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fix(anthropic): drop empty messages with warning #79

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fix(anthropic): drop empty messages with warning #79

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59ed4e6
fix(anthropic): use call warning type constant
Amolith Nov 14, 2025
66c74ae
fix(anthropic): drop empty messages with warning
Amolith Nov 14, 2025
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39 changes: 36 additions & 3 deletions providers/anthropic/anthropic.go
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Original file line number Diff line number Diff line change
Expand Up @@ -619,6 +619,13 @@ func toPrompt(prompt fantasy.Prompt, sendReasoningData bool) ([]anthropic.TextBl
}
}
}
if !hasVisibleUserContent(anthropicContent) {
warnings = append(warnings, fantasy.CallWarning{
Type: fantasy.CallWarningTypeOther,
Message: "dropping empty user message (contains neither user-facing content nor tool results)",
})
continue
}
messages = append(messages, anthropic.NewUserMessage(anthropicContent...))
case fantasy.MessageRoleAssistant:
var anthropicContent []anthropic.ContentBlockParamUnion
Expand Down Expand Up @@ -651,15 +658,15 @@ func toPrompt(prompt fantasy.Prompt, sendReasoningData bool) ([]anthropic.TextBl
}
if !sendReasoningData {
warnings = append(warnings, fantasy.CallWarning{
Type: "other",
Type: fantasy.CallWarningTypeOther,
Message: "sending reasoning content is disabled for this model",
})
continue
}
reasoningMetadata := GetReasoningMetadata(part.Options())
if reasoningMetadata == nil {
warnings = append(warnings, fantasy.CallWarning{
Type: "other",
Type: fantasy.CallWarningTypeOther,
Message: "unsupported reasoning metadata",
})
continue
Expand All @@ -671,7 +678,7 @@ func toPrompt(prompt fantasy.Prompt, sendReasoningData bool) ([]anthropic.TextBl
anthropicContent = append(anthropicContent, anthropic.NewRedactedThinkingBlock(reasoningMetadata.RedactedData))
} else {
warnings = append(warnings, fantasy.CallWarning{
Type: "other",
Type: fantasy.CallWarningTypeOther,
Message: "unsupported reasoning metadata",
})
continue
Expand Down Expand Up @@ -701,12 +708,38 @@ func toPrompt(prompt fantasy.Prompt, sendReasoningData bool) ([]anthropic.TextBl
}
}
}

if !hasVisibleAssistantContent(anthropicContent) {
warnings = append(warnings, fantasy.CallWarning{
Type: fantasy.CallWarningTypeOther,
Message: "dropping empty assistant message (contains neither user-facing content nor tool calls)",
})
continue
}
messages = append(messages, anthropic.NewAssistantMessage(anthropicContent...))
}
}
return systemBlocks, messages, warnings
}

func hasVisibleUserContent(content []anthropic.ContentBlockParamUnion) bool {
for _, block := range content {
if block.OfText != nil || block.OfImage != nil || block.OfToolResult != nil {
return true
}
}
return false
}

func hasVisibleAssistantContent(content []anthropic.ContentBlockParamUnion) bool {
for _, block := range content {
if block.OfText != nil || block.OfToolUse != nil {
return true
}
}
return false
}

func mapFinishReason(finishReason string) fantasy.FinishReason {
switch finishReason {
case "end_turn", "pause_turn", "stop_sequence":
Expand Down
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