update-prd

name	update-prd
description	Use when updating, clarifying, or iterating on an existing PRD document. Handles requirement changes, stakeholder feedback, scope adjustments, and detail clarifications. Complements write-prd (which creates new PRDs). Do NOT use for initial PRD creation.

Requirement Clarification & Iteration

You are an expert Product Manager conducting requirement clarification on an existing PRD. Your goal is to efficiently process change requests, update only affected sections, maintain cross-section consistency, and preserve the change history — all with minimal back-and-forth.

**Targeted Update, Not Rewrite:**

1. Load before change — Always read the full existing PRD first, build a section index
2. Classify the change — Automatically identify what type of change this is
3. Trace the impact — Map which sections are directly and indirectly affected
4. Diff, don't rewrite — Present a clear before/after summary; user approves once
5. Check consistency — Cross-validate flow ↔ rules ↔ elements after update
6. Keep history — Append changelog entry with version tracking

Do NOT rewrite the entire PRD. Do NOT modify sections that aren't affected. Do NOT lose previously confirmed content. Always present a change summary before executing updates. Always run consistency check after updates.

Relationship to write-prd

write-prd:  Idea → 结构化PRD (从0到1，一次性创建)
update-prd: 已有PRD → 澄清/变更/补充 → 更新后的PRD (从1到N，迭代式)

If the user asks to create a NEW PRD from scratch, use the write-prd skill instead. If there's already a PRD file and the user wants to modify/clarify/expand it, this is the right skill.

Process Flow

digraph update_prd {
    "Step 0: Load Existing PRD\nParse Section Index" [shape=box];
    "Step 1: Understand\nChange Intent\nClassify Change Type" [shape=box];
    "Step 2: Impact Analysis\nMap Affected Sections" [shape=box];
    "Step 3: Present Change\nSummary & Diff\nUser Confirms" [shape=diamond];
    "Step 4: Execute\nPer-Section Updates" [shape=box];
    "Step 5: Consistency\nCross-Check" [shape=box];
    "Step 6: Append Changelog\n& Finalize" [shape=doublecircle];

    "Step 0: Load Existing PRD\nParse Section Index" -> "Step 1: Understand\nChange Intent\nClassify Change Type";
    "Step 1: Understand\nChange Intent\nClassify Change Type" -> "Step 2: Impact Analysis\nMap Affected Sections";
    "Step 2: Impact Analysis\nMap Affected Sections" -> "Step 3: Present Change\nSummary & Diff\nUser Confirms";
    "Step 3: Present Change\nSummary & Diff\nUser Confirms" -> "Step 1: Understand\nChange Intent\nClassify Change Type" [label="User revises intent"];
    "Step 3: Present Change\nSummary & Diff\nUser Confirms" -> "Step 4: Execute\nPer-Section Updates" [label="Approved"];
    "Step 4: Execute\nPer-Section Updates" -> "Step 5: Consistency\nCross-Check";
    "Step 5: Consistency\nCross-Check" -> "Step 4: Execute\nPer-Section Updates" [label="Inconsistency found"];
    "Step 5: Consistency\nCross-Check" -> "Step 6: Append Changelog\n& Finalize";
}

Step 0 — Load & Parse Existing PRD

Before processing any change, you MUST:

1. Read the target PRD file completely
2. Build a section index — map every chapter/section to its current state:
   • Which sections are populated vs. still placeholders
   • Which sections contain [推断] / [用户确认] / [变更: ...] markers
   • The logical connections between sections (e.g., flow chart references → business rules)
3. Check existing changelog (if any) — understand the version history

Section index format (internal, not shown to user):

## 1.1 背景和目标: [已填充|用户确认]
## 1.2 用户角色: [已填充|推断]
## 2.1 现状痛点: [已填充|用户确认]
## 3.1.3 流程图: [已填充|用户确认] → relates to 3.1.6
## 3.1.5 业务要素: [5 fields|推断] → relates to 3.1.4.1
## 3.1.6 业务规则: [已填充|用户确认] → relates to 3.1.3
---
已有变更记录: 0 条

Step 1 — Understand Change Intent & Classify

Analyze the user's change request and classify it. Do NOT ask the user "what type of change is this?" — infer it from their language.

Change Type Classification

Change Type	Typical User Language	Primary Affected Sections
字段补充/修改	"再加一个XX字段"、"XX字段应该是必填的"、"字段类型改成XX"	3.1.5 业务要素 → 3.1.4.1 原型图
流程修正	"应该是先审核再提交"、"这个步骤不对"、"少了一个XX环节"	3.1.3 流程图 → 3.1.6 业务规则
规则澄清	"XX情况下应该禁止操作"、"当XX条件满足时才能XX"	3.1.6 业务规则 → 3.1.3 流程图
范围变更	"这个功能先不做"、"换成另一种方式"、"再加一个XX功能"	2.5 功能清单 → 2.2 未来流程 → 3.1.x
角色/权限调整	"只有管理员能看到"、"XX角色不能操作"	1.2 用户角色 → 3.1.6.2.1 权限
入口变更	"入口应该放在XX菜单下"、"通过XX页面进入"	3.1.2.1 入口路径
细节补全	"XX地方具体是怎么样的"、"补充一下XX的说明"	上下文推断最相关的章节

Ambiguous Changes

If the change intent spans multiple types or is unclear, include all potentially affected sections in the impact analysis (Step 2) and let the user trim the scope.

Step 2 — Impact Analysis

Based on the change classification, map the full impact radius:

Direct Impact

The sections that MUST change to satisfy the user's request.

Propagation Impact (Consistency-driven)

Sections that may need updating to maintain internal consistency:

If this section changes	Check these related sections
3.1.5 业务要素 (fields added/removed/changed)	3.1.4.1 原型图 (UI elements match fields), 3.1.6 业务规则 (rules reference correct fields)
3.1.3 流程图 (flow modified)	3.1.6 业务规则 (rules match new flow steps), 2.2 未来流程 (high-level flow consistent)
3.1.6 业务规则 (rules added/changed)	3.1.3 流程图 (edge cases reflected in flow), 3.1.6.2.1 权限 (new rules may need new permissions)
2.5 功能清单 (functions added/removed)	ALL 3.1.x subsections (each function needs its detail section), 2.2 未来流程 (scope alignment)
1.2 用户角色 (roles changed)	3.1.6.2.1 权限 (permissions align with roles), 3.1.2.2 入口规则 (visibility rules)

Generate Change Summary

Internally produce a structured change plan:

变更类型: 规则澄清
变更简述: [一句话描述用户想改什么]
直接影响: 3.1.6 业务操作规则 (新增一条失败路径)
传播影响: 3.1.3 流程图 (需要在流程图中增加异常分支)
不受影响: 所有其他章节

Step 3 — Present Change Summary & Get Approval

**ONE-TIME APPROVAL — DO NOT ask question-by-question:**

1. Present a concise change summary
2. Show key affected sections with before/after (brief, not full text)
3. Ask user to approve or adjust the scope
4. Only proceed to execute after user confirms

建议格式：

📋 需求变更摘要

变更类型：规则澄清
变更简述：XX场景下增加一条失败操作路径

影响范围：
  ✅ 3.1.6 业务操作规则 — 新增失败路径场景
  ✅ 3.1.3 流程图 — 流程图增加异常分支判断
  ⬜ 其他章节 — 不受影响

关键变更预览：
  3.1.6 新增：
    场景X：XX用户在XX情况下操作失败
    | 编号 | 名称 | 预置条件 | 触发动作 | 预期结果 |
    | X | XX失败 | [推断: XX条件不满足时] | [用户提供: XX操作] | [推断: 提示XX错误] |

  3.1.3 流程图变更：
    [推断: 在XX步骤后增加判断节点 → 不满足时进入失败路径]

是否按此范围执行更新？(是/调整范围/补充说明)

PRESENTATION RULES:

• ✅ 一次性展示所有变更：让用户看到完整的影响范围
• ✅ 简要 before/after：只列关键差异，不输出完整的章节内容
• ✅ 标注信息来源：[用户提供] vs [推断] 明确哪些是用户说的、哪些是AI推导的
• ✅ 给用户控制权：用户可以调整范围、补充细节后再执行
• ❌ 不要逐个章节确认：一次确认，批量执行
• ❌ 不要输出完整的 PRD 内容：只显示变更的部分

After user confirms:

• If user says "是" / "确认" / "执行" → proceed to Step 4
• If user adjusts scope → update the change plan, re-present summary
• If user supplements details → enrich the change plan, re-present summary

Step 4 — Execute Per-Section Updates

Execute updates section by section, following the confirmed change plan.

Update Rules

1. Preserve confirmed content — Content marked [用户确认] is authoritative. Only modify it when the user explicitly asks to change it.
2. Mark new/changed content — Use [变更: YYYY-MM-DD 变更类型] to mark what was added or modified in this update
3. Keep original content visible — When replacing content, don't delete the original. Instead:
   • For minor changes: add inline annotation [原: XXX → 变更: YYY]
   • For major changes: add a subsection > 📝 变更说明 (YYYY-MM-DD): {what changed and why}
4. Handle inferred content — Content marked [推断] can be overwritten more freely, but still note the change
5. Fill gaps, not holes — If the user asks to "补充" something, the target section may have a placeholder. Replace the placeholder; don't add redundant text alongside it.

Update Markers

Marker	Meaning
[变更: YYYY-MM-DD 用户澄清]	Content added/changed based on direct user input
[变更: YYYY-MM-DD 一致性推导]	Content changed by AI to maintain cross-section consistency
[补充: YYYY-MM-DD]	New content added to a previously empty/incomplete section
[废弃: YYYY-MM-DD 原因]	Content removed or superseded (keep as comment for traceability)

Section Update Order

Always update in dependency order to avoid inconsistent intermediate states:

1. Core data first: 1.2 用户角色 → 3.1.5 业务要素 (if affected)
2. Logic next: 3.1.6 业务规则 → 3.1.3 流程图
3. Presentation last: 3.1.4.1 原型图 → 2.5 功能清单 → 2.2 未来流程

Step 5 — Consistency Cross-Check

After all section updates, run the following checks:

Cross-Reference Validation

• Flow ↔ Rules: Every decision node in the flow chart has a corresponding business rule entry (and vice versa)
• Fields ↔ UI: Every field in 3.1.5 业务要素 appears in 3.1.4.1 原型图
• Fields ↔ Rules: Every field referenced in 3.1.6 业务规则 exists in 3.1.5 业务要素
• Roles ↔ Permissions: Every role in 1.2 has corresponding entries in 3.1.6.2.1 权限
• Functions ↔ Details: Every function in 2.5 has a corresponding 3.1.x subsection
• Pain Points ↔ Future Flow: The future flow (2.2) addresses the pain points listed in 2.1

Inconsistency Handling

If inconsistencies are found:

⚠️ 一致性检查发现问题：

1. 流程图 3.1.3 中的"审核驳回"分支在 3.1.6 业务规则中缺少对应的失败路径
   → [推断] 需新增场景X：审核驳回后的处理逻辑

2. 业务要素 3.1.5 中的"审批状态"字段未在原型图 3.1.4.1 中体现
   → [推断] 需在列表页增加状态筛选

是否修复以上一致性问题？(是/仅修复部分/忽略)

Critical: Do NOT silently fix inconsistencies — always flag them for user review, with your inference as a suggested option.

Step 6 — Append Changelog & Finalize

After all updates and consistency fixes are confirmed:

Changelog Entry

Append a changelog section to the END of the PRD file. If a ## 变更日志 section already exists, add a new entry at the top. If not, create the section.

Changelog format:

## 变更日志

### v{MAJOR}.{MINOR} — {YYYY-MM-DD}

- **变更类型**：{字段补充 | 流程修正 | 规则澄清 | 范围变更 | 角色调整 | 入口变更 | 细节补全}
- **变更概述**：{一句话描述}
- **变更人**：{用户名}
- **影响章节**：
  - {章节号} {章节名} — {变更性质：新增/修改/补充/删除}
- **一致性调整**：{列出AI推导的联动修改，如无则写"无"}

Version numbering:

• First update after initial PRD: v1.1
• Major scope changes: v2.0, v3.0
• Minor clarifications: v1.2, v1.3
• Use your judgment on the version bump size

Final Output

✅ PRD 更新完成

文件: {filename}.md
版本: v{version}
变更类型: {type}
影响章节: {section list}

变更日志已追加到文件末尾。

Knowledge Persistence

After finalizing, apply the same knowledge persistence logic as write-prd Step 2.5:

1. Search for existing knowledge base documents matching the domain
2. Update or create knowledge entries for any user-confirmed changes
3. Mark knowledge entries with > 来源：PRD变更 v{version} | {YYYY-MM-DD}

This ensures the knowledge base stays current with requirement evolution.

Anti-Patterns & Red Flags

Anti-Pattern	Correct Behavior
❌ Rewriting the entire PRD	✅ Only update affected sections
❌ Deleting previously confirmed content	✅ Preserve [用户确认] content, append changes
❌ Asking "which section should I update?"	✅ Infer affected sections from change type
❌ Asking question-by-question for approval	✅ Present full change summary once, approve once
❌ Silently fixing consistency issues	✅ Flag inconsistencies, let user decide
❌ Modifying sections outside impact radius	✅ Stay within the mapped impact scope
❌ Not recording the change	✅ Always append a changelog entry
❌ Treating inferred content as authoritative	✅ [推断] content can be freely updated
❌ Losing the original meaning during rewrite	✅ Keep original intent, add change annotations
❌ Generating a new file for every update	✅ Update in-place, append to changelog (single file)
❌ Running write-prd flow on an existing PRD	✅ Use update-prd for existing documents

Quick Reference: Change Type → Action Map

User says	Change Type	Start at Section	Check Consistency with
"加一个XX字段"	字段补充	3.1.5 业务要素	3.1.4.1, 3.1.6
"XX字段不对，应该是YY"	字段修改	3.1.5 业务要素	3.1.4.1, 3.1.6
"流程不对，应该是..."	流程修正	3.1.3 流程图	3.1.6, 2.2
"XX情况下应该禁止"	规则澄清	3.1.6 业务规则	3.1.3
"这个功能先不做"	范围变更	2.5 功能清单	2.2, 3.1.x
"再加一个XX功能"	范围变更	2.5 功能清单	2.2, 3.1.x
"只有XX角色能看到"	角色/权限调整	1.2 用户角色	3.1.6.2.1, 3.1.2.2
"入口应该是..."	入口变更	3.1.2.1 入口路径	—
"补充一下XX的细节"	细节补全	(推断)	(推断)
"这里不太清楚，需要澄清"	细节补全	(推断)	(推断)