ENG-1315: Disable node type change in canvas create-node modal (#906)

Prevent node type mismatch by disabling the node type selector when
creating nodes from canvas contexts (DiscourseNodeTools, Convert-to,
shape select). Non-canvas flows (command palette, node tag popup)
remain unaffected.

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: trangdoan982

apps/roam/src/components/ModifyNodeDialog.tsx

@@ -47,6 +47,7 @@ export type ModifyNodeDialogProps = {
   extensionAPI?: OnloadArgs["extensionAPI"];
   includeDefaultNodes?: boolean; // Include default nodes (Page, Block) in node type selector
   imageUrl?: string; // For image conversion from canvas
+  disableNodeTypeChange?: boolean; // Disable node type selector (e.g. canvas contexts)
   onSuccess: (result: {
     text: string;
     uid: string;
@@ -65,6 +66,7 @@ const ModifyNodeDialog = ({
   extensionAPI,
   includeDefaultNodes = false,
   imageUrl,
+  disableNodeTypeChange = false,
   onSuccess,
   onClose,
 }: RoamOverlayProps<ModifyNodeDialogProps>) => {
@@ -520,8 +522,13 @@ const ModifyNodeDialog = ({
                     setReferencedNodeValue({ text: "", uid: "" });
                   }
                 }}
-                disabled={mode === "edit"}
+                disabled={mode === "edit" || disableNodeTypeChange}
                 popoverProps={{ openOnTargetFocus: false }}
+                className={
+                  mode === "edit" || disableNodeTypeChange
+                    ? "cursor-not-allowed opacity-50"
+                    : ""
+                }
               />
             </Label>
           </div>

apps/roam/src/components/canvas/DiscourseNodeUtil.tsx

@@ -543,6 +543,7 @@ export class BaseDiscourseNodeUtil extends BaseBoxShapeUtil<DiscourseNodeShape>
               : undefined,
           extensionAPI,
           includeDefaultNodes: true,
+          disableNodeTypeChange: true,
           onSuccess: async ({ text, uid, action }) => {
             if (action === "edit") {
               if (isPageUid(shape.props.uid))
@@ -665,6 +666,7 @@ export class BaseDiscourseNodeUtil extends BaseBoxShapeUtil<DiscourseNodeShape>
                   initialValue: { text: cleanedText, uid: "" },
                   extensionAPI,
                   includeDefaultNodes: true,
+                  disableNodeTypeChange: true,
                   onSuccess: async ({ text, uid }) => {
                     if (!extensionAPI) return;
                     try {

apps/roam/src/components/canvas/uiOverrides.tsx

@@ -162,6 +162,7 @@ export const getOnSelectForShape = ({
       initialValue: { text: initialText, uid: "" },
       extensionAPI,
       includeDefaultNodes: true,
+      disableNodeTypeChange: true,
       imageUrl,
       onSuccess: async ({ text, uid }) => {
         editor.deleteShapes([shape.id]);