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Support gpt-5.1 model in Tiktoken tokenizer #7556

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Merged
merged 2 commits into from
Nov 19, 2025
Merged

Support gpt-5.1 model in Tiktoken tokenizer #7556

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63a3bca
Support gpt-5.1 model in Tiktoken tokenizer
tarekgh Nov 18, 2025
aace8b8
Fix spaces
tarekgh Nov 18, 2025
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16 changes: 9 additions & 7 deletions src/Microsoft.ML.Tokenizers/Model/TiktokenTokenizer.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -1044,13 +1044,14 @@ private static readonly (string Prefix, ModelEncoding Encoding)[] _modelPrefixTo
( "o4-mini-", ModelEncoding.O200kBase ), // e.g. o4-mini

// chat
( "gpt-5-", ModelEncoding.O200kBase),
( "gpt-4.1-", ModelEncoding.O200kBase), // e.g., gpt-4.1-mini
( "gpt-4.5-", ModelEncoding.O200kBase), // e.g., gpt-4.5
( "gpt-4o-", ModelEncoding.O200kBase), // e.g., gpt-4o-2024-05-13
( "chatgpt-4o-", ModelEncoding.O200kBase),
( "gpt-4-", ModelEncoding.Cl100kBase), // e.g., gpt-4-0314, etc., plus gpt-4-32k
( "gpt-3.5-", ModelEncoding.Cl100kBase), // e.g, gpt-3.5-turbo-0301, -0401, etc.
( "gpt-5.1-", ModelEncoding.O200kBase ),
( "gpt-5-", ModelEncoding.O200kBase ),
( "gpt-4.1-", ModelEncoding.O200kBase ), // e.g., gpt-4.1-mini
( "gpt-4.5-", ModelEncoding.O200kBase ), // e.g., gpt-4.5
( "gpt-4o-", ModelEncoding.O200kBase ), // e.g., gpt-4o-2024-05-13
( "chatgpt-4o-", ModelEncoding.O200kBase ),
( "gpt-4-", ModelEncoding.Cl100kBase ), // e.g., gpt-4-0314, etc., plus gpt-4-32k
( "gpt-3.5-", ModelEncoding.Cl100kBase ), // e.g, gpt-3.5-turbo-0301, -0401, etc.
( "gpt-35-", ModelEncoding.Cl100kBase ), // Azure deployment name
( "gpt-oss-", ModelEncoding.O200kHarmony ),

Expand All @@ -1071,6 +1072,7 @@ private static readonly (string Prefix, ModelEncoding Encoding)[] _modelPrefixTo
{ "o4-mini", ModelEncoding.O200kBase },

// chat
{ "gpt-5.1", ModelEncoding.O200kBase },
{ "gpt-5", ModelEncoding.O200kBase },
{ "gpt-4.1", ModelEncoding.O200kBase },
{ "gpt-4o", ModelEncoding.O200kBase },
Expand Down
6 changes: 5 additions & 1 deletion test/Microsoft.ML.Tokenizers.Tests/TiktokenTests.cs
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Expand Up @@ -36,6 +36,7 @@ public class TiktokenTests
public static Tokenizer P50kEdit { get; } = TiktokenTokenizer.CreateForModel("text-davinci-edit-001");
public static Tokenizer GPT4o { get; } = TiktokenTokenizer.CreateForModel("gpt-4o");
public static Tokenizer GPT5 { get; } = TiktokenTokenizer.CreateForModel("gpt-5");
public static Tokenizer GPT5_1 { get; } = TiktokenTokenizer.CreateForModel("gpt-5.1");
public static Tokenizer Phi4 { get; } = TiktokenTokenizer.CreateForModel("phi-4");
public static TiktokenTokenizer GptOss { get; } = TiktokenTokenizer.CreateForModel("gpt-oss-20b");

Expand Down Expand Up @@ -286,7 +287,7 @@ public void TestEncode5()
[Fact]
public void TestEncodeO200kBaseEncoding()
{
foreach (TiktokenTokenizer tokenizer in new[] { GPT4o, GptOss, GPT5 })
foreach (TiktokenTokenizer tokenizer in new[] { GPT4o, GptOss, GPT5, GPT5_1 })
{
string text = ReadAndSanitizeFile("./Data/lib.rs.txt");
IReadOnlyList<int> encoded = tokenizer.EncodeToIds(text);
Expand Down Expand Up @@ -415,6 +416,8 @@ public void TestEncodeR50kBase()
[InlineData("gpt-4o-")]
[InlineData("gpt-5")]
[InlineData("gpt-5-chat")]
[InlineData("gpt-5.1")]
[InlineData("gpt-5.1-mini")]
[InlineData("chatgpt-4o-")]
[InlineData("gpt-4")]
[InlineData("gpt-4-")]
Expand Down Expand Up @@ -533,6 +536,7 @@ public void TestEncodingNamesNegativeCases()
[InlineData("gpt-4.1")]
[InlineData("gpt-4o")]
[InlineData("gpt-5")]
[InlineData("gpt-5.1")]
[InlineData("o1")]
[InlineData("o3")]
[InlineData("o4-mini")]
Expand Down
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