100644
index 0000000..87475d9
--- /dev/null
+++ b/packages/mcp/src/tools/validate.ts
@@ -0,0 +1,41 @@
+import type { ComponentRegistry } from "../registry.js";
+
+interface ValidateInput { component: string; schema?: string; props?: Record<string, unknown>; parts?: string[]; }
+interface ValidateResult { valid: boolean; errors: string[]; }
+
+/** Validates props against schema and/or checks required parts are present. */
+export function handleValidate(registry: ComponentRegistry, input: ValidateInput): ValidateResult {
+  const comp = registry.getComponent(input.component);
+  if (!comp) return { valid: false, errors: [`Component "${input.component}" not found`] };
+
+  const errors: string[] = [];
+
+  // Validate props against named schema
+  if (input.props !== undefined && input.schema) {
+    const schema = comp.schemas[input.schema];
+    if (!schema) {
+      errors.push(`Schema "${input.schema}" not found on ${comp.meta.name}`);
+    } else {
+      // schema is a Zod schema — call safeParse
+      const zSchema = schema as { safeParse: (data: unknown) => { success: boolean; error?: { issues: Array<{ message: string; path: (string | number)[] }> } } };
+      const result = zSchema.safeParse(input.props);
+      if (!result.success && result.error) {
+        for (const issue of result.error.issues) {
+          const pathStr = issue.path.length > 0 ? ` at "${issue.path.join(".")}"` : "";
+          errors.push(`${issue.message}${pathStr}`);
+        }
+      }
+    }
+  }
+
+  // Check required parts
+  if (input.parts !== undefined) {
+    for (const required of comp.meta.requiredParts) {
+      if (!input.parts.includes(required)) {
+        errors.push(`Missing required part: ${required}`);
+      }
+    }
+  }
+
+  return { valid: errors.length === 0, errors };
+}
diff --git a/packages/mcp/tests/tools/add.test.ts b/packages/mcp/tests/tools/add.test.ts
new file mode 100644
index 0000000..342f96d
--- /dev/null
+++ b/packages/mcp/tests/tools/add.test.ts
@@ -0,0 +1,30 @@
+import { describe, it, expect } from "vitest";
+import { handleAdd } from "../../src/tools/add.js";
+import { ComponentRegistry } from "../../src/registry.js";
+
+describe("pettyui.add", () => {
+  const registry = new ComponentRegistry();
+
+  it("returns styled source for Dialog", () => {
+    const result = handleAdd(registry, { component: "Dialog" });
+    expect(result).not.toBeNull();
+    expect(result?.files[0].content).toContain("Dialog");
+    expect(result?.dependencies).toContain("pettyui/dialog");
+  });
+
+  it("returns null without styled version", () => {
+    const result = handleAdd(registry, { component: "Checkbox" });
+    expect(result).toBeNull();
+  });
+
+  it("returns null for unknown component", () => {
+    const result = handleAdd(registry, { component: "FakeComponent" });
+    expect(result).toBeNull();
+  });
+
+  it("uses custom target dir", () => {
+    const result = handleAdd(registry, { component: "Dialog", targetDir: "src/ui" });
+    expect(result).not.toBeNull();
+    expect(result?.files[0].path).toContain("src/ui");
+  });
+});
diff --git a/packages/mcp/tests/tools/discover.test.ts b/packages/mcp/tests/tools/discover.test.ts
new file mode 100644
index 0000000..bbf65b7
--- /dev/null
+++ b/packages/mcp/tests/tools/discover.test.ts
@@ -0,0 +1,29 @@
+import { describe, it, expect } from "vitest";
+import { handleDiscover } from "../../src/tools/discover.js";
+import { ComponentRegistry } from "../../src/registry.js";
+
+describe("pettyui.discover", () => {
+  const registry = new ComponentRegistry();
+
+  it("finds components matching intent — modal overlay → Dialog first", () => {
+    const results = handleDiscover(registry, { intent: "modal overlay" });
+    expect(results.length).toBeGreaterThan(0);
+    expect(results[0].name).toBe("Dialog");
+  });
+
+  it("returns multiple ranked matches — select option includes Select", () => {
+    const results = handleDiscover(registry, { intent: "select option" });
+    const names = results.map((r) => r.name);
+    expect(names).toContain("Select");
+  });
+
+  it("returns empty for no matches — xyznonexistent → []", () => {
+    const results = handleDiscover(registry, { intent: "xyznonexistent" });
+    expect(results).toEqual([]);
+  });
+
+  it("limits results with maxResults: 3", () => {
+    const results = handleDiscover(registry, { intent: "a", maxResults: 3 });
+    expect(results.length).toBeLessThanOrEqual(3);
+  });
+});