Create mermaid_renderer.py

flows_04/mermaid_renderer.py

@@ -0,0 +1,43 @@
+from .graph_models import FlowGraph
+
+
+def build_mermaid(flow: FlowGraph) -> str:
+    """
+    Build a Mermaid graph string from a FlowGraph.
+
+    - Nodes become:   id[Label]
+    - Edges become:   source -->|label| target
+    - Node styles:    style id <style>
+    - Edge styles:    linkStyle <index> <style>
+    """
+    lines = ["graph TD"]
+
+    # Nodes
+    for node in flow.nodes:
+        safe_label = node.label or node.id
+        lines.append(f"  {node.id}[{safe_label}]")
+
+    # Edges (keep index for linkStyle)
+    edge_styles = []
+    for idx, edge in enumerate(flow.edges):
+        if edge.label:
+            lines.append(f"  {edge.source} -->|{edge.label}| {edge.target}")
+        else:
+            lines.append(f"  {edge.source} --> {edge.target}")
+
+        style = edge.metadata.get("style") if edge.metadata else None
+        if style:
+            edge_styles.append((idx, style))
+
+    # Node styles
+    for node in flow.nodes:
+        style = node.metadata.get("style") if node.metadata else None
+        if style:
+            lines.append(f"  style {node.id} {style}")
+
+    # Edge styles (Mermaid linkStyle uses numeric index)
+    for idx, style in edge_styles:
+        lines.append(f"  linkStyle {idx} {style}")
+
+    mermaid = "```mermaid\n" + "\n".join(lines) + "\n```"
+    return mermaid