diff --git a/codex-wrapper/main.go b/codex-wrapper/main.go
index 56d13b7..4837704 100644
--- a/codex-wrapper/main.go
+++ b/codex-wrapper/main.go
@@ -24,9 +24,9 @@ const (
 
 // Test hooks for dependency injection
 var (
-	stdinReader   io.Reader = os.Stdin
-	isTerminalFn            = defaultIsTerminal
-	codexCommand            = "codex"
+	stdinReader  io.Reader = os.Stdin
+	isTerminalFn           = defaultIsTerminal
+	codexCommand           = "codex"
 )
 
 // Config holds CLI configuration
@@ -347,9 +347,7 @@ func runCodexProcess(codexArgs []string, taskText string, useStdin bool, timeout
 
 func parseJSONStream(r io.Reader) (message, threadID string) {
 	scanner := bufio.NewScanner(r)
-	// Set larger buffer for long lines
-	buf := make([]byte, 0, 64*1024)
-	scanner.Buffer(buf, 1024*1024)
+	scanner.Buffer(make([]byte, 64*1024), 10*1024*1024)
 
 	for scanner.Scan() {
 		line := strings.TrimSpace(scanner.Text())
@@ -369,18 +367,15 @@ func parseJSONStream(r io.Reader) (message, threadID string) {
 		}
 
 		// Capture agent_message
-		if event.Type == "item.completed" && event.Item != nil {
-			if event.Item.Type == "agent_message" {
-				text := normalizeText(event.Item.Text)
-				if text != "" {
-					message = text
-				}
+		if event.Type == "item.completed" && event.Item != nil && event.Item.Type == "agent_message" {
+			if text := normalizeText(event.Item.Text); text != "" {
+				message = text
 			}
 		}
 	}
 
-	if err := scanner.Err(); err != nil {
-		logWarn("Scanner error: " + err.Error())
+	if err := scanner.Err(); err != nil && err != io.EOF {
+		logWarn("Read stdout error: " + err.Error())
 	}
 
 	return message, threadID
diff --git a/codex-wrapper/main_test.go b/codex-wrapper/main_test.go
index 112330b..ab123cb 100644
--- a/codex-wrapper/main_test.go
+++ b/codex-wrapper/main_test.go
@@ -330,12 +330,16 @@ func TestNormalizeText(t *testing.T) {
 }
 
 func TestParseJSONStream(t *testing.T) {
-	tests := []struct {
+	type testCase struct {
 		name         string
 		input        string
 		wantMessage  string
 		wantThreadID string
-	}{
+	}
+
+	longText := strings.Repeat("a", 2*1024*1024) // >1MB agent_message payload
+
+	tests := []testCase{
 		{
 			name: "thread started and agent message",
 			input: `{"type":"thread.started","thread_id":"abc-123"}
@@ -364,6 +368,12 @@ func TestParseJSONStream(t *testing.T) {
 			wantMessage:  "Valid",
 			wantThreadID: "",
 		},
+		{
+			name:         "super long single line (>1MB)",
+			input:        `{"type":"item.completed","item":{"type":"agent_message","text":"` + longText + `"}}`,
+			wantMessage:  longText,
+			wantThreadID: "",
+		},
 		{
 			name:         "empty input",
 			input:        "",
@@ -371,23 +381,25 @@ func TestParseJSONStream(t *testing.T) {
 			wantThreadID: "",
 		},
 		{
-			name:         "invalid JSON (skipped)",
-			input:        "not valid json\n{\"type\":\"thread.started\",\"thread_id\":\"xyz\"}",
+			name: "item completed with nil item",
+			input: strings.Join([]string{
+				`{"type":"thread.started","thread_id":"nil-item-thread"}`,
+				`{"type":"item.completed","item":null}`,
+			}, "\n"),
 			wantMessage:  "",
-			wantThreadID: "xyz",
+			wantThreadID: "nil-item-thread",
 		},
 		{
-			name:         "blank lines ignored",
-			input:        "\n\n{\"type\":\"thread.started\",\"thread_id\":\"test\"}\n\n",
+			name:         "agent message with non-string text",
+			input:        `{"type":"item.completed","item":{"type":"agent_message","text":12345}}`,
 			wantMessage:  "",
-			wantThreadID: "test",
+			wantThreadID: "",
 		},
 	}
 
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			r := strings.NewReader(tt.input)
-			gotMessage, gotThreadID := parseJSONStream(r)
+			gotMessage, gotThreadID := parseJSONStream(strings.NewReader(tt.input))
 
 			if gotMessage != tt.wantMessage {
 				t.Errorf("parseJSONStream() message = %q, want %q", gotMessage, tt.wantMessage)