4 files changed, 139 insertions, 0 deletions
diff --git a/packages/core/src/tools/list-files.ts b/packages/core/src/tools/list-files.ts
new file mode 100644
index 0000000..360ac98
--- /dev/null
+++ b/packages/core/src/tools/list-files.ts
@@ -0,0 +1,38 @@
+import { readdir } from "node:fs/promises";
+import { join, resolve } from "node:path";
+import { z } from "zod";
+import type { ToolDefinition } from "../types/index.js";
+
+export function createListFilesTool(workingDirectory: string): ToolDefinition {
+	return {
+		name: "list_files",
+		description: "List files and directories at a path relative to the working directory.",
+		parameters: z.object({
+			path: z
+				.string()
+				.optional()
+				.describe("Path to list, relative to the working directory. Defaults to '.'"),
+		}),
+		execute: async (args: Record<string, unknown>): Promise<string> => {
+			const relPath = (args.path as string | undefined) ?? ".";
+			const absolutePath = resolve(join(workingDirectory, relPath));
+			const absoluteWorkDir = resolve(workingDirectory);
+
+			if (!absolutePath.startsWith(`${absoluteWorkDir}/`) && absolutePath !== absoluteWorkDir) {
+				return `Error: Path "${relPath}" is outside the working directory.`;
+			}
+
+			try {
+				const entries = await readdir(absolutePath, { withFileTypes: true });
+				if (entries.length === 0) {
+					return "(empty directory)";
+				}
+				return entries
+					.map((entry) => (entry.isDirectory() ? `${entry.name}/` : entry.name))
+					.join("\n");
+			} catch (err) {
+				return `Error listing files: ${err instanceof Error ? err.message : String(err)}`;
+			}
+		},
+	};
+}
diff --git a/packages/core/src/tools/read-file.ts b/packages/core/src/tools/read-file.ts
new file mode 100644
index 0000000..476f243
--- /dev/null
+++ b/packages/core/src/tools/read-file.ts
@@ -0,0 +1,33 @@
+import { readFile } from "node:fs/promises";
+import { join, resolve } from "node:path";
+import { z } from "zod";
+import type { ToolDefinition } from "../types/index.js";
+
+export function createReadFileTool(workingDirectory: string): ToolDefinition {
+	return {
+		name: "read_file",
+		description: "Read the contents of a file relative to the working directory.",
+		parameters: z.object({
+			path: z.string().describe("Path to the file, relative to the working directory"),
+		}),
+		execute: async (args: Record<string, unknown>): Promise<string> => {
+			const filePath = args.path as string;
+			const absolutePath = resolve(join(workingDirectory, filePath));
+			const absoluteWorkDir = resolve(workingDirectory);
+
+			if (!absolutePath.startsWith(`${absoluteWorkDir}/`) && absolutePath !== absoluteWorkDir) {
+				return `Error: Path "${filePath}" is outside the working directory.`;
+			}
+
+			try {
+				return await readFile(absolutePath, "utf8");
+			} catch (err) {
+				const code = (err as NodeJS.ErrnoException).code;
+				if (code === "ENOENT") {
+					return `Error: File "${filePath}" not found.`;
+				}
+				return `Error reading file: ${err instanceof Error ? err.message : String(err)}`;
+			}
+		},
+	};
+}
diff --git a/packages/core/src/tools/registry.ts b/packages/core/src/tools/registry.ts
new file mode 100644
index 0000000..4699c93
--- /dev/null
+++ b/packages/core/src/tools/registry.ts
@@ -0,0 +1,35 @@
+import { tool } from "ai";
+import { z } from "zod";
+import type { ToolDefinition } from "../types/index.js";
+
+export function createToolRegistry(tools: ToolDefinition[]) {
+	const toolMap = new Map<string, ToolDefinition>(tools.map((t) => [t.name, t]));
+
+	return {
+		getTools(): ToolDefinition[] {
+			return [...toolMap.values()];
+		},
+
+		getTool(name: string): ToolDefinition | undefined {
+			return toolMap.get(name);
+		},
+
+		getAISDKTools() {
+			const result: Record<string, ReturnType<typeof tool>> = {};
+			for (const [name, def] of toolMap) {
+				const schema = def.parameters;
+				const t = tool({
+					description: def.description,
+					parameters: schema instanceof z.ZodObject ? schema : z.object({}),
+					execute: async (args) => {
+						return def.execute(args as Record<string, unknown>);
+					},
+				});
+				// The AI SDK tool() overloads cause type narrowing issues when
+				// execute is provided. The runtime value is correct.
+				result[name] = t as unknown as ReturnType<typeof tool>;
+			}
+			return result;
+		},
+	};
+}
diff --git a/packages/core/src/tools/write-file.ts b/packages/core/src/tools/write-file.ts
new file mode 100644
index 0000000..23bc72a
--- /dev/null
+++ b/packages/core/src/tools/write-file.ts
@@ -0,0 +1,33 @@
+import { mkdir, writeFile } from "node:fs/promises";
+import { dirname, join, resolve } from "node:path";
+import { z } from "zod";
+import type { ToolDefinition } from "../types/index.js";
+
+export function createWriteFileTool(workingDirectory: string): ToolDefinition {
+	return {
+		name: "write_file",
+		description: "Write content to a file relative to the working directory.",
+		parameters: z.object({
+			path: z.string().describe("Path to the file, relative to the working directory"),
+			content: z.string().describe("Content to write to the file"),
+		}),
+		execute: async (args: Record<string, unknown>): Promise<string> => {
+			const filePath = args.path as string;
+			const content = args.content as string;
+			const absolutePath = resolve(join(workingDirectory, filePath));
+			const absoluteWorkDir = resolve(workingDirectory);
+
+			if (!absolutePath.startsWith(`${absoluteWorkDir}/`) && absolutePath !== absoluteWorkDir) {
+				return `Error: Path "${filePath}" is outside the working directory.`;
+			}
+
+			try {
+				await mkdir(dirname(absolutePath), { recursive: true });
+				await writeFile(absolutePath, content, "utf8");
+				return `Successfully wrote to "${filePath}".`;
+			} catch (err) {
+				return `Error writing file: ${err instanceof Error ? err.message : String(err)}`;
+			}
+		},
+	};
+}