diff --git a/plugin/scripts/bun-runner.js b/plugin/scripts/bun-runner.js
index 6804f8fe..d34efef2 100644
--- a/plugin/scripts/bun-runner.js
+++ b/plugin/scripts/bun-runner.js
@@ -47,12 +47,20 @@ function fixBrokenScriptPath(argPath) {
  * Find Bun executable - checks PATH first, then common install locations
  */
 function findBun() {
-  // Try PATH first
-  const pathCheck = spawnSync(IS_WINDOWS ? 'where' : 'which', ['bun'], {
-    encoding: 'utf-8',
-    stdio: ['pipe', 'pipe', 'pipe'],
-    shell: IS_WINDOWS
-  });
+  // Try PATH first.
+  // On Windows, pass a single command string to avoid Node 22+ DEP0190 deprecation warning
+  // (triggered when an args array is combined with shell:true, as the args are only
+  // concatenated, not escaped). Fixes #1503.
+  const pathCheck = IS_WINDOWS
+    ? spawnSync('where bun', {
+        encoding: 'utf-8',
+        stdio: ['pipe', 'pipe', 'pipe'],
+        shell: true
+      })
+    : spawnSync('which', ['bun'], {
+        encoding: 'utf-8',
+        stdio: ['pipe', 'pipe', 'pipe']
+      });
 
   if (pathCheck.status === 0 && pathCheck.stdout.trim()) {
     // On Windows, prefer bun.cmd over bun (bun is a shell script, bun.cmd is the Windows batch file)
diff --git a/tests/bun-runner.test.ts b/tests/bun-runner.test.ts
new file mode 100644
index 00000000..abc45db5
--- /dev/null
+++ b/tests/bun-runner.test.ts
@@ -0,0 +1,47 @@
+import { describe, it, expect } from 'bun:test';
+import { readFileSync } from 'fs';
+import { join } from 'path';
+
+/**
+ * Regression tests for bun-runner.js to prevent the re-introduction of
+ * platform-specific issues that are difficult to catch in CI.
+ *
+ * These tests inspect the source code for known-bad patterns rather than
+ * executing the script, because bun-runner.js is a top-level side-effecting
+ * Node.js script (not an importable module) and the Windows-specific code
+ * paths cannot be exercised on non-Windows CI runners.
+ */
+
+const BUN_RUNNER_PATH = join(import.meta.dir, '..', 'plugin', 'scripts', 'bun-runner.js');
+const source = readFileSync(BUN_RUNNER_PATH, 'utf-8');
+
+describe('bun-runner.js findBun: DEP0190 regression guard (#1503)', () => {
+  it('does not use separate args array with shell:true (DEP0190 trigger pattern)', () => {
+    // Node 22+ emits DEP0190 when spawnSync is called with a separate args array
+    // AND shell:true, because the args are only concatenated (not escaped).
+    // The vulnerable pattern looks like: spawnSync(cmd, ['bun'], { shell: true/IS_WINDOWS })
+    // This test verifies the fix in findBun() has not been reverted.
+    const vulnerablePattern = /spawnSync\s*\(\s*(?:IS_WINDOWS\s*\?\s*['"]where['"]\s*:[^)]+|['"]where['"]),\s*\[[^\]]+\],\s*\{[^}]*shell\s*:\s*(?:true|IS_WINDOWS)/;
+    expect(vulnerablePattern.test(source)).toBe(false);
+  });
+
+  it('uses a single string command for Windows where-bun lookup', () => {
+    // The safe pattern: pass a single combined string 'where bun' with shell:true
+    // so no separate args array is involved. This is the fix for DEP0190.
+    expect(source).toContain("spawnSync('where bun'");
+  });
+
+  it('uses no shell option for Unix which-bun lookup', () => {
+    // On Unix, spawnSync('which', ['bun']) without shell:true is safe and avoids
+    // the deprecation warning entirely.
+    // Check that the unix path does NOT pass shell:true alongside the args array.
+    // We look for the pattern: spawnSync('which', ['bun'], { ... }) — shell should be absent.
+    const unixCallMatch = source.match(/spawnSync\('which',\s*\['bun'\],\s*\{([^}]+)\}/)
+    if (unixCallMatch) {
+      expect(unixCallMatch[1]).not.toContain('shell');
+    }
+    // If the pattern is not found as expected, that means the code changed shape —
+    // either way we shouldn't have shell:true on the unix path
+    expect(source).toContain("spawnSync('which', ['bun']");
+  });
+});