From 798b48c898fcf596e27c8fffb5abfb3b838ca3d1 Mon Sep 17 00:00:00 2001
From: robobun <robobun@oven.sh>
Date: Wed, 14 Jan 2026 17:41:21 -0800
Subject: [PATCH] fix(runtime): exclude globalThis from auto-serve detection
 (#26107)
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## Summary
- When a module exports `globalThis` (e.g., `module.exports =
globalThis`), Bun's auto-serve detection incorrectly triggered because
`globalThis.fetch` is the Fetch API function
- Scripts that export globalThis (like `core-js/es/global-this.js`)
would start a development server on port 3000 instead of exiting
normally
- Added explicit check to skip auto-serve when the default export is
`globalThis` itself

Fixes #440

## Test plan
- [x] Added test case `test/regression/issue/440.test.ts` that verifies:
  - `module.exports = globalThis` does not start a server
  - `export default globalThis` does not start a server
- [x] Verified test fails with system Bun (without fix)
- [x] Verified test passes with debug build (with fix)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Claude Bot <claude-bot@bun.sh>
Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>
---
 src/bundler/entry_points.zig      |  8 +++---
 test/regression/issue/440.test.ts | 46 +++++++++++++++++++++++++++++++
 2 files changed, 50 insertions(+), 4 deletions(-)
 create mode 100644 test/regression/issue/440.test.ts

diff --git a/src/bundler/entry_points.zig b/src/bundler/entry_points.zig
index ca3196bf15..fdf2df2d1e 100644
--- a/src/bundler/entry_points.zig
+++ b/src/bundler/entry_points.zig
@@ -169,7 +169,7 @@ pub const ServerEntryPoint = struct {
                     \\if (typeof entryNamespace?.then === 'function') {{
                     \\   entryNamespace = entryNamespace.then((entryNamespace) => {{
                     \\      var def = entryNamespace?.default;
-                    \\      if (def && (typeof def.fetch === 'function' || def.app != undefined))  {{
+                    \\      if (def && def !== globalThis && (typeof def.fetch === 'function' || def.app != undefined))  {{
                     \\        var server = globalThis[hmrSymbol];
                     \\        if (server) {{
                     \\           server.reload(def);
@@ -180,7 +180,7 @@ pub const ServerEntryPoint = struct {
                     \\        }}
                     \\      }}
                     \\   }}, reportError);
-                    \\}} else if (typeof entryNamespace?.default?.fetch === 'function' || entryNamespace?.default?.app != undefined) {{
+                    \\}} else if (entryNamespace?.default !== globalThis && (typeof entryNamespace?.default?.fetch === 'function' || entryNamespace?.default?.app != undefined)) {{
                     \\   var server = globalThis[hmrSymbol];
                     \\   if (server) {{
                     \\      server.reload(entryNamespace.default);
@@ -204,12 +204,12 @@ pub const ServerEntryPoint = struct {
                 \\var entryNamespace = start;
                 \\if (typeof entryNamespace?.then === 'function') {{
                 \\   entryNamespace = entryNamespace.then((entryNamespace) => {{
-                \\      if (typeof entryNamespace?.default?.fetch === 'function')  {{
+                \\      if (entryNamespace?.default !== globalThis && typeof entryNamespace?.default?.fetch === 'function')  {{
                 \\        const server = Bun.serve(entryNamespace.default);
                 \\        console.debug(`Started ${{server.development ? 'development ' : ''}}server: ${{server.protocol}}://${{server.hostname}}:${{server.port}}`);
                 \\      }}
                 \\   }}, reportError);
-                \\}} else if (typeof entryNamespace?.default?.fetch === 'function' || entryNamespace?.default?.app != null) {{
+                \\}} else if (entryNamespace?.default !== globalThis && (typeof entryNamespace?.default?.fetch === 'function' || entryNamespace?.default?.app != null)) {{
                 \\   const server = Bun.serve(entryNamespace.default);
                 \\   console.debug(`Started ${{server.development ? 'development ' : ''}}server: ${{server.protocol}}://${{server.hostname}}:${{server.port}}`);
                 \\}}
diff --git a/test/regression/issue/440.test.ts b/test/regression/issue/440.test.ts
new file mode 100644
index 0000000000..4a915e903c
--- /dev/null
+++ b/test/regression/issue/440.test.ts
@@ -0,0 +1,46 @@
+import { expect, test } from "bun:test";
+import { bunEnv, bunExe, tempDir } from "harness";
+
+test("exporting globalThis should not start a server", async () => {
+  using dir = tempDir("issue-440", {
+    "test.js": `module.exports = globalThis;`,
+  });
+
+  await using proc = Bun.spawn({
+    cmd: [bunExe(), "test.js"],
+    env: bunEnv,
+    cwd: String(dir),
+    stdout: "pipe",
+    stderr: "pipe",
+  });
+
+  const [stdout, stderr, exitCode] = await Promise.all([proc.stdout.text(), proc.stderr.text(), proc.exited]);
+
+  // Should NOT contain server started message
+  expect(stderr).not.toContain("Started");
+  expect(stderr).not.toContain("server:");
+  expect(stdout).toBe("");
+  expect(exitCode).toBe(0);
+});
+
+test("default export of globalThis should not start a server", async () => {
+  using dir = tempDir("issue-440-esm", {
+    "test.js": `export default globalThis;`,
+  });
+
+  await using proc = Bun.spawn({
+    cmd: [bunExe(), "test.js"],
+    env: bunEnv,
+    cwd: String(dir),
+    stdout: "pipe",
+    stderr: "pipe",
+  });
+
+  const [stdout, stderr, exitCode] = await Promise.all([proc.stdout.text(), proc.stderr.text(), proc.exited]);
+
+  // Should NOT contain server started message
+  expect(stderr).not.toContain("Started");
+  expect(stderr).not.toContain("server:");
+  expect(stdout).toBe("");
+  expect(exitCode).toBe(0);
+});