refactor: extract module_edges() to CodeGraph domain — removes duplication from Mermaid and D2 renderers

crates/adapters/d2/src/d2_renderer.rs

@@ -92,49 +92,14 @@ fn render_type(graph: &CodeGraph) -> String {
 }
 
 fn render_module(graph: &CodeGraph) -> String {
-    use archlens_domain::RelationshipKind;
-    use std::collections::{HashMap, HashSet};
-
     let mut lines = Vec::new();
-    let mut modules: HashSet<String> = HashSet::new();
-    let mut name_to_module: HashMap<&str, &str> = HashMap::new();
 
-    for el in graph.elements() {
-        if let Some(m) = el.module() {
-            modules.insert(m.as_str().to_string());
-            name_to_module.insert(el.qualified_name(), m.as_str());
-            name_to_module.insert(el.name(), m.as_str());
-        }
+    for module in graph.modules() {
+        let id = sanitize(module.as_str());
+        lines.push(format!("{id}: {}", module.as_str()));
     }
 
-    for module in &modules {
-        let id = sanitize(module);
-        lines.push(format!("{id}: {module}"));
-    }
-
-    let mut edges: HashSet<(String, String)> = HashSet::new();
-    for rel in graph.relationships() {
-        if rel.kind() == RelationshipKind::Import {
-            continue;
-        }
-        // Direct module-to-module edge (from merged project deps)
-        if modules.contains(rel.source())
-            && modules.contains(rel.target())
-            && rel.source() != rel.target()
-        {
-            edges.insert((rel.source().to_string(), rel.target().to_string()));
-            continue;
-        }
-        let src_mod = name_to_module.get(rel.source());
-        let tgt_mod = name_to_module.get(rel.target());
-        if let (Some(s), Some(t)) = (src_mod, tgt_mod)
-            && s != t
-        {
-            edges.insert((s.to_string(), t.to_string()));
-        }
-    }
-
-    for (src, tgt) in &edges {
+    for (src, tgt) in graph.module_edges().keys() {
         lines.push(format!("{} -> {}", sanitize(src), sanitize(tgt)));
     }