Swadhin Biswas feat: implement mervelas cli engine, built-in tools, and reactive UI · 4/3/2026
0358986
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// This file represents useful wrappers over node:child_process
// These wrappers ease error handling and cross-platform compatbility
// By using execa, Windows automatically gets shell escaping + BAT / CMD handling
import { type ExecaError, execa } from 'execa'
import { getCwd } from '../utils/cwd.js'
import { logError } from './log.js'
export { execSyncWithDefaults_DEPRECATED } from './execFileNoThrowPortable.js'
const MS_IN_SECOND = 1000
const SECONDS_IN_MINUTE = 60
type ExecFileOptions = {
abortSignal?: AbortSignal
timeout?: number
preserveOutputOnError?: boolean
// Setting useCwd=false avoids circular dependencies during initialization
// getCwd() -> PersistentShell -> logEvent() -> execFileNoThrow
useCwd?: boolean
env?: NodeJS.ProcessEnv
stdin?: 'ignore' | 'inherit' | 'pipe'
input?: string
}
export function execFileNoThrow(
file: string,
args: string[],
options: ExecFileOptions = {
timeout: 10 * SECONDS_IN_MINUTE * MS_IN_SECOND,
preserveOutputOnError: true,
useCwd: true,
},
): Promise<{ stdout: string; stderr: string; code: number; error?: string }> {
return execFileNoThrowWithCwd(file, args, {
abortSignal: options.abortSignal,
timeout: options.timeout,
preserveOutputOnError: options.preserveOutputOnError,
cwd: options.useCwd ? getCwd() : undefined,
env: options.env,
stdin: options.stdin,
input: options.input,
})
}
type ExecFileWithCwdOptions = {
abortSignal?: AbortSignal
timeout?: number
preserveOutputOnError?: boolean
maxBuffer?: number
cwd?: string
env?: NodeJS.ProcessEnv
shell?: boolean | string | undefined
stdin?: 'ignore' | 'inherit' | 'pipe'
input?: string
}
type ExecaResultWithError = {
shortMessage?: string
signal?: string
}
/**
* Extracts a human-readable error message from an execa result.
*
* Priority order:
* 1. shortMessage - execa's human-readable error (e.g., "Command failed with exit code 1: ...")
* This is preferred because it already includes signal info when a process is killed,
* making it more informative than just the signal name.
* 2. signal - the signal that killed the process (e.g., "SIGTERM")
* 3. errorCode - fallback to just the numeric exit code
*/
function getErrorMessage(
result: ExecaResultWithError,
errorCode: number,
): string {
if (result.shortMessage) {
return result.shortMessage
}
if (typeof result.signal === 'string') {
return result.signal
}
return String(errorCode)
}
/**
* execFile, but always resolves (never throws)
*/
export function execFileNoThrowWithCwd(
file: string,
args: string[],
{
abortSignal,
timeout: finalTimeout = 10 * SECONDS_IN_MINUTE * MS_IN_SECOND,
preserveOutputOnError: finalPreserveOutput = true,
cwd: finalCwd,
env: finalEnv,
maxBuffer,
shell,
stdin: finalStdin,
input: finalInput,
}: ExecFileWithCwdOptions = {
timeout: 10 * SECONDS_IN_MINUTE * MS_IN_SECOND,
preserveOutputOnError: true,
maxBuffer: 1_000_000,
},
): Promise<{ stdout: string; stderr: string; code: number; error?: string }> {
return new Promise(resolve => {
// Use execa for cross-platform .bat/.cmd compatibility on Windows
execa(file, args, {
maxBuffer,
signal: abortSignal,
timeout: finalTimeout,
cwd: finalCwd,
env: finalEnv,
shell,
stdin: finalStdin,
input: finalInput,
reject: false, // Don't throw on non-zero exit codes
})
.then(result => {
if (result.failed) {
if (finalPreserveOutput) {
const errorCode = result.exitCode ?? 1
void resolve({
stdout: result.stdout || '',
stderr: result.stderr || '',
code: errorCode,
error: getErrorMessage(
result as unknown as ExecaResultWithError,
errorCode,
),
})
} else {
void resolve({ stdout: '', stderr: '', code: result.exitCode ?? 1 })
}
} else {
void resolve({
stdout: result.stdout,
stderr: result.stderr,
code: 0,
})
}
})
.catch((error: ExecaError) => {
logError(error)
void resolve({ stdout: '', stderr: '', code: 1 })
})
})
}