fix: address PR review feedback

- Add error logging for malformed JSON in Codex tool arguments unmarshal
- Add test case for malformed JSON arguments in transcript parsing
- Add test cases for nil/empty ToolInput in convertCodexEntries and convertGeminiEntries

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: sky-xo

internal/codex/transcript.go

@@ -94,7 +94,9 @@ func parseEntry(data []byte) TranscriptEntry {
 		// Parse arguments JSON string into map
 		var toolInput map[string]interface{}
 		if argsStr, ok := payload["arguments"].(string); ok && argsStr != "" {
-			_ = json.Unmarshal([]byte(argsStr), &toolInput)
+			if err := json.Unmarshal([]byte(argsStr), &toolInput); err != nil {
+				fmt.Fprintf(os.Stderr, "codex: failed to unmarshal tool arguments for %s: %v\n", name, err)
+			}
 		}
 
 		return TranscriptEntry{

internal/codex/transcript_test.go

@@ -55,6 +55,29 @@ func TestParseEntryFunctionCallWithArguments(t *testing.T) {
 	}
 }
 
+func TestParseEntryFunctionCallMalformedArguments(t *testing.T) {
+	// Malformed JSON in arguments field - should handle gracefully (not panic)
+	data := []byte(`{"type":"response_item","payload":{"type":"function_call","name":"shell_command","arguments":"{invalid json here"}}`)
+
+	entry := parseEntry(data)
+
+	// Should still return a valid tool entry
+	if entry.Type != "tool" {
+		t.Errorf("Type = %q, want %q", entry.Type, "tool")
+	}
+	if entry.ToolName != "shell_command" {
+		t.Errorf("ToolName = %q, want %q", entry.ToolName, "shell_command")
+	}
+	// ToolInput should be nil when JSON parsing fails
+	if entry.ToolInput != nil {
+		t.Errorf("ToolInput = %v, want nil for malformed JSON", entry.ToolInput)
+	}
+	// Content should still be populated
+	if entry.Content != "[tool: shell_command]" {
+		t.Errorf("Content = %q, want %q", entry.Content, "[tool: shell_command]")
+	}
+}
+
 func TestParseEntryFunctionCallOutput(t *testing.T) {
 	// Actual Codex format: type is "response_item", payload.type is "function_call_output"
 	data := []byte(`{"type":"response_item","payload":{"type":"function_call_output","output":"Exit code: 0\nOutput: hello"}}`)

internal/tui/commands_test.go

@@ -177,3 +177,111 @@ func TestConvertGeminiEntriesRichFormatting(t *testing.T) {
 		t.Errorf("ToolName() = %q, want %q", entries[0].ToolName(), "Read")
 	}
 }
+
+func TestConvertCodexEntriesNilToolInput(t *testing.T) {
+	// Verify that nil ToolInput doesn't cause panic
+	codexEntries := []codex.TranscriptEntry{
+		{
+			Type:      "tool",
+			Content:   "[tool: shell_command]",
+			ToolName:  "shell_command",
+			ToolInput: nil, // nil input (can happen with malformed JSON)
+		},
+	}
+
+	// Should not panic
+	entries := convertCodexEntries(codexEntries)
+
+	if len(entries) != 1 {
+		t.Fatalf("len(entries) = %d, want 1", len(entries))
+	}
+
+	// Should still normalize tool name
+	if entries[0].ToolName() != "Bash" {
+		t.Errorf("ToolName() = %q, want %q", entries[0].ToolName(), "Bash")
+	}
+
+	// ToolInput should be empty map, not nil
+	toolInput := entries[0].ToolInput()
+	if toolInput == nil {
+		t.Error("ToolInput() = nil, want empty map")
+	}
+}
+
+func TestConvertCodexEntriesEmptyToolInput(t *testing.T) {
+	// Verify that empty ToolInput works correctly
+	codexEntries := []codex.TranscriptEntry{
+		{
+			Type:      "tool",
+			Content:   "[tool: read_file]",
+			ToolName:  "read_file",
+			ToolInput: map[string]interface{}{}, // empty map
+		},
+	}
+
+	// Should not panic
+	entries := convertCodexEntries(codexEntries)
+
+	if len(entries) != 1 {
+		t.Fatalf("len(entries) = %d, want 1", len(entries))
+	}
+
+	// Should still normalize tool name
+	if entries[0].ToolName() != "Read" {
+		t.Errorf("ToolName() = %q, want %q", entries[0].ToolName(), "Read")
+	}
+}
+
+func TestConvertGeminiEntriesNilToolInput(t *testing.T) {
+	// Verify that nil ToolInput doesn't cause panic
+	geminiEntries := []gemini.TranscriptEntry{
+		{
+			Type:      "tool",
+			Content:   "[tool: shell]",
+			ToolName:  "shell",
+			ToolInput: nil, // nil input (can happen with malformed JSON)
+		},
+	}
+
+	// Should not panic
+	entries := convertGeminiEntries(geminiEntries)
+
+	if len(entries) != 1 {
+		t.Fatalf("len(entries) = %d, want 1", len(entries))
+	}
+
+	// Should still normalize tool name
+	if entries[0].ToolName() != "Bash" {
+		t.Errorf("ToolName() = %q, want %q", entries[0].ToolName(), "Bash")
+	}
+
+	// ToolInput should be empty map, not nil
+	toolInput := entries[0].ToolInput()
+	if toolInput == nil {
+		t.Error("ToolInput() = nil, want empty map")
+	}
+}
+
+func TestConvertGeminiEntriesEmptyToolInput(t *testing.T) {
+	// Verify that empty ToolInput works correctly
+	geminiEntries := []gemini.TranscriptEntry{
+		{
+			Type:      "tool",
+			Content:   "[tool: read_file]",
+			ToolName:  "read_file",
+			ToolInput: map[string]interface{}{}, // empty map
+		},
+	}
+
+	// Should not panic
+	entries := convertGeminiEntries(geminiEntries)
+
+	if len(entries) != 1 {
+		t.Fatalf("len(entries) = %d, want 1", len(entries))
+	}
+
+	// Should still normalize tool name
+	if entries[0].ToolName() != "Read" {
+		t.Errorf("ToolName() = %q, want %q", entries[0].ToolName(), "Read")
+	}
+}