From e96e02a00642fcc64ac10b2aa0eb8c7174bddff1 Mon Sep 17 00:00:00 2001
From: Danielle Maywood <danielle@themaywoods.com>
Date: Fri, 15 Aug 2025 12:01:15 +0000
Subject: [PATCH 1/2] refactor: replace fmt.Errorf with MessageTooBigError

---
 read.go | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/read.go b/read.go
index aab9e141..672e8f36 100644
--- a/read.go
+++ b/read.go
@@ -17,6 +17,14 @@ import (
 	"github.com/coder/websocket/internal/util"
 )
 
+type MessageTooBigError struct {
+	Limit int64
+}
+
+func (e MessageTooBigError) Error() string {
+	return fmt.Sprintf("read limited at %v bytes", e.Limit)
+}
+
 // Reader reads from the connection until there is a WebSocket
 // data message to be read. It will handle ping, pong and close frames as appropriate.
 //
@@ -520,7 +528,7 @@ func (lr *limitReader) Read(p []byte) (int, error) {
 	}
 
 	if lr.n == 0 {
-		err := fmt.Errorf("read limited at %v bytes", lr.limit.Load())
+		err := MessageTooBigError{Limit: lr.limit.Load()}
 		lr.c.writeError(StatusMessageTooBig, err)
 		return 0, err
 	}

From c44f12f2ac7c6363176eef98f1c96fbb572bf9b7 Mon Sep 17 00:00:00 2001
From: Danielle Maywood <danielle@themaywoods.com>
Date: Fri, 15 Aug 2025 14:06:19 +0000
Subject: [PATCH 2/2] refactor: replace MessageTooBigError with
 ErrMessageTooBig

---
 read.go  | 10 ++--------
 ws_js.go |  4 +++-
 2 files changed, 5 insertions(+), 9 deletions(-)

diff --git a/read.go b/read.go
index 672e8f36..85e09893 100644
--- a/read.go
+++ b/read.go
@@ -17,13 +17,7 @@ import (
 	"github.com/coder/websocket/internal/util"
 )
 
-type MessageTooBigError struct {
-	Limit int64
-}
-
-func (e MessageTooBigError) Error() string {
-	return fmt.Sprintf("read limited at %v bytes", e.Limit)
-}
+var ErrMessageTooBig = errors.New("websocket: message too big")
 
 // Reader reads from the connection until there is a WebSocket
 // data message to be read. It will handle ping, pong and close frames as appropriate.
@@ -528,7 +522,7 @@ func (lr *limitReader) Read(p []byte) (int, error) {
 	}
 
 	if lr.n == 0 {
-		err := MessageTooBigError{Limit: lr.limit.Load()}
+		err := fmt.Errorf("%w: %d bytes", ErrMessageTooBig, lr.limit.Load())
 		lr.c.writeError(StatusMessageTooBig, err)
 		return 0, err
 	}
diff --git a/ws_js.go b/ws_js.go
index 8d52aeab..2381fe13 100644
--- a/ws_js.go
+++ b/ws_js.go
@@ -19,6 +19,8 @@ import (
 	"github.com/coder/websocket/internal/wsjs"
 )
 
+var ErrMessageTooBig = errors.New("websocket: message too big")
+
 // opcode represents a WebSocket opcode.
 type opcode int
 
@@ -144,7 +146,7 @@ func (c *Conn) Read(ctx context.Context) (MessageType, []byte, error) {
 	}
 	readLimit := c.msgReadLimit.Load()
 	if readLimit >= 0 && int64(len(p)) > readLimit {
-		err := fmt.Errorf("read limited at %v bytes", c.msgReadLimit.Load())
+		err := fmt.Errorf("%w: %d bytes", ErrMessageTooBig, c.msgReadLimit.Load())
 		c.Close(StatusMessageTooBig, err.Error())
 		return 0, nil, err
 	}