chore: import upstream snapshot with attribution

ai/model.go

@@ -0,0 +1,240 @@
+// Package ai provides abstraction for AI model providers
+package ai
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"strings"
+)
+
+// Model provides an interface for interacting with AI model providers
+type Model interface {
+	// Init initializes the model with options
+	Init(...Option) error
+	// Options returns the model options
+	Options() Options
+	// Generate generates a response from the model
+	Generate(ctx context.Context, req *Request, opts ...GenerateOption) (*Response, error)
+	// Stream generates a streaming response (for future implementation)
+	Stream(ctx context.Context, req *Request, opts ...GenerateOption) (Stream, error)
+	// String returns the name of the provider
+	String() string
+}
+
+// Tool represents a tool/function that can be called by the model
+type Tool struct {
+	Name         string // LLM-safe name (e.g., "greeter_Greeter_Hello")
+	OriginalName string // Original name (e.g., "greeter.Greeter.Hello")
+	Description  string
+	Properties   map[string]any // JSON schema for tool parameters
+}
+
+// Request represents a request to generate content from a model
+type Request struct {
+	// Prompt is the user's message/prompt
+	Prompt string
+	// SystemPrompt is the system instruction for the model
+	SystemPrompt string
+	// Tools available for the model to use
+	Tools []Tool
+	// Messages for continuing a conversation (optional).
+	// Use ai.History to accumulate these across turns.
+	Messages []Message
+}
+
+// Message represents a conversation message
+type Message struct {
+	Role    string // "user", "assistant", "system", "tool"
+	Content any    // Can be string or structured content
+}
+
+// Usage describes token counts returned by model providers.
+type Usage struct {
+	InputTokens  int `json:"input_tokens,omitempty"`
+	OutputTokens int `json:"output_tokens,omitempty"`
+	TotalTokens  int `json:"total_tokens,omitempty"`
+}
+
+// Response represents the response from a model
+type Response struct {
+	// Reply is the text response from the model
+	Reply string
+	// ToolCalls are tool calls requested by the model
+	ToolCalls []ToolCall
+	// Answer is the final answer after tool execution (if tools were used)
+	Answer string
+	// Usage contains provider token usage when available.
+	Usage Usage
+}
+
+// ToolCall represents a request to call a tool and its result
+type ToolCall struct {
+	ID     string         // Tool call ID (for correlation)
+	Name   string         // Tool name
+	Input  map[string]any // Tool input arguments
+	Result string         // Tool execution result (populated after execution)
+	Error  string         // Tool execution error (populated after execution)
+}
+
+// Scan decodes the call's Input into v (a pointer to a struct or map),
+// the same way a codec decodes an RPC request body. Use it when a tool
+// wants typed arguments instead of the raw map:
+//
+//	var args struct{ Query string `json:"query"` }
+//	if err := call.Scan(&args); err != nil { ... }
+func (c ToolCall) Scan(v any) error {
+	b, err := json.Marshal(c.Input)
+	if err != nil {
+		return err
+	}
+	return json.Unmarshal(b, v)
+}
+
+// ToolResult represents the result of a tool execution
+type ToolResult struct {
+	ID       string // Tool call ID (for correlation)
+	Value    any    // Structured result (optional)
+	Content  string // Tool execution result (JSON string), shown to the model
+	Attempts int    `json:"attempts,omitempty"` // Tool execution attempts, set when retried.
+	// Refused names the reason a guardrail blocked the call before it ran
+	// ("max_steps", "loop", "approval"); empty when the call executed. A
+	// tool wrapper can switch on it to build reliability tooling — react to
+	// a detected loop, audit refusals — without parsing the message.
+	Refused string `json:"refused,omitempty"`
+}
+
+// Refusal reason codes set on ToolResult.Refused by the agent's guardrails.
+const (
+	RefusedMaxSteps = "max_steps"
+	RefusedLoop     = "loop"
+	RefusedApproval = "approval"
+	// RefusedSpendBudget means an agent refused a paid tool before execution
+	// because the configured per-run x402 spend budget would be exceeded.
+	RefusedSpendBudget = "spend_budget"
+)
+
+// RunInfo describes the agent run a tool call belongs to. The agent
+// attaches it to the context passed to a ToolHandler, so a wrapper can
+// correlate calls within a run and across delegation without coupling to
+// the agent package. Flows also attach their name and current step so
+// tools and agents called from a workflow can be tied back to the
+// services → agents → workflows lifecycle that invoked them. Per-call
+// detail (tool name, id) is on the ToolCall. Attempt and MaxAttempts are
+// set while a model Generate call is in progress, so tools and wrappers can
+// tell which provider attempt produced the call and whether it is part of a
+// retry budget. They are zero when no model-attempt context is known.
+type RunInfo struct {
+	RunID                string // correlation id for this agent or flow run
+	ParentID             string // the run that delegated to this one, if any
+	Agent                string // the agent's name
+	Flow                 string // the flow's name, when the call is part of a workflow
+	Step                 string // the flow step currently executing, when known
+	Attempt              int    // current model Generate attempt, starting at 1 when known
+	MaxAttempts          int    // configured model Generate attempt budget when known
+	VerificationFeedback string // feedback from the previous failed verifier attempt, when retrying a flow step
+	Dispatch             string // how the run was dispatched (direct, broker, schedule, resume) when known
+	Trigger              string // external trigger or schedule label that started the run, when known
+	Spent                int64  // cumulative paid x402 spend in this run, in the asset's smallest unit
+	ToolSpend            int64  // paid x402 spend attributed to the current tool call, in the asset's smallest unit
+}
+
+type runInfoKey struct{}
+
+// WithRunInfo attaches run info to ctx.
+func WithRunInfo(ctx context.Context, r RunInfo) context.Context {
+	return context.WithValue(ctx, runInfoKey{}, r)
+}
+
+// RunInfoFrom returns the run info attached to ctx, and whether it was set.
+func RunInfoFrom(ctx context.Context) (RunInfo, bool) {
+	r, ok := ctx.Value(runInfoKey{}).(RunInfo)
+	return r, ok
+}
+
+// ErrStreamingUnsupported is returned by providers that implement the Model
+// interface but do not yet support token streaming. Use errors.Is so callers
+// can distinguish an unsupported capability from transient provider failures.
+var ErrStreamingUnsupported = errors.New("ai: streaming unsupported")
+
+// Stream is the interface for streaming responses.
+type Stream interface {
+	// Recv receives the next chunk of the response
+	Recv() (*Response, error)
+	// Close closes the stream
+	Close() error
+}
+
+// ToolHandler executes a tool call and returns its result. It mirrors a
+// go-micro RPC handler — context first, a request in, a result out — so
+// the same mental model carries over from services to tools.
+type ToolHandler func(ctx context.Context, call ToolCall) ToolResult
+
+// ToolWrapper wraps a ToolHandler to add behavior around execution —
+// logging, metrics, retries, guardrails. It is the tool-side analog of
+// client.CallWrapper and server.HandlerWrapper: a wrapper takes the next
+// handler and returns a new one, and code before the next(...) call runs
+// before the tool, code after runs after.
+type ToolWrapper func(ToolHandler) ToolHandler
+
+// NewFunc creates a new Model instance
+type NewFunc func(...Option) Model
+
+var providers = make(map[string]NewFunc)
+
+// Register registers a model provider
+func Register(name string, fn NewFunc) {
+	providers[name] = fn
+}
+
+// New creates a new Model instance based on the provider name
+func New(provider string, opts ...Option) Model {
+	if fn, ok := providers[provider]; ok {
+		return fn(opts...)
+	}
+
+	// Default to first registered provider
+	if len(providers) > 0 {
+		for _, fn := range providers {
+			return fn(opts...)
+		}
+	}
+
+	return nil
+}
+
+// AutoDetectProvider attempts to detect the provider from the base URL
+func AutoDetectProvider(baseURL string) string {
+	if baseURL == "" {
+		return "openai"
+	}
+	switch {
+	case strings.Contains(baseURL, "anthropic"):
+		return "anthropic"
+	case strings.Contains(baseURL, "atlascloud"):
+		return "atlascloud"
+	case strings.Contains(baseURL, "googleapis.com"), strings.Contains(baseURL, "google"):
+		return "gemini"
+	case strings.Contains(baseURL, "groq"):
+		return "groq"
+	case strings.Contains(baseURL, "minimax"):
+		return "minimax"
+	case strings.Contains(baseURL, "mistral"):
+		return "mistral"
+	case strings.Contains(baseURL, "together"):
+		return "together"
+	default:
+		return "openai"
+	}
+}
+
+// DefaultModel is a default model instance
+var DefaultModel Model
+
+// Generate generates a response using the default model.
+func Generate(ctx context.Context, req *Request, opts ...GenerateOption) (*Response, error) {
+	if DefaultModel == nil {
+		return nil, nil
+	}
+	return DefaultModel.Generate(ctx, req, opts...)
+}