单次变更从来不像问题：一个按钮、一版配色、「手机上也能用就行」。问题在于它们只在加总时才现形，而多数人从不加总——于是到了第八次，你已经白做了小半个项目，却拿不出一个能发给对方的数字。
把变更记录贴进来，代码做四件事：加总工时并算出它占原约定工时的百分比、区分收过钱的和白做的、按你的真实时薪算出白做部分值多少钱，然后——用合同金额除以「原工时＋白做工时」，算出你的实际时薪掉到了多少。最后一个数字是这个工具的重点：它不是观点，是除法，也是最该发给对方看的东西。不是抱怨，是说明为什么下一次变更需要单独计价。
交付日也一并算：新增工时 ÷ 每天可投入小时 = 多少个工作日，跳过周末和中国法定节假日（数据来自公开的节假日日历），给出顺延后的具体日期。变更谈判最常见的失败是只谈钱——对方同意加钱，然后默认交付日不变。
$2 解锁可直接发出的正式变更单、三档沟通话术（温和提示→明确报价→暂停开工），以及下一份合同里该补的两句范围定义。
No single change looks like a problem: one button, one more colour pass, "just make it work on phones". They only become visible in aggregate, and most people never aggregate — so by the eighth request you've given away a third of the project with no number you can send anyone.
Paste the log and the code does four things: totals the hours and expresses them as a percentage of the original scope, separates billed from unbilled, values the unbilled work at your real rate, and then — divides the contract amount by original-plus-unbilled hours to show what your effective rate has fallen to. That last figure is the point of this tool. It isn't an opinion, it's division, and it's the number worth sending: not a complaint, but the reason the next change gets quoted.
The delivery date is computed too: added hours ÷ hours per day = working days, skipping weekends and Chinese public holidays from a public calendar. The most common failure in these conversations is discussing only money — the client agrees to pay and still expects the original date.
$2 unlocks a formal change order you can send, three escalation scripts, and the two clauses your next contract is missing.
正式变更单（新增范围／工时／费用／顺延后的交付日，可直接复制发出）+ 三档沟通话术（温和提示 → 明确报价 → 暂停开工提醒）+ 防复发条款（下一份合同里该补的范围定义与变更计价方式）。A formal change order — added scope, hours, fee and the new delivery date, ready to send — three escalation scripts from gentle notice to work-stops-here, and the scope and change-pricing clauses to add to your next contract.
所有计算都基于你自己填写的工时估算、合同金额与每日投入，估算不准结果就不准——工时请按「改完并联调完」计，不是纯编码时间。判定档位（≤10%／10-25%／>25%）是本工具给的粗口径参考，不是行业标准或合同依据。顺延日期跳过周末与中国大陆法定节假日（数据来自公开日历，可能滞后或不适用于你所在地区），仅供排期参考，不构成对交付日的承诺。是否属于「超出原范围」最终以你与对方签署的合同条款为准，本工具不提供法律意见；金额较大或已产生争议时请咨询律师。你填写的内容不入库。
Every figure derives from your own hour estimates, contract amount and daily capacity — estimate badly and the output is wrong. Count hours through integration and rework, not just coding. The bands (≤10% / 10-25% / >25%) are this tool's rough convention, not an industry standard or contractual basis. The projected date skips weekends and mainland-China public holidays from a public calendar that may lag or not apply where you are; it is scheduling guidance, not a commitment. Whether something exceeds the original scope is determined by your signed contract; this is not legal advice. Consult a lawyer where the amounts are significant or a dispute has started. Nothing you enter is stored.