More stuff, didn't test

src/layout.rs

@@ -111,21 +111,16 @@ impl<'a> Layout<'a> {
     }
 
     pub fn recipe_patches(&self, recipe: &Recipe) -> anyhow::Result<Vec<PathBuf>> {
-        let patches_dir = recipe.dir().join("patches");
-        if !patches_dir.exists() {
+        let Some(data_dir) = recipe.data_dir() else {
             return Ok(Vec::new());
-        }
-        let mut patches = Vec::new();
-        for entry in fs::read_dir(&patches_dir)
-            .with_context(|| format!("reading patches directory {}", patches_dir.display()))?
-        {
-            let entry = entry?;
-            let path = entry.path();
-            if path.is_file() {
-                patches.push(path);
+        };
+        let patches_dir = data_dir.join("patches");
+        let mut out = Vec::new();
+        for (_, source) in recipe.sources().entries() {
+            for name in source.patches() {
+                out.push(patches_dir.join(name));
             }
         }
-        patches.sort();
-        Ok(patches)
+        Ok(out)
     }
 }