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fix(errors): empty prompt logic #103

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fix(errors): empty prompt logic #103

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d80fa09
Support empty prompt when messages exist
rmay1er Dec 18, 2025
36c4d4a
Make agent system role more priority
rmay1er Dec 18, 2025
c274228
fix: checking len(messages) before checking system role
rmay1er Dec 18, 2025
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25 changes: 22 additions & 3 deletions agent.go
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Original file line number Diff line number Diff line change
Expand Up @@ -986,17 +986,36 @@ func (a *agent) validateToolCall(toolCall ToolCallContent, availableTools []Agen
}

func (a *agent) createPrompt(system, prompt string, messages []Message, files ...FilePart) (Prompt, error) {
if prompt == "" {
if prompt == "" && len(messages) < 1 {
return nil, &Error{Title: "invalid argument", Message: "prompt can't be empty"}
}

var preparedPrompt Prompt

var newsystem string
// Check first message for system role
if len(messages) > 0 && messages[0].Role == MessageRoleSystem {
if len(messages[0].Content) > 0 {
Comment on lines +997 to +998
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@kujtimiihoxha kujtimiihoxha Jan 5, 2026

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We should probably iterate over all messages and collect system role messages, + all message content instead of just the first message.

if tp, ok := messages[0].Content[0].(TextPart); ok {
newsystem = tp.Text
}
}
}
// Rewrite system role with main role of agent if it exist
if system != "" {
preparedPrompt = append(preparedPrompt, NewSystemMessage(system))
newsystem = system
}

if newsystem != "" {
preparedPrompt = append(preparedPrompt, NewSystemMessage(newsystem))
}

preparedPrompt = append(preparedPrompt, messages...)
preparedPrompt = append(preparedPrompt, NewUserMessage(prompt, files...))

if prompt != "" {
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@kujtimiihoxha kujtimiihoxha Jan 5, 2026

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if prompt is empty we should guard that the last message in the message list is a user message, or a tool response.

I think its not expected that we send a message with the last message being an assistant message.

preparedPrompt = append(preparedPrompt, NewUserMessage(prompt, files...))
}

return preparedPrompt, nil
}

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