Function buildSystemPrompt

coderd/x/chatd/chatd.go:6725–6761

buildSystemPrompt applies system-level prompt injections in the canonical order. It is used by both the initial prompt assembly and the ReloadMessages callback to keep them in sync.

(
	prompt []fantasy.Message,
	subagentInstruction string,
	instruction string,
	resolvedSkills []skillspkg.ResolvedSkill,
	userPrompt string,
	behaviorContext systemPromptBehaviorContext,
)

// canonical order. It is used by both the initial prompt assembly
// and the ReloadMessages callback to keep them in sync.
func buildSystemPrompt(
	prompt []fantasy.Message,
	subagentInstruction string,
	instruction string,
	resolvedSkills []skillspkg.ResolvedSkill,
	userPrompt string,
	behaviorContext systemPromptBehaviorContext,
) []fantasy.Message {
	if subagentInstruction != "" {
		prompt = chatprompt.InsertSystem(prompt, subagentInstruction)
	}
	if instruction != "" {
		prompt = chatprompt.InsertSystem(prompt, instruction)
	}
	if skillIndex := chattool.FormatResolvedSkillIndex(resolvedSkills); skillIndex != "" {
		prompt = chatprompt.InsertSystem(prompt, skillIndex)
	}
	if userPrompt != "" {
		prompt = chatprompt.InsertSystem(prompt, userPrompt)
	}
	if isExploreSubagentMode(behaviorContext.chatMode) {
		prompt = chatprompt.InsertSystem(prompt, ExploreSubagentOverlayPrompt)
		return prompt
	}
	isPlanModeTurn := behaviorContext.planMode.Valid && behaviorContext.planMode.ChatPlanMode == database.ChatPlanModePlan
	if isPlanModeTurn {
		if behaviorContext.isRootChat {
			prompt = chatprompt.InsertSystem(prompt, PlanningOverlayPrompt())
			if behaviorContext.planModeInstructions != "" {
				prompt = chatprompt.InsertSystem(prompt, behaviorContext.planModeInstructions)
			}
		} else {
			prompt = chatprompt.InsertSystem(prompt, PlanningSubagentOverlayPrompt)
		}
	}
	return prompt
}

func removeSkillIndexMessages(prompt []fantasy.Message) []fantasy.Message {
	out := make([]fantasy.Message, 0, len(prompt))