Minimalist HTML repr for jupyter

src/projspec/html.py

@@ -0,0 +1,47 @@
+def dict_to_html(data: dict, title="Data", open_level=2) -> str:
+    """
+    Convert a nested dictionary to expandable HTML using <details> tags.
+
+    Args:
+        data: The dictionary to convert
+        title: Title for the details element
+        open_level: whether to set elements as expanded; yes if > 0, and will
+            decrement for inner levels.
+
+    Returns:
+        String containing HTML with expandable details elements
+    """
+    # With help from Claude Sonnet 4.
+    if not isinstance(data, dict):
+        return f"<span>{data}</span>"
+
+    if not data:
+        return ""
+    open = "open" if open_level > 0 else "closed"
+
+    html = [
+        f'<details {open} style="margin-left: 20px; margin-bottom: 10px;"><summary style="cursor: pointer; color: #2c5aa0; padding: 5px;"><strong>{title}</strong></summary>'
+    ]
+
+    for key, value in data.items():
+        if isinstance(value, dict):
+            html.append(dict_to_html(value, key, open_level - 1))
+        elif isinstance(value, (list, tuple)):
+            html.append(
+                f'<details style="margin-left: 20px; margin-bottom: 10px;"><summary style="cursor: pointer; color: #2c5aa0; padding: 5px;"><strong>{key}</strong></summary>'
+            )
+            for i, item in enumerate(value):
+                if isinstance(item, dict):
+                    html.append(
+                        dict_to_html(item, f"{key}[{i}]", open_level - 1)
+                    )
+                else:
+                    html.append(f'<div style=" margin: 5px 0;"> {item}</div>')
+            html.append("</details>")
+        else:
+            html.append(
+                f'<div style=" margin: 5px 0;"><strong>{key}:</strong> {value}</div>'
+            )
+
+    html.append("</details>")
+    return "".join(html)

src/projspec/proj/base.py

@@ -189,9 +189,15 @@ def to_dict(self, compact=True) -> dict:
             url=self.url,
             storage_options=self.storage_options,
         )
-        dic["klass"] = "project"
+        if not compact:
+            dic["klass"] = "project"
         return dic.to_dict(compact=compact)
 
+    def _repr_html_(self):
+        from projspec.html import dict_to_html
+
+        return dict_to_html(self.to_dict(), title=self.url)
+
     @staticmethod
     def from_dict(dic):
         from projspec.utils import from_dict
@@ -285,9 +291,11 @@ def to_dict(self, compact=True) -> dict:
         dic = AttrDict(
             _contents=self.contents,
             _artifacts=self.artifacts,
-            subpath=self.subpath,
-            klass=["projspec", self.snake_name()],
         )
+        if self.subpath:
+            dic["subpath"] = self.subpath
+        if not compact:
+            dic["klass"] = ["projspec", self.snake_name()]
         return dic.to_dict(compact=compact)
 
     @classmethod

tests/test_basic.py

@@ -14,6 +14,7 @@ def test_basic():
     assert proj.artifacts
     assert proj.children
     repr(proj)
+    proj._repr_html_()
 
 
 def test_contains():