WP1: Create bash-executor.ts with unified bash execution

packages/coding-agent/src/core/bash-executor.ts

@@ -0,0 +1,177 @@
+/**
+ * Bash command execution with streaming support and cancellation.
+ *
+ * This module provides a unified bash execution implementation used by:
+ * - AgentSession.executeBash() for interactive and RPC modes
+ * - Direct calls from modes that need bash execution
+ */
+
+import { randomBytes } from "node:crypto";
+import { createWriteStream, type WriteStream } from "node:fs";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+import { type ChildProcess, spawn } from "child_process";
+import stripAnsi from "strip-ansi";
+import { getShellConfig, killProcessTree, sanitizeBinaryOutput } from "../shell.js";
+import { DEFAULT_MAX_BYTES, truncateTail } from "../tools/truncate.js";
+
+// ============================================================================
+// Types
+// ============================================================================
+
+export interface BashExecutorOptions {
+	/** Callback for streaming output chunks (already sanitized) */
+	onChunk?: (chunk: string) => void;
+	/** AbortSignal for cancellation */
+	signal?: AbortSignal;
+}
+
+export interface BashResult {
+	/** Combined stdout + stderr output (sanitized, possibly truncated) */
+	output: string;
+	/** Process exit code (null if killed/cancelled) */
+	exitCode: number | null;
+	/** Whether the command was cancelled via signal */
+	cancelled: boolean;
+	/** Whether the output was truncated */
+	truncated: boolean;
+	/** Path to temp file containing full output (if output exceeded threshold) */
+	fullOutputPath?: string;
+}
+
+// ============================================================================
+// Implementation
+// ============================================================================
+
+/**
+ * Execute a bash command with optional streaming and cancellation support.
+ *
+ * Features:
+ * - Streams sanitized output via onChunk callback
+ * - Writes large output to temp file for later retrieval
+ * - Supports cancellation via AbortSignal
+ * - Sanitizes output (strips ANSI, removes binary garbage, normalizes newlines)
+ * - Truncates output if it exceeds the default max bytes
+ *
+ * @param command - The bash command to execute
+ * @param options - Optional streaming callback and abort signal
+ * @returns Promise resolving to execution result
+ */
+export function executeBash(command: string, options?: BashExecutorOptions): Promise<BashResult> {
+	return new Promise((resolve, reject) => {
+		const { shell, args } = getShellConfig();
+		const child: ChildProcess = spawn(shell, [...args, command], {
+			detached: true,
+			stdio: ["ignore", "pipe", "pipe"],
+		});
+
+		// Track sanitized output for truncation
+		const outputChunks: string[] = [];
+		let outputBytes = 0;
+		const maxOutputBytes = DEFAULT_MAX_BYTES * 2;
+
+		// Temp file for large output
+		let tempFilePath: string | undefined;
+		let tempFileStream: WriteStream | undefined;
+		let totalBytes = 0;
+
+		// Handle abort signal
+		const abortHandler = () => {
+			if (child.pid) {
+				killProcessTree(child.pid);
+			}
+		};
+
+		if (options?.signal) {
+			if (options.signal.aborted) {
+				// Already aborted, don't even start
+				child.kill();
+				resolve({
+					output: "",
+					exitCode: null,
+					cancelled: true,
+					truncated: false,
+				});
+				return;
+			}
+			options.signal.addEventListener("abort", abortHandler, { once: true });
+		}
+
+		const handleData = (data: Buffer) => {
+			totalBytes += data.length;
+
+			// Sanitize once at the source: strip ANSI, replace binary garbage, normalize newlines
+			const text = sanitizeBinaryOutput(stripAnsi(data.toString())).replace(/\r/g, "");
+
+			// Start writing to temp file if exceeds threshold
+			if (totalBytes > DEFAULT_MAX_BYTES && !tempFilePath) {
+				const id = randomBytes(8).toString("hex");
+				tempFilePath = join(tmpdir(), `pi-bash-${id}.log`);
+				tempFileStream = createWriteStream(tempFilePath);
+				// Write already-buffered chunks to temp file
+				for (const chunk of outputChunks) {
+					tempFileStream.write(chunk);
+				}
+			}
+
+			if (tempFileStream) {
+				tempFileStream.write(text);
+			}
+
+			// Keep rolling buffer of sanitized text
+			outputChunks.push(text);
+			outputBytes += text.length;
+			while (outputBytes > maxOutputBytes && outputChunks.length > 1) {
+				const removed = outputChunks.shift()!;
+				outputBytes -= removed.length;
+			}
+
+			// Stream to callback if provided
+			if (options?.onChunk) {
+				options.onChunk(text);
+			}
+		};
+
+		child.stdout?.on("data", handleData);
+		child.stderr?.on("data", handleData);
+
+		child.on("close", (code) => {
+			// Clean up abort listener
+			if (options?.signal) {
+				options.signal.removeEventListener("abort", abortHandler);
+			}
+
+			if (tempFileStream) {
+				tempFileStream.end();
+			}
+
+			// Combine buffered chunks for truncation (already sanitized)
+			const fullOutput = outputChunks.join("");
+			const truncationResult = truncateTail(fullOutput);
+
+			// code === null means killed (cancelled)
+			const cancelled = code === null;
+
+			resolve({
+				output: truncationResult.truncated ? truncationResult.content : fullOutput,
+				exitCode: code,
+				cancelled,
+				truncated: truncationResult.truncated,
+				fullOutputPath: tempFilePath,
+			});
+		});
+
+		child.on("error", (err) => {
+			// Clean up abort listener
+			if (options?.signal) {
+				options.signal.removeEventListener("abort", abortHandler);
+			}
+
+			if (tempFileStream) {
+				tempFileStream.end();
+			}
+
+			reject(err);
+		});
+	});
+}