Client: Mermaid diagrams, drawn by the server

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

Client/LiveMarkdown.py

@@ -6,7 +6,8 @@ another block, puts it back rendered.
 A block is what Markdown itself separates: a heading line, a fenced code
 block, a horizontal rule, or a run of lines up to a blank line (a paragraph,
 list, table or quote). The text between blocks (blank lines) is kept
-byte for byte, so editing one block never reformats the rest of the file."""
+byte for byte, so editing one block never reformats the rest of the file.
+A ```mermaid block shows as its diagram when MakeDiagram gives one (Diagrams.py)."""
 
 import re
 from dataclasses import dataclass
@@ -101,7 +102,8 @@ def SplitBlocks(Document: str) -> list[Block]:
 
 class LiveMarkdown(ft.Column):
     def __init__(self, Document: str, FontSize: int, OnChange: Callable[[], None],
-                 OnFocusChange: Callable[[bool], None], OnTapLink: Callable):
+                 OnFocusChange: Callable[[bool], None], OnTapLink: Callable,
+                 MakeDiagram: Optional[Callable[[str, int], Optional[ft.Control]]] = None):
         super().__init__(scroll=ft.ScrollMode.AUTO, expand=True, spacing=0,
                          horizontal_alignment=ft.CrossAxisAlignment.STRETCH)
         self.Document = Document
@@ -109,6 +111,7 @@ class LiveMarkdown(ft.Column):
         self.OnChange = OnChange
         self.OnFocusChange = OnFocusChange
         self.OnTapLink = OnTapLink
+        self.MakeDiagram = MakeDiagram
         self.Blocks: list[Block] = []
         self.BlockControls: list[ft.Control] = []
         # Rendered blocks by their text, reused when the layout is rebuilt so
@@ -217,8 +220,9 @@ class LiveMarkdown(ft.Column):
     # --- Rendering -------------------------------------------------------
 
     def _Render(self, Text: str) -> ft.Control:
+        Diagram = self.MakeDiagram(Text, self.FontSize) if self.MakeDiagram else None
         Rendered = ft.Container(
-            content=ft.Markdown(
+            content=Diagram or ft.Markdown(
                 value=Text,
                 extension_set=ft.MarkdownExtensionSet.GITHUB_FLAVORED,
                 md_style_sheet=MarkdownSheet(self.FontSize),