fix: default to run mode when stdin is not a TTY

docs/config/index.md

@@ -686,11 +686,15 @@ Update snapshot files. This will update all changed snapshots and delete obsolet
 ### watch<NonProjectOption />
 
 - **Type:** `boolean`
-- **Default:** `!process.env.CI`
+- **Default:** `!process.env.CI && process.stdin.isTTY`
 - **CLI:** `-w`, `--watch`, `--watch=false`
 
 Enable watch mode
 
+In interactive environments, this is the default, unless `--run` is specified explicitly.
+
+In CI, or when run from a non-interactive shell, "watch" mode is not the default, but can be enabled explicitly with this flag.
+
 ### root
 
 - **Type:** `string`

docs/guide/cli.md

@@ -9,7 +9,7 @@ outline: deep
 
 ### `vitest`
 
-Start Vitest in the current directory. Will enter the watch mode in development environment and run mode in CI automatically.
+Start Vitest in the current directory. Will enter the watch mode in development environment and run mode in CI (or non-interactive terminal) automatically.
 
 You can pass an additional argument as the filter of the test files to run. For example:
 
@@ -50,7 +50,7 @@ Perform a single run without watch mode.
 
 ### `vitest watch`
 
-Run all test suites but watch for changes and rerun tests when they change. Same as calling `vitest` without an argument. Will fallback to `vitest run` in CI.
+Run all test suites but watch for changes and rerun tests when they change. Same as calling `vitest` without an argument. Will fallback to `vitest run` in CI or when stdin is not a TTY (non-interactive environment).
 
 ### `vitest dev`
 

packages/vitest/src/defaults.ts

@@ -131,7 +131,7 @@ export const configDefaults: Readonly<{
 }> = Object.freeze({
   allowOnly: !isCI,
   isolate: true,
-  watch: !isCI,
+  watch: !isCI && process.stdin.isTTY,
   globals: false,
   environment: 'node' as const,
   pool: 'forks' as const,