fix(console): send console.trace to stderr like Node

docs/runtime/nodejs-compat.mdx

@@ -21,7 +21,7 @@ We update this page regularly. It reflects the latest version of Bun's compatibi
 
 ### [`node:console`](https://nodejs.org/api/console.html)
 
-🟢 Fully implemented. Bun writes console output directly to the stdout/stderr file descriptors and formats it with its own inspector. As a result, replacing `process.stdout.write` does not capture the output, and object layout differs from `util.inspect`. `console.trace()` writes to stdout and `console.time*()` to stderr.
+🟢 Fully implemented. Bun writes console output directly to the stdout/stderr file descriptors and formats it with its own inspector. As a result, replacing `process.stdout.write` does not capture the output, and object layout differs from `util.inspect`. `console.trace()` writes to stderr (Node-compatible) and `console.time*()` to stderr.
 
 ### [`node:dgram`](https://nodejs.org/api/dgram.html)
 

src/jsc/ConsoleObject.rs

@@ -407,8 +407,9 @@ fn message_with_type_and_level_(
 
     // Lock/unlock a mutex incase two JS threads are console.log'ing at the same
     // time. We do this the slightly annoying way to avoid assigning a pointer.
+    // Node routes console.trace to stderr; keep Assert / warn / error there too.
     let use_stderr = matches!(level, MessageLevel::Warning | MessageLevel::Error)
-        || message_type == MessageType::Assert;
+        || matches!(message_type, MessageType::Assert | MessageType::Trace);
     let _stream_lock = ConsoleStreamLock::acquire(use_stderr);
 
     if message_type == MessageType::Clear {
@@ -431,7 +432,9 @@ fn message_with_type_and_level_(
         return Ok(());
     }
 
-    let enable_colors = if matches!(level, MessageLevel::Warning | MessageLevel::Error) {
+    let enable_colors = if matches!(level, MessageLevel::Warning | MessageLevel::Error)
+        || message_type == MessageType::Trace
+    {
         Output::enable_ansi_colors_stderr()
     } else {
         Output::enable_ansi_colors_stdout()
@@ -450,7 +453,9 @@ fn message_with_type_and_level_(
     // long-lived `&mut ConsoleObject` across the re-derive in the empty-`Log`
     // arm below.
     let raw_writer: &mut bun_core::io::Writer = unsafe {
-        if matches!(level, MessageLevel::Warning | MessageLevel::Error) {
+        if matches!(level, MessageLevel::Warning | MessageLevel::Error)
+            || message_type == MessageType::Trace
+        {
             (*console).error_writer()
         } else {
             (*console).writer()

test/js/bun/console/console-trace-stderr.test.ts

@@ -0,0 +1,16 @@
+import { expect, test } from "bun:test";
+import { bunEnv, bunExe } from "harness";
+
+test("console.trace writes to stderr, not stdout", async () => {
+  await using proc = Bun.spawn({
+    cmd: [bunExe(), "-e", `console.trace("hello")`],
+    env: bunEnv,
+    stdout: "pipe",
+    stderr: "pipe",
+  });
+  const [stdout, stderr, exitCode] = await Promise.all([proc.stdout.text(), proc.stderr.text(), proc.exited]);
+  expect(exitCode).toBe(0);
+  expect(stdout).toBe("");
+  expect(stderr).toContain("hello");
+  expect(stderr.toLowerCase()).toMatch(/trace/i);
+});