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/src/file_output_writer.rs

@@ -0,0 +1,52 @@
+use std::fs;
+use std::path::PathBuf;
+
+use archlens_domain::{DomainError, RenderOutput, ports::OutputWriter};
+
+pub struct FileOutputWriter {
+    output_path: OutputPath,
+}
+
+enum OutputPath {
+    Directory(PathBuf),
+    File(PathBuf),
+}
+
+impl FileOutputWriter {
+    pub fn new(output_dir: PathBuf) -> Self {
+        Self {
+            output_path: OutputPath::Directory(output_dir),
+        }
+    }
+
+    pub fn single_file(path: PathBuf) -> Self {
+        Self {
+            output_path: OutputPath::File(path),
+        }
+    }
+}
+
+impl OutputWriter for FileOutputWriter {
+    fn write(&self, output: &RenderOutput) -> Result<(), DomainError> {
+        match &self.output_path {
+            OutputPath::File(path) => {
+                if let Some(parent) = path.parent() {
+                    fs::create_dir_all(parent).map_err(|e| DomainError::IoError(e.to_string()))?;
+                }
+                let content = output.files().first().map(|f| f.content()).unwrap_or("");
+                fs::write(path, content).map_err(|e| DomainError::IoError(e.to_string()))?;
+            }
+            OutputPath::Directory(dir) => {
+                fs::create_dir_all(dir).map_err(|e| DomainError::IoError(e.to_string()))?;
+
+                for file in output.files() {
+                    let path = dir.join(file.name());
+                    fs::write(&path, file.content())
+                        .map_err(|e| DomainError::IoError(e.to_string()))?;
+                }
+            }
+        }
+
+        Ok(())
+    }
+}

crates/adapters/file-writer/src/lib.rs

@@ -0,0 +1,3 @@
+mod file_output_writer;
+
+pub use file_output_writer::FileOutputWriter;