feat(api,web): 模拟认购订单创建/读取，幂等与预留现金（3d-1）

- API: POST/GET /api/funds/{fundId}/orders，advisory lock + 行级锁事务预留现金，
  幂等键重放/冲突/校验/目录缺失错误码齐全，基金响应新增 reservedCash
- Persistence: subscription_orders 与幂等表 + 保留现金列迁移
- Web: 认购表单与待确认订单列表（已提交·待确认），失败重试复用幂等键，
  token 轮换隔离延迟响应
- 测试: API 41（含并发不足/回滚/真实宿主重启回归）、Web 17、Domain 19；
  浏览器 QA 58 项全过

3 files changed, 347 insertions, 4 deletions

diff --git a/src/FundLab.Web/App.fs b/src/FundLab.Web/App.fs
index 43c438f..5a89b5b 100644
--- a/src/FundLab.Web/App.fs
+++ b/src/FundLab.Web/App.fs
@@ -117,9 +117,29 @@ type FundSummary =
         initialUnitNav: string
         isSynthetic: bool
         availableCash: string
+        reservedCash: string
         status: string
     }
 
+type CreateOrderPayload =
+    {
+        idempotencyKey: string
+        fundCode: string
+        amount: string
+        feeAmount: string
+    }
+
+type RawOrder =
+    {
+        id: string
+        fundCode: string
+        amount: string
+        feeAmount: string
+        reservedTotal: string
+        status: string
+        submittedAt: string
+    }
+
 type CreateAttempt =
     {
         idempotencyKey: string
@@ -127,6 +147,14 @@ type CreateAttempt =
         cash: string
     }
 
+type OrderAttempt =
+    {
+        idempotencyKey: string
+        fundCode: string
+        amount: string
+        feeAmount: string
+    }
+
 module Api =
     [<Import("searchInstruments", "./src/api.js")>]
     let searchInstruments (token: string) (query: string) : JS.Promise<RawSearchResponse> = jsNative
@@ -143,6 +171,12 @@ module Api =
     [<Import("getFund", "./src/api.js")>]
     let getFund (token: string) (fundId: string) : JS.Promise<FundSummary> = jsNative
 
+    [<Import("createOrder", "./src/api.js")>]
+    let createOrder (token: string) (fundId: string) (payload: CreateOrderPayload) : JS.Promise<RawOrder> = jsNative
+
+    [<Import("getOrders", "./src/api.js")>]
+    let getOrders (token: string) (fundId: string) : JS.Promise<RawOrder array> = jsNative
+
     let decodeOptionalText (raw: obj) : string option =
         if isNull raw then
             None
@@ -191,6 +225,13 @@ type Model =
         fundInFlight: bool
         createdFund: FundSummary option
         lastCreateAttempt: CreateAttempt option
+        orderCode: string
+        orderAmount: string
+        orderFee: string
+        orderSeq: int
+        orderInFlight: bool
+        lastOrderAttempt: OrderAttempt option
+        pendingOrders: RawOrder list
         error: string option
     }
 
@@ -213,6 +254,15 @@ type Msg =
     | FundReadRequested
     | FundReadCompleted of requestId: int * fund: FundSummary
     | FundReadFailed of requestId: int * message: string
+    | OrderCodeChanged of string
+    | OrderAmountChanged of string
+    | OrderFeeChanged of string
+    | OrderCreateRequested
+    | OrderCreateCompleted of requestId: int * order: RawOrder
+    | OrderCreateFailed of requestId: int * message: string
+    | OrdersReadRequested
+    | OrdersReadCompleted of requestId: int * orders: RawOrder array
+    | OrdersReadFailed of requestId: int * message: string
 
 let defaultInitialUnitNav = "1.00000000"
 
@@ -221,11 +271,22 @@ let private cashPattern =
 
 let isValidCashText (text: string) = cashPattern.IsMatch text
 
+let isPositiveCash (text: string) =
+    match Decimal.TryParse(text, NumberStyles.Float, CultureInfo.InvariantCulture) with
+    | true, value -> value > 0M
+    | false, _ -> false
+
 let resolveCreateKey (lastAttempt: CreateAttempt option) (name: string) (cash: string) =
     match lastAttempt with
     | Some attempt when attempt.name = name && attempt.cash = cash -> attempt.idempotencyKey
     | _ -> Guid.NewGuid().ToString("N")
 
+let resolveOrderKey (lastAttempt: OrderAttempt option) (code: string) (amount: string) (fee: string) =
+    match lastAttempt with
+    | Some attempt when attempt.fundCode = code && attempt.amount = amount && attempt.feeAmount = fee ->
+        attempt.idempotencyKey
+    | _ -> Guid.NewGuid().ToString("N")
+
 let init () =
     {
         token = ""
@@ -243,6 +304,13 @@ let init () =
         fundInFlight = false
         createdFund = None
         lastCreateAttempt = None
+        orderCode = ""
+        orderAmount = ""
+        orderFee = ""
+        orderSeq = 0
+        orderInFlight = false
+        lastOrderAttempt = None
+        pendingOrders = []
         error = None
     }
 
@@ -287,6 +355,20 @@ let private readFundCommand token fundId requestId =
         (fun fund -> FundReadCompleted(requestId, fund))
         (fun error -> FundReadFailed(requestId, errorText error))
 
+let private createOrderCommand token fundId payload requestId =
+    Cmd.OfPromise.either
+        (fun () -> Api.createOrder token fundId payload)
+        ()
+        (fun order -> OrderCreateCompleted(requestId, order))
+        (fun error -> OrderCreateFailed(requestId, errorText error))
+
+let private readOrdersCommand token fundId requestId =
+    Cmd.OfPromise.either
+        (fun () -> Api.getOrders token fundId)
+        ()
+        (fun orders -> OrdersReadCompleted(requestId, orders))
+        (fun error -> OrdersReadFailed(requestId, errorText error))
+
 let update message model =
     match message with
     | TokenChanged token ->
@@ -306,6 +388,13 @@ let update message model =
                 fundInFlight = false
                 createdFund = None
                 lastCreateAttempt = None
+                orderCode = ""
+                orderAmount = ""
+                orderFee = ""
+                orderSeq = model.orderSeq + 1
+                orderInFlight = false
+                lastOrderAttempt = None
+                pendingOrders = []
                 error = None
         },
         Cmd.none
@@ -456,7 +545,7 @@ let update message model =
                     lastCreateAttempt = None
                     error = None
             },
-            Cmd.none
+            Cmd.ofMsg OrdersReadRequested
         else
             model, Cmd.none
     | FundCreateFailed (requestId, message) ->
@@ -488,6 +577,102 @@ let update message model =
             { model with fundInFlight = false; error = Some message }, Cmd.none
         else
             model, Cmd.none
+    | OrderCodeChanged value ->
+        { model with orderCode = value; error = None; lastOrderAttempt = None }, Cmd.none
+    | OrderAmountChanged value ->
+        { model with orderAmount = value; error = None; lastOrderAttempt = None }, Cmd.none
+    | OrderFeeChanged value ->
+        { model with orderFee = value; error = None; lastOrderAttempt = None }, Cmd.none
+    | OrderCreateRequested ->
+        let code = model.orderCode.Trim()
+        let amount = model.orderAmount.Trim()
+        let fee = model.orderFee.Trim()
+
+        if String.IsNullOrWhiteSpace model.token then
+            { model with error = Some "请输入 API token" }, Cmd.none
+        elif model.createdFund.IsNone then
+            { model with error = Some "请先创建一个基金" }, Cmd.none
+        elif code = "" then
+            { model with error = Some "请输入基金代码" }, Cmd.none
+        elif not (isValidCashText amount) || not (isPositiveCash amount) then
+            { model with error = Some "认购金额必须是大于零的两位小数金额，例如 100.00" }, Cmd.none
+        elif not (isValidCashText fee) || not (isPositiveCash fee) then
+            { model with error = Some "认购手续费必须是大于零的两位小数金额，例如 1.50" }, Cmd.none
+        elif model.orderInFlight then
+            model, Cmd.none
+        else
+            let requestId = model.orderSeq + 1
+            let idempotencyKey = resolveOrderKey model.lastOrderAttempt code amount fee
+
+            {
+                model with
+                    orderCode = code
+                    orderAmount = amount
+                    orderFee = fee
+                    orderSeq = requestId
+                    orderInFlight = true
+                    lastOrderAttempt =
+                        Some
+                            {
+                                idempotencyKey = idempotencyKey
+                                fundCode = code
+                                amount = amount
+                                feeAmount = fee
+                            }
+                    error = None
+            },
+            createOrderCommand
+                model.token
+                model.createdFund.Value.id
+                {
+                    idempotencyKey = idempotencyKey
+                    fundCode = code
+                    amount = amount
+                    feeAmount = fee
+                }
+                requestId
+    | OrderCreateCompleted (requestId, order) ->
+        if requestId = model.orderSeq then
+            {
+                model with
+                    orderInFlight = false
+                    lastOrderAttempt = None
+                    error = None
+            },
+            Cmd.batch [ Cmd.ofMsg FundReadRequested; Cmd.ofMsg OrdersReadRequested ]
+        else
+            model, Cmd.none
+    | OrderCreateFailed (requestId, message) ->
+        if requestId = model.orderSeq then
+            { model with orderInFlight = false; error = Some message }, Cmd.none
+        else
+            model, Cmd.none
+    | OrdersReadRequested ->
+        match model.createdFund with
+        | Some fund when not (String.IsNullOrWhiteSpace model.token) ->
+            let requestId = model.orderSeq + 1
+
+            { model with orderSeq = requestId; error = None },
+            readOrdersCommand model.token fund.id requestId
+        | Some _ ->
+            { model with error = Some "请输入 API token" }, Cmd.none
+        | None ->
+            model, Cmd.none
+    | OrdersReadCompleted (requestId, orders) ->
+        if requestId = model.orderSeq then
+            {
+                model with
+                    pendingOrders = orders |> Array.toList
+                    error = None
+            },
+            Cmd.none
+        else
+            model, Cmd.none
+    | OrdersReadFailed (requestId, message) ->
+        if requestId = model.orderSeq then
+            { model with error = Some message }, Cmd.none
+        else
+            model, Cmd.none
 
 let private navText (text: string) =
     match Decimal.TryParse(text, NumberStyles.Float, CultureInfo.InvariantCulture) with
@@ -794,6 +979,7 @@ let private fundPanel model dispatch =
                         fundSummaryRow "币种" fund.currency
                         fundSummaryRow "初始现金" fund.initialCash
                         fundSummaryRow "可用现金" fund.availableCash
+                        fundSummaryRow "保留现金" fund.reservedCash
                         fundSummaryRow "初始单位净值" fund.initialUnitNav
                         fundSummaryRow "份额" "0（新基金尚未买入持仓）"
                         fundSummaryRow "状态" fund.status
@@ -819,6 +1005,109 @@ let private fundPanel model dispatch =
         ]
     ]
 
+let private orderStatusText (status: string) =
+    if status = "submitted" then "已提交 · 待确认" else status
+
+let private orderRow (order: RawOrder) =
+    Html.div [
+        prop.className "order-row"
+        prop.children [
+            Html.span [ prop.className "order-code"; prop.text order.fundCode ]
+            Html.span [ prop.className "order-cell"; prop.text (sprintf "金额 %s" order.amount) ]
+            Html.span [ prop.className "order-cell"; prop.text (sprintf "手续费 %s" order.feeAmount) ]
+            Html.span [ prop.className "order-cell"; prop.text (sprintf "预留合计 %s" order.reservedTotal) ]
+            Html.span [ prop.className "order-status"; prop.text (orderStatusText order.status) ]
+            Html.span [ prop.className "order-cell"; prop.text order.submittedAt ]
+        ]
+    ]
+
+let private subscribePanel model dispatch =
+    Html.section [
+        prop.className "panel subscribe-panel"
+        prop.children [
+            Html.div [
+                prop.className "section-heading"
+                prop.children [
+                    Html.div [
+                        Html.p [ prop.className "eyebrow"; prop.text "04 / SUBSCRIBE" ]
+                        Html.h2 "认购一笔基金（模拟）"
+                    ]
+                    Html.span [ prop.className "section-note"; prop.text "Pending · no execution" ]
+                ]
+            ]
+            Html.div [
+                prop.className "fund-form-row"
+                prop.children [
+                    Html.label [
+                        prop.className "field-label"
+                        prop.children [
+                            Html.span "基金代码"
+                            Html.input [
+                                prop.className "text-input order-code-input"
+                                prop.placeholder "六位基金代码"
+                                prop.value model.orderCode
+                                prop.onChange (fun value -> dispatch (OrderCodeChanged value))
+                            ]
+                        ]
+                    ]
+                    Html.label [
+                        prop.className "field-label"
+                        prop.children [
+                            Html.span "认购金额（元）"
+                            Html.input [
+                                prop.className "text-input order-amount-input"
+                                prop.placeholder "例如 100.00"
+                                prop.value model.orderAmount
+                                prop.onChange (fun value -> dispatch (OrderAmountChanged value))
+                            ]
+                        ]
+                    ]
+                    Html.label [
+                        prop.className "field-label"
+                        prop.children [
+                            Html.span "认购手续费（元）"
+                            Html.input [
+                                prop.className "text-input order-fee-input"
+                                prop.placeholder "例如 1.50"
+                                prop.value model.orderFee
+                                prop.onChange (fun value -> dispatch (OrderFeeChanged value))
+                            ]
+                        ]
+                    ]
+                    Html.button [
+                        prop.className "primary-action order-submit-action"
+                        prop.disabled model.orderInFlight
+                        prop.onClick (fun _ -> dispatch OrderCreateRequested)
+                        prop.text ((if model.orderInFlight then "下单中..." else "认购下单"): string)
+                    ]
+                ]
+            ]
+            Html.p [
+                prop.className "hint"
+                prop.text "金额与手续费按两位小数字符串提交；下单即冻结现金，订单保持已提交 · 待确认，不产生任何份额或收益。"
+            ]
+            Html.div [
+                prop.className "pending-orders"
+                prop.children [
+                    if List.isEmpty model.pendingOrders then
+                        Html.p [ prop.className "hint"; prop.text "暂无待确认订单" ]
+                    else
+                        yield! (model.pendingOrders |> List.map orderRow)
+                ]
+            ]
+            Html.div [
+                prop.className "panel-actions"
+                prop.children [
+                    Html.button [
+                        prop.className "secondary-action orders-refresh-action"
+                        prop.onClick (fun _ -> dispatch OrdersReadRequested)
+                        prop.text "刷新订单"
+                    ]
+                ]
+            ]
+        ]
+    ]
+
 let view model dispatch =
     Html.main [
         prop.className "app-shell"
@@ -833,7 +1122,7 @@ let view model dispatch =
                             Html.span "FUND LAB"
                         ]
                     ]
-                    Html.span [ prop.className "topbar-status"; prop.text "LEDGER / 3C-1" ]
+                    Html.span [ prop.className "topbar-status"; prop.text "LEDGER / 3D-1" ]
                 ]
             ]
             Html.div [
@@ -844,7 +1133,7 @@ let view model dispatch =
                         prop.children [
                             Html.p [ prop.className "eyebrow"; prop.text "人民币模拟基金 · 观察台" ]
                             Html.h1 "把净值曲线，先看清楚。"
-                            Html.p "从真实基金代码开始，读取、校验并追踪每日单位净值。这里不下单，只保留可复核的数据。"
+                            Html.p "从真实基金代码开始，读取、校验并追踪每日单位净值。认购只生成待确认订单并冻结现金，不执行真实交易。"
                         ]
                     ]
                     Html.div [
@@ -874,7 +1163,8 @@ let view model dispatch =
             searchPanel model dispatch
             navPanel model dispatch
             fundPanel model dispatch
-            Html.footer [ prop.className "footer-note"; prop.text "SOURCE · AKShare   /   STORAGE · PostgreSQL   /   LEDGER · CREATE & READ" ]
+            subscribePanel model dispatch
+            Html.footer [ prop.className "footer-note"; prop.text "SOURCE · AKShare   /   STORAGE · PostgreSQL   /   LEDGER · CREATE & READ & SUBSCRIBE" ]
         ]
     ]
 
diff --git a/src/FundLab.Web/src/api.js b/src/FundLab.Web/src/api.js
index 0d3b6fd..7b4f738 100644
--- a/src/FundLab.Web/src/api.js
+++ b/src/FundLab.Web/src/api.js
@@ -52,3 +52,19 @@ export function createFund(token, payload) {
 export function getFund(token, fundId) {
   return requestJson(`/api/funds/${encodeURIComponent(fundId)}`, token);
 }
+
+export function createOrder(token, fundId, payload) {
+  const body = `{"fundCode":${JSON.stringify(payload.fundCode)},"amount":${JSON.stringify(payload.amount)},"feeAmount":${JSON.stringify(payload.feeAmount)}}`;
+  return requestJson(`/api/funds/${encodeURIComponent(fundId)}/orders`, token, {
+    method: "POST",
+    headers: {
+      "Content-Type": "application/json",
+      "Idempotency-Key": payload.idempotencyKey
+    },
+    body
+  });
+}
+
+export function getOrders(token, fundId) {
+  return requestJson(`/api/funds/${encodeURIComponent(fundId)}/orders`, token);
+}
diff --git a/src/FundLab.Web/src/styles.css b/src/FundLab.Web/src/styles.css
index dcd8833..58d340d 100644
--- a/src/FundLab.Web/src/styles.css
+++ b/src/FundLab.Web/src/styles.css
@@ -479,6 +479,43 @@ h2 {
   margin-top: 10px;
 }
 
+.pending-orders {
+  display: flex;
+  flex-direction: column;
+  gap: 8px;
+}
+
+.order-row {
+  display: flex;
+  flex-wrap: wrap;
+  align-items: center;
+  gap: 10px;
+  padding: 10px 14px;
+  border: 1px solid #e2e8f0;
+  border-radius: 10px;
+  background: #ffffff;
+  font-size: 12px;
+  color: #1f2937;
+}
+
+.order-code {
+  font-family: "SFMono-Regular", Consolas, monospace;
+  font-weight: 700;
+  color: #1e40af;
+}
+
+.order-cell {
+  color: #475569;
+}
+
+.order-status {
+  padding: 2px 10px;
+  border: 1px solid #f1b6b6;
+  border-radius: 999px;
+  color: #b45309;
+  font-size: 11px;
+}
+
 .footer-note {
   padding: 16px 0 34px;
   font-family: "SFMono-Regular", Consolas, monospace;