Client: Mermaid diagrams, drawn by the server

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

Client/Sources.py

@@ -114,6 +114,7 @@ class Source:
     def LocalFile(self, Root: str, RelativePath: str) -> Path: ...
     def Book(self, Root: str, RelativePath: str) -> dict: ...
     def Graph(self, Root: str, RelativePath: str) -> dict: ...
+    def Diagram(self, Source: str, ThemePalette: dict[str, str], FontSize: int) -> bytes: ...
 
     @property
     def CanWrite(self) -> bool:
@@ -275,6 +276,9 @@ class LocalSource(Source):
 
         return BuildLocalGraph(self, Root, RelativePath)
 
+    def Diagram(self, Source: str, ThemePalette: dict[str, str], FontSize: int) -> bytes:
+        raise SourceError("Diagrams are drawn by a SaraView server.")
+
 
 class ServerSource(Source):
     """A SaraView server, through the same /api endpoints the web frontend
@@ -464,6 +468,11 @@ class ServerSource(Source):
         # A big root takes the server a while to read through.
         return self._Json("GET", "/graph", params=self._At(Root, RelativePath), timeout=120)
 
+    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}
+        return self._Request("POST", "/diagram", json=Body).content
+
 
 def MakeSource(Config: AppConfig, Token: str = "") -> Source:
     return ServerSource(Config, Token) if Config.Mode == "Server" else LocalSource(Config)