From fd5fd24d223be4b6ed4f5420b733a725f0b921d5 Mon Sep 17 00:00:00 2001
From: Arya <arya.mohanan@ibm.com>
Date: Fri, 19 Sep 2025 15:40:42 +0530
Subject: [PATCH 1/2] fix: provide fallback for diagChannel.tracingChannel in
 older Node versions

---
 lib/tools.js             | 14 +++++++++++++-
 test/diagnostics.test.js |  7 +++++--
 2 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/lib/tools.js b/lib/tools.js
index 5cd5825a4..efd6197f3 100644
--- a/lib/tools.js
+++ b/lib/tools.js
@@ -28,7 +28,19 @@ const {
 const { isMainThread } = require('worker_threads')
 const transport = require('./transport')
 
-const asJsonChan = diagChan.tracingChannel('pino_asJson')
+let asJsonChan
+// Node >= 18.19 supports diagnostics_channel.tracingChannel
+if (typeof diagChan.tracingChannel === 'function') {
+  asJsonChan = diagChan.tracingChannel('pino_asJson')
+} else {
+  // Older Node 18.x (e.g. 18.18), provided a no-op fallback
+  asJsonChan = {
+    hasSubscribers: false,
+    traceSync (fn, store, thisArg, ...args) {
+      return fn.call(thisArg, ...args)
+    }
+  }
+}
 
 function noop () {
 }
diff --git a/test/diagnostics.test.js b/test/diagnostics.test.js
index 143892011..2291fa898 100644
--- a/test/diagnostics.test.js
+++ b/test/diagnostics.test.js
@@ -13,6 +13,9 @@ const { pid } = process
 const AS_JSON_START = 'tracing:pino_asJson:start'
 const AS_JSON_END = 'tracing:pino_asJson:end'
 
+// Skip tests if diagnostics_channel.tracingChannel is not available (Node < 18.19)
+const skip = typeof diagChan.tracingChannel !== 'function'
+
 test.beforeEach(ctx => {
   ctx.pino = {
     ts: 1757512800000, // 2025-09-10T10:00:00.000-05:00
@@ -33,7 +36,7 @@ test.afterEach(ctx => {
   Date.now = ctx.pino.now
 })
 
-test('asJson emits events', async (t) => {
+test('asJson emits events', { skip }, async (t) => {
   const plan = tspl(t, { plan: 8 })
   const { dest } = t.pino
   const logger = pino({}, dest)
@@ -74,7 +77,7 @@ test('asJson emits events', async (t) => {
   }
 })
 
-test('asJson context is not lost', async (t) => {
+test('asJson context is not lost', { skip }, async (t) => {
   const plan = tspl(t, { plan: 2 })
   const { dest } = t.pino
   const logger = pino({}, dest)

From e39299369f065d415e1df3f3827532e503af4eea Mon Sep 17 00:00:00 2001
From: Arya <arya.mohanan@ibm.com>
Date: Fri, 19 Sep 2025 20:45:43 +0530
Subject: [PATCH 2/2] ci: add node 18.18 to test matrix

---
 .github/workflows/ci.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 39eeca43f..522254d04 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -43,7 +43,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [macOS-latest, windows-latest, ubuntu-latest]
-        node-version: [18, 20, 22]
+        node-version: [18, '18.18', 20, 22]
         exclude:
           - os: windows-latest
             node-version: 22