Fix 3 subagent-found bugs: trimmedPattern in search, Razor HTML escaping, whitespace-only type guard

- BookListingTool.cs: use trimmedPattern (not pattern) in Contains() search call
- Index.cshtml: fix Razor HTML escaping of optional badge via @if block
- BookGuidelinesTool.cs: use IsNullOrWhiteSpace guard for type param
- BookGuidelinesTool.cs: fix description to say substring match not exact text

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: BenjaminMichaelis

EssentialCSharp.Web/Tools/BookGuidelinesTool.cs

@@ -18,18 +18,18 @@ public BookGuidelinesTool(IGuidelinesService guidelinesService)
     }
 
     [McpServerTool(Title = "Get C# Guidelines", ReadOnly = true, Destructive = false, Idempotent = true, OpenWorld = false),
-     Description("Retrieve C# coding guidelines from the Essential C# book. Filter by keyword (exact text match), chapter number, or guideline type. Use the 'topic' parameter for relevance-ranked discovery by concept (e.g., 'exception handling', 'naming', 'async'). Each guideline includes its chapter and subsection context. Tip: use 'topic' for broad discovery; use 'keyword' for precise text matching.")]
+     Description("Retrieve C# coding guidelines from the Essential C# book. Filter by keyword (case-insensitive substring match), chapter number, or guideline type. Use the 'topic' parameter for relevance-ranked discovery by concept (e.g., 'exception handling', 'naming', 'async'). Each guideline includes its chapter and subsection context. Tip: use 'topic' for broad discovery; use 'keyword' for precise substring matching.")]
     public string GetCSharpGuidelines(
-        [Description("Optional keyword for exact-text search in guideline text and subsection name.")] string? keyword = null,
+        [Description("Optional keyword for case-insensitive substring search in guideline text and subsection name.")] string? keyword = null,
         [Description("Optional chapter number to restrict results to a specific chapter.")] int? chapter = null,
         [Description("Optional guideline type: 'do', 'consider', 'avoid', or 'donot' (also accepts 'do not', 'dont').")] string? type = null,
-        [Description("Optional topic or concept for relevance-ranked search (e.g., 'exception handling', 'naming', 'async'). Results are ordered by relevance. Use for broad discovery; use 'keyword' for exact text matching.")] string? topic = null,
+        [Description("Optional topic or concept for relevance-ranked search (e.g., 'exception handling', 'naming', 'async'). Results are ordered by relevance. Use for broad discovery; use 'keyword' for substring text matching.")] string? topic = null,
         [Description("Maximum number of guidelines to return (1–50).")] int maxResults = 20)
     {
         maxResults = Math.Clamp(maxResults, 1, 50);
         GuidelineType? typeFilter = ParseGuidelineType(type);
 
-        if (type is not null && typeFilter is null)
+        if (!string.IsNullOrWhiteSpace(type) && typeFilter is null)
         {
             return "Invalid guideline type. Valid values: 'do', 'consider', 'avoid', 'donot' (also accepts 'do not', 'dont').";
         }

EssentialCSharp.Web/Tools/BookListingTool.cs

@@ -73,7 +73,7 @@ public async Task<string> SearchListingsByCode(
             foreach (var listing in listings)
             {
                 if (found >= maxResults) break;
-                if (listing.Content.Contains(pattern, StringComparison.OrdinalIgnoreCase))
+                if (listing.Content.Contains(trimmedPattern, StringComparison.OrdinalIgnoreCase))
                 {
                     string langHint = listing.FileExtension == "cs" ? "csharp" : listing.FileExtension;
                     sb.AppendLine(CultureInfo.InvariantCulture, $"### Listing {listing.ChapterNumber}.{listing.ListingNumber}");

EssentialCSharp.Web/Views/McpSetup/Index.cshtml

@@ -278,7 +278,10 @@
                         <dl class="row mb-0 small">
                             @foreach (var param in tool.Parameters)
                             {
-                                <dt class="col-sm-3"><code>@param.Name</code>@(param.Required ? "" : " <span class=\"text-muted\">(optional)</span>")</dt>
+                                <dt class="col-sm-3">
+                                    <code>@param.Name</code>
+                                    @if (!param.Required) { <span class="text-muted">(optional)</span> }
+                                </dt>
                                 <dd class="col-sm-9">@param.Description</dd>
                             }
                         </dl>