feat(prompts): support Sprig in templates

[mudler]

This PR adds support to Sprig into prompt templates

[Copilot]

Pull Request Overview

This PR enhances the template system by integrating the Sprig template function library and refactoring template handling. The main goal is to add support for Sprig template functions across the agent's prompt processing system.

• Switched from html/template to text/template package
• Added Sprig v3 template function support via new helper functions
• Applied template processing to message content and system prompts

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
core/agent/templates.go	Added templateBase and templateExecute helper functions with Sprig support, updated import from html/template to text/template, refactored renderTemplate to use new helpers
core/agent/agent.go	Applied template processing to message content and system prompts using the new template helpers

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[Copilot]

When template execution fails (line 375-378), the error is logged but content remains empty. The code then proceeds to check conversation.Exist(content) with an empty string on line 379, which may cause unintended behavior. Consider returning early or handling the error to prevent using an empty content value.

[Copilot]

Template processing is applied to all message content regardless of whether it contains template directives. Consider checking if the content contains template markers (e.g., '{{') before creating and executing templates to avoid unnecessary parsing overhead for non-templated content.

Suggested change

	promptTemplate, err := templateBase("template", content)
	if err != nil {
	xlog.Error("Error rendering template", "error", err)
	continue
	}
	content, err = templateExecute(promptTemplate, struct{}{})
	if err != nil {
	xlog.Error("Error executing template", "error", err)
	continue
	if strings.Contains(content, "{{") {
	promptTemplate, err := templateBase("template", content)
	if err != nil {
	xlog.Error("Error rendering template", "error", err)
	continue
	}
	content, err = templateExecute(promptTemplate, struct{}{})
	if err != nil {
	xlog.Error("Error executing template", "error", err)
	continue
	}

[Copilot]

An empty struct struct{}{} is passed as template data, which means templates cannot access any dynamic values. Consider defining a proper data structure with relevant context (e.g., agent state, character info, timestamps) to make the template functionality more useful.