feat: ensure newline in CreateOutputFile and improve tests

- Add newline to `CreateOutputFile` if missing
- Use `t.Cleanup` for file removal in tests
- Add test for message with trailing newline
- Introduce `printedStream` flag in `Chatter.Send`
- Print newline if stream printed without trailing newline

cmd/generate_changelog/incoming/1830.txt

@@ -0,0 +1,7 @@
+### PR [#1830](https://github.com/danielmiessler/Fabric/pull/1830) by [ksylvan](https://github.com/ksylvan): Ensure final newline in model generated outputs
+
+- Feat: ensure newline in `CreateOutputFile` and improve tests
+- Add newline to `CreateOutputFile` if missing
+- Use `t.Cleanup` for file removal in tests
+- Add test for message with trailing newline
+- Introduce `printedStream` flag in `Chatter.Send`

internal/cli/output.go

@@ -29,6 +29,9 @@ func CreateOutputFile(message string, fileName string) (err error) {
 		return
 	}
 	defer file.Close()
+	if !strings.HasSuffix(message, "\n") {
+		message += "\n"
+	}
 	if _, err = file.WriteString(message); err != nil {
 		err = fmt.Errorf("%s", fmt.Sprintf(i18n.T("error_writing_to_file"), err))
 	} else {

internal/cli/output_test.go

@@ -24,5 +24,34 @@ func TestCreateOutputFile(t *testing.T) {
 		t.Fatalf("CreateOutputFile() error = %v", err)
 	}
 
-	defer os.Remove(fileName)
+	t.Cleanup(func() { os.Remove(fileName) })
+
+	data, err := os.ReadFile(fileName)
+	if err != nil {
+		t.Fatalf("failed to read output file: %v", err)
+	}
+
+	expected := message + "\n"
+	if string(data) != expected {
+		t.Fatalf("expected file contents %q, got %q", expected, data)
+	}
+}
+
+func TestCreateOutputFileMessageWithTrailingNewline(t *testing.T) {
+	fileName := "test_output_with_newline.txt"
+	message := "test message with newline\n"
+
+	if err := CreateOutputFile(message, fileName); err != nil {
+		t.Fatalf("CreateOutputFile() error = %v", err)
+	}
+	t.Cleanup(func() { os.Remove(fileName) })
+
+	data, err := os.ReadFile(fileName)
+	if err != nil {
+		t.Fatalf("failed to read output file: %v", err)
+	}
+
+	if string(data) != message {
+		t.Fatalf("expected file contents %q, got %q", message, data)
+	}
 }

internal/core/chatter.go

@@ -69,6 +69,7 @@ func (o *Chatter) Send(request *domain.ChatRequest, opts *domain.ChatOptions) (s
 		responseChan := make(chan string)
 		errChan := make(chan error, 1)
 		done := make(chan struct{})
+		printedStream := false
 
 		go func() {
 			defer close(done)
@@ -81,9 +82,14 @@ func (o *Chatter) Send(request *domain.ChatRequest, opts *domain.ChatOptions) (s
 			message += response
 			if !opts.SuppressThink {
 				fmt.Print(response)
+				printedStream = true
 			}
 		}
 
+		if printedStream && !opts.SuppressThink && !strings.HasSuffix(message, "\n") {
+			fmt.Println()
+		}
+
 		// Wait for goroutine to finish
 		<-done