classDiagram
    direction LR

    %% ====== 数据模型（已存在） ======
    class Message {
        +UUID id
        +UUID conversation_id
        +string sender_type
        +string sender_id
        +string content
        +string msg_type
        +dict extra_data
        +datetime created_at
        +string status
    }

    class OptionSelectExtraData {
        +string question_id
        +string option_id
        +string option_value
        +string client_msg_id
        +string selected_from_message_id
        +string option_label_masked
        +string option_label_original
    }
    OptionSelectExtraData --o Message : embedded in extra_data JSONB

    %% ====== 服务类（已存在 + v1.1 新增） ======
    class OptionSelectHandler {
        +__init__(session_factory)
        +handle(payload, employee_id) Message
        -acquire_advisory_lock(db, key)
        -find_duplicate(db, payload)
        -persist(db, payload, employee_id)
    }

    class ConnectionManager {
        +dict active_connections
        +dict employee_connections
        +__init__()
        +broadcast(data)
        +broadcast_to_employees(ids, data)
    }
    OptionSelectHandler --> ConnectionManager : broadcast + broadcast_to_employees (v1.1)

    %% ★ 新增 v1.1
    class BackendObserver {
        <<singleton>>
        +list events
        +record_event(metric_name, value, tags) void
        +get_metrics(name_filter) list
        +metric_names$ list~string~
    }
    ConnectionManager ..> BackendObserver : triggers latency record
    OptionSelectHandler ..> BackendObserver : commit_ts record

    class SensitiveMask {
        <<utility>>
        +mask_sensitive_text(text) string
        +mask_sensitive_value(value) string
    }
    class H5MessageEndpoint {
        +h5_get_messages(limit, before)
        -_mask_outbound(messages) list
    }
    H5MessageEndpoint --> SensitiveMask : masks option_select content

    %% ====== 前端 store / component ======
    class ConversationStore {
        +Message[] messages
        +bool wsConnected
        +Ref~string[]~ selectedOptionLabels
        +Ref~string[]~ selectedOptionIdsFromHistory
        +sendOptionSelect(value,label,sourceId,qId,oId) void
        +handleNewMessage(data) void
        +handleAiReply(data) void
        +groupedMessagesByQuestion() Message[]
        +latestSelectionForQuestion(qId) string|null
    }
    ConversationStore o-- Message : owns

    class MessageBubble {
        +Message msg
        +bool isLatestInGroup
        +bool isOptionSelectedComputed
        +computed data-question-id
    }
    MessageBubble --> ConversationStore : reads
    MessageBubble --> Message : renders

    class ChatPanel {
        +computed groupedMessages
        +render bubbles
    }
    ChatPanel --> ConversationStore : groupedMessagesByQuestion
    ChatPanel --> MessageBubble : iter

    class UseH5WebSocket {
        +Ref wsConnected
        +computed rttMs
        +onmessage handler
    }
    UseH5WebSocket --> BackendObserver : report e2e latency
    UseH5WebSocket --> ConversationStore : dispatch

    class MeasureOptionLatencyScript {
        <<puppeteer script>>
        +run() Report
        -employeeClick() timestamp
        -agentRender() timestamp
        -diff() ms
    }
    MeasureOptionLatencyScript ..> BackendObserver : queries metrics

    %% 不变量标注
    note for ConversationStore "selectedOptionLabels v1.1 标 deprecated\n仅作日志兼容, UI 判定走 selectedOptionIdsFromHistory"
    note for BackendObserver "命名约定: {feature}_{aspect}_{metric}_{unit}\n例: option_select_broadcast_latency_ms"
    note for Message "msg_type 选项 select 类型\nv1.1 不引入新枚举"