440 lines
14 KiB
Go
440 lines
14 KiB
Go
package mcp
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import (
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"context"
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"encoding/json"
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"fmt"
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"git.k6n.net/mats/go-cart-actor/pkg/cart"
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messages "git.k6n.net/mats/go-cart-actor/proto/cart"
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)
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// tool is one MCP tool: a name, a description, a JSON-Schema for its arguments,
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// and the handler that runs it.
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type tool struct {
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Name string `json:"name"`
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Description string `json:"description"`
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InputSchema json.RawMessage `json:"inputSchema"`
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invoke func(args json.RawMessage) (any, error) `json:"-"`
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}
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func (s *Server) callTool(req *rpcRequest) *rpcResponse {
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var p struct {
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Name string `json:"name"`
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Arguments json.RawMessage `json:"arguments"`
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}
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if err := json.Unmarshal(req.Params, &p); err != nil {
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return errorResponse(req.ID, codeInvalidParams, "invalid params")
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}
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var t *tool
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for i := range s.tools {
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if s.tools[i].Name == p.Name {
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t = &s.tools[i]
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break
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}
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}
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if t == nil {
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return errorResponse(req.ID, codeInvalidParams, "unknown tool: "+p.Name)
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}
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out, err := t.invoke(p.Arguments)
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if err != nil {
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return result(req.ID, toolError(err))
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}
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return result(req.ID, toolText(out))
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}
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func (s *Server) buildTools() []tool {
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return []tool{
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{
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Name: "get_cart",
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Description: "Get the full state of a cart by its base62 cart id: items, totals, vouchers, promotions, user info, currency, language, checkout status, subscription details, and all applied/pending promotions with progress nudges.",
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InputSchema: object(props{
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"cartId": str("the base62 cart id"),
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}, []string{"cartId"}),
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invoke: func(args json.RawMessage) (any, error) {
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var a struct {
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CartID string `json:"cartId"`
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}
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if err := decode(args, &a); err != nil {
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return nil, err
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}
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id, ok := cart.ParseCartId(a.CartID)
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if !ok {
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return nil, fmt.Errorf("invalid cart id %q", a.CartID)
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}
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g, err := s.applier.Get(context.Background(), uint64(id))
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if err != nil {
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return nil, fmt.Errorf("get cart: %w", err)
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}
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return g, nil
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},
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},
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{
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Name: "get_cart_items",
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Description: "List all items in a cart with their SKU, name, quantity, unit price, total price, stock, tax rate, markings, custom fields, and optional child/parent relationships.",
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InputSchema: object(props{
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"cartId": str("the base62 cart id"),
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}, []string{"cartId"}),
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invoke: func(args json.RawMessage) (any, error) {
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var a struct {
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CartID string `json:"cartId"`
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}
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if err := decode(args, &a); err != nil {
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return nil, err
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}
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id, ok := cart.ParseCartId(a.CartID)
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if !ok {
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return nil, fmt.Errorf("invalid cart id %q", a.CartID)
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}
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g, err := s.applier.Get(context.Background(), uint64(id))
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if err != nil {
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return nil, fmt.Errorf("get cart: %w", err)
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}
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return map[string]any{"items": g.Items, "count": len(g.Items)}, nil
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},
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},
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{
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Name: "get_cart_totals",
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Description: "Get price breakdown for a cart: total incVat, total exVat, VAT breakdown by rate, total discount (vouchers + promotions), and per-item totals.",
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InputSchema: object(props{
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"cartId": str("the base62 cart id"),
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}, []string{"cartId"}),
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invoke: func(args json.RawMessage) (any, error) {
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var a struct {
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CartID string `json:"cartId"`
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}
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if err := decode(args, &a); err != nil {
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return nil, err
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}
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id, ok := cart.ParseCartId(a.CartID)
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if !ok {
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return nil, fmt.Errorf("invalid cart id %q", a.CartID)
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}
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g, err := s.applier.Get(context.Background(), uint64(id))
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if err != nil {
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return nil, fmt.Errorf("get cart: %w", err)
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}
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return map[string]any{
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"totalPrice": g.TotalPrice,
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"totalDiscount": g.TotalDiscount,
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"currency": g.Currency,
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"language": g.Language,
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"vouchers": g.Vouchers,
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}, nil
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},
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},
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{
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Name: "get_cart_promotions",
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Description: "Get all applied and pending promotions on a cart, including discount amounts and progress nudges (e.g. 'spend 1200 SEK more for free shipping').",
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InputSchema: object(props{
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"cartId": str("the base62 cart id"),
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}, []string{"cartId"}),
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invoke: func(args json.RawMessage) (any, error) {
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var a struct {
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CartID string `json:"cartId"`
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}
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if err := decode(args, &a); err != nil {
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return nil, err
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}
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id, ok := cart.ParseCartId(a.CartID)
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if !ok {
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return nil, fmt.Errorf("invalid cart id %q", a.CartID)
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}
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g, err := s.applier.Get(context.Background(), uint64(id))
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if err != nil {
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return nil, fmt.Errorf("get cart: %w", err)
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}
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return map[string]any{
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"appliedPromotions": g.AppliedPromotions,
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"totalDiscount": g.TotalDiscount,
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}, nil
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},
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},
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{
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Name: "get_cart_vouchers",
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Description: "List all vouchers applied to a cart with their codes, values, rules, and whether they are currently active.",
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InputSchema: object(props{
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"cartId": str("the base62 cart id"),
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}, []string{"cartId"}),
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invoke: func(args json.RawMessage) (any, error) {
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var a struct {
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CartID string `json:"cartId"`
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}
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if err := decode(args, &a); err != nil {
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return nil, err
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}
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id, ok := cart.ParseCartId(a.CartID)
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if !ok {
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return nil, fmt.Errorf("invalid cart id %q", a.CartID)
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}
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g, err := s.applier.Get(context.Background(), uint64(id))
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if err != nil {
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return nil, fmt.Errorf("get cart: %w", err)
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}
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return map[string]any{"vouchers": g.Vouchers, "count": len(g.Vouchers)}, nil
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},
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},
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{
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Name: "update_item_quantity",
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Description: "Change the quantity of a line item in a cart. Use quantity=0 to remove the item. Returns the updated cart state.",
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InputSchema: object(props{
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"cartId": str("the base62 cart id"),
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"itemId": integer("the line item id (numeric, e.g. 1, 2, 3)"),
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"quantity": integer("the new quantity (0 removes the item)"),
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}, []string{"cartId", "itemId", "quantity"}),
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invoke: func(args json.RawMessage) (any, error) {
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var a struct {
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CartID string `json:"cartId"`
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ItemID int `json:"itemId"`
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Quantity int32 `json:"quantity"`
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}
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if err := decode(args, &a); err != nil {
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return nil, err
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}
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id, ok := cart.ParseCartId(a.CartID)
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if !ok {
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return nil, fmt.Errorf("invalid cart id %q", a.CartID)
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}
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res, err := s.applier.Apply(context.Background(), uint64(id), &messages.ChangeQuantity{
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Id: uint32(a.ItemID),
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Quantity: a.Quantity,
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})
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if err != nil {
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return nil, fmt.Errorf("change quantity: %w", err)
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}
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// Check for per-mutation errors.
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for _, m := range res.Mutations {
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if m.Error != nil {
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return nil, m.Error
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}
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}
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return map[string]any{"cartId": a.CartID, "cart": &res.Result}, nil
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},
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},
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{
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Name: "remove_cart_item",
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Description: "Remove a line item (and its children) from a cart by item id. Returns the updated cart state.",
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InputSchema: object(props{
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"cartId": str("the base62 cart id"),
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"itemId": integer("the line item id to remove (numeric, e.g. 1, 2, 3)"),
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}, []string{"cartId", "itemId"}),
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invoke: func(args json.RawMessage) (any, error) {
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var a struct {
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CartID string `json:"cartId"`
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ItemID int `json:"itemId"`
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}
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if err := decode(args, &a); err != nil {
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return nil, err
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}
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id, ok := cart.ParseCartId(a.CartID)
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if !ok {
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return nil, fmt.Errorf("invalid cart id %q", a.CartID)
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}
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res, err := s.applier.Apply(context.Background(), uint64(id), &messages.RemoveItem{Id: uint32(a.ItemID)})
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if err != nil {
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return nil, fmt.Errorf("remove item: %w", err)
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}
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for _, m := range res.Mutations {
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if m.Error != nil {
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return nil, m.Error
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}
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}
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return map[string]any{"cartId": a.CartID, "cart": &res.Result}, nil
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},
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},
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{
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Name: "clear_cart",
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Description: "Remove all items and vouchers from a cart, resetting it to an empty state. The cart id, user id, and currency are preserved. Returns the updated (empty) cart.",
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InputSchema: object(props{
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"cartId": str("the base62 cart id"),
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}, []string{"cartId"}),
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invoke: func(args json.RawMessage) (any, error) {
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var a struct {
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CartID string `json:"cartId"`
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}
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if err := decode(args, &a); err != nil {
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return nil, err
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}
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id, ok := cart.ParseCartId(a.CartID)
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if !ok {
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return nil, fmt.Errorf("invalid cart id %q", a.CartID)
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}
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res, err := s.applier.Apply(context.Background(), uint64(id), &messages.ClearCartRequest{})
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if err != nil {
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return nil, fmt.Errorf("clear cart: %w", err)
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}
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for _, m := range res.Mutations {
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if m.Error != nil {
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return nil, m.Error
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}
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}
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return map[string]any{"cartId": a.CartID, "cart": &res.Result}, nil
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},
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},
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{
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Name: "apply_voucher",
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Description: "Apply a voucher code to a cart. The voucher value is in öre (e.g. 10000 = 100 kr). Returns the updated cart with the voucher applied.",
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InputSchema: object(props{
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"cartId": str("the base62 cart id"),
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"code": str("the voucher code"),
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"value": integer("the voucher value in öre (e.g. 10000 = 100 kr)"),
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"description": str("optional description of the voucher"),
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"rules": stringArray("optional list of rule expressions for when the voucher applies"),
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}, []string{"cartId", "code", "value"}),
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invoke: func(args json.RawMessage) (any, error) {
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var a struct {
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CartID string `json:"cartId"`
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Code string `json:"code"`
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Value int64 `json:"value"`
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Description string `json:"description"`
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Rules []string `json:"rules"`
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}
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if err := decode(args, &a); err != nil {
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return nil, err
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}
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id, ok := cart.ParseCartId(a.CartID)
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if !ok {
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return nil, fmt.Errorf("invalid cart id %q", a.CartID)
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}
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res, err := s.applier.Apply(context.Background(), uint64(id), &messages.AddVoucher{
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Code: a.Code,
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Value: a.Value,
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Description: a.Description,
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VoucherRules: a.Rules,
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})
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if err != nil {
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return nil, fmt.Errorf("apply voucher: %w", err)
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}
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for _, m := range res.Mutations {
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if m.Error != nil {
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return nil, m.Error
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}
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}
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return map[string]any{"cartId": a.CartID, "cart": &res.Result}, nil
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},
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},
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{
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Name: "remove_voucher",
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Description: "Remove a voucher from a cart by its voucher id. Returns the updated cart.",
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InputSchema: object(props{
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"cartId": str("the base62 cart id"),
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"voucherId": integer("the voucher id to remove (numeric)"),
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}, []string{"cartId", "voucherId"}),
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invoke: func(args json.RawMessage) (any, error) {
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var a struct {
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CartID string `json:"cartId"`
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VoucherID int `json:"voucherId"`
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}
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if err := decode(args, &a); err != nil {
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return nil, err
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}
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id, ok := cart.ParseCartId(a.CartID)
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if !ok {
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return nil, fmt.Errorf("invalid cart id %q", a.CartID)
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}
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res, err := s.applier.Apply(context.Background(), uint64(id), &messages.RemoveVoucher{Id: uint32(a.VoucherID)})
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if err != nil {
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return nil, fmt.Errorf("remove voucher: %w", err)
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}
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for _, m := range res.Mutations {
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if m.Error != nil {
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return nil, m.Error
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}
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}
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return map[string]any{"cartId": a.CartID, "cart": &res.Result}, nil
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},
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},
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{
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Name: "set_cart_user",
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Description: "Set or update the user ID on a cart, linking it to a customer account. Returns the updated cart.",
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InputSchema: object(props{
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"cartId": str("the base62 cart id"),
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"userId": str("the user/customer id"),
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}, []string{"cartId", "userId"}),
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invoke: func(args json.RawMessage) (any, error) {
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var a struct {
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CartID string `json:"cartId"`
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UserID string `json:"userId"`
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}
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if err := decode(args, &a); err != nil {
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return nil, err
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}
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id, ok := cart.ParseCartId(a.CartID)
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if !ok {
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return nil, fmt.Errorf("invalid cart id %q", a.CartID)
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}
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res, err := s.applier.Apply(context.Background(), uint64(id), &messages.SetUserId{UserId: a.UserID})
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if err != nil {
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return nil, fmt.Errorf("set user: %w", err)
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}
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for _, m := range res.Mutations {
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if m.Error != nil {
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return nil, m.Error
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}
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}
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return map[string]any{"cartId": a.CartID, "cart": &res.Result}, nil
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},
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},
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}
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}
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// ---- result + schema helpers -----------------------------------------------
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func toolText(v any) map[string]any {
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b, err := json.Marshal(v)
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if err != nil {
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return toolError(err)
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}
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return map[string]any{
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"content": []map[string]any{{"type": "text", "text": string(b)}},
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}
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}
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func toolError(err error) map[string]any {
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return map[string]any{
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"isError": true,
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"content": []map[string]any{{"type": "text", "text": err.Error()}},
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}
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}
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// decode unmarshals tool arguments, tolerating empty/absent arguments.
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func decode(args json.RawMessage, v any) error {
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if len(args) == 0 || string(args) == "null" {
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return nil
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}
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if err := json.Unmarshal(args, v); err != nil {
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return fmt.Errorf("invalid arguments: %w", err)
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}
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return nil
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}
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type props map[string]json.RawMessage
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func object(p props, required []string) json.RawMessage {
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m := map[string]any{
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"type": "object",
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"properties": p,
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}
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if len(required) > 0 {
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m["required"] = required
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}
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b, _ := json.Marshal(m)
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return b
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}
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func str(desc string) json.RawMessage { return scalar("string", desc) }
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func integer(d string) json.RawMessage { return scalar("integer", d) }
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func obj(desc string) json.RawMessage { return scalar("object", desc) }
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func scalar(typ, desc string) json.RawMessage {
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b, _ := json.Marshal(map[string]any{"type": typ, "description": desc})
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return b
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}
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func stringArray(desc string) json.RawMessage {
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b, _ := json.Marshal(map[string]any{
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"type": "array", "description": desc, "items": map[string]string{"type": "string"},
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})
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return b
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}
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