Function prependAgentChatContextSentinelIfNeeded

coderd/workspaceagents.go:2869–2901

prependAgentChatContextSentinelIfNeeded adds an empty context-file part when the request only carries skills. The turn pipeline uses the sentinel's agent metadata to trust the skill parts.

(
	parts []codersdk.ChatMessagePart,
	agentID uuid.UUID,
	operatingSystem string,
	directory string,
)

// part when the request only carries skills. The turn pipeline uses
// the sentinel's agent metadata to trust the skill parts.
func prependAgentChatContextSentinelIfNeeded(
	parts []codersdk.ChatMessagePart,
	agentID uuid.UUID,
	operatingSystem string,
	directory string,
) []codersdk.ChatMessagePart {
	hasContextFile := false
	hasSkill := false
	for _, part := range parts {
		switch part.Type {
		case codersdk.ChatMessagePartTypeContextFile:
			hasContextFile = true
		case codersdk.ChatMessagePartTypeSkill:
			hasSkill = true
		}
		if hasContextFile && hasSkill {
			return parts
		}
	}
	if !hasSkill || hasContextFile {
		return parts
	}
	return append([]codersdk.ChatMessagePart{{
		Type:            codersdk.ChatMessagePartTypeContextFile,
		ContextFilePath: chatd.AgentChatContextSentinelPath,
		ContextFileAgentID: uuid.NullUUID{
			UUID:  agentID,
			Valid: true,
		},
		ContextFileOS:        operatingSystem,
		ContextFileDirectory: directory,
	}}, parts...)
}

func sortChatMessagesByCreatedAtAndID(messages []database.ChatMessage) {
	sort.SliceStable(messages, func(i, j int) bool {