Merge pull request #579 from Chris0Jeky/enhance/571-intent-classifier-nlp

Improve LlmIntentClassifier NLP coverage

Author: Chris0Jeky

backend/src/Taskdeck.Application/Services/LlmIntentClassifier.cs

@@ -1,43 +1,219 @@
+using System.Text.RegularExpressions;
+
 namespace Taskdeck.Application.Services;
 
 public static class LlmIntentClassifier
 {
+    // Timeout to prevent catastrophic backtracking
+    private static readonly TimeSpan RegexTimeout = TimeSpan.FromMilliseconds(100);
+
+    // Negative context patterns — suppress matches in these contexts
+    private static readonly Regex NegationPattern = new(
+        @"\b(don'?t|do not|never|stop|cancel|undo|avoid)\b(\s+\w+){0,6}\s+\b(create|add|make|move|archive|delete|remove|update|edit|rename|generate|build|set up|prepare)\b",
+        RegexOptions.Compiled | RegexOptions.IgnoreCase,
+        RegexTimeout);
+
+    private static readonly Regex OtherToolPattern = new(
+        @"\b(in|for|with|using|on)\s+(jira|trello|asana|notion|monday|clickup|linear|github issues|azure devops)\b",
+        RegexOptions.Compiled | RegexOptions.IgnoreCase,
+        RegexTimeout);
+
+    private static readonly Regex QuestionAboutHowPattern = new(
+        @"^\s*(how|what|where|when|why|can\s+i|is\s+it)\b.*\?$",
+        RegexOptions.Compiled | RegexOptions.IgnoreCase,
+        RegexTimeout);
+
+    // Card creation — verbs followed by optional words then card/task nouns
+    private static readonly Regex CardCreatePattern = new(
+        @"\b(create|add|make|generate|build|prepare|set\s+up)\b(\s+\w+){0,5}\s+\b(cards?|tasks?|items?)\b",
+        RegexOptions.Compiled | RegexOptions.IgnoreCase,
+        RegexTimeout);
+
+    // "new card/task" with optional words between
+    private static readonly Regex NewCardPattern = new(
+        @"\b(new)\b(\s+\w+){0,4}\s+\b(cards?|tasks?|items?)\b",
+        RegexOptions.Compiled | RegexOptions.IgnoreCase,
+        RegexTimeout);
+
+    // Card move — "move" + optional words + "card/task"
+    private static readonly Regex CardMovePattern = new(
+        @"\bmove\b(\s+\w+){0,4}\s+\b(cards?|tasks?)\b",
+        RegexOptions.Compiled | RegexOptions.IgnoreCase,
+        RegexTimeout);
+
+    // Card archive — "archive/delete/remove" + optional words + "card/task"
+    private static readonly Regex CardArchivePattern = new(
+        @"\b(archive|delete|remove)\b(\s+\w+){0,4}\s+\b(cards?|tasks?)\b",
+        RegexOptions.Compiled | RegexOptions.IgnoreCase,
+        RegexTimeout);
+
+    // Card update — "update/edit/rename" + optional words + "card/task"
+    private static readonly Regex CardUpdatePattern = new(
+        @"\b(update|edit|rename|modify|change)\b(\s+\w+){0,4}\s+\b(cards?|tasks?)\b",
+        RegexOptions.Compiled | RegexOptions.IgnoreCase,
+        RegexTimeout);
+
+    // Board creation — verbs + optional words + "board"
+    private static readonly Regex BoardCreatePattern = new(
+        @"\b(create|add|make|generate|build|prepare|set\s+up|new)\b(\s+\w+){0,4}\s+\b(boards?|project\s+boards?)\b",
+        RegexOptions.Compiled | RegexOptions.IgnoreCase,
+        RegexTimeout);
+
+    // Board rename
+    private static readonly Regex BoardRenamePattern = new(
+        @"\b(rename|update|edit)\b(\s+\w+){0,4}\s+\bboards?\b",
+        RegexOptions.Compiled | RegexOptions.IgnoreCase,
+        RegexTimeout);
+
+    // Column reorder / sort
+    private static readonly Regex ReorderPattern = new(
+        @"\b(reorder|sort|rearrange|reorganize)\b(\s+\w+){0,4}\s+\b(cards?|columns?|boards?)\b",
+        RegexOptions.Compiled | RegexOptions.IgnoreCase,
+        RegexTimeout);
+
     public static (bool IsActionable, string? ActionIntent) Classify(string message)
     {
         if (string.IsNullOrWhiteSpace(message))
             return (false, null);
 
         var lower = message.ToLowerInvariant();
 
-        // Card creation — explicit commands and natural language
-        if (lower.Contains("create card") || lower.Contains("add card")
-            || lower.Contains("create a card") || lower.Contains("add a card")
-            || lower.Contains("create task") || lower.Contains("add task")
-            || lower.Contains("create a task") || lower.Contains("add a task")
-            || lower.Contains("new card") || lower.Contains("new task")
-            || lower.Contains("make a card") || lower.Contains("make a task")
-            || lower.Contains("make card") || lower.Contains("make task"))
-            return (true, "card.create");
+        // Check negative context first — suppress if negated or about another tool
+        if (IsNegativeContext(lower, message))
+            return (false, null);
 
-        if (lower.Contains("move card"))
-            return (true, "card.move");
-        if (lower.Contains("archive card") || lower.Contains("delete card")
-            || lower.Contains("remove card"))
+        // Archive/delete/remove must be checked BEFORE move to fix the
+        // "remove card" substring bug (remove contains "move")
+        if (MatchesCardArchive(lower))
             return (true, "card.archive");
-        if (lower.Contains("update card") || lower.Contains("edit card")
-            || lower.Contains("rename card"))
+
+        if (MatchesCardMove(lower))
+            return (true, "card.move");
+
+        if (MatchesCardUpdate(lower))
             return (true, "card.update");
-        if (lower.Contains("create board") || lower.Contains("add board")
-            || lower.Contains("new board"))
+
+        if (MatchesCardCreate(lower))
+            return (true, "card.create");
+
+        if (MatchesBoardCreate(lower))
             return (true, "board.create");
-        if (lower.Contains("rename board"))
+
+        if (MatchesBoardRename(lower))
             return (true, "board.update");
-        if (lower.Contains("reorder cards") || lower.Contains("reorder column")
-            || lower.Contains("reorder columns") || lower.Contains("reorder board")
-            || lower.Contains("sort cards") || lower.Contains("sort column")
-            || lower.Contains("sort columns") || lower.Contains("sort board"))
+
+        if (MatchesReorder(lower))
             return (true, "column.reorder");
 
         return (false, null);
     }
+
+    private static bool IsNegativeContext(string lower, string original)
+    {
+        try
+        {
+            // Negation: "don't create task yet"
+            if (NegationPattern.IsMatch(lower))
+                return true;
+
+            // Asking about another tool: "how do I create a card in Jira?"
+            if (OtherToolPattern.IsMatch(lower) && QuestionAboutHowPattern.IsMatch(original.Trim()))
+                return true;
+        }
+        catch (RegexMatchTimeoutException)
+        {
+            // On timeout, fall through to normal classification
+        }
+
+        return false;
+    }
+
+    private static bool MatchesCardCreate(string lower)
+    {
+        try
+        {
+            if (CardCreatePattern.IsMatch(lower))
+                return true;
+            if (NewCardPattern.IsMatch(lower))
+                return true;
+        }
+        catch (RegexMatchTimeoutException)
+        {
+            // Fall through — don't match on timeout
+        }
+
+        return false;
+    }
+
+    private static bool MatchesCardMove(string lower)
+    {
+        try
+        {
+            if (CardMovePattern.IsMatch(lower))
+                return true;
+        }
+        catch (RegexMatchTimeoutException) { }
+
+        return false;
+    }
+
+    private static bool MatchesCardArchive(string lower)
+    {
+        try
+        {
+            if (CardArchivePattern.IsMatch(lower))
+                return true;
+        }
+        catch (RegexMatchTimeoutException) { }
+
+        return false;
+    }
+
+    private static bool MatchesCardUpdate(string lower)
+    {
+        try
+        {
+            if (CardUpdatePattern.IsMatch(lower))
+                return true;
+        }
+        catch (RegexMatchTimeoutException) { }
+
+        return false;
+    }
+
+    private static bool MatchesBoardCreate(string lower)
+    {
+        try
+        {
+            if (BoardCreatePattern.IsMatch(lower))
+                return true;
+        }
+        catch (RegexMatchTimeoutException) { }
+
+        return false;
+    }
+
+    private static bool MatchesBoardRename(string lower)
+    {
+        try
+        {
+            if (BoardRenamePattern.IsMatch(lower))
+                return true;
+        }
+        catch (RegexMatchTimeoutException) { }
+
+        return false;
+    }
+
+    private static bool MatchesReorder(string lower)
+    {
+        try
+        {
+            if (ReorderPattern.IsMatch(lower))
+                return true;
+        }
+        catch (RegexMatchTimeoutException) { }
+
+        return false;
+    }
 }