fix: --port flag no longer affects file import URLs

Fixes #14096

The --port flag is intended to set the default port for Bun.serve(),
not to modify asset import URLs. Previously, using --port would cause
file imports (e.g., `import txt from "./a.txt" with { type: "file" }`)
to return HTTP URLs like `http://localhost:3000/a.txt` instead of the
actual file path.

This fix adds a check for `is_from_devserver` flag before applying the
origin to file imports, ensuring that --port only affects Bun.serve()
and dev server contexts, not regular file imports.

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

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

src/bun.js/ModuleLoader.zig

@@ -1516,7 +1516,9 @@ pub fn transpileSourceCode(
             }
 
             const value = brk: {
-                if (!jsc_vm.origin.isEmpty()) {
+                // Only use origin for file imports when running from dev server
+                // --port flag should only affect Bun.serve, not file import URLs
+                if (!jsc_vm.origin.isEmpty() and jsc_vm.is_from_devserver) {
                     var buf = bun.handleOom(MutableString.init2048(jsc_vm.allocator));
                     defer buf.deinit();
                     var writer = buf.writer();

test/regression/issue/14096.test.ts

@@ -0,0 +1,103 @@
+// Regression test for issue #14096: --port should not affect file imports
+// https://github.com/oven-sh/bun/issues/14096
+import { test, expect } from "bun:test";
+import { bunEnv, bunExe, tempDir } from "harness";
+
+test("--port should not convert file imports to HTTP URLs", async () => {
+  using dir = tempDir("issue-14096", {
+    "index.js": `
+      import txt from "./test.txt" with { type: "file" };
+      console.log(txt);
+    `,
+    "test.txt": "hello world",
+  });
+
+  await using proc = Bun.spawn({
+    cmd: [bunExe(), "run", "--port", "3000", "index.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,
+  ]);
+
+  expect(stderr).toBe("");
+  expect(exitCode).toBe(0);
+
+  // Should print the file path, NOT http://localhost:3000/test.txt
+  const output = stdout.trim();
+  expect(output).not.toContain("http://");
+  expect(output).not.toContain("localhost");
+  expect(output).not.toContain("3000");
+  expect(output).toEndWith("test.txt");
+});
+
+test("--port should not affect asset imports (image files)", async () => {
+  using dir = tempDir("issue-14096-assets", {
+    "index.js": `
+      import bmp from "./abc.bmp" with { type: "file" };
+      console.log(bmp);
+    `,
+    "abc.bmp": "fake bmp data",
+  });
+
+  await using proc = Bun.spawn({
+    cmd: [bunExe(), "run", "--port", "4000", "index.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,
+  ]);
+
+  expect(stderr).toBe("");
+  expect(exitCode).toBe(0);
+
+  // Should print the file path, NOT http://localhost:4000/abc.bmp
+  const output = stdout.trim();
+  expect(output).not.toContain("http://");
+  expect(output).not.toContain("localhost");
+  expect(output).not.toContain("4000");
+  expect(output).toEndWith("abc.bmp");
+});
+
+test("file imports work without --port flag (baseline)", async () => {
+  using dir = tempDir("issue-14096-baseline", {
+    "index.js": `
+      import txt from "./test.txt" with { type: "file" };
+      console.log(txt);
+    `,
+    "test.txt": "hello world",
+  });
+
+  await using proc = Bun.spawn({
+    cmd: [bunExe(), "run", "index.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,
+  ]);
+
+  expect(stderr).toBe("");
+  expect(exitCode).toBe(0);
+
+  // Should print the file path
+  const output = stdout.trim();
+  expect(output).toEndWith("test.txt");
+});