fix: prevent FORCE_COLOR auto-add when stdout is not a terminal

The auto-add FORCE_COLOR logic was causing issues on Windows CI where
stdout might be detected as supporting colors even when it's not a TTY.
This caused oxlint to output ANSI color codes in its output.

Changes:
- Add IsTerminal check before auto-adding FORCE_COLOR
- Also check FORCE_COLOR=0 in reporter color detection

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: branchseer

crates/vite_task/src/session/reporter.rs

@@ -15,16 +15,29 @@ use super::{
     event::{CacheStatus, ExecutionEvent, ExecutionEventKind, ExecutionId, ExecutionItemDisplay},
 };
 
-/// Wrap of `OwoColorize` that ignores style if `NO_COLOR` is set.
+/// Wrap of `OwoColorize` that ignores style if colors are disabled.
+///
+/// Colors are disabled if:
+/// - `NO_COLOR` environment variable is set and non-empty
+/// - `FORCE_COLOR` environment variable is set to "0"
 trait ColorizeExt {
     fn style(&self, style: Style) -> Styled<&Self>;
 }
 
 impl<T: owo_colors::OwoColorize> ColorizeExt for T {
     fn style(&self, style: Style) -> Styled<&Self> {
-        static NO_COLOR: LazyLock<bool> =
-            LazyLock::new(|| std::env::var_os("NO_COLOR").is_some_and(|v| !v.is_empty()));
-        owo_colors::OwoColorize::style(self, if *NO_COLOR { Style::new() } else { style })
+        static DISABLE_COLOR: LazyLock<bool> = LazyLock::new(|| {
+            // NO_COLOR takes precedence per https://no-color.org/
+            if std::env::var_os("NO_COLOR").is_some_and(|v| !v.is_empty()) {
+                return true;
+            }
+            // FORCE_COLOR=0 explicitly disables colors
+            if std::env::var_os("FORCE_COLOR").is_some_and(|v| v == "0") {
+                return true;
+            }
+            false
+        });
+        owo_colors::OwoColorize::style(self, if *DISABLE_COLOR { Style::new() } else { style })
     }
 }
 

crates/vite_task_plan/src/envs.rs

@@ -65,8 +65,15 @@ impl EnvFingerprints {
             // Automatically add FORCE_COLOR environment variable if not already set
             // This enables color output in subprocesses when color is supported
             // TODO: will remove this temporarily until we have a better solution
+            //
+            // Only add FORCE_COLOR if:
+            // 1. FORCE_COLOR is not already set (including FORCE_COLOR=0)
+            // 2. NO_COLOR is not set
+            // 3. stdout is a terminal (not just supports colors)
+            // 4. Terminal supports colors
             if !all_envs.contains_key(OsStr::new("FORCE_COLOR"))
                 && !all_envs.contains_key(OsStr::new("NO_COLOR"))
+                && std::io::IsTerminal::is_terminal(&std::io::stdout())
                 && let Some(support) = on(Stream::Stdout)
             {
                 let force_color_value = if support.has_16m {