fix: correct mermaid flowchart edge label syntax (-->|label| not --|"label"|)

crates/adapters/mermaid/src/mermaid_renderer.rs

@@ -225,17 +225,17 @@ impl MermaidRenderer {
         }
 
         for ((source, target), count) in &module_edges {
-            let arrow = if self.show_weights {
+            let line = if self.show_weights {
                 let label = if *count == 1 {
-                    r#"|"1 dep"|"#.to_string()
+                    "1 dep".to_string()
                 } else {
-                    format!(r#"|"{count} deps"|"#)
+                    format!("{count} deps")
                 };
-                format!("--{label}")
+                format!("    {source} -->|{label}| {target}")
             } else {
-                "-->".to_string()
+                format!("    {source} --> {target}")
             };
-            lines.push(format!("    {source} {arrow} {target}"));
+            lines.push(line);
         }
 
         lines.join("\n")

crates/adapters/mermaid/tests/mermaid_renderer_tests.rs

@@ -321,7 +321,7 @@ fn module_level_aggregates_cross_module_deps_into_single_arrow() {
     let content = output.files()[0].content();
 
     let arrow_count =
-        content.matches("Orders --> Infra").count() + content.matches("Orders --|").count();
+        content.matches("Orders --> Infra").count() + content.matches("Orders -->|").count();
     assert_eq!(
         arrow_count, 1,
         "should have exactly one aggregated arrow, got:\n{content}"
@@ -374,7 +374,7 @@ fn module_level_shows_dep_count_as_edge_label() {
     let content = output.files()[0].content();
 
     assert!(
-        content.contains(r#"|"2 deps"|"#),
+        content.contains("|2 deps|"),
         "expected dep count label in: {content}"
     );
 }
@@ -412,7 +412,7 @@ fn module_level_single_dep_uses_singular_label() {
     let content = output.files()[0].content();
 
     assert!(
-        content.contains(r#"|"1 dep"|"#),
+        content.contains("|1 dep|"),
         "expected singular dep label in: {content}"
     );
 }