feat: implement data migration service to convert ANSI escape codes to printable color tags

src/EchoHub.Client/UI/ChatRenderer.cs

@@ -90,22 +90,17 @@ public partial class ChatLine
     }
 
     /// <summary>
-    /// Returns true if a line contains color tags (new format or legacy ANSI).
+    /// Returns true if a line contains printable color tags.
     /// </summary>
     public static bool HasColorTags(string text) =>
-        text.Contains("{F:") || text.Contains("{B:") || text.Contains("{X}") || text.Contains('\x1b');
+        text.Contains("{F:") || text.Contains("{B:") || text.Contains("{X}");
 
     /// <summary>
-    /// Parse a string containing color tags into colored segments.
-    /// Supports the new printable format ({F:RRGGBB}, {B:RRGGBB}, {X})
-    /// and legacy ANSI format (\x1b[38;2;R;G;Bm, \x1b[48;2;R;G;Bm, \x1b[0m).
+    /// Parse a string containing printable color tags into colored segments.
+    /// Format: {F:RRGGBB} (foreground), {B:RRGGBB} (background), {X} (reset).
     /// </summary>
     public static ChatLine FromColoredText(string text, Attribute? defaultAttr = null)
     {
-        // Detect which format is used and pick the right regex
-        var regex = text.Contains('\x1b') ? AnsiColorRegex() : ColorTagRegex();
-        bool isAnsi = text.Contains('\x1b');
-
         var segments = new List<ChatSegment>();
         int lastIndex = 0;
         Color? currentFg = null;
@@ -121,7 +116,7 @@ public partial class ChatLine
             return new Attribute(fg, bg);
         }
 
-        foreach (Match match in regex.Matches(text))
+        foreach (Match match in ColorTagRegex().Matches(text))
         {
             if (match.Index > lastIndex)
             {
@@ -130,46 +125,23 @@ public partial class ChatLine
                     segments.Add(new ChatSegment(t, BuildAttr()));
             }
 
-            if (isAnsi)
-            {
-                // Legacy ANSI format
-                if (match.Groups[1].Value == "0")
-                {
-                    currentFg = null;
-                    currentBg = null;
-                }
-                else if (match.Groups[2].Success)
-                {
-                    var r = int.Parse(match.Groups[3].Value);
-                    var g = int.Parse(match.Groups[4].Value);
-                    var b = int.Parse(match.Groups[5].Value);
-                    if (match.Groups[2].Value == "38;2")
-                        currentFg = new Color(r, g, b);
-                    else
-                        currentBg = new Color(r, g, b);
-                }
-            }
-            else
-            {
-                // New printable tag format: {F:RRGGBB}, {B:RRGGBB}, {X}
-                if (match.Groups[6].Success)
+            if (match.Groups[1].Success)
             {
                 // Reset {X}
                 currentFg = null;
                 currentBg = null;
             }
-                else if (match.Groups[7].Success)
+            else if (match.Groups[2].Success)
             {
-                    var hex = match.Groups[8].Value;
+                var hex = match.Groups[3].Value;
                 var r = Convert.ToInt32(hex[..2], 16);
                 var g = Convert.ToInt32(hex[2..4], 16);
                 var b = Convert.ToInt32(hex[4..6], 16);
-                    if (match.Groups[7].Value == "F")
+                if (match.Groups[2].Value == "F")
                     currentFg = new Color(r, g, b);
                 else
                     currentBg = new Color(r, g, b);
             }
-            }
 
             lastIndex = match.Index + match.Length;
         }
@@ -184,11 +156,7 @@ public partial class ChatLine
         return segments.Count > 0 ? new ChatLine(segments) : new ChatLine("");
     }
 
-    // Legacy: \x1b[0m, \x1b[38;2;R;G;Bm, \x1b[48;2;R;G;Bm
-    [GeneratedRegex(@"\x1b\[(?:(0)|(?:(38;2|48;2);(\d{1,3});(\d{1,3});(\d{1,3})))m")]
-    private static partial Regex AnsiColorRegex();
-
-    // New: {X} (reset), {F:RRGGBB} (foreground), {B:RRGGBB} (background)
+    // {X} (reset), {F:RRGGBB} (foreground), {B:RRGGBB} (background)
     [GeneratedRegex(@"\{(?:(X)|(?:(F|B):([0-9A-Fa-f]{6})))\}")]
     private static partial Regex ColorTagRegex();
 }

src/EchoHub.Server/Setup/DataMigrationService.cs

@@ -0,0 +1,78 @@
+using System.Text.RegularExpressions;
+using EchoHub.Server.Data;
+using Microsoft.EntityFrameworkCore;
+
+namespace EchoHub.Server.Setup;
+
+public static partial class DataMigrationService
+{
+    public static async Task RunAsync(IServiceProvider services)
+    {
+        using var scope = services.CreateScope();
+        var db = scope.ServiceProvider.GetRequiredService<EchoHubDbContext>();
+        var logger = scope.ServiceProvider.GetRequiredService<ILoggerFactory>()
+            .CreateLogger("EchoHub.Server.Setup.DataMigration");
+
+        await MigrateAnsiMessagesAsync(db, logger);
+    }
+
+    private static async Task MigrateAnsiMessagesAsync(EchoHubDbContext db, ILogger logger)
+    {
+        // Load messages that contain the ESC byte (0x1B) — these have legacy ANSI color codes.
+        // Filter by Image type first (only images have ANSI art), then check content in memory.
+        var messages = await db.Messages
+            .Where(m => m.Type == Core.Models.MessageType.Image)
+            .ToListAsync();
+
+        var toMigrate = messages.Where(m => m.Content.Contains('\x1b')).ToList();
+
+        if (toMigrate.Count == 0)
+            return;
+
+        logger.LogInformation("Found {Count} messages with legacy ANSI color codes. Migrating to color tag format...", toMigrate.Count);
+
+        var modified = 0;
+        foreach (var message in toMigrate)
+        {
+            var converted = AnsiToColorTags(message.Content);
+            if (converted != message.Content)
+            {
+                message.Content = converted;
+                modified++;
+            }
+        }
+
+        if (modified > 0)
+        {
+            await db.SaveChangesAsync();
+            logger.LogInformation("Migrated {Count} messages from ANSI escape codes to printable color tags.", modified);
+        }
+    }
+
+    /// <summary>
+    /// Convert ANSI escape codes to printable color tags.
+    /// \x1b[38;2;R;G;Bm → {F:RRGGBB}, \x1b[48;2;R;G;Bm → {B:RRGGBB}, \x1b[0m → {X}
+    /// </summary>
+    public static string AnsiToColorTags(string text)
+    {
+        return AnsiColorRegex().Replace(text, match =>
+        {
+            if (match.Groups[1].Value == "0")
+                return "{X}";
+
+            if (match.Groups[2].Success)
+            {
+                var r = int.Parse(match.Groups[3].Value);
+                var g = int.Parse(match.Groups[4].Value);
+                var b = int.Parse(match.Groups[5].Value);
+                var type = match.Groups[2].Value == "38;2" ? "F" : "B";
+                return $"{{{type}:{r:X2}{g:X2}{b:X2}}}";
+            }
+
+            return match.Value;
+        });
+    }
+
+    [GeneratedRegex(@"\x1b\[(?:(0)|(?:(38;2|48;2);(\d{1,3});(\d{1,3});(\d{1,3})))m")]
+    private static partial Regex AnsiColorRegex();
+}

src/EchoHub.Server/Setup/DatabaseSetup.cs

@@ -16,6 +16,9 @@ public static class DatabaseSetup
 
         await MigrateAsync(db, logger);
         await SeedDefaultChannelAsync(db, logger);
+
+        // Run data migrations (e.g. ANSI → color tag format)
+        await DataMigrationService.RunAsync(services);
     }
 
     private static async Task MigrateAsync(EchoHubDbContext db, ILogger logger)