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dkalinowski merged 8 commits into from
Jan 21, 2026
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GPT-OSS less strict parser, allow for function calls in analysis channel #3786

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dkalinowski Nov 13, 2025
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dkalinowski Nov 13, 2025
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Merge remote-tracking branch 'origin/main' into gpt-hacks
dkalinowski Jan 21, 2026
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Merge remote-tracking branch 'origin/main' into gpt-hacks
dkalinowski Jan 21, 2026
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dkalinowski Jan 21, 2026
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Merge branch 'main' into gpt-hacks
dkalinowski Jan 21, 2026
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2 changes: 1 addition & 1 deletion src/llm/io_processing/gptoss/harmony.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -97,7 +97,7 @@ ToolCalls_t Harmony::getToolCalls() {
static const std::string tool_prefix = "to=functions.";
ToolCalls_t toolCalls;
for (const auto& msg : messages) {
if (startsWith(msg.getChannel(), "commentary")) {
if (startsWith(msg.getChannel(), "commentary") || startsWith(msg.getChannel(), "analysis")) {
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@atobiszei atobiszei Nov 13, 2025

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Just a comment. For GenAI/OV testing purposes it could be useful to be able to turn off such workarounds, to check accuracy fixes, otherwise we may just mask those issues

size_t marker = msg.getChannel().find(tool_prefix);
if (marker != std::string::npos) {
marker += tool_prefix.length();
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8 changes: 5 additions & 3 deletions src/llm/io_processing/gptoss/tool_parser.cpp
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Expand Up @@ -86,9 +86,11 @@ std::optional<rapidjson::Document> GptOssToolParser::parseChunk(const std::strin
std::string chunk = newChunk;
std::optional<rapidjson::Document> result;

if (chunk.find(getParsingStartTags()[0]) != std::string::npos) {
toolCallIndex++; // starting with -1, first call will be 0
return std::nullopt;
for (const auto& parsingStartTag : getParsingStartTags()) {
if (chunk.find(parsingStartTag) != std::string::npos) {
toolCallIndex++; // starting with -1, first call will be 0
return std::nullopt;
}
}
Comment on lines +89 to 94
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Copilot AI Jan 21, 2026

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The loop performs multiple string searches on the same chunk. If the chunk matches an early tag, subsequent searches are unnecessary. Since the function returns immediately on match, this is already optimized, but consider adding a comment explaining that the order of tags in getParsingStartTags() may affect performance if one pattern is more common than others.

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@dkalinowski dkalinowski Jan 21, 2026

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both start tags differ from each other significantly, new tags are not planned


// This should only happen during channel read if model does not produce garbage
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5 changes: 4 additions & 1 deletion src/llm/io_processing/gptoss/tool_parser.hpp
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Expand Up @@ -58,7 +58,10 @@ class GptOssToolParser : public BaseOutputParser {
std::optional<rapidjson::Document> parseChunk(const std::string& chunk, ov::genai::GenerationFinishReason finishReason) override;

const std::vector<std::string>& getParsingStartTags() const override {
static const std::vector<std::string> parsingStartTags{parsingStartTag};
static const std::vector<std::string> parsingStartTags{
parsingStartTag,
"<|channel|>analysis to=", // Workaround: allow tool calls emitted from the analysis channel (non-standard behavior observed in some model outputs).
};
return parsingStartTags;
}

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101 changes: 101 additions & 0 deletions src/test/llm/output_parsers/gptoss_output_parser_test.cpp
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Expand Up @@ -288,6 +288,36 @@ TEST_F(GptOssOutputUnaryParserTest, SingleToolCallWithConstrain) {
}
}

// This does not conform to OpenAI Harmony format, however tests show that sometimes model produces tools in analysis channel
TEST_F(GptOssOutputUnaryParserTest, SingleToolCallWithConstrainInAnalysisChannel) {
for (auto closureToken : std::vector<Harmony::TokenID>{
Harmony::TokenID::RETURN, // ending with <|return|>
Harmony::TokenID::END, // ending with <|end|>
Harmony::TokenID::CALL}) { // ending with <|call|>
for (auto functionDeclaration : std::vector<std::string>{
"analysis to=functions.hello", // valid channel with to=
"analysis to=functions.hello ",
"analysis to=functions.hello",
"analysis ANYTHING IN BETWEEN to=functions.hello",
}) { // spaces after hello
builder
.clear()
.add(Harmony::TokenID::CHANNEL)
.add(functionDeclaration)
.add(Harmony::TokenID::MESSAGE)
.add(R"({"Hello": "world!"})")
.add(closureToken);
Harmony harmony(*gptOssTokenizer, builder.build());
ASSERT_TRUE(harmony.parse()) << "Failed for closure token: " << static_cast<int64_t>(closureToken) << " function declaration: " << functionDeclaration;
ASSERT_EQ(harmony.getContent(), "") << "Failed for closure token: " << static_cast<int64_t>(closureToken) << " function declaration: " << functionDeclaration;
ASSERT_EQ(harmony.getReasoning(), "") << "Failed for closure token: " << static_cast<int64_t>(closureToken) << " function declaration: " << functionDeclaration;
ASSERT_EQ(harmony.getToolCalls().size(), 1) << "Failed for closure token: " << static_cast<int64_t>(closureToken) << " function declaration: " << functionDeclaration;
ASSERT_EQ(harmony.getToolCalls()[0].name, "hello") << "Failed for closure token: " << static_cast<int64_t>(closureToken) << " function declaration: " << functionDeclaration;
ASSERT_EQ(harmony.getToolCalls()[0].arguments, R"({"Hello": "world!"})") << "Failed for closure token: " << static_cast<int64_t>(closureToken) << " function declaration: " << functionDeclaration;
}
}
}

TEST_F(GptOssOutputUnaryParserTest, InvalidSingleToolCallWithConstrain) {
for (auto closureToken : std::vector<Harmony::TokenID>{
Harmony::TokenID::RETURN, // ending with <|return|>
Expand Down Expand Up @@ -637,3 +667,74 @@ TEST_F(GptOssOutputStreamParserTest, ConstrainAndCallGluedWithToolCall) {
};
test(chunkToDeltaVec);
}

// This does not conform to OpenAI Harmony format, however tests show that sometimes model produces tools in analysis channel
TEST_F(GptOssOutputStreamParserTest, HolisticStreamingToolsInAnalysisChannel) {
std::vector<std::tuple<std::string, ov::genai::GenerationFinishReason, std::optional<std::string>>> chunkToDeltaVec{
// Reasoning
{"<|channel|>", ov::genai::GenerationFinishReason::NONE, std::nullopt},
{"analysis", ov::genai::GenerationFinishReason::NONE, std::nullopt},
{"<|message|>", ov::genai::GenerationFinishReason::NONE, std::nullopt},
{"I", ov::genai::GenerationFinishReason::NONE, {R"({"delta":{"reasoning_content":"I"}})"}},
{" will", ov::genai::GenerationFinishReason::NONE, {R"({"delta":{"reasoning_content":" will"}})"}},
{" call", ov::genai::GenerationFinishReason::NONE, {R"({"delta":{"reasoning_content":" call"}})"}},
{" fun", ov::genai::GenerationFinishReason::NONE, {R"({"delta":{"reasoning_content":" fun"}})"}},
{"ction.", ov::genai::GenerationFinishReason::NONE, {R"({"delta":{"reasoning_content":"ction."}})"}},
{"<|end|>", ov::genai::GenerationFinishReason::NONE, std::nullopt},
// Preamble
{"<|channel|>", ov::genai::GenerationFinishReason::NONE, std::nullopt},
{"commentary", ov::genai::GenerationFinishReason::NONE, std::nullopt},
{"<|message|>", ov::genai::GenerationFinishReason::NONE, std::nullopt},
{"I", ov::genai::GenerationFinishReason::NONE, {R"({"delta":{"content":"I"}})"}},
{" have", ov::genai::GenerationFinishReason::NONE, {R"({"delta":{"content":" have"}})"}},
{" to", ov::genai::GenerationFinishReason::NONE, {R"({"delta":{"content":" to"}})"}},
{" call", ov::genai::GenerationFinishReason::NONE, {R"({"delta":{"content":" call"}})"}},
{" fun", ov::genai::GenerationFinishReason::NONE, {R"({"delta":{"content":" fun"}})"}},
{"ction.", ov::genai::GenerationFinishReason::NONE, {R"({"delta":{"content":"ction."}})"}},
{"<|end|>", ov::genai::GenerationFinishReason::NONE, std::nullopt},
// Tool 1 (with ignored constrain)
{"<|channel|>", ov::genai::GenerationFinishReason::NONE, std::nullopt},
{"analysis", ov::genai::GenerationFinishReason::NONE, std::nullopt},
{" to=", ov::genai::GenerationFinishReason::NONE, std::nullopt},
{"fun", ov::genai::GenerationFinishReason::NONE, std::nullopt},
{"ctions", ov::genai::GenerationFinishReason::NONE, std::nullopt},
{".hello ", ov::genai::GenerationFinishReason::NONE, std::nullopt},
{"<|message|>", ov::genai::GenerationFinishReason::NONE, "{\"delta\":{\"tool_calls\":[{\"id\":\"XXXXXXXXX\",\"type\":\"function\",\"index\":0,\"function\":{\"name\":\"hello\"}}]}}"},
{" {\"", ov::genai::GenerationFinishReason::NONE, R"({"delta":{"tool_calls":[{"index":0,"function":{"arguments":" {\""}}]}})"},
{"location", ov::genai::GenerationFinishReason::NONE, R"({"delta":{"tool_calls":[{"index":0,"function":{"arguments":"location"}}]}})"},
{"\":", ov::genai::GenerationFinishReason::NONE, R"({"delta":{"tool_calls":[{"index":0,"function":{"arguments":"\":"}}]}})"},
{" \"", ov::genai::GenerationFinishReason::NONE, R"({"delta":{"tool_calls":[{"index":0,"function":{"arguments":" \""}}]}})"},
{"Paris", ov::genai::GenerationFinishReason::NONE, R"({"delta":{"tool_calls":[{"index":0,"function":{"arguments":"Paris"}}]}})"},
{"\"}", ov::genai::GenerationFinishReason::NONE, R"({"delta":{"tool_calls":[{"index":0,"function":{"arguments":"\"}"}}]}})"},
{"<|call|>", ov::genai::GenerationFinishReason::NONE, std::nullopt},
// Tool 2 (with constrain)
{"<|channel|>", ov::genai::GenerationFinishReason::NONE, std::nullopt},
{"analysis", ov::genai::GenerationFinishReason::NONE, std::nullopt},
{" to=", ov::genai::GenerationFinishReason::NONE, std::nullopt},
{"fun", ov::genai::GenerationFinishReason::NONE, std::nullopt},
{"ctions", ov::genai::GenerationFinishReason::NONE, std::nullopt},
{".world ", ov::genai::GenerationFinishReason::NONE, std::nullopt},
{"<|constrain|>", ov::genai::GenerationFinishReason::NONE, "{\"delta\":{\"tool_calls\":[{\"id\":\"XXXXXXXXX\",\"type\":\"function\",\"index\":1,\"function\":{\"name\":\"world\"}}]}}"},
{"json", ov::genai::GenerationFinishReason::NONE, std::nullopt},
{"<|message|>", ov::genai::GenerationFinishReason::NONE, std::nullopt},
{" {\"", ov::genai::GenerationFinishReason::NONE, R"({"delta":{"tool_calls":[{"index":1,"function":{"arguments":" {\""}}]}})"},
{"location", ov::genai::GenerationFinishReason::NONE, R"({"delta":{"tool_calls":[{"index":1,"function":{"arguments":"location"}}]}})"},
{"\":", ov::genai::GenerationFinishReason::NONE, R"({"delta":{"tool_calls":[{"index":1,"function":{"arguments":"\":"}}]}})"},
{" \"", ov::genai::GenerationFinishReason::NONE, R"({"delta":{"tool_calls":[{"index":1,"function":{"arguments":" \""}}]}})"},
{"Warsaw", ov::genai::GenerationFinishReason::NONE, R"({"delta":{"tool_calls":[{"index":1,"function":{"arguments":"Warsaw"}}]}})"},
{"\"}", ov::genai::GenerationFinishReason::NONE, R"({"delta":{"tool_calls":[{"index":1,"function":{"arguments":"\"}"}}]}})"},
{"<|call|>", ov::genai::GenerationFinishReason::NONE, std::nullopt},
// Tool 3 (glued with call token)
{"<|channel|>", ov::genai::GenerationFinishReason::NONE, std::nullopt},
{"analysis", ov::genai::GenerationFinishReason::NONE, std::nullopt},
{" to=", ov::genai::GenerationFinishReason::NONE, std::nullopt},
{"fun", ov::genai::GenerationFinishReason::NONE, std::nullopt},
{"ctions", ov::genai::GenerationFinishReason::NONE, std::nullopt},
{".world ", ov::genai::GenerationFinishReason::NONE, std::nullopt},
{"<|constrain|>", ov::genai::GenerationFinishReason::NONE, "{\"delta\":{\"tool_calls\":[{\"id\":\"XXXXXXXXX\",\"type\":\"function\",\"index\":2,\"function\":{\"name\":\"world\"}}]}}"},
{"json", ov::genai::GenerationFinishReason::NONE, std::nullopt},
{"<|message|>", ov::genai::GenerationFinishReason::NONE, std::nullopt},
{"{}<|call|>", ov::genai::GenerationFinishReason::NONE, R"({"delta":{"tool_calls":[{"index":2,"function":{"arguments":"{}"}}]}})"},
};
test(chunkToDeltaVec);
}