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.

watchlists/results.go

@@ -0,0 +1,55 @@
+package watchlists
+
+import (
+	"encoding/json"
+
+	"s1d3sw1ped/robinhood-agentic-mcp/internal/wire"
+)
+
+func (r *OptionListResult) UnmarshalJSON(b []byte) error {
+	type row struct {
+		OptionID     string `json:"option_id"`
+		ID           string `json:"id"`
+		Symbol       string `json:"symbol"`
+		Title        string `json:"title"`
+		PositionType string `json:"position_type"`
+	}
+	rows, _, err := wire.UnmarshalRows[row](b, "items", "results", "options")
+	if err != nil {
+		return err
+	}
+	r.Items = make([]OptionWatchItem, 0, len(rows))
+	for _, row := range rows {
+		id := row.OptionID
+		if id == "" {
+			id = row.ID
+		}
+		r.Items = append(r.Items, OptionWatchItem{
+			OptionID: id, Symbol: row.Symbol, Title: row.Title, PositionType: row.PositionType,
+		})
+	}
+	return nil
+}
+
+func (r *PopularResult) UnmarshalJSON(b []byte) error {
+	type row struct {
+		ID    string `json:"id"`
+		Title string `json:"title"`
+		Name  string `json:"name"`
+	}
+	rows, _, err := wire.UnmarshalRows[row](b, "watchlists", "results")
+	if err != nil {
+		return err
+	}
+	r.Watchlists = make([]Watchlist, 0, len(rows))
+	for _, row := range rows {
+		title := row.Title
+		if title == "" {
+			title = row.Name
+		}
+		r.Watchlists = append(r.Watchlists, Watchlist{ID: row.ID, Title: title})
+	}
+	return nil
+}
+
+var _ json.Unmarshaler = (*OptionListResult)(nil)

watchlists/watchlists.go

@@ -63,14 +63,26 @@ type ItemsResult struct {
 // OptionListRequest is the argument set for get_option_watchlist (none).
 type OptionListRequest struct{}
 
+// OptionWatchItem is one contract on the options watchlist.
+type OptionWatchItem struct {
+	OptionID     string
+	Symbol       string
+	Title        string
+	PositionType string
+}
+
 // OptionListResult is the parsed get_option_watchlist payload.
-type OptionListResult struct{}
+type OptionListResult struct {
+	Items []OptionWatchItem
+}
 
 // PopularRequest is the argument set for get_popular_watchlists (none).
 type PopularRequest struct{}
 
 // PopularResult is the parsed get_popular_watchlists payload.
-type PopularResult struct{}
+type PopularResult struct {
+	Watchlists []Watchlist
+}
 
 // CreateRequest is the argument set for create_watchlist.
 type CreateRequest struct {