feat(chat): CT-A5 — clicking a speaker's name opens a tell

Campaign CT slice A5, closing Group A. Retail's
gmMainChatUI::RecvNotice_TextTag_IIDStringClick @0x004CCE10 ->
ChatInterface::StartTell @0x004F41F0 writes "@tell {Name}, " into the chat
entry and takes keyboard focus; clicking a green name here now does the same.

The trailing space is deliberate — without it the first character the player
types joins the comma.

Three seams, each narrow on purpose:

  - UiText.OnCharClick is offered the character under a left click before the
    element-wide OnClick, and consuming it suppresses that. Kept separate
    because a tag click is POSITIONAL and an element click is not; folding
    them together would make every text element with an OnClick swallow tag
    clicks.
  - TaggedRangesForFragment returns tagged column ranges relative to the
    FRAGMENT, because that is what a click resolves to — UiText.HitChar gives
    a line index into the WRAPPED list plus a column within it. Line-relative
    ranges would land every click on a wrapped line at the wrong characters.
  - The controller caches those ranges alongside the runs it already caches,
    so the per-click lookup reads the same cache the draw does.

The hit test is half-open: a caret slot sits BETWEEN glyphs, so clicking just
past a name's last letter belongs to the space after it, not the name. Pinned
by theory rather than left to chance, since off-by-one here means clicking a
name sometimes does nothing.

StartTell uses the tag's NAME, not its object id — retail carries the id but
this handler never reads it, so the tell still addresses correctly for someone
who has since moved out of range.

Group A is complete: names are green (A4) and clickable (A5). Ready for the
user's visual gate.

Solution builds clean; full hermetic gate green.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/AcDream.App/UI/Layout/ChatTranscriptRenderer.cs

@@ -114,6 +114,45 @@ internal static class ChatTranscriptRenderer
         return sawTag ? runs : null;
     }
 
+    /// <summary>
+    /// The tagged column ranges inside one wrapped fragment, or
+    /// <see langword="null"/> when it holds none.
+    /// </summary>
+    /// <remarks>
+    /// Columns are relative to the FRAGMENT, because that is what a click
+    /// resolves to: <c>UiText.HitChar</c> returns a line index into the
+    /// wrapped list plus a column within that line.
+    /// </remarks>
+    internal static IReadOnlyList<(int Start, int Length, ChatTextTag Tag)>?
+        TaggedRangesForFragment(
+            IReadOnlyList<ChatTextSpan> spans,
+            int fragmentStart,
+            int fragmentLength)
+    {
+        int fragmentEnd = fragmentStart + fragmentLength;
+        List<(int Start, int Length, ChatTextTag Tag)>? ranges = null;
+        int at = 0;
+
+        foreach (ChatTextSpan span in spans)
+        {
+            int spanStart = at;
+            int spanEnd = at + span.Text.Length;
+            at = spanEnd;
+
+            if (span.Tag is not { } tag)
+                continue;
+
+            int from = Math.Max(spanStart, fragmentStart);
+            int to = Math.Min(spanEnd, fragmentEnd);
+            if (to <= from)
+                continue;
+
+            (ranges ??= new()).Add((from - fragmentStart, to - from, tag));
+        }
+
+        return ranges;
+    }
+
     public static List<UiText.Line> BuildLines(
         IReadOnlyList<FormattedLine> detailed,
         float maxW,
@@ -121,10 +160,12 @@ internal static class ChatTranscriptRenderer
         Func<uint, bool>? accept,
         Vector4 defaultColor,
         Vector4? tagColor = null,
-        List<IReadOnlyList<UiText.TextRun>?>? runsPerLine = null)
+        List<IReadOnlyList<UiText.TextRun>?>? runsPerLine = null,
+        List<IReadOnlyList<(int Start, int Length, ChatTextTag Tag)>?>? tagsPerLine = null)
     {
         var result = new List<UiText.Line>(detailed.Count);
         runsPerLine?.Clear();
+        tagsPerLine?.Clear();
         if (detailed.Count == 0)
             return result;
 
@@ -149,12 +190,13 @@ internal static class ChatTranscriptRenderer
             {
                 result.Add(new UiText.Line(frag, currentColor));
 
-                if (runsPerLine is null)
+                if (runsPerLine is null && tagsPerLine is null)
                     continue;
 
                 if (d.Spans is not { Count: > 0 } spans || frag.Length == 0)
                 {
-                    runsPerLine.Add(null);
+                    runsPerLine?.Add(null);
+                    tagsPerLine?.Add(null);
                     continue;
                 }
 
@@ -163,17 +205,19 @@ internal static class ChatTranscriptRenderer
                 {
                     // Should not happen; a fragment always comes from the line.
                     // Fall back to the flat colour rather than mis-colouring.
-                    runsPerLine.Add(null);
+                    runsPerLine?.Add(null);
+                    tagsPerLine?.Add(null);
                     continue;
                 }
                 searchFrom = at + frag.Length;
 
-                runsPerLine.Add(RunsForFragment(
+                runsPerLine?.Add(RunsForFragment(
                     spans,
                     at,
                     frag.Length,
                     currentColor,
                     tagColor ?? currentColor));
+                tagsPerLine?.Add(TaggedRangesForFragment(spans, at, frag.Length));
             }
         }
         return result;