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/adapters/file-writer/tests/file_writer_tests.rs

@@ -0,0 +1,35 @@
+use std::fs;
+
+use archlens_domain::{RenderOutput, RenderedFile, ports::OutputWriter};
+use archlens_file_writer::FileOutputWriter;
+
+#[test]
+fn writes_single_file_to_directory() {
+    let dir = tempfile::tempdir().unwrap();
+    let writer = FileOutputWriter::new(dir.path().to_path_buf());
+
+    let file = RenderedFile::new("arch.mmd", "classDiagram").unwrap();
+    let output = RenderOutput::single(file);
+
+    writer.write(&output).unwrap();
+
+    let content = fs::read_to_string(dir.path().join("arch.mmd")).unwrap();
+    assert_eq!(content, "classDiagram");
+}
+
+#[test]
+fn writes_multiple_files_to_directory() {
+    let dir = tempfile::tempdir().unwrap();
+    let writer = FileOutputWriter::new(dir.path().to_path_buf());
+
+    let files = vec![
+        RenderedFile::new("overview.mmd", "graph TD").unwrap(),
+        RenderedFile::new("orders.mmd", "classDiagram").unwrap(),
+    ];
+    let output = RenderOutput::new(files);
+
+    writer.write(&output).unwrap();
+
+    assert!(dir.path().join("overview.mmd").exists());
+    assert!(dir.path().join("orders.mmd").exists());
+}