fix: parse MCP result payloads and drop place idempotency_key

Typed result structs replace empty envelopes. Equity place sends
ref_id only so live additionalProperties:false schemas accept the call.

equity/write.go

@@ -2,6 +2,7 @@ package equity
 
 import (
 	"context"
+	"encoding/json"
 
 	decimal "github.com/alpacahq/alpacadecimal"
 	"s1d3sw1ped/robinhood-agentic-mcp/client"
@@ -42,9 +43,73 @@ type ReviewResult struct {
 	Warnings []string `json:"warnings"`
 }
 
-// Order is a placed equity order.
+// Order is a placed or listed equity order.
 type Order struct {
-	ID string `json:"id"`
+	ID             string          `json:"id"`
+	IdempotencyKey string          `json:"idempotency_key"`
+	Symbol         string          `json:"symbol"`
+	Side           string          `json:"side"`
+	Qty            decimal.Decimal `json:"-"`
+	FilledQty      decimal.Decimal `json:"-"`
+	Price          decimal.Decimal `json:"-"`
+	State          string          `json:"state"`
+}
+
+func (o *Order) UnmarshalJSON(b []byte) error {
+	var row struct {
+		ID             string `json:"id"`
+		IdempotencyKey string `json:"idempotency_key"`
+		Symbol         string `json:"symbol"`
+		Side           string `json:"side"`
+		Quantity       any    `json:"quantity"`
+		Qty            any    `json:"qty"`
+		FilledQty      any    `json:"filled_quantity"`
+		CumulativeQty  any    `json:"cumulative_quantity"`
+		Price          any    `json:"price"`
+		AveragePrice   any    `json:"average_price"`
+		State          string `json:"state"`
+		Status         string `json:"status"`
+	}
+	if err := json.Unmarshal(b, &row); err != nil {
+		return err
+	}
+	o.ID = row.ID
+	o.IdempotencyKey = row.IdempotencyKey
+	o.Symbol = row.Symbol
+	o.Side = row.Side
+	o.State = row.State
+	if o.State == "" {
+		o.State = row.Status
+	}
+	var err error
+	if o.Qty, err = firstDec(row.Quantity, row.Qty); err != nil {
+		return err
+	}
+	if o.FilledQty, err = firstDec(row.FilledQty, row.CumulativeQty); err != nil {
+		return err
+	}
+	if o.Price, err = firstDec(row.Price, row.AveragePrice); err != nil {
+		return err
+	}
+	return nil
+}
+
+func parseOrders(raw json.RawMessage) ([]Order, error) {
+	rows, _, err := wire.UnmarshalRows[Order](raw, "orders", "results")
+	if err != nil {
+		return nil, err
+	}
+	if len(rows) > 0 {
+		return rows, nil
+	}
+	var one Order
+	if err := json.Unmarshal(wire.Unwrap(raw), &one); err != nil {
+		return nil, err
+	}
+	if one.ID != "" {
+		return []Order{one}, nil
+	}
+	return nil, nil
 }
 
 // CancelOrderRequest is the argument set for cancel_equity_order.
@@ -62,13 +127,23 @@ func (c *Client) ReviewOrder(ctx context.Context, req PlaceOrderRequest) (Review
 	return out, nil
 }
 
-// PlaceOrder calls place_equity_order. RefID is sent as both ref_id and idempotency_key.
+// PlaceOrder calls place_equity_order. RefID is sent as ref_id only.
 func (c *Client) PlaceOrder(ctx context.Context, req PlaceOrderRequest) (Order, error) {
-	var out Order
-	if err := c.parse(ctx, toolPlace, placeArgs(req, true), &out); err != nil {
+	raw, err := c.c.Call(ctx, toolPlace, placeArgs(req, true))
+	if err != nil {
 		return Order{}, err
 	}
-	return out, nil
+	ords, err := parseOrders(raw)
+	if err != nil {
+		return Order{}, client.ToolErrorf(toolPlace, "parse: %w", err)
+	}
+	if len(ords) == 1 {
+		return ords[0], nil
+	}
+	if len(ords) > 1 {
+		return ords[0], nil
+	}
+	return Order{}, nil
 }
 
 // CancelOrder calls cancel_equity_order.
@@ -128,7 +203,6 @@ func placeArgs(req PlaceOrderRequest, withRef bool) map[string]any {
 	}
 	if withRef && req.RefID != "" {
 		args["ref_id"] = req.RefID
-		args["idempotency_key"] = req.RefID
 	}
 	return args
 }