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/edit.ts

@@ -1,8 +1,9 @@
 import * as os from "node:os";
 import type { AgentTool } from "@mariozechner/pi-ai";
 import { Type } from "@sinclair/typebox";
-import { existsSync, readFileSync, writeFileSync } from "fs";
-import { resolve } from "path";
+import { constants } from "fs";
+import { access, readFile, writeFile } from "fs/promises";
+import { resolve as resolvePath } from "path";
 
 /**
  * Expand ~ to home directory
@@ -34,42 +35,116 @@ export const editTool: AgentTool<typeof editSchema> = {
 		{ path, oldText, newText }: { path: string; oldText: string; newText: string },
 		signal?: AbortSignal,
 	) => {
-		// Check if already aborted
-		if (signal?.aborted) {
-			throw new Error("Operation aborted");
-		}
+		const absolutePath = resolvePath(expandPath(path));
 
-		const absolutePath = resolve(expandPath(path));
+		return new Promise<{ output: string; details: undefined }>((resolve, reject) => {
+			// Check if already aborted
+			if (signal?.aborted) {
+				reject(new Error("Operation aborted"));
+				return;
+			}
 
-		if (!existsSync(absolutePath)) {
-			throw new Error(`File not found: ${path}`);
-		}
+			let aborted = false;
 
-		const content = readFileSync(absolutePath, "utf-8");
+			// Set up abort handler
+			const onAbort = () => {
+				aborted = true;
+				reject(new Error("Operation aborted"));
+			};
 
-		// Check if old text exists
-		if (!content.includes(oldText)) {
-			throw new Error(
-				`Could not find the exact text in ${path}. The old text must match exactly including all whitespace and newlines.`,
-			);
-		}
+			if (signal) {
+				signal.addEventListener("abort", onAbort, { once: true });
+			}
 
-		// Count occurrences
-		const occurrences = content.split(oldText).length - 1;
+			// Perform the edit operation
+			(async () => {
+				try {
+					// Check if file exists
+					try {
+						await access(absolutePath, constants.R_OK | constants.W_OK);
+					} catch {
+						if (signal) {
+							signal.removeEventListener("abort", onAbort);
+						}
+						reject(new Error(`File not found: ${path}`));
+						return;
+					}
 
-		if (occurrences > 1) {
-			throw new Error(
-				`Found ${occurrences} occurrences of the text in ${path}. The text must be unique. Please provide more context to make it unique.`,
-			);
-		}
+					// Check if aborted before reading
+					if (aborted) {
+						return;
+					}
 
-		// Perform replacement
-		const newContent = content.replace(oldText, newText);
-		writeFileSync(absolutePath, newContent, "utf-8");
+					// Read the file
+					const content = await readFile(absolutePath, "utf-8");
 
-		return {
-			output: `Successfully replaced text in ${path}. Changed ${oldText.length} characters to ${newText.length} characters.`,
-			details: undefined,
-		};
+					// Check if aborted after reading
+					if (aborted) {
+						return;
+					}
+
+					// Check if old text exists
+					if (!content.includes(oldText)) {
+						if (signal) {
+							signal.removeEventListener("abort", onAbort);
+						}
+						reject(
+							new Error(
+								`Could not find the exact text in ${path}. The old text must match exactly including all whitespace and newlines.`,
+							),
+						);
+						return;
+					}
+
+					// Count occurrences
+					const occurrences = content.split(oldText).length - 1;
+
+					if (occurrences > 1) {
+						if (signal) {
+							signal.removeEventListener("abort", onAbort);
+						}
+						reject(
+							new Error(
+								`Found ${occurrences} occurrences of the text in ${path}. The text must be unique. Please provide more context to make it unique.`,
+							),
+						);
+						return;
+					}
+
+					// Check if aborted before writing
+					if (aborted) {
+						return;
+					}
+
+					// Perform replacement
+					const newContent = content.replace(oldText, newText);
+					await writeFile(absolutePath, newContent, "utf-8");
+
+					// Check if aborted after writing
+					if (aborted) {
+						return;
+					}
+
+					// Clean up abort handler
+					if (signal) {
+						signal.removeEventListener("abort", onAbort);
+					}
+
+					resolve({
+						output: `Successfully replaced text in ${path}. Changed ${oldText.length} characters to ${newText.length} characters.`,
+						details: undefined,
+					});
+				} catch (error: any) {
+					// Clean up abort handler
+					if (signal) {
+						signal.removeEventListener("abort", onAbort);
+					}
+
+					if (!aborted) {
+						reject(error);
+					}
+				}
+			})();
+		});
 	},
 };