feat: add MCP tool handlers, definitions, and collection resource

Wrap existing service layer with MCP-compatible tool handlers for items,
categories, threads/candidates, setups, and image fetching. Add collection
summary resource for overview data. All 14 MCP-specific tests passing.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/server/mcp/tools/items.ts

@@ -0,0 +1,190 @@
+import type { db as prodDb } from "@/db/index.ts";
+import {
+	createItem,
+	deleteItem,
+	getAllItems,
+	getItemById,
+	updateItem,
+} from "../../services/item.service.ts";
+
+type Db = typeof prodDb;
+
+interface ToolResult {
+	content: Array<{ type: "text"; text: string }>;
+}
+
+function textResult(data: unknown): ToolResult {
+	return { content: [{ type: "text", text: JSON.stringify(data, null, 2) }] };
+}
+
+function errorResult(message: string): ToolResult {
+	return {
+		content: [{ type: "text", text: JSON.stringify({ error: message }) }],
+	};
+}
+
+export const itemToolDefinitions = [
+	{
+		name: "list_items",
+		description:
+			"List all items in the gear collection, optionally filtered by category.",
+		inputSchema: {
+			type: "object" as const,
+			properties: {
+				categoryId: {
+					type: "number",
+					description: "Filter items by category ID",
+				},
+			},
+		},
+	},
+	{
+		name: "get_item",
+		description: "Get a single item by its ID, including all details.",
+		inputSchema: {
+			type: "object" as const,
+			properties: {
+				id: { type: "number", description: "The item ID" },
+			},
+			required: ["id"],
+		},
+	},
+	{
+		name: "create_item",
+		description:
+			"Add a new item to the gear collection. Use this for items you've already decided on. For items you're still researching, use create_thread instead.",
+		inputSchema: {
+			type: "object" as const,
+			properties: {
+				name: { type: "string", description: "Item name" },
+				categoryId: { type: "number", description: "Category ID" },
+				weightGrams: { type: "number", description: "Weight in grams" },
+				priceCents: { type: "number", description: "Price in cents" },
+				notes: { type: "string", description: "Notes about the item" },
+				productUrl: { type: "string", description: "URL to the product page" },
+				imageFilename: {
+					type: "string",
+					description: "Filename of an uploaded image",
+				},
+				imageSourceUrl: {
+					type: "string",
+					description: "Original URL the image was fetched from",
+				},
+			},
+			required: ["name", "categoryId"],
+		},
+	},
+	{
+		name: "update_item",
+		description: "Update an existing item's fields.",
+		inputSchema: {
+			type: "object" as const,
+			properties: {
+				id: { type: "number", description: "The item ID to update" },
+				name: { type: "string", description: "Item name" },
+				categoryId: { type: "number", description: "Category ID" },
+				weightGrams: { type: "number", description: "Weight in grams" },
+				priceCents: { type: "number", description: "Price in cents" },
+				notes: { type: "string", description: "Notes about the item" },
+				productUrl: { type: "string", description: "URL to the product page" },
+				imageFilename: {
+					type: "string",
+					description: "Filename of an uploaded image",
+				},
+				imageSourceUrl: {
+					type: "string",
+					description: "Original URL the image was fetched from",
+				},
+			},
+			required: ["id"],
+		},
+	},
+	{
+		name: "delete_item",
+		description: "Delete an item from the gear collection by ID.",
+		inputSchema: {
+			type: "object" as const,
+			properties: {
+				id: { type: "number", description: "The item ID to delete" },
+			},
+			required: ["id"],
+		},
+	},
+];
+
+export function registerItemTools(db: Db) {
+	return {
+		list_items: async (args: { categoryId?: number }): Promise<ToolResult> => {
+			try {
+				const items = getAllItems(db);
+				if (args.categoryId) {
+					return textResult(
+						items.filter((i) => i.categoryId === args.categoryId),
+					);
+				}
+				return textResult(items);
+			} catch (err) {
+				return errorResult((err as Error).message);
+			}
+		},
+
+		get_item: async (args: { id: number }): Promise<ToolResult> => {
+			try {
+				const item = getItemById(db, args.id);
+				if (!item) return errorResult(`Item ${args.id} not found`);
+				return textResult(item);
+			} catch (err) {
+				return errorResult((err as Error).message);
+			}
+		},
+
+		create_item: async (args: {
+			name: string;
+			categoryId: number;
+			weightGrams?: number;
+			priceCents?: number;
+			notes?: string;
+			productUrl?: string;
+			imageFilename?: string;
+			imageSourceUrl?: string;
+		}): Promise<ToolResult> => {
+			try {
+				const item = createItem(db, args);
+				return textResult(item);
+			} catch (err) {
+				return errorResult((err as Error).message);
+			}
+		},
+
+		update_item: async (args: {
+			id: number;
+			name?: string;
+			categoryId?: number;
+			weightGrams?: number;
+			priceCents?: number;
+			notes?: string;
+			productUrl?: string;
+			imageFilename?: string;
+			imageSourceUrl?: string;
+		}): Promise<ToolResult> => {
+			try {
+				const { id, ...data } = args;
+				const item = updateItem(db, id, data);
+				if (!item) return errorResult(`Item ${id} not found`);
+				return textResult(item);
+			} catch (err) {
+				return errorResult((err as Error).message);
+			}
+		},
+
+		delete_item: async (args: { id: number }): Promise<ToolResult> => {
+			try {
+				const item = deleteItem(db, args.id);
+				if (!item) return errorResult(`Item ${args.id} not found`);
+				return textResult({ deleted: true, item });
+			} catch (err) {
+				return errorResult((err as Error).message);
+			}
+		},
+	};
+}