fix: disable colors if agent is detected

packages/vitest/src/node/config/serializeConfig.ts

@@ -1,6 +1,7 @@
 import type { TestProject } from '../project'
 import type { ApiConfig, SerializedConfig } from '../types/config'
 import { configDefaults } from '../../defaults'
+import { isAgent } from '../../utils/env'
 
 export function serializeConfig(project: TestProject): SerializedConfig {
   const { config, globalConfig } = project
@@ -146,5 +147,6 @@ export function serializeConfig(project: TestProject): SerializedConfig {
       config.slowTestThreshold
       ?? globalConfig.slowTestThreshold
       ?? configDefaults.slowTestThreshold,
+    isAgent,
   }
 }

packages/vitest/src/node/core.ts

@@ -21,10 +21,12 @@ import { SnapshotManager } from '@vitest/snapshot/manager'
 import { deepClone, deepMerge, nanoid, toArray } from '@vitest/utils/helpers'
 import { serializeValue } from '@vitest/utils/serialize'
 import { join, normalize, relative } from 'pathe'
+import { disableDefaultColors } from 'tinyrainbow'
 import { isRunnableDevEnvironment } from 'vite'
 import { version } from '../../package.json' with { type: 'json' }
 import { distDir } from '../paths'
 import { wildcardPatternToRegExp } from '../utils/base'
+import { isAgent } from '../utils/env'
 import { NativeModuleRunner } from '../utils/nativeModuleRunner'
 import { convertTasksToEvents } from '../utils/tasks'
 import { Traces } from '../utils/traces'
@@ -137,6 +139,10 @@ export class Vitest {
     cliOptions: UserConfig,
     options: VitestOptions = {},
   ) {
+    if (isAgent) {
+      disableDefaultColors()
+    }
+
     this._cliOptions = cliOptions
     this.logger = new Logger(this, options.stdout, options.stderr)
     this.packageInstaller = options.packageInstaller || new VitestPackageInstaller()

packages/vitest/src/runtime/config.ts

@@ -146,6 +146,7 @@ export interface SerializedConfig {
   tagsFilter: string[] | undefined
   strictTags: boolean
   slowTestThreshold: number | undefined
+  isAgent: boolean
 }
 
 export interface SerializedCoverageConfig {

packages/vitest/src/runtime/workers/init.ts

@@ -3,6 +3,7 @@ import type { WorkerRequest, WorkerResponse } from '../../node/pools/types'
 import type { WorkerSetupContext } from '../../types/worker'
 import type { VitestWorker } from './types'
 import { serializeError } from '@vitest/utils/error'
+import { disableDefaultColors } from 'tinyrainbow'
 import { Traces } from '../../utils/traces'
 import * as listeners from '../listeners'
 import { createRuntimeRpc } from '../rpc'
@@ -49,6 +50,10 @@ export function init(worker: Options): void {
         process.env.VITEST_WORKER_ID = String(message.workerId)
         reportMemory = message.options.reportMemory
 
+        if (message.context.config.isAgent) {
+          disableDefaultColors()
+        }
+
         traces ??= await new Traces({
           enabled: message.traces.enabled,
           sdkPath: message.traces.sdkPath,

pnpm-workspace.yaml

@@ -83,7 +83,7 @@ catalog:
   tinyexec: ^1.0.2
   tinyglobby: ^0.2.15
   tinyhighlight: ^0.3.2
-  tinyrainbow: ^3.0.3
+  tinyrainbow: ^3.1.0
   tinyspy: ^4.0.4
   typescript: ^5.9.3
   unocss: ^66.6.6

test/config/test/console-color.test.ts

@@ -1,5 +1,5 @@
 import { expect, test } from 'vitest'
-import { runVitest } from '../../test-utils'
+import { runVitest, runVitestCli } from '../../test-utils'
 
 test('with color', async () => {
   const { stdout } = await runVitest({
@@ -30,6 +30,20 @@ test('without color', async () => {
   expect(stdout).not.toContain('\x1B[33mtrue\x1B[39m\n')
 })
 
+test('agent', async () => {
+  // Agent check is done on module import, so new process is needed
+  const { stdout } = await runVitestCli({
+    preserveAnsi: true,
+    nodeOptions: { env: { AI_AGENT: 'copilot' } },
+  }, '--root', 'fixtures/console-color', '--reporter', 'default')
+
+  expect.soft(stdout).toContain('true\n')
+  expect.soft(stdout).not.toContain('\x1B[33mtrue\x1B[39m\n')
+
+  expect.soft(stdout).toContain(' RUN')
+  expect.soft(stdout).not.toContain('\x1B[46m RUN')
+})
+
 test.skipIf(process.platform === 'win32')('without color, forks pool in non-TTY parent', async () => {
   const { stdout } = await runVitest({
     root: 'fixtures/console-color',