refactor: use GeneratedRegex in HtmlSanitizer for compile-time optimization

- Convert HtmlSanitizer to partial class with [GeneratedRegex] attributes
- Replace 11 runtime Regex.Replace/Matches calls with generated methods
- Eliminates regex compilation overhead for HTML sanitization operations
- Update REFACTORING_SUMMARY.md to document the optimization

Co-Authored-By: Oz <oz-agent@warp.dev>

Journal.Core/Services/Entries/HtmlSanitizer.cs

@@ -3,8 +3,43 @@ using System.Text.RegularExpressions;
 
 namespace Journal.Core.Services.Entries;
 
-public static class HtmlSanitizer
+public static partial class HtmlSanitizer
 {
+    [GeneratedRegex("<(script|style)\\b[^>]*>.*?</\\1>", RegexOptions.IgnoreCase | RegexOptions.Singleline)]
+    private static partial Regex ScriptStyleRegex();
+
+    [GeneratedRegex("<br\\s*/?>", RegexOptions.IgnoreCase)]
+    private static partial Regex BrTagRegex();
+
+    [GeneratedRegex("</(p|div|h[1-6]|tr|table|ul|ol|blockquote)>", RegexOptions.IgnoreCase)]
+    private static partial Regex BlockEndTagRegex();
+
+    [GeneratedRegex("<li\\b[^>]*>", RegexOptions.IgnoreCase)]
+    private static partial Regex LiStartTagRegex();
+
+    [GeneratedRegex("</li>", RegexOptions.IgnoreCase)]
+    private static partial Regex LiEndTagRegex();
+
+    [GeneratedRegex("<(td|th)\\b[^>]*>", RegexOptions.IgnoreCase)]
+    private static partial Regex CellStartTagRegex();
+
+    [GeneratedRegex("</(td|th)>", RegexOptions.IgnoreCase)]
+    private static partial Regex CellEndTagRegex();
+
+    [GeneratedRegex("<hr\\b[^>]*>", RegexOptions.IgnoreCase)]
+    private static partial Regex HrTagRegex();
+
+    [GeneratedRegex("<[^>]+>", RegexOptions.Singleline)]
+    private static partial Regex AllTagsRegex();
+
+    [GeneratedRegex("[ \\t]{2,}")]
+    private static partial Regex MultipleSpacesRegex();
+
+    [GeneratedRegex("\n{3,}")]
+    private static partial Regex MultipleNewlinesRegex();
+
+    [GeneratedRegex("</?[a-z][^>]*>")]
+    private static partial Regex HtmlTagCountRegex();
     public static string StripRichHtml(string content)
     {
         if (string.IsNullOrWhiteSpace(content))
@@ -13,21 +48,21 @@ public static class HtmlSanitizer
             return content;
 
         var text = content.Replace("\r\n", "\n").Replace("\r", "\n");
-        text = Regex.Replace(text, "<(script|style)\\b[^>]*>.*?</\\1>", "", RegexOptions.IgnoreCase | RegexOptions.Singleline);
+        text = ScriptStyleRegex().Replace(text, "");
-        text = Regex.Replace(text, "<br\\s*/?>", "\n", RegexOptions.IgnoreCase);
+        text = BrTagRegex().Replace(text, "\n");
-        text = Regex.Replace(text, "</(p|div|h[1-6]|tr|table|ul|ol|blockquote)>", "\n", RegexOptions.IgnoreCase);
+        text = BlockEndTagRegex().Replace(text, "\n");
-        text = Regex.Replace(text, "<li\\b[^>]*>", "\n- ", RegexOptions.IgnoreCase);
+        text = LiStartTagRegex().Replace(text, "\n- ");
-        text = Regex.Replace(text, "</li>", "\n", RegexOptions.IgnoreCase);
+        text = LiEndTagRegex().Replace(text, "\n");
-        text = Regex.Replace(text, "<(td|th)\\b[^>]*>", " | ", RegexOptions.IgnoreCase);
+        text = CellStartTagRegex().Replace(text, " | ");
-        text = Regex.Replace(text, "</(td|th)>", " ", RegexOptions.IgnoreCase);
+        text = CellEndTagRegex().Replace(text, " ");
-        text = Regex.Replace(text, "<hr\\b[^>]*>", "\n---\n", RegexOptions.IgnoreCase);
+        text = HrTagRegex().Replace(text, "\n---\n");
-        text = Regex.Replace(text, "<[^>]+>", "", RegexOptions.Singleline);
+        text = AllTagsRegex().Replace(text, "");
         text = WebUtility.HtmlDecode(text)
             .Replace('\u00a0', ' ')
             .Replace("\u200b", "", StringComparison.Ordinal);
         text = string.Join("\n", text.Split('\n').Select(line => line.TrimEnd()));
-        text = Regex.Replace(text, "[ \\t]{2,}", " ");
+        text = MultipleSpacesRegex().Replace(text, " ");
-        text = Regex.Replace(text, "\n{3,}", "\n\n").Trim();
+        text = MultipleNewlinesRegex().Replace(text, "\n\n").Trim();
         return string.IsNullOrEmpty(text) ? content : text;
     }
 
@@ -41,6 +76,6 @@ public static class HtmlSanitizer
         ];
         if (markers.Any(marker => lowered.Contains(marker, StringComparison.Ordinal)))
             return true;
-        return Regex.Matches(lowered, "</?[a-z][^>]*>").Count >= 8;
+        return HtmlTagCountRegex().Matches(lowered).Count >= 8;
     }
 }

REFACTORING_SUMMARY.md

@@ -9,7 +9,7 @@
 Removed all business logic, HTML processing, logging implementation, and private record types. `Entry` now only parses the incoming JSON command, routes to the correct service, and returns the `{ok, data}` / `{ok: false, error}` envelope.
 
 ### 2. Extracted `HtmlSanitizer` (new file)
-`StripRichHtml` and `LooksLikeRichHtml` moved from `Entry.cs` to `Services/HtmlSanitizer.cs` as a static utility class.
+`StripRichHtml` and `LooksLikeRichHtml` moved from `Entry.cs` to `Services/Entries/HtmlSanitizer.cs` as a static utility class. Refactored to use `[GeneratedRegex]` attributes for compile-time regex generation, improving performance by eliminating runtime regex compilation overhead.
 
 ### 3. Extracted `CommandLogger` (new file)
 `LogStart`, `LogSuccess`, `LogFailure`, `EmitLog`, `ShouldLog`, and `LogLevelRank` moved from `Entry.cs` to `Services/CommandLogger.cs`. Entry now receives this as a dependency.