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Fix Gemini 3+ tool calling by preserving ThoughtSignature #12

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Merged
jredl-va merged 1 commit into from
Jan 6, 2026
Merged

Fix Gemini 3+ tool calling by preserving ThoughtSignature #12

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4 changes: 2 additions & 2 deletions examples/llmsummarization-chain-example/go.mod
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Original file line number Diff line number Diff line change
@@ -1,6 +1,6 @@
module github.com/vendasta/langchaingo/examples/llmsummarization-chain-example

go 1.24.3
go 1.24.4

require github.com/vendasta/langchaingo v0.1.14-pre.4

Expand All @@ -14,7 +14,7 @@ require (
cloud.google.com/go/iam v1.2.2 // indirect
cloud.google.com/go/longrunning v0.6.2 // indirect
cloud.google.com/go/vertexai v0.12.0 // indirect
github.com/AssemblyAI/assemblyai-go-sdk v1.3.0 // indirect
github.com/AssemblyAI/assemblyai-go-sdk v1.10.0 // indirect
github.com/Masterminds/goutils v1.1.1 // indirect
github.com/Masterminds/semver/v3 v3.2.0 // indirect
github.com/Masterminds/sprig/v3 v3.2.3 // indirect
Expand Down
1 change: 1 addition & 0 deletions examples/llmsummarization-chain-example/go.sum
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Original file line number Diff line number Diff line change
Expand Up @@ -21,6 +21,7 @@ filippo.io/edwards25519 v1.1.0 h1:FNf4tywRC1HmFuKW5xopWpigGjJKiJSV0Cqo0cJWDaA=
filippo.io/edwards25519 v1.1.0/go.mod h1:BxyFTGdWcka3PhytdK4V28tE5sGfRvvvRV7EaN4VDT4=
github.com/AssemblyAI/assemblyai-go-sdk v1.3.0 h1:AtOVgGxUycvK4P4ypP+1ZupecvFgnfH+Jsum0o5ILoU=
github.com/AssemblyAI/assemblyai-go-sdk v1.3.0/go.mod h1:H0naZbvpIW49cDA5ZZ/gggeXqi7ojSGB1mqshRk6kNE=
github.com/AssemblyAI/assemblyai-go-sdk v1.10.0/go.mod h1:dwv8jDdg+UKPU9ClZzhQNXIVj3Yw68IaTVRuyKRLigw=
github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
github.com/Masterminds/goutils v1.1.1 h1:5nUrii3FMTL5diU80unEVvNevw1nH4+ZV4DSLVJLSYI=
github.com/Masterminds/goutils v1.1.1/go.mod h1:8cTjp+g8YejhMuvIA5y2vz3BpJxksy863GQaJW2MFNU=
Expand Down
4 changes: 2 additions & 2 deletions examples/mistral-summarization-example/go.mod
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Original file line number Diff line number Diff line change
@@ -1,11 +1,11 @@
module github.com/vendasta/langchaingo/examples/mistral-summarization-example

go 1.24.3
go 1.24.4

require github.com/vendasta/langchaingo v0.1.14-pre.4

require (
github.com/AssemblyAI/assemblyai-go-sdk v1.3.0 // indirect
github.com/AssemblyAI/assemblyai-go-sdk v1.10.0 // indirect
github.com/Masterminds/goutils v1.1.1 // indirect
github.com/Masterminds/semver/v3 v3.2.0 // indirect
github.com/Masterminds/sprig/v3 v3.2.3 // indirect
Expand Down
1 change: 1 addition & 0 deletions examples/mistral-summarization-example/go.sum
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Original file line number Diff line number Diff line change
Expand Up @@ -21,6 +21,7 @@ filippo.io/edwards25519 v1.1.0 h1:FNf4tywRC1HmFuKW5xopWpigGjJKiJSV0Cqo0cJWDaA=
filippo.io/edwards25519 v1.1.0/go.mod h1:BxyFTGdWcka3PhytdK4V28tE5sGfRvvvRV7EaN4VDT4=
github.com/AssemblyAI/assemblyai-go-sdk v1.3.0 h1:AtOVgGxUycvK4P4ypP+1ZupecvFgnfH+Jsum0o5ILoU=
github.com/AssemblyAI/assemblyai-go-sdk v1.3.0/go.mod h1:H0naZbvpIW49cDA5ZZ/gggeXqi7ojSGB1mqshRk6kNE=
github.com/AssemblyAI/assemblyai-go-sdk v1.10.0/go.mod h1:dwv8jDdg+UKPU9ClZzhQNXIVj3Yw68IaTVRuyKRLigw=
github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
github.com/Masterminds/goutils v1.1.1 h1:5nUrii3FMTL5diU80unEVvNevw1nH4+ZV4DSLVJLSYI=
github.com/Masterminds/goutils v1.1.1/go.mod h1:8cTjp+g8YejhMuvIA5y2vz3BpJxksy863GQaJW2MFNU=
Expand Down
1 change: 0 additions & 1 deletion go.mod
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Original file line number Diff line number Diff line change
Expand Up @@ -167,7 +167,6 @@ require (
github.com/xdg-go/scram v1.1.2 // indirect
github.com/xdg-go/stringprep v1.0.4 // indirect
github.com/youmark/pkcs8 v0.0.0-20240726163527-a2c0da244d78 // indirect

)

// Database drivers - indirect
Expand Down
3 changes: 3 additions & 0 deletions llms/generatecontent.go
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Original file line number Diff line number Diff line change
Expand Up @@ -102,6 +102,9 @@ type ToolCall struct {
Type string `json:"type"`
// FunctionCall is the function call to be executed.
FunctionCall *FunctionCall `json:"function,omitempty"`
// ThoughtSignature is an opaque signature for Gemini 3+ models that must be
// preserved when echoing back function calls. Required for tool calling to work.
ThoughtSignature []byte `json:"thought_signature,omitempty"`
}

func (ToolCall) isPart() {}
Expand Down
9 changes: 7 additions & 2 deletions llms/googleaiv2/googleai.go
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Original file line number Diff line number Diff line change
Expand Up @@ -305,7 +305,7 @@ func convertCandidates(candidates []*genai.Candidate, usage *genai.GenerateConte
for i, candidate := range candidates {
var textContent string
var toolCalls []llms.ToolCall

// Use the response's Text() method if available (more reliable, handles thoughts correctly)
// For multi-candidate responses, we need to extract text per candidate
if response != nil && i == 0 {
Expand Down Expand Up @@ -349,6 +349,8 @@ func convertCandidates(candidates []*genai.Candidate, usage *genai.GenerateConte
Name: part.FunctionCall.Name,
Arguments: string(b),
},
// Preserve ThoughtSignature for Gemini 3+ models - required for tool calling
ThoughtSignature: part.ThoughtSignature,
}
toolCalls = append(toolCalls, toolCall)
}
Expand Down Expand Up @@ -446,7 +448,10 @@ func convertParts(parts []llms.ContentPart) ([]*genai.Part, error) {
Name: fc.Name,
Args: argsMap,
}
out = &genai.Part{FunctionCall: functionCall}
out = &genai.Part{
FunctionCall: functionCall,
ThoughtSignature: p.ThoughtSignature, // Required for Gemini 3+ tool calling
}
case llms.ToolCallResponse:
functionResponse := &genai.FunctionResponse{
Name: p.Name,
Expand Down