From c862beb0b1f36f9f6af51049613d40eadc3ebfff Mon Sep 17 00:00:00 2001
From: Josh Mock <joshua.mock@elastic.co>
Date: Tue, 9 Dec 2025 12:20:04 -0600
Subject: [PATCH] Detect Deno and Bun usage

---
 src/client.ts            |  5 +++++
 test/unit/client.test.ts | 36 ++++++++++++++++++++++++++++++++++++
 2 files changed, 41 insertions(+)

diff --git a/src/client.ts b/src/client.ts
index d8739e87d..ebaa69d41 100644
--- a/src/client.ts
+++ b/src/client.ts
@@ -314,6 +314,11 @@ export default class Client extends API {
         // assumes HttpConnection
         clientMeta += `,hc=${nodeVersion}`
       }
+
+      // detect alternative runtimes
+      if (process.versions.bun != null) clientMeta += `,bn=${process.versions.bun}`
+      if (process.versions.deno != null) clientMeta += `,dn=${process.versions.deno}`
+
       options.headers['x-elastic-client-meta'] = clientMeta
     }
 
diff --git a/test/unit/client.test.ts b/test/unit/client.test.ts
index ac8203f55..a3c4a6ead 100644
--- a/test/unit/client.test.ts
+++ b/test/unit/client.test.ts
@@ -493,6 +493,42 @@ test('Meta header indicates when HttpConnection is used', async t => {
   await client.transport.request({ method: 'GET', path: '/' })
 })
 
+test('Meta header indicates when Bun is used', async t => {
+  t.plan(1)
+
+  function handler(req: http.IncomingMessage, res: http.ServerResponse) {
+    t.equal(req.headers['x-elastic-client-meta'], `es=${clientVersion},js=${nodeVersion},t=${transportVersion},un=${nodeVersion},bn=1.2.3`)
+    res.end('ok')
+  }
+
+  const [{ port }, server] = await buildServer(handler)
+  t.after(() => server.stop())
+
+  process.versions.bun = "1.2.3"
+  const client = new Client({ node: `http://localhost:${port}` })
+  delete process.versions.bun
+
+  await client.transport.request({ method: 'GET', path: '/' })
+})
+
+test('Meta header indicates when Deno is used', async t => {
+  t.plan(1)
+
+  function handler(req: http.IncomingMessage, res: http.ServerResponse) {
+    t.equal(req.headers['x-elastic-client-meta'], `es=${clientVersion},js=${nodeVersion},t=${transportVersion},un=${nodeVersion},dn=1.2.3`)
+    res.end('ok')
+  }
+
+  const [{ port }, server] = await buildServer(handler)
+  t.after(() => server.stop())
+
+  process.versions.deno = "1.2.3"
+  const client = new Client({ node: `http://localhost:${port}` })
+  delete process.versions.deno
+
+  await client.transport.request({ method: 'GET', path: '/' })
+})
+
 test('caFingerprint', t => {
   const client = new Client({
     node: 'https://localhost:9200',