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

5 files changed, 777 insertions, 8 deletions

diff --git a/src/FundLab.Api/App.fs b/src/FundLab.Api/App.fs
index f61e760..a2aa271 100644
--- a/src/FundLab.Api/App.fs
+++ b/src/FundLab.Api/App.fs
@@ -22,9 +22,23 @@ type FundApiResponse =
         initialUnitNav: string
         isSynthetic: bool
         availableCash: string
+        reservedCash: string
         status: string
     }
 
+type SubscriptionOrderApiResponse =
+    {
+        id: Guid
+        fundId: Guid
+        fundCode: string
+        amount: string
+        feeAmount: string
+        reservedTotal: string
+        status: string
+        submittedAt: string
+        isSynthetic: bool
+    }
+
 type ApiErrorResponse =
     {
         error: string
@@ -86,9 +100,23 @@ module App =
             initialUnitNav = unitNavText fund.InitialUnitNav
             isSynthetic = fund.IsSynthetic
             availableCash = cashText fund.AvailableCash
+            reservedCash = cashText fund.ReservedCash
             status = fund.Status
         }
 
+    let private orderResponse (order: SubscriptionOrderRecord) : SubscriptionOrderApiResponse =
+        {
+            id = order.Id
+            fundId = order.FundId
+            fundCode = order.FundCode
+            amount = cashText order.Amount
+            feeAmount = cashText order.FeeAmount
+            reservedTotal = cashText order.ReservedTotal
+            status = order.Status
+            submittedAt = timestampText order.SubmittedAt
+            isSynthetic = order.IsSynthetic
+        }
+
     let private errorResponse status error message : HttpHandler =
         setStatusCode status
         >=> json ({
@@ -148,6 +176,30 @@ module App =
         with
         | :? JsonException -> Error "request body must be valid JSON"
 
+    let private parseOrderCommand (body: string) =
+        try
+            use document = JsonDocument.Parse(body)
+            let root = document.RootElement
+
+            if root.ValueKind <> JsonValueKind.Object then
+                Error "request body must be a JSON object"
+            else
+                match tryStringProperty root "fundCode", tryStringProperty root "amount", tryStringProperty root "feeAmount" with
+                | Some fundCode, Some amountText, Some feeAmountText ->
+                    match tryDecimal "amount" amountText, tryDecimal "feeAmount" feeAmountText with
+                    | Ok amount, Ok feeAmount ->
+                        Ok {
+                            FundCode = fundCode
+                            Amount = amount
+                            FeeAmount = feeAmount
+                        }
+                    | Error message, _
+                    | _, Error message -> Error message
+                | _ ->
+                    Error "fundCode, amount and feeAmount are required"
+        with
+        | :? JsonException -> Error "request body must be valid JSON"
+
     let private invokeHandler handler next ctx = handler next ctx
 
     let private unauthorized : HttpHandler =
@@ -216,6 +268,55 @@ module App =
                 with _ ->
                     errorResponse 500 "PERSISTENCE_ERROR" "fund persistence failed" next ctx
 
+    let private createOrder (repository: FundRepository) (fundIdText: string) : HttpHandler =
+        fun next ctx ->
+            task {
+                match Guid.TryParse fundIdText with
+                | false, _ ->
+                    return! invokeHandler (errorResponse 400 "INVALID_FUND_ID" "fund id must be a UUID") next ctx
+                | true, fundId ->
+                    use reader = new StreamReader(ctx.Request.Body)
+                    let! body = reader.ReadToEndAsync()
+                    let idempotencyKey = ctx.Request.Headers["Idempotency-Key"].ToString()
+
+                    match parseOrderCommand body with
+                    | Error message ->
+                        return! invokeHandler (errorResponse 400 "INVALID_ORDER_REQUEST" message) next ctx
+                    | Ok command ->
+                        try
+                            match repository.CreateSubscriptionOrder(idempotencyKey, fundId, command) with
+                            | SubscriptionOrderWriteResult.OrderCreated order ->
+                                return! invokeHandler (setStatusCode 201 >=> json (orderResponse order)) next ctx
+                            | SubscriptionOrderWriteResult.OrderReplayed order ->
+                                return! invokeHandler (json (orderResponse order)) next ctx
+                            | SubscriptionOrderWriteResult.OrderIdempotencyConflict ->
+                                return! invokeHandler (errorResponse 409 "IDEMPOTENCY_CONFLICT" "idempotency key was used with a different request") next ctx
+                            | SubscriptionOrderWriteResult.OrderInvalid message ->
+                                return! invokeHandler (errorResponse 400 "INVALID_ORDER_REQUEST" message) next ctx
+                            | SubscriptionOrderWriteResult.OrderFundNotFound ->
+                                return! invokeHandler (errorResponse 404 "FUND_NOT_FOUND" "fund was not found") next ctx
+                            | SubscriptionOrderWriteResult.OrderInstrumentNotFound ->
+                                return! invokeHandler (errorResponse 404 "INSTRUMENT_NOT_FOUND" "fund code was not found in the instrument catalog") next ctx
+                            | SubscriptionOrderWriteResult.OrderInsufficientFunds ->
+                                return! invokeHandler (errorResponse 409 "INSUFFICIENT_FUNDS" "available cash is not enough to reserve the amount plus fee") next ctx
+                        with _ ->
+                            return! invokeHandler (errorResponse 500 "PERSISTENCE_ERROR" "order persistence failed") next ctx
+            }
+
+    let private getOrders (repository: FundRepository) (fundIdText: string) : HttpHandler =
+        fun next ctx ->
+            match Guid.TryParse fundIdText with
+            | false, _ -> errorResponse 400 "INVALID_FUND_ID" "fund id must be a UUID" next ctx
+            | true, fundId ->
+                try
+                    match repository.GetFund fundId with
+                    | None -> errorResponse 404 "FUND_NOT_FOUND" "fund was not found" next ctx
+                    | Some _ ->
+                        let orders = repository.GetSubscriptionOrders fundId
+                        json (orders |> List.map orderResponse) next ctx
+                with _ ->
+                    errorResponse 500 "PERSISTENCE_ERROR" "order persistence failed" next ctx
+
     let private marketDataError (failure: MarketDataFailure) : HttpHandler =
         let status, error, message =
             match failure with
@@ -311,6 +412,8 @@ module App =
             [
                 GET >=> route "/portfolio/summary" >=> emptyPortfolio
                 POST >=> route "/funds" >=> createFund repository
+                POST >=> routef "/funds/%s/orders" (createOrder repository)
+                GET >=> routef "/funds/%s/orders" (getOrders repository)
                 GET >=> routef "/funds/%s" (getFund repository)
             ]
             @ (marketData |> Option.map marketDataRoutes |> Option.defaultValue [])
diff --git a/src/FundLab.Api/Persistence.fs b/src/FundLab.Api/Persistence.fs
index e48d9b1..88c0350 100644
--- a/src/FundLab.Api/Persistence.fs
+++ b/src/FundLab.Api/Persistence.fs
@@ -28,6 +28,7 @@ type FundRecord =
         InitialUnitNav: decimal
         IsSynthetic: bool
         AvailableCash: decimal
+        ReservedCash: decimal
         Status: string
     }
 
@@ -37,6 +38,36 @@ type FundWriteResult =
     | IdempotencyConflict
     | Invalid of string
 
+[<CLIMutable>]
+type SubscriptionOrderCommand =
+    {
+        FundCode: string
+        Amount: decimal
+        FeeAmount: decimal
+    }
+
+type SubscriptionOrderRecord =
+    {
+        Id: Guid
+        FundId: Guid
+        FundCode: string
+        Amount: decimal
+        FeeAmount: decimal
+        ReservedTotal: decimal
+        Status: string
+        SubmittedAt: DateTimeOffset
+        IsSynthetic: bool
+    }
+
+type SubscriptionOrderWriteResult =
+    | OrderCreated of SubscriptionOrderRecord
+    | OrderReplayed of SubscriptionOrderRecord
+    | OrderIdempotencyConflict
+    | OrderInvalid of string
+    | OrderFundNotFound
+    | OrderInstrumentNotFound
+    | OrderInsufficientFunds
+
 type FundRepository(connectionString: string) =
     let cashMaximum = 999999999999999999.99m
     let unitNavMaximum = 99999999999999999999.99999999m
@@ -92,6 +123,28 @@ type FundRepository(connectionString: string) =
 
         CREATE INDEX IF NOT EXISTS fund_nav_observations_date_idx
             ON fund_nav_observations (instrument_code, nav_date);
+
+        ALTER TABLE funds ADD COLUMN IF NOT EXISTS reserved_cash numeric(20, 2) NOT NULL DEFAULT 0;
+
+        CREATE TABLE IF NOT EXISTS subscription_orders (
+            id uuid PRIMARY KEY,
+            fund_id uuid NOT NULL REFERENCES funds(id),
+            fund_code text NOT NULL,
+            amount numeric(20, 2) NOT NULL CHECK (amount > 0),
+            fee_amount numeric(20, 2) NOT NULL CHECK (fee_amount > 0),
+            reserved_total numeric(20, 2) NOT NULL CHECK (reserved_total > 0),
+            status text NOT NULL,
+            is_synthetic boolean NOT NULL,
+            submitted_at timestamptz NOT NULL DEFAULT now()
+        );
+
+        CREATE TABLE IF NOT EXISTS subscription_order_idempotencies (
+            idempotency_key text PRIMARY KEY,
+            request_hash text NOT NULL,
+            order_id uuid NOT NULL REFERENCES subscription_orders(id),
+            fund_id uuid NOT NULL REFERENCES funds(id),
+            created_at timestamptz NOT NULL DEFAULT now()
+        );
         """
 
     let statusText status =
@@ -109,6 +162,7 @@ type FundRepository(connectionString: string) =
             InitialUnitNav = fund.InitialUnitNav
             IsSynthetic = fund.IsSynthetic
             AvailableCash = fund.AvailableCash
+            ReservedCash = fund.FrozenCash
             Status = statusText fund.Status
         }
 
@@ -121,7 +175,8 @@ type FundRepository(connectionString: string) =
             InitialUnitNav = reader.GetDecimal(4)
             IsSynthetic = reader.GetBoolean(5)
             AvailableCash = reader.GetDecimal(6)
-            Status = reader.GetString(7)
+            ReservedCash = reader.GetDecimal(7)
+            Status = reader.GetString(8)
         }
 
     let dateTimeOffsetFromReader (reader: DbDataReader) index =
@@ -189,7 +244,7 @@ type FundRepository(connectionString: string) =
                 transaction
                 """
                 SELECT id, name, currency, initial_cash, initial_unit_nav,
-                       is_synthetic, available_cash, status
+                       is_synthetic, available_cash, reserved_cash, status
                 FROM funds
                 WHERE id = @fund_id
                 """
@@ -219,10 +274,10 @@ type FundRepository(connectionString: string) =
                 """
                 INSERT INTO funds
                     (id, name, currency, initial_cash, initial_unit_nav,
-                     is_synthetic, available_cash, status)
+                     is_synthetic, available_cash, reserved_cash, status)
                 VALUES
                     (@id, @name, @currency, @initial_cash, @initial_unit_nav,
-                     @is_synthetic, @available_cash, @status)
+                     @is_synthetic, @available_cash, @reserved_cash, @status)
                 """
 
         addParameter command "id" NpgsqlDbType.Uuid (box fund.Id) |> ignore
@@ -232,6 +287,7 @@ type FundRepository(connectionString: string) =
         addParameter command "initial_unit_nav" NpgsqlDbType.Numeric (box fund.InitialUnitNav) |> ignore
         addParameter command "is_synthetic" NpgsqlDbType.Boolean (box fund.IsSynthetic) |> ignore
         addParameter command "available_cash" NpgsqlDbType.Numeric (box fund.AvailableCash) |> ignore
+        addParameter command "reserved_cash" NpgsqlDbType.Numeric (box fund.FrozenCash) |> ignore
         addParameter command "status" NpgsqlDbType.Text (box (statusText fund.Status)) |> ignore
         command.ExecuteNonQuery() |> ignore
 
@@ -250,6 +306,121 @@ type FundRepository(connectionString: string) =
         addParameter command "fund_id" NpgsqlDbType.Uuid (box fundId) |> ignore
         command.ExecuteNonQuery() |> ignore
 
+    let orderStatusText = "submitted"
+
+    let orderRecordFromReader (reader: DbDataReader) : SubscriptionOrderRecord =
+        {
+            Id = reader.GetGuid(0)
+            FundId = reader.GetGuid(1)
+            FundCode = reader.GetString(2)
+            Amount = reader.GetDecimal(3)
+            FeeAmount = reader.GetDecimal(4)
+            ReservedTotal = reader.GetDecimal(5)
+            Status = reader.GetString(6)
+            IsSynthetic = reader.GetBoolean(7)
+            SubmittedAt = reader.GetFieldValue<DateTimeOffset>(8)
+        }
+
+    let findOrder connection transaction orderId =
+        use command =
+            commandWithTransaction
+                connection
+                transaction
+                """
+                SELECT id, fund_id, fund_code, amount, fee_amount,
+                       reserved_total, status, is_synthetic, submitted_at
+                FROM subscription_orders
+                WHERE id = @order_id
+                """
+
+        addParameter command "order_id" NpgsqlDbType.Uuid (box orderId) |> ignore
+
+        use reader = command.ExecuteReader()
+        if reader.Read() then Some(orderRecordFromReader reader) else None
+
+    let findOrderIdempotency connection transaction key =
+        use command =
+            commandWithTransaction
+                connection
+                transaction
+                "SELECT request_hash, fund_id, order_id FROM subscription_order_idempotencies WHERE idempotency_key = @idempotency_key"
+
+        addParameter command "idempotency_key" NpgsqlDbType.Text (box key) |> ignore
+
+        use reader = command.ExecuteReader()
+        if reader.Read() then
+            Some(reader.GetString(0), reader.GetGuid(1), reader.GetGuid(2))
+        else
+            None
+
+    let instrumentExists connection transaction code =
+        use command =
+            commandWithTransaction
+                connection
+                transaction
+                "SELECT 1 FROM instruments WHERE code = @code"
+
+        addParameter command "code" NpgsqlDbType.Text (box code) |> ignore
+
+        use reader = command.ExecuteReader()
+        reader.Read()
+
+    let lockFundForOrder connection transaction fundId =
+        use command =
+            commandWithTransaction
+                connection
+                transaction
+                "SELECT is_synthetic FROM funds WHERE id = @fund_id FOR UPDATE"
+
+        addParameter command "fund_id" NpgsqlDbType.Uuid (box fundId) |> ignore
+
+        use reader = command.ExecuteReader()
+        if reader.Read() then Some(reader.GetBoolean(0)) else None
+
+    let insertSubscriptionOrder connection transaction (order: SubscriptionOrderRecord) =
+        use command =
+            commandWithTransaction
+                connection
+                transaction
+                """
+                INSERT INTO subscription_orders
+                    (id, fund_id, fund_code, amount, fee_amount,
+                     reserved_total, status, is_synthetic)
+                VALUES
+                    (@id, @fund_id, @fund_code, @amount, @fee_amount,
+                     @reserved_total, @status, @is_synthetic)
+                RETURNING submitted_at
+                """
+
+        addParameter command "id" NpgsqlDbType.Uuid (box order.Id) |> ignore
+        addParameter command "fund_id" NpgsqlDbType.Uuid (box order.FundId) |> ignore
+        addParameter command "fund_code" NpgsqlDbType.Text (box order.FundCode) |> ignore
+        addParameter command "amount" NpgsqlDbType.Numeric (box order.Amount) |> ignore
+        addParameter command "fee_amount" NpgsqlDbType.Numeric (box order.FeeAmount) |> ignore
+        addParameter command "reserved_total" NpgsqlDbType.Numeric (box order.ReservedTotal) |> ignore
+        addParameter command "status" NpgsqlDbType.Text (box order.Status) |> ignore
+        addParameter command "is_synthetic" NpgsqlDbType.Boolean (box order.IsSynthetic) |> ignore
+
+        use reader = command.ExecuteReader()
+        reader.Read() |> ignore
+        reader.GetFieldValue<DateTimeOffset>(0)
+
+    let insertOrderIdempotency connection transaction key requestHash orderId fundId =
+        use command =
+            commandWithTransaction
+                connection
+                transaction
+                """
+                INSERT INTO subscription_order_idempotencies (idempotency_key, request_hash, order_id, fund_id)
+                VALUES (@idempotency_key, @request_hash, @order_id, @fund_id)
+                """
+
+        addParameter command "idempotency_key" NpgsqlDbType.Text (box key) |> ignore
+        addParameter command "request_hash" NpgsqlDbType.Text (box requestHash) |> ignore
+        addParameter command "order_id" NpgsqlDbType.Uuid (box orderId) |> ignore
+        addParameter command "fund_id" NpgsqlDbType.Uuid (box fundId) |> ignore
+        command.ExecuteNonQuery() |> ignore
+
     let upsertInstrument connection transaction (payload: MarketDataSearchPayload) payloadHash (instrument: MarketDataInstrument) =
         use command =
             commandWithTransaction
@@ -371,6 +542,43 @@ type FundRepository(connectionString: string) =
         else
             Ok()
 
+    let orderRequestHash (fundId: Guid) (command: SubscriptionOrderCommand) =
+        let invariant = CultureInfo.InvariantCulture
+        let encoded (value: string) = sprintf "%d:%s" value.Length value
+        let fundCode = if isNull command.FundCode then "" else command.FundCode
+        let payload =
+            String.concat
+                "|"
+                [
+                    "subscription-order"
+                    encoded (fundId.ToString("D"))
+                    encoded fundCode
+                    (encoded (command.Amount.ToString("G29", invariant)))
+                    (encoded (command.FeeAmount.ToString("G29", invariant)))
+                ]
+
+        Convert.ToHexString(SHA256.HashData(Encoding.UTF8.GetBytes(payload)))
+
+    let validateOrderCommand (command: SubscriptionOrderCommand) =
+        if String.IsNullOrWhiteSpace command.FundCode then
+            Error "fund code cannot be empty"
+        elif command.Amount <= 0m then
+            Error "amount must be positive"
+        elif command.FeeAmount <= 0m then
+            Error "fee amount must be positive"
+        elif Decimal.Round(command.Amount, 2) <> command.Amount then
+            Error "amount exceeds cash precision"
+        elif Decimal.Round(command.FeeAmount, 2) <> command.FeeAmount then
+            Error "fee amount exceeds cash precision"
+        elif command.Amount > cashMaximum then
+            Error "amount exceeds database precision"
+        elif command.FeeAmount > cashMaximum then
+            Error "fee amount exceeds database precision"
+        elif command.Amount + command.FeeAmount > cashMaximum then
+            Error "reserved total exceeds database precision"
+        else
+            Ok()
+
     let ledgerErrorMessage error =
         match error with
         | InvalidIdentifier label -> sprintf "%s is invalid" label
@@ -552,3 +760,118 @@ type FundRepository(connectionString: string) =
                         ()
 
                     raise error
+
+    member _.CreateSubscriptionOrder(idempotencyKey: string, fundId: Guid, command: SubscriptionOrderCommand) =
+        if String.IsNullOrWhiteSpace idempotencyKey then
+            OrderInvalid "idempotency key cannot be empty"
+        else
+            match validateOrderCommand command with
+            | Error message -> OrderInvalid message
+            | Ok() ->
+                let fingerprint = orderRequestHash fundId command
+                let reservedTotal = command.Amount + command.FeeAmount
+                use connection = new NpgsqlConnection(connectionString)
+                connection.Open()
+                use transaction = connection.BeginTransaction(IsolationLevel.ReadCommitted)
+
+                try
+                    use lockCommand =
+                        commandWithTransaction
+                            connection
+                            (Some transaction)
+                            "SELECT pg_advisory_xact_lock(hashtext(@lock_key))"
+
+                    addParameter lockCommand "lock_key" NpgsqlDbType.Text (box idempotencyKey) |> ignore
+                    lockCommand.ExecuteNonQuery() |> ignore
+
+                    match findOrderIdempotency connection (Some transaction) idempotencyKey with
+                    | Some(existingHash, existingFundId, orderId)
+                        when existingHash = fingerprint && existingFundId = fundId ->
+                        match findOrder connection (Some transaction) orderId with
+                        | Some order ->
+                            transaction.Commit()
+                            OrderReplayed order
+                        | None ->
+                            transaction.Rollback()
+                            OrderInvalid "idempotency record references a missing order"
+                    | Some _ ->
+                        transaction.Rollback()
+                        OrderIdempotencyConflict
+                    | None ->
+                        match lockFundForOrder connection (Some transaction) fundId with
+                        | None ->
+                            transaction.Rollback()
+                            OrderFundNotFound
+                        | Some isSynthetic ->
+                            if instrumentExists connection (Some transaction) command.FundCode then
+                                use cashCommand =
+                                    commandWithTransaction
+                                        connection
+                                        (Some transaction)
+                                        """
+                                        UPDATE funds
+                                        SET available_cash = available_cash - @reserved_total,
+                                            reserved_cash = reserved_cash + @reserved_total
+                                        WHERE id = @fund_id AND available_cash >= @reserved_total
+                                        """
+
+                                addParameter cashCommand "reserved_total" NpgsqlDbType.Numeric (box reservedTotal) |> ignore
+                                addParameter cashCommand "fund_id" NpgsqlDbType.Uuid (box fundId) |> ignore
+
+                                if cashCommand.ExecuteNonQuery() = 0 then
+                                    transaction.Rollback()
+                                    OrderInsufficientFunds
+                                else
+                                    let order: SubscriptionOrderRecord =
+                                        {
+                                            Id = Guid.NewGuid()
+                                            FundId = fundId
+                                            FundCode = command.FundCode
+                                            Amount = command.Amount
+                                            FeeAmount = command.FeeAmount
+                                            ReservedTotal = reservedTotal
+                                            Status = orderStatusText
+                                            SubmittedAt = DateTimeOffset.UnixEpoch
+                                            IsSynthetic = isSynthetic
+                                        }
+
+                                    let submittedAt = insertSubscriptionOrder connection (Some transaction) order
+                                    insertOrderIdempotency connection (Some transaction) idempotencyKey fingerprint order.Id fundId
+                                    transaction.Commit()
+                                    OrderCreated { order with SubmittedAt = submittedAt }
+                            else
+                                transaction.Rollback()
+                                OrderInstrumentNotFound
+                with error ->
+                    try
+                        transaction.Rollback()
+                    with _ ->
+                        ()
+
+                    raise error
+
+    member _.GetSubscriptionOrders(fundId: Guid) =
+        use connection = new NpgsqlConnection(connectionString)
+        connection.Open()
+
+        use command =
+            commandWithTransaction
+                connection
+                None
+                """
+                SELECT id, fund_id, fund_code, amount, fee_amount,
+                       reserved_total, status, is_synthetic, submitted_at
+                FROM subscription_orders
+                WHERE fund_id = @fund_id
+                ORDER BY submitted_at DESC, id
+                """
+
+        addParameter command "fund_id" NpgsqlDbType.Uuid (box fundId) |> ignore
+
+        use reader = command.ExecuteReader()
+        let records = ResizeArray<SubscriptionOrderRecord>()
+
+        while reader.Read() do
+            records.Add(orderRecordFromReader reader)
+
+        records |> Seq.toList
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;