made the chunking process more robust

app/MindWork AI Studio/Components/ChatComponent.razor.cs

@@ -1121,16 +1121,7 @@ public partial class ChatComponent : MSGComponentBase, IAsyncDisposable
             return;
         }
 
-        var tokenizerResponse = await this.RustService.EnsureTokenizer(this.Provider.InstanceName, this.Provider.TokenizerPath);
+        var response = await this.RustService.GetTokenCount(this.Provider.InstanceName, this.Provider.TokenizerPath, this.inputField.Value);
-        if (tokenizerResponse is null)
-            return;
-        if (!tokenizerResponse.Value.Success)
-        {
-            this.Logger.LogWarning($"Failed to initialize the tokenizer for the provider: status='{tokenizerResponse.Value.Status}', reason='{tokenizerResponse.Value.Message}'");
-            return;
-        }
-
-        var response = await this.RustService.GetTokenCount(this.inputField.Value);
         if (response is null)
             return;
         if (!response.Value.Success)

app/MindWork AI Studio/Components/Settings/SettingsPanelEmbeddings.razor.cs

@@ -80,6 +80,7 @@ public partial class SettingsPanelEmbeddings : SettingsPanelProviderBase
             { x => x.IsEditing, true },
             { x => x.DataHost, embeddingProvider.Host },
             { x => x.DataTokenizerPath, embeddingProvider.TokenizerPath },
+            { x => x.DataTokenLimit, embeddingProvider.EffectiveTokenLimit },
         };
 
         var dialogReference = await this.DialogService.ShowAsync<EmbeddingProviderDialog>(T("Edit Embedding Provider"), dialogParameters, DialogOptions.FULLSCREEN);

app/MindWork AI Studio/Dialogs/EmbeddingProviderDialog.razor

@@ -128,6 +128,18 @@
                 <MudJustifiedText Typo="Typo.body1" Class="mb-3">
                     @T("For better embeddings and less storage usage, it's recommended to use a custom tokenizer to enable a more accurate token count.")
                 </MudJustifiedText>
+                <MudNumericField
+                    T="int"
+                    @bind-Value="@this.DataTokenLimit"
+                    Label="@T("Token limit")"
+                    Class="mb-3"
+                    Min="1"
+                    Immediate="@true"
+                    Adornment="Adornment.Start"
+                    AdornmentIcon="@Icons.Material.Filled.Numbers"
+                    AdornmentColor="Color.Info"
+                    Validation="@this.ValidateTokenLimit"
+                    HelperText="@T("Maximum number of tokens sent to the embedding model per chunk.")"/>
                 <SelectFile 
                     File="@this.dataFilePath" 
                     FileChanged="@this.OnDataFilePathChanged" 

app/MindWork AI Studio/Dialogs/EmbeddingProviderDialog.razor.cs

@@ -74,6 +74,9 @@ public partial class EmbeddingProviderDialog : MSGComponentBase, ISecretId
     [Parameter]
     public string DataTokenizerPath { get; set; } = string.Empty;
 
+    [Parameter]
+    public int DataTokenLimit { get; set; } = EmbeddingProvider.DEFAULT_TOKEN_LIMIT;
+    
     [Inject]
     private RustService RustService { get; init; } = null!;
 
@@ -148,6 +151,7 @@ public partial class EmbeddingProviderDialog : MSGComponentBase, ISecretId
             IsEnterpriseConfiguration = false,
             EnterpriseConfigurationPluginId = Guid.Empty,
             TokenizerPath = this.dataFilePath,
+            TokenLimit = this.DataTokenLimit,
         };
     }
     
@@ -277,6 +281,14 @@ public partial class EmbeddingProviderDialog : MSGComponentBase, ISecretId
         return null;
     }
 
+    private string? ValidateTokenLimit(int tokenLimit)
+    {
+        if (tokenLimit < 1)
+            return T("Please enter a token limit greater than 0.");
+
+        return null;
+    }
+
     private void Cancel() => this.MudDialog.Cancel();
 
     private async Task OnAPIKeyChanged(string apiKey)

app/MindWork AI Studio/Plugins/configuration/plugin.lua

@@ -136,6 +136,9 @@ CONFIG["EMBEDDING_PROVIDERS"] = {}
 --     -- Optional: tokenizer path for this provider relative to the plugin directory.
 --     -- ["TokenizerPath"] = "",
 --
+--     -- Optional: maximum number of tokens per embedding chunk. If omitted, AI Studio uses its default.
+--     -- ["TokenLimit"] = 8191,
+--
 --     ["Model"] = {
 --         ["Id"] = "<the model ID, e.g., nomic-embed-text>",
 --         ["DisplayName"] = "<user-friendly name of the model>",

app/MindWork AI Studio/Settings/EmbeddingProvider.cs

@@ -21,8 +21,11 @@ public sealed record EmbeddingProvider(
     Guid EnterpriseConfigurationPluginId = default,
     string Hostname = "http://localhost:1234",
     Host Host = Host.NONE,
-    string TokenizerPath = "") : ConfigurationBaseObject, ISecretId
+    string TokenizerPath = "",
+    int TokenLimit = 8_191) : ConfigurationBaseObject, ISecretId
 {
+    public const int DEFAULT_TOKEN_LIMIT = 8_191;
+
     private static readonly ILogger<EmbeddingProvider> LOGGER = Program.LOGGER_FACTORY.CreateLogger<EmbeddingProvider>();
 
     public static readonly EmbeddingProvider NONE = new();
@@ -51,6 +54,9 @@ public sealed record EmbeddingProvider(
     [JsonIgnore]
     public string SecretName => this.Name;
 
+    [JsonIgnore]
+    public int EffectiveTokenLimit => this.TokenLimit > 0 ? this.TokenLimit : DEFAULT_TOKEN_LIMIT;
+
     #endregion
 
     public static bool TryParseEmbeddingProviderTable(int idx, LuaTable table, Guid configPluginId, out ConfigurationBaseObject provider)
@@ -105,6 +111,13 @@ public sealed record EmbeddingProvider(
             tokenizerPath = string.Empty;
         }
 
+        var tokenLimit = DEFAULT_TOKEN_LIMIT;
+        if (table.TryGetValue("TokenLimit", out var tokenLimitValue) && (!tokenLimitValue.TryRead<int>(out tokenLimit) || tokenLimit < 1))
+        {
+            LOGGER.LogWarning($"The configured embedding provider {idx} does not contain a valid token limit. Falling back to {DEFAULT_TOKEN_LIMIT}. (Plugin ID: {configPluginId})");
+            tokenLimit = DEFAULT_TOKEN_LIMIT;
+        }
+
         provider = new EmbeddingProvider
         {
             Num = 0, // will be set later by the PluginConfigurationObject
@@ -118,6 +131,7 @@ public sealed record EmbeddingProvider(
             Hostname = hostname,
             Host = host,
             TokenizerPath = tokenizerPath,
+            TokenLimit = tokenLimit,
         };
 
         // Handle encrypted API key if present:
@@ -192,6 +206,7 @@ public sealed record EmbeddingProvider(
                     ["UsedLLMProvider"] = "{{this.UsedLLMProvider}}",
                     
                     ["TokenizerPath"] = "{{this.TokenizerPath}}",
+                    ["TokenLimit"] = {{this.EffectiveTokenLimit}},
                  
                     ["Host"] = "{{this.Host}}",
                     ["Hostname"] = "{{LuaTools.EscapeLuaString(this.Hostname)}}",

app/MindWork AI Studio/Tools/Services/DataSourceEmbeddingService.Files.cs

@@ -1,5 +1,6 @@
 using System.Security.Cryptography;
 using System.Text;
+using System.Text.RegularExpressions;
 
 using AIStudio.Settings;
 using AIStudio.Settings.DataModel;
@@ -24,11 +25,13 @@ public sealed partial class DataSourceEmbeddingService
         UNSUPPORTED,
     }
 
-    private async IAsyncEnumerable<string> StreamEmbeddingChunksAsync(string filePath, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken token)
+    private async IAsyncEnumerable<string> StreamEmbeddingChunksAsync(string filePath, EmbeddingProvider embeddingProvider, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken token)
     {
         if (this.IsImageFilePath(filePath))
         {
-            yield return this.BuildImageIndexText(filePath);
+            await foreach (var imageChunk in this.SplitChunkByEmbeddingTokenLimitAsync(this.BuildImageIndexText(filePath), embeddingProvider, token))
+                yield return imageChunk;
+
             yield break;
         }
 
@@ -46,7 +49,10 @@ public sealed partial class DataSourceEmbeddingService
                 {
                     var chunk = currentChunk.ToString().Trim();
                     if (!string.IsNullOrWhiteSpace(chunk))
-                        yield return chunk;
+                    {
+                        await foreach (var finalChunk in this.SplitChunkByEmbeddingTokenLimitAsync(chunk, embeddingProvider, token))
+                            yield return finalChunk;
+                    }
 
                     var overlap = chunk.Length > CHUNK_OVERLAP_LENGTH
                         ? chunk[^CHUNK_OVERLAP_LENGTH..]
@@ -68,7 +74,141 @@ public sealed partial class DataSourceEmbeddingService
 
         var finalChunk = currentChunk.ToString().Trim();
         if (!string.IsNullOrWhiteSpace(finalChunk))
-            yield return finalChunk;
+        {
+            await foreach (var chunk in this.SplitChunkByEmbeddingTokenLimitAsync(finalChunk, embeddingProvider, token))
+                yield return chunk;
+        }
+    }
+
+    private async IAsyncEnumerable<string> SplitChunkByEmbeddingTokenLimitAsync(string chunk, EmbeddingProvider embeddingProvider, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken token)
+    {
+        var tokenLimit = embeddingProvider.EffectiveTokenLimit;
+        var tokenCount = await this.GetEmbeddingTokenCountAsync(embeddingProvider, chunk, token);
+        if (tokenCount <= tokenLimit)
+        {
+            yield return chunk;
+            yield break;
+        }
+
+        logger.LogDebug(
+            "Splitting an embedding chunk for provider '{EmbeddingProviderName}' because it has {TokenCount} tokens and the configured limit is {TokenLimit}.",
+            embeddingProvider.Name,
+            tokenCount,
+            tokenLimit);
+
+        await foreach (var splitChunk in this.SplitTextByTokenLimitAsync(chunk, embeddingProvider, tokenLimit, token))
+            yield return splitChunk;
+    }
+
+    private async IAsyncEnumerable<string> SplitTextByTokenLimitAsync(string text, EmbeddingProvider embeddingProvider, int tokenLimit, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken token)
+    {
+        var units = SplitTextIntoTokenUnits(text);
+        var index = 0;
+
+        while (index < units.Count)
+        {
+            token.ThrowIfCancellationRequested();
+
+            var unitCount = await this.FindLargestUnitCountWithinTokenLimitAsync(units, index, embeddingProvider, tokenLimit, token);
+            if (unitCount > 0)
+            {
+                var chunk = string.Concat(units.Skip(index).Take(unitCount)).Trim();
+                if (!string.IsNullOrWhiteSpace(chunk))
+                    yield return chunk;
+
+                index += unitCount;
+                continue;
+            }
+
+            await foreach (var splitUnit in this.SplitOversizedTextUnitByTokenLimitAsync(units[index], embeddingProvider, tokenLimit, token))
+                yield return splitUnit;
+
+            index++;
+        }
+    }
+
+    private async Task<int> FindLargestUnitCountWithinTokenLimitAsync(IReadOnlyList<string> units, int startIndex, EmbeddingProvider embeddingProvider, int tokenLimit, CancellationToken token)
+    {
+        var low = 1;
+        var high = units.Count - startIndex;
+        var best = 0;
+
+        while (low <= high)
+        {
+            token.ThrowIfCancellationRequested();
+
+            var mid = low + (high - low) / 2;
+            var candidate = string.Concat(units.Skip(startIndex).Take(mid)).Trim();
+            var tokenCount = await this.GetEmbeddingTokenCountAsync(embeddingProvider, candidate, token);
+            if (tokenCount <= tokenLimit)
+            {
+                best = mid;
+                low = mid + 1;
+            }
+            else
+                high = mid - 1;
+        }
+
+        return best;
+    }
+
+    private async IAsyncEnumerable<string> SplitOversizedTextUnitByTokenLimitAsync(string text, EmbeddingProvider embeddingProvider, int tokenLimit, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken token)
+    {
+        var startIndex = 0;
+        while (startIndex < text.Length)
+        {
+            token.ThrowIfCancellationRequested();
+
+            var low = startIndex + 1;
+            var high = text.Length;
+            var bestEndIndex = startIndex;
+
+            while (low <= high)
+            {
+                var mid = low + (high - low) / 2;
+                var candidate = text[startIndex..mid].Trim();
+                var tokenCount = await this.GetEmbeddingTokenCountAsync(embeddingProvider, candidate, token);
+                if (tokenCount <= tokenLimit)
+                {
+                    bestEndIndex = mid;
+                    low = mid + 1;
+                }
+                else
+                    high = mid - 1;
+            }
+
+            if (bestEndIndex == startIndex)
+            {
+                var smallestCandidate = text[startIndex..Math.Min(startIndex + 1, text.Length)].Trim();
+                var smallestCandidateTokenCount = await this.GetEmbeddingTokenCountAsync(embeddingProvider, smallestCandidate, token);
+                throw new InvalidOperationException($"The token limit for embedding provider '{embeddingProvider.Name}' is too low. The smallest possible split still has {smallestCandidateTokenCount} tokens, but the configured limit is {tokenLimit}.");
+            }
+
+            var chunk = text[startIndex..bestEndIndex].Trim();
+            if (!string.IsNullOrWhiteSpace(chunk))
+                yield return chunk;
+
+            startIndex = bestEndIndex;
+        }
+    }
+
+    private async Task<int> GetEmbeddingTokenCountAsync(EmbeddingProvider embeddingProvider, string text, CancellationToken token)
+    {
+        var response = await rustService.GetTokenCount(embeddingProvider.Name, embeddingProvider.TokenizerPath, text, token);
+        if (response is { Success: true, Status: TokenizerStatus.AVAILABLE })
+            return response.Value.TokenCount;
+
+        var message = response?.Message ?? "No response was returned by the tokenizer service.";
+        throw new InvalidOperationException($"Could not count tokens for embedding provider '{embeddingProvider.Name}'. {message}");
+    }
+
+    private static List<string> SplitTextIntoTokenUnits(string text)
+    {
+        var matches = Regex.Matches(text, @"\S+\s*", RegexOptions.CultureInvariant);
+        if (matches.Count == 0)
+            return [text];
+
+        return matches.Cast<Match>().Select(match => match.Value).ToList();
     }
 
     private FileEnumerationResult GetInputFiles(IDataSource dataSource)
@@ -289,7 +429,8 @@ public sealed partial class DataSourceEmbeddingService
             embeddingProvider.Model.Id,
             embeddingProvider.Host,
             embeddingProvider.Hostname,
-            embeddingProvider.TokenizerPath);
+            embeddingProvider.TokenizerPath,
+            embeddingProvider.EffectiveTokenLimit);
     }
 
     private async Task<string> BuildFingerprintAsync(FileInfo file, CancellationToken token)

app/MindWork AI Studio/Tools/Services/DataSourceEmbeddingService.cs

@@ -378,7 +378,7 @@ public sealed partial class DataSourceEmbeddingService(SettingsManager settingsM
         var batch = new List<(string Text, int ChunkIndex)>(EMBEDDING_BATCH_SIZE);
         var totalChunkCount = 0;
 
-        await foreach (var chunk in this.StreamEmbeddingChunksAsync(file.FullName, token))
+        await foreach (var chunk in this.StreamEmbeddingChunksAsync(file.FullName, embeddingProvider, token))
         {
             batch.Add((chunk, totalChunkCount));
             totalChunkCount++;

app/MindWork AI Studio/Tools/Services/RustService.Tokenizer.cs

@@ -84,11 +84,33 @@ public sealed partial class RustService
         return await result.Content.ReadFromJsonAsync<TokenizerResponse>(this.jsonRustSerializerOptions);
     }
     
-    public async Task<TokenizerResponse?> GetTokenCount(string text)
+    public Task<TokenizerResponse?> GetTokenCount(string text)
+    {
+        return this.GetTokenCountCoreAsync(text);
+    }
+
+    public async Task<TokenizerResponse?> GetTokenCount(string providerName, string path, string text, CancellationToken cancellationToken = default)
+    {
+        await this.tokenizerLock.WaitAsync(cancellationToken);
+        try
+        {
+            var tokenizerResponse = await this.EnsureTokenizerCoreAsync(providerName, path);
+            if (tokenizerResponse is not { Success: true, Status: TokenizerStatus.AVAILABLE })
+                return tokenizerResponse;
+
+            return await this.GetTokenCountCoreAsync(text, cancellationToken);
+        }
+        finally
+        {
+            this.tokenizerLock.Release();
+        }
+    }
+
+    private async Task<TokenizerResponse?> GetTokenCountCoreAsync(string text, CancellationToken cancellationToken = default)
     {
         var result = await this.http.PostAsJsonAsync("/tokenizer/count", new {
             text = text,
-        }, this.jsonRustSerializerOptions);
+        }, this.jsonRustSerializerOptions, cancellationToken);
 
         if (!result.IsSuccessStatusCode)
         {
@@ -130,26 +152,31 @@ public sealed partial class RustService
         await this.tokenizerLock.WaitAsync();
         try
         {
-            if (this.hasInitializedTokenizer && this.currentTokenizerPath == path)
+            return await this.EnsureTokenizerCoreAsync(providerName, path);
-                return new TokenizerResponse(true, 0, string.Empty, TokenizerStatus.AVAILABLE);
-
-            var response = await this.SetTokenizer(providerName, path);
-            if (response is { Success: true, Status: TokenizerStatus.AVAILABLE })
-            {
-                this.currentTokenizerPath = path;
-                this.hasInitializedTokenizer = true;
-            }
-            else
-            {
-                this.currentTokenizerPath = string.Empty;
-                this.hasInitializedTokenizer = false;
-            }
-
-            return response;
         }
         finally
         {
             this.tokenizerLock.Release();
         }
     }
+
+    private async Task<TokenizerResponse?> EnsureTokenizerCoreAsync(string providerName, string path)
+    {
+        if (this.hasInitializedTokenizer && this.currentTokenizerPath == path)
+            return new TokenizerResponse(true, 0, string.Empty, TokenizerStatus.AVAILABLE);
+
+        var response = await this.SetTokenizer(providerName, path);
+        if (response is { Success: true, Status: TokenizerStatus.AVAILABLE })
+        {
+            this.currentTokenizerPath = path;
+            this.hasInitializedTokenizer = true;
+        }
+        else
+        {
+            this.currentTokenizerPath = string.Empty;
+            this.hasInitializedTokenizer = false;
+        }
+
+        return response;
+    }
 }