Stabilize editor typing render path (#28)

Author: KSemenenko

AGENTS.md

@@ -136,6 +136,7 @@ Rule format:
 - Do not push branches or `main` without an explicit user command for that push; local commits are allowed, but network publish actions require clear approval in the current conversation.
 - Issue-driven implementation work must create or reference the GitHub issue first, mention the issue number in related commits, and leave issue closure to the user after their verification.
 - For feedback issue triage, treat issues assigned to `byskyphy` as implemented and waiting for user verification, and treat unassigned issues as not ready unless issue comments explicitly say otherwise; after the release containing an implemented issue ships, add a comment to that issue with the app version where it was added.
+- GitHub Project status `Ready for review` is only for issue work that is implemented, committed, pushed, and covered by a green GitHub Actions release build; do not move issues there while the relevant build is still running or failed.
 - Feature or improvement issues must include UI acceptance coverage expectations, and implementation commits for those issues must add or update browser/UI tests unless the issue explicitly documents why UI coverage is not applicable.
 - Stakeholder feedback issues should be interpreted as additive feature or presentation requests by default; do not remove existing behavior from wording such as "replace", "remove", or "rename" unless the user explicitly confirms deletion.
 - When a CI test job fails, times out, or is cancelled, the workflow summary must still state which tests failed or that the run ended before per-test failure data was available; do not leave browser-suite failures represented only by generic job annotations.

src/PrompterOne.Shared/Editor/Pages/EditorPage.SourceEditing.cs

@@ -56,14 +56,40 @@ private async Task OnHistoryRequestedAsync(EditorHistoryCommand command)
 
     private Task OnSelectionChangedAsync(EditorSelectionViewModel selection)
     {
+        var previousSelection = _selection;
+        var previousSegmentIndex = _activeSegmentIndex;
+        var previousBlockIndex = _activeBlockIndex;
+
         _selection = selection;
         _history.UpdateSelection(selection.Range);
         RefreshSelectionState();
         PublishEditorAiContext();
-        StateHasChanged();
+        if (ShouldRenderSelectionChange(previousSelection, previousSegmentIndex, previousBlockIndex))
+        {
+            StateHasChanged();
+        }
+
         return Task.CompletedTask;
     }
 
+    private bool ShouldRenderSelectionChange(
+        EditorSelectionViewModel previousSelection,
+        int previousSegmentIndex,
+        int? previousBlockIndex)
+    {
+        if (previousSelection.HasSelection || _selection.HasSelection)
+        {
+            return true;
+        }
+
+        if (previousSegmentIndex != _activeSegmentIndex || previousBlockIndex != _activeBlockIndex)
+        {
+            return true;
+        }
+
+        return previousSelection.Line != _selection.Line;
+    }
+
     private Task OnSourceChangedAsync(string text)
     {
         var sourceText = text ?? string.Empty;