dsh-long-context-budget

每会话上下文预算：超过预算触发比例时自动剪枝并压缩最早历史，输入框右侧滑杆分级选择，档位与触发比例随配置下发。 / Per-session context budget: prunes and compacts the oldest history at a configurable trigger ratio, with a tiered composer slider whose tiers and trigger ratio follow the host config.