Merge branch 'claudedo/c1d2a92d8d8c4705ac93d5f0b2cacaa0'

src/ClaudeDo.Worker/External/ExternalMcpService.cs

@@ -1,5 +1,8 @@
 using System.ComponentModel;
 using System.Diagnostics;
+using System.Globalization;
+using System.Text;
+using System.Text.RegularExpressions;
 using ClaudeDo.Data;
 using ClaudeDo.Data.Git;
 using ClaudeDo.Data.Models;
@@ -56,6 +59,12 @@ public sealed record ListTasksResult(
     IReadOnlyList<TaskRefDto>? Tasks,
     IReadOnlyList<TaskDto>? TasksFull);
 
+// Deliberately small: no descriptions, capped candidate count (see AddTask's duplicate check).
+public sealed record PossibleDuplicateDto(string TaskId, string Title, string Status);
+
+public sealed record AddTaskResult(TaskRefDto Task, IReadOnlyList<PossibleDuplicateDto> PossibleDuplicates);
+
+
 public sealed record WorktreeInfoDto(
     string Path, string Branch, string HeadCommit, string BaseCommit,
     int Ahead, int Behind, bool IsDirty, string? MergeCommit = null);
@@ -209,8 +218,12 @@ public sealed class ExternalMcpService
         "Set model to the cheapest model that can do the task well — 'haiku' for trivial/mechanical work, " +
         "'sonnet' for normal coding (the default), 'opus' only for complex or cross-cutting work. " +
         "Leave model null to inherit the list/global default. " +
-        "Returns a lean task reference (id, listId, title, status, sortOrder, isMyDay) — not the description you just sent.")]
-    public async Task<TaskRefDto> AddTask(
+        "Returns { task, possibleDuplicates }: task is a lean reference (id, listId, title, status, " +
+        "sortOrder, isMyDay) — not the description you just sent. The task is always created — " +
+        "possibleDuplicates is a non-blocking heads-up (up to 3 open tasks in the same list with a " +
+        "strongly overlapping title, id/title/status only); check it and mention any hit to the caller, " +
+        "but do not treat it as an error.")]
+    public async Task<AddTaskResult> AddTask(
         string listId,
         string title,
         string? description = null,
@@ -227,6 +240,8 @@ public sealed class ExternalMcpService
         var list = await _lists.GetByIdAsync(listId, cancellationToken)
             ?? throw new InvalidOperationException($"List {listId} not found.");
 
+        var possibleDuplicates = await FindPossibleDuplicatesAsync(listId, title, cancellationToken);
+
         var entity = new TaskEntity
         {
             Id = Guid.NewGuid().ToString(),
@@ -252,7 +267,77 @@ public sealed class ExternalMcpService
         }
 
         await _broadcaster.TaskUpdated(entity.Id);
-        return ToRefDto(entity);
+        return new AddTaskResult(ToRefDto(entity), possibleDuplicates);
+    }
+
+    // Non-terminal: a task still open enough that a new, similarly-titled task might be a duplicate
+    // of it. Done/Failed/Cancelled tasks are retired and never flagged.
+    private static readonly TaskStatus[] NonTerminalStatuses =
+    [
+        TaskStatus.Idle, TaskStatus.Queued, TaskStatus.Running,
+        TaskStatus.WaitingForChildren, TaskStatus.WaitingForReview,
+    ];
+
+    private const int MaxPossibleDuplicates = 3;
+
+    // Cheap, dependency-free "near-duplicate title" heuristic — no embeddings, no LLM call, just a
+    // normalized-word overlap coefficient (shared significant words / smaller word-set size, not
+    // Jaccard). Overlap-coefficient beats Jaccard here because titles in this project vary wildly in
+    // length (a terse one-liner vs. a fully-spelled-out German sentence) — dividing by the union
+    // would wash out a real match against a longer title. Threshold tuned against the pair that
+    // motivated this check: "MaxTurnsCeiling ohne Bedienoberflaeche im Settings-Modal" vs.
+    // "Settings: MaxTurnsCeiling editierbar machen" (>=2 shared significant words, >=50% overlap of
+    // the shorter title's words) without over-firing on titles that merely share one generic word.
+    private async Task<IReadOnlyList<PossibleDuplicateDto>> FindPossibleDuplicatesAsync(
+        string listId, string title, CancellationToken ct)
+    {
+        var newWords = NormalizeTitleWords(title);
+        if (newWords.Count == 0) return [];
+
+        var candidates = await _tasks.GetByListIdAsync(listId, ct);
+
+        return candidates
+            .Where(t => NonTerminalStatuses.Contains(t.Status))
+            .Select(t => (Task: t, Words: NormalizeTitleWords(t.Title)))
+            .Select(x => (x.Task, Shared: newWords.Count(x.Words.Contains), x.Words))
+            .Where(x => x.Shared >= 2 && x.Words.Count > 0
+                        && (double)x.Shared / Math.Min(newWords.Count, x.Words.Count) >= 0.5)
+            .OrderByDescending(x => (double)x.Shared / Math.Min(newWords.Count, x.Words.Count))
+            .ThenByDescending(x => x.Shared)
+            .Take(MaxPossibleDuplicates)
+            .Select(x => new PossibleDuplicateDto(x.Task.Id, x.Task.Title, x.Task.Status.ToString()))
+            .ToList();
+    }
+
+    private static readonly Regex NonWordChars = new(@"[^a-z0-9]+", RegexOptions.Compiled);
+
+    // Common structural filler that would otherwise dominate the overlap score across most titles
+    // in this project's lists without indicating a real duplicate (German articles/prepositions
+    // plus the recurring "mcp"/"task(s)"/"cleanup" nouns called out in the task write-up).
+    private static readonly HashSet<string> TitleStopWords = new(StringComparer.Ordinal)
+    {
+        "der", "die", "das", "und", "von", "auf", "mit", "fur", "ein", "eine",
+        "ist", "sind", "oder", "nicht", "mcp", "task", "tasks", "cleanup",
+    };
+
+    // Lowercases, transliterates German umlauts/ß to their digraph spelling (ä→ae, ß→ss, ...) so
+    // "Prüfung" and "Pruefung" normalize to the same token, strips remaining diacritics/punctuation,
+    // then drops short (<3 char) and stopword tokens.
+    private static HashSet<string> NormalizeTitleWords(string title)
+    {
+        var s = title.ToLowerInvariant()
+            .Replace("ä", "ae").Replace("ö", "oe").Replace("ü", "ue").Replace("ß", "ss");
+        s = s.Normalize(NormalizationForm.FormD);
+
+        var sb = new StringBuilder(s.Length);
+        foreach (var ch in s)
+            if (CharUnicodeInfo.GetUnicodeCategory(ch) != UnicodeCategory.NonSpacingMark)
+                sb.Append(ch);
+
+        var ascii = NonWordChars.Replace(sb.ToString(), " ");
+        return ascii.Split(' ', StringSplitOptions.RemoveEmptyEntries)
+            .Where(w => w.Length >= 3 && !TitleStopWords.Contains(w))
+            .ToHashSet(StringComparer.Ordinal);
     }
 
     [McpServerTool, Description(