From e37419dd004be6f2d6f78287c33f8601581ef898 Mon Sep 17 00:00:00 2001
From: "Kamat, Trivikram" <16024985+trivikr@users.noreply.github.com>
Date: Sat, 11 Jul 2026 00:02:31 -0700
Subject: [PATCH] stream: use RangeError for broadcast overflow

Reject strict-backpressure writes with a RangeError when the broadcast
pending writes queue is full.

Signed-off-by: Kamat, Trivikram <16024985+trivikr@users.noreply.github.com>
---
 lib/internal/streams/iter/broadcast.js        |  2 +-
 ...test-stream-iter-broadcast-backpressure.js | 23 +++++++++++++++++++
 2 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/lib/internal/streams/iter/broadcast.js b/lib/internal/streams/iter/broadcast.js
index 3592453036d303..ec8c347e6e05ba 100644
--- a/lib/internal/streams/iter/broadcast.js
+++ b/lib/internal/streams/iter/broadcast.js
@@ -582,7 +582,7 @@ class BroadcastWriter {
 
     if (policy === 'strict') {
       if (this.#pendingWrites.length >= hwm) {
-        throw new ERR_INVALID_STATE.TypeError(
+        throw new ERR_INVALID_STATE.RangeError(
           'Backpressure violation: too many pending writes. ' +
           'Await each write() call to respect backpressure.');
       }
diff --git a/test/parallel/test-stream-iter-broadcast-backpressure.js b/test/parallel/test-stream-iter-broadcast-backpressure.js
index d1e466c3ac44cf..7135a71b8e2806 100644
--- a/test/parallel/test-stream-iter-broadcast-backpressure.js
+++ b/test/parallel/test-stream-iter-broadcast-backpressure.js
@@ -105,6 +105,28 @@ async function testBlockBackpressureContent() {
   assert.strictEqual(done.done, true);
 }
 
+async function testStrictBackpressureOverflow() {
+  const { writer } = broadcast({
+    highWaterMark: 1,
+    backpressure: 'strict',
+  });
+
+  await writer.write('a');
+  const pending = writer.write('b');
+
+  await assert.rejects(writer.write('c'), {
+    name: 'RangeError',
+    code: 'ERR_INVALID_STATE',
+  });
+
+  writer.fail();
+  await assert.rejects(pending, {
+    name: 'TypeError',
+    code: 'ERR_INVALID_STATE',
+    message: 'Invalid state: Failed',
+  });
+}
+
 // Writev async path
 async function testWritevAsync() {
   const { writer, broadcast: bc } = broadcast({ highWaterMark: 10 });
@@ -133,6 +155,7 @@ Promise.all([
   testDropNewest(),
   testBlockBackpressure(),
   testBlockBackpressureContent(),
+  testStrictBackpressureOverflow(),
   testWritevAsync(),
   testEndSyncReturnValue(),
 ]).then(common.mustCall());