Function joinPrompts

pkg/runtime/runtime.go:1904–1913

joinPrompts concatenates two non-empty prompt fragments with a blank line, returning whichever is non-empty when the other isn't. Used by compactWithReason to splice pre_compact's additional_context into the caller's additionalPrompt without having to special-case empty strings at the callsite.

(a, b string)

// the caller's additionalPrompt without having to special-case empty
// strings at the callsite.
func joinPrompts(a, b string) string {
	switch {
	case a == "":
		return b
	case b == "":
		return a
	default:
		return a + "\n\n" + b
	}
}