Function SafeSplitPoint

internal/compact/strategy.go:23–36

SafeSplitPoint walks backward from `desired` to find an index where the conversation is in a "clean" state — no tool_use without its tool_result on either side of the split. The split happens just before a user message that is plain text (not tool_results). Returns 0 if no safe boundary is found, me

(messages []api.Message, desired int)

// that is plain text (not tool_results). Returns 0 if no safe boundary is
// found, meaning "do nothing."
func SafeSplitPoint(messages []api.Message, desired int) int {
	if desired <= 0 {
		return 0
	}
	if desired >= len(messages) {
		return len(messages)
	}
	for i := desired; i > 0; i-- {
		if messages[i].Role == api.RoleUser && !messages[i].HasToolResult() {
			return i
		}
	}
	return 0
}