Client: variables resolved in the live editor and reading view

Co-Authored-By: Claude Opus 5.5 <[email protected]>

Client/Sources.py

@@ -543,6 +543,10 @@ class ServerSource(Source):
     def RemoveLock(self, Root: str, RelativePath: str) -> None:
         self._Json("DELETE", "/lock", params=self._At(Root, RelativePath))
 
+    def Spans(self, Root: str, RelativePath: str, Content: str) -> list[dict]:
+        """Where Content's variables are and what they resolve to (Variables.py)."""
+        return self._Json("POST", "/file/spans", params=self._At(Root, RelativePath), json={"Content": Content})["Spans"]
+
     def Diagram(self, Source: str, ThemePalette: dict[str, str], FontSize: int) -> bytes:
         """A ```mermaid block as a PNG, drawn by the server (Diagrams.py)."""
         Body = {"Source": Source, "Palette": ThemePalette, "FontSize": FontSize}