feat(agent): add AgentHarness execution tools

packages/agent/src/harness/tools/write.ts

@@ -0,0 +1,43 @@
+import { type Static, Type } from "typebox";
+import type { AgentHarnessTool, ExecutionEnv } from "../types.ts";
+import { getOrThrow } from "../types.ts";
+import { withFileMutationQueue } from "./file-mutation-queue.ts";
+import { resolveToolPath } from "./path-utils.ts";
+
+const writeSchema = Type.Object({
+	path: Type.String({ description: "Path to the file to write (relative or absolute)" }),
+	content: Type.String({ description: "Content to write to the file" }),
+});
+
+export type WriteToolInput = Static<typeof writeSchema>;
+
+export interface WriteToolContext {
+	env: ExecutionEnv;
+	sessionId: string;
+}
+
+export function createWriteTool<TContext extends WriteToolContext = WriteToolContext>(): AgentHarnessTool<
+	TContext,
+	typeof writeSchema,
+	undefined
+> {
+	return {
+		name: "write",
+		label: "write",
+		description:
+			"Write content to a file. Creates the file if it doesn't exist, overwrites if it does. Automatically creates parent directories.",
+		parameters: writeSchema,
+		async execute(_toolCallId, { path, content }, signal, _onUpdate, { env }) {
+			const absolutePath = await resolveToolPath(env, path, signal);
+			return withFileMutationQueue(env, absolutePath, async () => {
+				if (signal?.aborted) throw new Error("Operation aborted");
+				getOrThrow(await env.writeFile(absolutePath, content, signal));
+				if (signal?.aborted) throw new Error("Operation aborted");
+				return {
+					content: [{ type: "text", text: `Successfully wrote ${content.length} bytes to ${path}` }],
+					details: undefined,
+				};
+			});
+		},
+	};
+}