Make file operations properly abortable with async operations

Replace synchronous file operations with async Promise-based operations
that listen to abort signals during execution:
- read, write, edit now use fs/promises async APIs
- Add abort event listeners that reject immediately on abort
- Check abort status before and after each async operation
- Clean up event listeners properly

This ensures pressing Esc during file operations shows red error state.

packages/coding-agent/src/tools/write.ts

@@ -1,8 +1,8 @@
 import * as os from "node:os";
 import type { AgentTool } from "@mariozechner/pi-ai";
 import { Type } from "@sinclair/typebox";
-import { mkdirSync, writeFileSync } from "fs";
-import { dirname, resolve } from "path";
+import { mkdir, writeFile } from "fs/promises";
+import { dirname, resolve as resolvePath } from "path";
 
 /**
  * Expand ~ to home directory
@@ -29,18 +29,64 @@ export const writeTool: AgentTool<typeof writeSchema> = {
 		"Write content to a file. Creates the file if it doesn't exist, overwrites if it does. Automatically creates parent directories.",
 	parameters: writeSchema,
 	execute: async (_toolCallId: string, { path, content }: { path: string; content: string }, signal?: AbortSignal) => {
-		// Check if already aborted
-		if (signal?.aborted) {
-			throw new Error("Operation aborted");
-		}
-
-		const absolutePath = resolve(expandPath(path));
+		const absolutePath = resolvePath(expandPath(path));
 		const dir = dirname(absolutePath);
 
-		// Create parent directories if needed
-		mkdirSync(dir, { recursive: true });
+		return new Promise<{ output: string; details: undefined }>((resolve, reject) => {
+			// Check if already aborted
+			if (signal?.aborted) {
+				reject(new Error("Operation aborted"));
+				return;
+			}
 
-		writeFileSync(absolutePath, content, "utf-8");
-		return { output: `Successfully wrote ${content.length} bytes to ${path}`, details: undefined };
+			let aborted = false;
+
+			// Set up abort handler
+			const onAbort = () => {
+				aborted = true;
+				reject(new Error("Operation aborted"));
+			};
+
+			if (signal) {
+				signal.addEventListener("abort", onAbort, { once: true });
+			}
+
+			// Perform the write operation
+			(async () => {
+				try {
+					// Create parent directories if needed
+					await mkdir(dir, { recursive: true });
+
+					// Check if aborted before writing
+					if (aborted) {
+						return;
+					}
+
+					// Write the file
+					await writeFile(absolutePath, content, "utf-8");
+
+					// Check if aborted after writing
+					if (aborted) {
+						return;
+					}
+
+					// Clean up abort handler
+					if (signal) {
+						signal.removeEventListener("abort", onAbort);
+					}
+
+					resolve({ output: `Successfully wrote ${content.length} bytes to ${path}`, details: undefined });
+				} catch (error: any) {
+					// Clean up abort handler
+					if (signal) {
+						signal.removeEventListener("abort", onAbort);
+					}
+
+					if (!aborted) {
+						reject(error);
+					}
+				}
+			})();
+		});
 	},
 };