init: archlens — architecture diagram generator

Hex arch + DDD, tree-sitter parsing, Mermaid/ASCII output.
Supports Rust + Python. 92 tests. CI, diff, --check for staleness detection.

crates/domain/tests/render_output_tests.rs

@@ -0,0 +1,37 @@
+use archlens_domain::{RenderOutput, RenderedFile};
+
+#[test]
+fn rendered_file_carries_name_and_content() {
+    let file = RenderedFile::new("overview.mmd", "graph TD;").unwrap();
+    assert_eq!(file.name(), "overview.mmd");
+    assert_eq!(file.content(), "graph TD;");
+}
+
+#[test]
+fn rendered_file_rejects_empty_name() {
+    let result = RenderedFile::new("", "content");
+    assert!(result.is_err());
+}
+
+#[test]
+fn rendered_file_rejects_empty_content() {
+    let result = RenderedFile::new("file.mmd", "");
+    assert!(result.is_err());
+}
+
+#[test]
+fn render_output_holds_multiple_files() {
+    let files = vec![
+        RenderedFile::new("overview.mmd", "graph TD;").unwrap(),
+        RenderedFile::new("orders.mmd", "classDiagram").unwrap(),
+    ];
+    let output = RenderOutput::new(files);
+    assert_eq!(output.files().len(), 2);
+}
+
+#[test]
+fn render_output_can_be_single_file() {
+    let file = RenderedFile::new("arch.mmd", "graph TD;").unwrap();
+    let output = RenderOutput::single(file);
+    assert_eq!(output.files().len(), 1);
+}