diff --git a/app/processor/base.py b/app/processor/base.py
index 33ca581..32dc489 100644
--- a/app/processor/base.py
+++ b/app/processor/base.py
@@ -1,4 +1,5 @@
 import logging
+import inspect
 import time
 from abc import ABC, abstractmethod
 from typing import TYPE_CHECKING, TypeVar
@@ -30,6 +31,8 @@ class BaseNode(ABC):
 
     def __call__(self, state: T) -> T:
         """执行节点，统一记录日志、耗时并保留业务异常类型"""
+        if inspect.iscoroutinefunction(self.process):
+            return self._acall(state)
         start_time = time.perf_counter()
         self.logger.info("--- %s 开始 ---", self.name)
         try:
@@ -52,6 +55,24 @@ class BaseNode(ABC):
     def process(self, state: T) -> T:
         """子类实现节点核心逻辑，返回状态更新"""
 
+    async def _acall(self, state: T) -> T:
+        """异步节点等待执行完成后再记录结果和耗时"""
+        start_time = time.perf_counter()
+        self.logger.info("--- %s 开始 ---", self.name)
+        try:
+            result = await self.process(state)
+        except (AppError, ValidationError):
+            self.logger.exception("%s 执行失败", self.name)
+            raise
+        except Exception as error:
+            self.logger.exception("%s 执行失败", self.name)
+            raise ImportProcessError(str(error), node_name=self.name) from error
+        else:
+            self.logger.info("--- %s 完成 ---", self.name)
+            return result
+        finally:
+            self.logger.info("%s 耗时 %.3f 秒", self.name, time.perf_counter() - start_time)
+
     def log_step(self, step_name: str, message: str = ""):
         """记录步骤日志。"""
         log_msg = f"[{step_name}]"
diff --git a/app/processor/nodes/requirement_node.py b/app/processor/nodes/requirement_node.py
index e69de29..89b475f 100644
--- a/app/processor/nodes/requirement_node.py
+++ b/app/processor/nodes/requirement_node.py
@@ -0,0 +1,132 @@
+"""需求理解节点"""
+
+from app.clients.decision import DecisionEngine, get_decision_engine
+from app.processor.base import BaseNode
+from app.processor.state import QueryState
+from app.prompt.requirement import build_intent_question
+from app.schemas.base import JsonObject
+from app.schemas.decision import DecisionRequest
+from app.schemas.input_context import InputContext
+
+
+class RequirementNode(BaseNode):
+    name = "requirement_node"
+
+    def __init__(self, *, decision_engine: DecisionEngine | None = None):
+        super().__init__()
+        self._decision_engine = decision_engine
+
+    @staticmethod
+    def build_decision_state(context: InputContext) -> JsonObject:
+        """只整理判断意图需要的摘要，完整 Screen 仍保留在输入上下文"""
+        nodes: list[JsonObject] = []
+        for node in context.screen.nodes:
+            option = node.props.get("option")
+            title = option.get("title") if isinstance(option, dict) else None
+            titles = title if isinstance(title, list) else [title]
+            nodes.append(
+                {
+                    "id": node.id,
+                    "type": node.type,
+                    "name": node.name,
+                    "titles": [
+                        item["text"]
+                        for item in titles
+                        if isinstance(item, dict) and isinstance(item.get("text"), str)
+                    ],
+                    "layout": node.layout.model_dump(mode="json", exclude_unset=True),
+                }
+            )
+        return {
+            "prompt": context.prompt,
+            "context": context.context.model_dump(mode="json", exclude_unset=True),
+            "screen_summary": {
+                "canvas": {
+                    "width": context.screen.canvas.width,
+                    "height": context.screen.canvas.height,
+                },
+                "nodes": nodes,
+                "data_sources": [
+                    {
+                        key: source[key]
+                        for key in ("id", "name", "type")
+                        if key in source
+                    }
+                    for source in context.screen.dataSource
+                ],
+            },
+            "attachments": [
+                {
+                    key: attachment[key]
+                    for key in ("id", "kind", "name")
+                    if key in attachment
+                }
+                for attachment in context.attachments
+            ],
+        }
+
+    async def process(self, state: QueryState) -> QueryState:
+        # 构建jev请求
+        request = DecisionRequest(
+            # 获取 InputNode 整理好的完整上下文
+            state=self.build_decision_state(state["input_context"]),
+            decisions={"intent": build_intent_question()},
+        )
+
+        # 调用 jev
+        engine = self._decision_engine or get_decision_engine()
+        decision = await engine.run(request)
+
+        updated_state: QueryState = {**state, "intent_decision": decision}
+        return updated_state
+
+
+if __name__ == "__main__":
+    import asyncio
+    import json
+
+    from pydantic import BaseModel
+
+    from app.processor.nodes.input_node import InputNode
+
+    async def main():
+        # 1. 修改这里的请求，测试不同意图
+        state: QueryState = {
+            "request": {
+                "prompt": "这个图太乱了，帮我重新排一下",
+                "screen": {
+                    "canvas": {"width": 1920, "height": 1080},
+                    "nodes": [
+                        {
+                            "id": "sales-chart",
+                            "type": "bar-chart",
+                            "name": "销售额统计",
+                            "layout": {"x": 26, "y": 34.8, "width": 400, "height": 260},
+                            "props": {"option": {"title": {"text": "销售额统计"}}},
+                        }
+                    ],
+                    "dataSource": [],
+                },
+                "context": {"selected_node_ids": ["sales-chart"]},
+            }
+        }
+        # 2. 先校验输入，再真实调用 Jev，退出时关闭连接
+        state = InputNode().process(state)
+        async with DecisionEngine() as engine:
+            node = RequirementNode(decision_engine=engine)
+            final_state = await node.process(state)
+        # 3. 打印完整 state，包含选项、概率、置信度和调用信息
+        print(
+            json.dumps(
+                {
+                    key: value.model_dump(mode="json", exclude_unset=True)
+                    if isinstance(value, BaseModel)
+                    else value
+                    for key, value in final_state.items()
+                },
+                ensure_ascii=False,
+                indent=2,
+            )
+        )
+
+    asyncio.run(main())
diff --git a/app/processor/state.py b/app/processor/state.py
index 1e755fb..3b680dd 100644
--- a/app/processor/state.py
+++ b/app/processor/state.py
@@ -2,8 +2,10 @@ from typing import NotRequired, TypedDict
 
 from app.schemas.base import JsonObject
 from app.schemas.input_context import InputContext
+from app.schemas.decision import DecisionResponse
 
 
 class QueryState(TypedDict):
     request: JsonObject
     input_context: NotRequired[InputContext]
+    intent_decision: NotRequired[DecisionResponse]
diff --git a/app/prompt/requirement.py b/app/prompt/requirement.py
new file mode 100644
index 0000000..5b64de2
--- /dev/null
+++ b/app/prompt/requirement.py
@@ -0,0 +1,24 @@
+"""需求节点的意图判断定义"""
+
+from app.schemas.decision import ChoiceDecision
+
+
+def build_intent_question() -> ChoiceDecision:
+    return ChoiceDecision(
+        # 判断主要意图；只有明确要求实际编辑时才判断为修改，不能仅根据选中节点判断
+        instructions=(
+            "Classify the user's primary intent. "
+            "Choose modify_screen only when the user explicitly requests an actual edit. "
+            "Do not infer editing solely from selected nodes."
+        ),
+        criteria={
+            # 创建新的大屏
+            "create_screen": "Create a new screen",
+            # 明确要求修改、增加、删除或重新设计已有大屏
+            "modify_screen": "Explicitly request modifying, adding, deleting, or redesigning an existing screen",
+            # 询问知识、原因、建议或如何修改，但没有要求实际执行
+            "qa": "Ask for information, reasons, suggestions, or how to improve something without requesting an actual edit",
+            # 无法判断意图或不属于上述类型
+            "unclear": "Intent is unclear or outside the above categories",
+        },
+    )
diff --git a/app/schemas/decision.py b/app/schemas/decision.py
index fa76de7..2de22db 100644
--- a/app/schemas/decision.py
+++ b/app/schemas/decision.py
@@ -6,42 +6,60 @@ from pydantic import BaseModel, ConfigDict, Field, JsonValue, model_validator
 
 from .base import NonBlankString
 
+# 文本或结构化 JSON，用于传递上下文和判断说明
 Content = str | dict[str, JsonValue] | list[JsonValue]
+# 概率和置信度都限制在 0～1
 Probability = Annotated[float, Field(ge=0, le=1)]
 
 
 class DecisionModel(BaseModel):
+    """公共校验规则：拒绝未知字段、隐式类型转换和非有限数值"""
+
     model_config = ConfigDict(extra="forbid", strict=True, allow_inf_nan=False)
 
 
 class ChoiceDecision(DecisionModel):
+    """选择题：从候选项中选择一个"""
+
     type: Literal["choice"] = "choice"
-    instructions: Content
+    instructions: Content  # 告诉模型要判断什么
     criteria: dict[NonBlankString, Content | None] = Field(min_length=1, max_length=255)
+    # criteria 的键是选项，值是说明，不需要说明时填 None
 
 
 class ScoreDecision(DecisionModel):
+    """评分题：按从低到高排列的等级进行评分"""
+
     type: Literal["score"] = "score"
     instructions: Content
-    criteria: list[Content] = Field(min_length=2, max_length=10)
+    criteria: list[Content] = Field(min_length=2, max_length=10)  # 等级从 0 开始编号
 
 
 class NoulDecision(DecisionModel):
+    """判断题：返回命题成立的概率，不直接返回布尔值"""
+
     type: Literal["noul"] = "noul"
     instructions: Content
-    criteria: dict[Literal["true", "false"], Content] | None = None
+    criteria: dict[Literal["true", "false"], Content] | None = (
+        None  # 可选的成立与不成立说明
+    )
 
 
+# 根据 type 选择对应模型，避免混用选择题和评分题的字段
 DecisionSchema = Annotated[
     ChoiceDecision | ScoreDecision | NoulDecision, Field(discriminator="type")
 ]
 
 
 class DecisionRequest(DecisionModel):
-    state: Content
-    decisions: dict[NonBlankString, DecisionSchema] = Field(min_length=1)
-    model: NonBlankString | None = None
-    # 官方扩展字段入口，不允许覆盖已经校验的协议字段。
+    """一次调用的输入，可同时提交多个独立判断"""
+
+    state: Content  # 所有判断共享的业务上下文
+    decisions: dict[NonBlankString, DecisionSchema] = Field(
+        min_length=1
+    )  # 键用于对应返回结果
+    model: NonBlankString | None = None  # 不传时使用客户端默认模型
+    # 官方扩展字段入口，不允许覆盖已经校验的协议字段
     extra_body: dict[str, JsonValue] = Field(default_factory=dict)
 
     @model_validator(mode="after")
@@ -52,37 +70,48 @@ class DecisionRequest(DecisionModel):
 
 
 class ChoiceResult(DecisionModel):
+    """选择结果及所有候选项的概率分布"""
+
     type: Literal["choice"] = "choice"
-    choice: str
-    confidence: Probability
-    probabilities: dict[str, Probability]
+    choice: str  # 选中的候选项
+    confidence: Probability  # 分布的集中程度，不等于选中项的概率
+    probabilities: dict[str, Probability]  # 选项 → 概率
 
 
 class ScoreResult(DecisionModel):
+    """评分结果，保留等级说明和概率分布"""
+
     type: Literal["score"] = "score"
-    score: float = Field(ge=0)
+    score: float = Field(ge=0)  # 按等级概率加权的分数，可能是小数
     confidence: Probability
-    legend: dict[str, Content]
-    probabilities: dict[str, Probability]
+    legend: dict[str, Content]  # 等级编号字符串 → 等级说明
+    probabilities: dict[str, Probability]  # 等级编号字符串 → 概率
 
 
 class NoulResult(DecisionModel):
+    """成立概率：接近 1 表示是，接近 0 表示否，接近 0.5 表示不确定"""
+
     type: Literal["noul"] = "noul"
-    noul: Probability
+    noul: Probability  # 没有单独的 confidence，业务自行决定判断阈值
 
 
+# 返回结果也按 type 区分，读取前先确认结果类型
 DecisionResult = Annotated[
     ChoiceResult | ScoreResult | NoulResult, Field(discriminator="type")
 ]
 
 
 class DecisionUsage(DecisionModel):
+    """本次调用的 token 用量，None 表示服务端未提供"""
+
     input_tokens: int | None = Field(default=None, ge=0)
     output_tokens: int | None = Field(default=None, ge=0)
 
 
 class DecisionResponse(DecisionModel):
-    results: dict[str, DecisionResult]
-    model: str
+    """统一返回结构，包含判断结果和调用信息"""
+
+    results: dict[str, DecisionResult]  # 键与请求中的 decisions 一一对应
+    model: str  # 实际执行判断的模型
     usage: DecisionUsage
-    request_id: str | None = None
+    request_id: str | None = None  # 服务端请求标识，方便排查问题
diff --git a/app/schemas/requirement.py b/app/schemas/requirement.py
new file mode 100644
index 0000000..e01407d
--- /dev/null
+++ b/app/schemas/requirement.py
@@ -0,0 +1,73 @@
+"""需求理解的输出协议，描述用户诉求，不包含前端执行动作。"""
+
+from typing import Literal, Self
+
+from pydantic import Field, model_validator
+
+from .base import ExtensibleModel, JsonObject, NonBlankString
+
+Intent = Literal["create_screen", "modify_screen", "qa", "unclear"]
+TargetScope = Literal["nodes", "canvas", "screen", "unresolved"]
+
+
+class RequirementChange(ExtensibleModel):
+    """一项需求变更。目标范围显式声明，避免空 ID 被理解成修改整个大屏。"""
+
+    target_scope: TargetScope = Field(
+        description="nodes=已有节点；canvas=画布属性；screen=整体或新增内容；unresolved=目标待确认"
+    )
+    target_ids: list[NonBlankString] = Field(
+        default_factory=list, description="已有节点的 ID；新增组件不能虚构 ID"
+    )
+    target_description: NonBlankString | None = Field(
+        default=None, description="目标的自然语言描述，例如右侧区域、用户所说的那个图"
+    )
+    operation: NonBlankString = Field(
+        description="需求操作，例如 move、resize、add、delete、restyle；允许后续扩展"
+    )
+    parameters: JsonObject = Field(
+        default_factory=dict,
+        description="需求参数，例如 delta_x=50；保留用户要求的单位与相对变化语义",
+    )
+
+    @model_validator(mode="after")
+    def validate_target(self) -> Self:
+        if len(self.target_ids) != len(set(self.target_ids)):
+            raise ValueError("target_ids 不能包含重复 ID")
+        if self.target_scope == "nodes":
+            if not self.target_ids:
+                raise ValueError("nodes 范围必须提供 target_ids")
+        elif self.target_ids:
+            raise ValueError("只有 nodes 范围可以提供 target_ids")
+        if self.target_scope == "unresolved" and self.target_description is None:
+            raise ValueError("目标待确认时必须提供 target_description")
+        return self
+
+
+class Requirement(ExtensibleModel):
+    intent: Intent
+    goal: NonBlankString = Field(description="忠实概括用户目标，不能擅自扩大修改范围")
+    changes: list[RequirementChange] = Field(default_factory=list)
+    needs_clarification: bool
+    clarification_question: NonBlankString | None = None
+    needs_planning: bool = Field(description="是否需要布局或设计规划，与修改范围分别判断")
+    needs_resources: bool = Field(description="是否需要补充查询组件、数据、模板或素材")
+    assumptions: list[NonBlankString] = Field(
+        default_factory=list, description="非阻塞信息采用的默认假设，不可用来猜测删除目标"
+    )
+    constraints: list[NonBlankString] = Field(
+        default_factory=list, description="用户明确提出的约束，例如只修改右侧、保留其他组件"
+    )
+
+    @model_validator(mode="after")
+    def validate_consistency(self) -> Self:
+        if self.needs_clarification != (self.clarification_question is not None):
+            raise ValueError("需要澄清时必须提供问题，不需要澄清时问题应为 null")
+        if self.intent == "unclear" and not self.needs_clarification:
+            raise ValueError("意图不明确时必须澄清")
+        if any(change.target_scope == "unresolved" for change in self.changes):
+            if not self.needs_clarification:
+                raise ValueError("存在待确认目标时必须澄清")
+        if self.intent == "qa" and self.changes:
+            raise ValueError("纯问答需求不应包含大屏变更")
+        return self
diff --git a/app/schemas/screen.py b/app/schemas/screen.py
new file mode 100644
index 0000000..c66349a
--- /dev/null
+++ b/app/schemas/screen.py
@@ -0,0 +1,48 @@
+"""大屏公共结构；组件属性、事件与数据源配置保持开放"""
+
+from typing import Annotated, Self
+
+from pydantic import Field, model_validator
+
+from .base import ExtensibleModel, JsonObject, NonBlankString
+
+Number = int | float
+PositiveNumber = Annotated[Number, Field(gt=0)]
+
+
+class Canvas(ExtensibleModel):
+    width: PositiveNumber
+    height: PositiveNumber
+
+
+class Layout(ExtensibleModel):
+    x: Number
+    y: Number
+    width: PositiveNumber
+    height: PositiveNumber
+
+
+class ScreenNode(ExtensibleModel):
+    id: NonBlankString
+    type: NonBlankString
+    layout: Layout
+    name: str | None = None
+    props: JsonObject = Field(default_factory=dict)
+    style: JsonObject | None = None
+    events: list[JsonObject] | None = None
+
+
+class Screen(ExtensibleModel):
+    canvas: Canvas
+    nodes: list[ScreenNode]
+    # 保持前端字段名；数据源的具体类型与绑定校验后续再引入
+    dataSource: list[JsonObject] = Field(default_factory=list)
+
+    @model_validator(mode="after")
+    def unique_node_ids(self) -> Self:
+        seen: set[str] = set()
+        for node in self.nodes:
+            if node.id in seen:
+                raise ValueError(f"重复的节点 ID: {node.id}")
+            seen.add(node.id)
+        return self