release: WRNexusJS 0.8.0

packages/ai/src/index.ts

@@ -245,5 +245,46 @@ export function createAI(config: AIConfig = {}): AI {
 
   return { generate, stream, streamResponse };
 }
-export { anthropicProvider, aiProvider, createAIClient } from "./providers.ts";
-export type { AIUsage, AIResult, AIProvider, AIClient, AIClientOptions } from "./providers.ts";
+export {
+  anthropicProvider,
+  aiProvider,
+  createAIClient,
+  deterministicAIProvider,
+} from "./providers.ts";
+export type {
+  AIAttemptEvent,
+  AICircuitBreakerOptions,
+  AIClient,
+  AIClientOptions,
+  AIProvider,
+  AIProviderCapabilities,
+  AIResult,
+  AIRetryOptions,
+  AITool,
+  AIToolCall,
+  AIUsage,
+  DeterministicAIProviderOptions,
+} from "./providers.ts";
+export {
+  aiRateLimiter,
+  createRagPipeline,
+  evaluateAI,
+  googleAIProvider,
+  guardedProvider,
+  localAIProvider,
+  maxPromptLength,
+  memoryConversationStore,
+  memoryVectorStore,
+  openAIEmbeddings,
+  openAIProvider,
+  promptTemplate,
+} from "./platform.ts";
+export type {
+  AIGuardrail,
+  ConversationStore,
+  EmbeddingProvider,
+  HttpAIProviderOptions,
+  VectorMatch,
+  VectorRecord,
+  VectorStore,
+} from "./platform.ts";

packages/ai/src/platform.ts

@@ -0,0 +1,353 @@
+import { AIError, type GenerateOptions, type Message } from "./index.ts";
+import type { AIProvider, AIResult } from "./providers.ts";
+
+export interface HttpAIProviderOptions {
+  apiKey?: string;
+  model: string;
+  baseUrl?: string;
+  fetch?: typeof fetch;
+  headers?: HeadersInit;
+}
+function key(configured: string | undefined, name: string): string {
+  const value = configured ?? process.env[name];
+  if (!value) throw new AIError(`Missing ${name}.`, 0, "authentication_error");
+  return value;
+}
+function promptMessages(prompt: string | Message[], options?: GenerateOptions) {
+  const messages =
+    options?.messages ??
+    (typeof prompt === "string" ? [{ role: "user" as const, content: prompt }] : prompt);
+  return options?.system ? [{ role: "system", content: options.system }, ...messages] : messages;
+}
+
+export function openAIProvider(options: HttpAIProviderOptions): AIProvider {
+  const send = options.fetch ?? fetch;
+  const base = (options.baseUrl ?? "https://api.openai.com/v1").replace(/\/$/, "");
+  return {
+    name: "openai",
+    capabilities: { streaming: false, structuredOutput: true, tools: true, usage: true },
+    async generate(prompt, call = {}) {
+      const response = await send(`${base}/chat/completions`, {
+        method: "POST",
+        headers: {
+          authorization: `Bearer ${key(options.apiKey, "OPENAI_API_KEY")}`,
+          "content-type": "application/json",
+          ...Object.fromEntries(new Headers(options.headers)),
+        },
+        body: JSON.stringify({
+          model: call.model ?? options.model,
+          messages: promptMessages(prompt, call),
+          ...(call.maxTokens ? { max_completion_tokens: call.maxTokens } : {}),
+        }),
+        signal: call.signal,
+      });
+      if (!response.ok)
+        throw new AIError(`OpenAI returned ${response.status}.`, response.status, "provider_error");
+      const body = (await response.json()) as any;
+      return {
+        value: String(body.choices?.[0]?.message?.content ?? ""),
+        provider: "openai",
+        model: body.model,
+        finishReason: body.choices?.[0]?.finish_reason,
+        usage: {
+          inputTokens: body.usage?.prompt_tokens,
+          outputTokens: body.usage?.completion_tokens,
+          totalTokens: body.usage?.total_tokens,
+        },
+        toolCalls: body.choices?.[0]?.message?.tool_calls?.map((tool: any) => ({
+          id: String(tool.id),
+          name: String(tool.function?.name),
+          arguments: JSON.parse(tool.function?.arguments ?? "{}"),
+        })),
+        raw: body,
+      };
+    },
+  };
+}
+
+export function googleAIProvider(options: HttpAIProviderOptions): AIProvider {
+  const send = options.fetch ?? fetch;
+  const base = (options.baseUrl ?? "https://generativelanguage.googleapis.com/v1beta").replace(
+    /\/$/,
+    "",
+  );
+  return {
+    name: "google",
+    capabilities: { streaming: false, structuredOutput: true, tools: true, usage: true },
+    async generate(prompt, call = {}) {
+      const response = await send(
+        `${base}/models/${encodeURIComponent(call.model ?? options.model)}:generateContent?key=${encodeURIComponent(key(options.apiKey, "GOOGLE_AI_API_KEY"))}`,
+        {
+          method: "POST",
+          headers: {
+            "content-type": "application/json",
+            ...Object.fromEntries(new Headers(options.headers)),
+          },
+          body: JSON.stringify({
+            contents: promptMessages(prompt, call)
+              .filter((message) => message.role !== "system")
+              .map((message) => ({
+                role: message.role === "assistant" ? "model" : "user",
+                parts: [{ text: message.content }],
+              })),
+            ...(call.system ? { systemInstruction: { parts: [{ text: call.system }] } } : {}),
+          }),
+          signal: call.signal,
+        },
+      );
+      if (!response.ok)
+        throw new AIError(
+          `Google AI returned ${response.status}.`,
+          response.status,
+          "provider_error",
+        );
+      const body = (await response.json()) as any;
+      return {
+        value: String(
+          body.candidates?.[0]?.content?.parts?.map((part: any) => part.text ?? "").join("") ?? "",
+        ),
+        provider: "google",
+        model: call.model ?? options.model,
+        finishReason: body.candidates?.[0]?.finishReason,
+        usage: {
+          inputTokens: body.usageMetadata?.promptTokenCount,
+          outputTokens: body.usageMetadata?.candidatesTokenCount,
+          totalTokens: body.usageMetadata?.totalTokenCount,
+        },
+        raw: body,
+      };
+    },
+  };
+}
+
+/** OpenAI-compatible local servers including Ollama, llama.cpp and vLLM. */
+export function localAIProvider(
+  options: Omit<HttpAIProviderOptions, "apiKey"> & { apiKey?: string },
+): AIProvider {
+  const provider = openAIProvider({
+    ...options,
+    apiKey: options.apiKey ?? "local",
+    baseUrl: options.baseUrl ?? "http://localhost:11434/v1",
+  });
+  return {
+    ...provider,
+    name: "local",
+    generate: async (prompt, call) => ({
+      ...(await provider.generate(prompt, call)),
+      provider: "local",
+    }),
+  };
+}
+
+export interface EmbeddingProvider {
+  name: string;
+  embed(
+    values: string[],
+    options?: { model?: string; signal?: AbortSignal },
+  ): Promise<{ vectors: number[][]; usage?: { tokens?: number } }>;
+}
+export function openAIEmbeddings(options: HttpAIProviderOptions): EmbeddingProvider {
+  return {
+    name: "openai",
+    async embed(values, call = {}) {
+      const response = await (options.fetch ?? fetch)(
+        `${(options.baseUrl ?? "https://api.openai.com/v1").replace(/\/$/, "")}/embeddings`,
+        {
+          method: "POST",
+          headers: {
+            authorization: `Bearer ${key(options.apiKey, "OPENAI_API_KEY")}`,
+            "content-type": "application/json",
+          },
+          body: JSON.stringify({ model: call.model ?? options.model, input: values }),
+          signal: call.signal,
+        },
+      );
+      if (!response.ok)
+        throw new AIError(`Embedding provider returned ${response.status}.`, response.status);
+      const body = (await response.json()) as any;
+      return {
+        vectors: body.data.map((item: any) => item.embedding as number[]),
+        usage: { tokens: body.usage?.total_tokens },
+      };
+    },
+  };
+}
+
+export interface VectorRecord<T = Record<string, unknown>> {
+  id: string;
+  vector: number[];
+  text: string;
+  metadata: T;
+}
+export interface VectorMatch<T = Record<string, unknown>> extends VectorRecord<T> {
+  score: number;
+}
+export interface VectorStore<T = Record<string, unknown>> {
+  upsert(records: VectorRecord<T>[]): Promise<void>;
+  query(
+    vector: number[],
+    limit?: number,
+    filter?: (metadata: T) => boolean,
+  ): Promise<VectorMatch<T>[]>;
+  delete(ids: string[]): Promise<void>;
+}
+export function memoryVectorStore<T = Record<string, unknown>>(): VectorStore<T> {
+  const records = new Map<string, VectorRecord<T>>();
+  const cosine = (a: number[], b: number[]) => {
+    if (a.length !== b.length || !a.length) return 0;
+    let dot = 0,
+      aa = 0,
+      bb = 0;
+    for (let i = 0; i < a.length; i++) {
+      dot += a[i]! * b[i]!;
+      aa += a[i]! ** 2;
+      bb += b[i]! ** 2;
+    }
+    return aa && bb ? dot / Math.sqrt(aa * bb) : 0;
+  };
+  return {
+    async upsert(values) {
+      for (const value of values) records.set(value.id, { ...value, vector: [...value.vector] });
+    },
+    async query(vector, limit = 5, filter) {
+      return [...records.values()]
+        .filter((record) => !filter || filter(record.metadata))
+        .map((record) => ({ ...record, score: cosine(vector, record.vector) }))
+        .sort((a, b) => b.score - a.score)
+        .slice(0, Math.max(0, limit));
+    },
+    async delete(ids) {
+      for (const id of ids) records.delete(id);
+    },
+  };
+}
+
+export function createRagPipeline<T>(options: {
+  embeddings: EmbeddingProvider;
+  store: VectorStore<T>;
+  generate: (prompt: string, options?: GenerateOptions) => Promise<AIResult<string>>;
+  maxContextCharacters?: number;
+}) {
+  return {
+    async index(documents: Array<{ id: string; text: string; metadata: T }>) {
+      const embedded = await options.embeddings.embed(documents.map((document) => document.text));
+      await options.store.upsert(
+        documents.map((document, index) => ({ ...document, vector: embedded.vectors[index]! })),
+      );
+      return documents.length;
+    },
+    async ask(
+      question: string,
+      call: GenerateOptions & { limit?: number; filter?: (metadata: T) => boolean } = {},
+    ) {
+      const embedded = await options.embeddings.embed([question], { signal: call.signal });
+      const matches = await options.store.query(embedded.vectors[0]!, call.limit, call.filter);
+      const context = matches
+        .map((match, index) => `[${index + 1}] ${match.text}`)
+        .join("\n\n")
+        .slice(0, options.maxContextCharacters ?? 12_000);
+      const result = await options.generate(
+        `Answer using only the supplied context. Cite sources as [n].\n\nContext:\n${context}\n\nQuestion: ${question}`,
+        call,
+      );
+      return { ...result, sources: matches };
+    },
+  };
+}
+
+export interface ConversationStore {
+  load(id: string): Promise<Message[]>;
+  append(id: string, messages: Message[]): Promise<void>;
+  clear(id: string): Promise<void>;
+}
+export function memoryConversationStore(maxMessages = 100): ConversationStore {
+  const conversations = new Map<string, Message[]>();
+  return {
+    async load(id) {
+      return [...(conversations.get(id) ?? [])];
+    },
+    async append(id, messages) {
+      conversations.set(id, [...(conversations.get(id) ?? []), ...messages].slice(-maxMessages));
+    },
+    async clear(id) {
+      conversations.delete(id);
+    },
+  };
+}
+export function promptTemplate(template: string) {
+  return (variables: Record<string, string | number>) =>
+    template.replace(/\{\{\s*([\w.-]+)\s*\}\}/g, (_match, name: string) => {
+      if (!(name in variables)) throw new Error(`WRN-AI-PROMPT-VARIABLE:${name}`);
+      return String(variables[name]);
+    });
+}
+export type AIGuardrail = (input: {
+  prompt: string | Message[];
+  output?: string;
+}) => void | Promise<void>;
+export const maxPromptLength =
+  (maximum: number): AIGuardrail =>
+  ({ prompt }) => {
+    const length =
+      typeof prompt === "string"
+        ? prompt.length
+        : prompt.reduce((sum, message) => sum + message.content.length, 0);
+    if (length > maximum)
+      throw new AIError("Prompt exceeds configured guardrail.", 400, "guardrail");
+  };
+export function guardedProvider(provider: AIProvider, guardrails: AIGuardrail[]): AIProvider {
+  return {
+    ...provider,
+    async generate(prompt, options) {
+      for (const guardrail of guardrails) await guardrail({ prompt });
+      const result = await provider.generate(prompt, options);
+      for (const guardrail of guardrails) await guardrail({ prompt, output: result.value });
+      return result;
+    },
+  };
+}
+export function aiRateLimiter(options: { limit: number; windowMs: number; now?: () => number }) {
+  const buckets = new Map<string, { count: number; reset: number }>();
+  const now = options.now ?? Date.now;
+  return (key: string) => {
+    const time = now();
+    const bucket = buckets.get(key);
+    if (!bucket || bucket.reset <= time) {
+      buckets.set(key, { count: 1, reset: time + options.windowMs });
+      return { allowed: true, remaining: options.limit - 1 };
+    }
+    if (bucket.count >= options.limit)
+      return { allowed: false, remaining: 0, retryAfterMs: bucket.reset - time };
+    bucket.count++;
+    return { allowed: true, remaining: options.limit - bucket.count };
+  };
+}
+export async function evaluateAI(
+  cases: Array<{
+    name: string;
+    prompt: string;
+    expected?: string;
+    score?: (output: string) => number | Promise<number>;
+  }>,
+  generate: (prompt: string) => Promise<string>,
+) {
+  const results = [];
+  for (const item of cases) {
+    const started = performance.now();
+    const output = await generate(item.prompt);
+    const score = item.score
+      ? await item.score(output)
+      : item.expected === undefined
+        ? 1
+        : output.includes(item.expected)
+          ? 1
+          : 0;
+    results.push({ name: item.name, output, score, durationMs: performance.now() - started });
+  }
+  return {
+    results,
+    score: results.length
+      ? results.reduce((sum, result) => sum + result.score, 0) / results.length
+      : 0,
+  };
+}

packages/ai/src/providers.ts

@@ -11,28 +11,79 @@ export interface AIUsage {
   inputTokens?: number;
   outputTokens?: number;
   totalTokens?: number;
+  costUsd?: number;
 }
+
 export interface AIResult<T = string> {
   value: T;
   provider: string;
   model?: string;
   usage?: AIUsage;
   finishReason?: string;
+  toolCalls?: AIToolCall[];
   raw?: unknown;
 }
+
+export interface AIProviderCapabilities {
+  streaming?: boolean;
+  structuredOutput?: boolean;
+  tools?: boolean;
+  usage?: boolean;
+}
+
+export interface AIToolCall {
+  id: string;
+  name: string;
+  arguments: unknown;
+}
+
+export interface AITool<TInput = unknown, TOutput = unknown> {
+  name: string;
+  description?: string;
+  validate?: (value: unknown) => value is TInput;
+  execute(input: TInput, context: { signal?: AbortSignal }): TOutput | Promise<TOutput>;
+}
+
 export interface AIProvider {
   name: string;
+  capabilities?: AIProviderCapabilities;
   generate(prompt: string | Message[], options?: GenerateOptions): Promise<AIResult<string>>;
   stream?(
     prompt: string | Message[],
     options?: GenerateOptions,
   ): AsyncGenerator<string, void, unknown>;
 }
+
+export interface AIRetryOptions {
+  attempts?: number;
+  baseDelayMs?: number;
+  maxDelayMs?: number;
+  retry?: (error: unknown) => boolean;
+}
+
+export interface AICircuitBreakerOptions {
+  failureThreshold?: number;
+  resetAfterMs?: number;
+}
+
 export interface AIClientOptions {
   providers: AIProvider[];
   fallback?: boolean;
-  onAttempt?: (provider: string, error?: unknown) => void | Promise<void>;
+  retry?: AIRetryOptions;
+  circuitBreaker?: AICircuitBreakerOptions;
+  /** Receives metadata only; prompts, provider raw responses, and credentials are never emitted. */
+  onAttempt?: (event: AIAttemptEvent) => void | Promise<void>;
 }
+
+export interface AIAttemptEvent {
+  provider: string;
+  attempt: number;
+  outcome: "start" | "success" | "error" | "circuit-open";
+  durationMs?: number;
+  error?: { name: string; type?: string; status?: number; message: string };
+  usage?: AIUsage;
+}
+
 export interface AIClient {
   generate(
     prompt: string | Message[],
@@ -42,40 +93,82 @@ export interface AIClient {
     prompt: string | Message[],
     options?: GenerateOptions & { provider?: string; validate?: (value: unknown) => value is T },
   ): Promise<AIResult<T>>;
+  executeTools(
+    result: AIResult,
+    tools: AITool[],
+    options?: { signal?: AbortSignal },
+  ): Promise<Array<{ call: AIToolCall; value: unknown }>>;
   stream(
     prompt: string | Message[],
     options?: GenerateOptions & { provider?: string },
   ): AsyncGenerator<string, void, unknown>;
+  capabilities(provider?: string): Record<string, AIProviderCapabilities>;
 }
 
 export function anthropicProvider(config: AIConfig = {}): AIProvider {
   const client = createAI(config);
   return {
     name: "anthropic",
-    async generate(prompt: string | Message[], options?: GenerateOptions) {
+    capabilities: { streaming: true, structuredOutput: true },
+    async generate(prompt, options) {
       return {
         value: await client.generate(prompt, options),
         provider: "anthropic",
         model: options?.model ?? config.model,
       };
     },
-    stream: (prompt: string | Message[], options?: GenerateOptions) =>
-      client.stream(prompt, options),
+    stream: (prompt, options) => client.stream(prompt, options),
   };
 }
 
-export function aiProvider(name: string, client: AI): AIProvider {
+export function aiProvider(
+  name: string,
+  client: AI,
+  capabilities: AIProviderCapabilities = {},
+): AIProvider {
   return {
     name,
-    async generate(prompt: string | Message[], options?: GenerateOptions) {
+    capabilities: { streaming: true, ...capabilities },
+    async generate(prompt, options) {
       return {
         value: await client.generate(prompt, options),
         provider: name,
         model: options?.model,
       };
     },
-    stream: (prompt: string | Message[], options?: GenerateOptions) =>
-      client.stream(prompt, options),
+    stream: (prompt, options) => client.stream(prompt, options),
+  };
+}
+
+export interface DeterministicAIProviderOptions {
+  name?: string;
+  responses?: Array<string | AIResult<string>>;
+  handler?: (
+    prompt: string | Message[],
+    options?: GenerateOptions,
+  ) => string | AIResult<string> | Promise<string | AIResult<string>>;
+}
+
+/** Offline provider for examples and tests. Responses are consumed in order. */
+export function deterministicAIProvider(options: DeterministicAIProviderOptions = {}): AIProvider {
+  let index = 0;
+  const name = options.name ?? "deterministic";
+  return {
+    name,
+    capabilities: { streaming: true, structuredOutput: true, tools: true, usage: true },
+    async generate(prompt, callOptions) {
+      const selected = options.handler
+        ? await options.handler(prompt, callOptions)
+        : options.responses?.[index++];
+      if (selected === undefined)
+        throw new AIError("No deterministic response configured", 0, "provider_error");
+      return typeof selected === "string"
+        ? { value: selected, provider: name }
+        : { ...selected, provider: name };
+    },
+    async *stream(prompt, callOptions) {
+      yield (await this.generate(prompt, callOptions)).value;
+    },
   };
 }
 
@@ -84,27 +177,116 @@ function jsonText(value: string): string {
   return (fenced?.[1] ?? value).trim();
 }
 
+function safeError(error: unknown): AIAttemptEvent["error"] {
+  if (error instanceof AIError)
+    return {
+      name: error.name,
+      type: error.type,
+      status: error.status,
+      message: error.message.slice(0, 300),
+    };
+  if (error instanceof Error) return { name: error.name, message: error.message.slice(0, 300) };
+  return { name: "Error", message: "Unknown provider error" };
+}
+
+function defaultRetry(error: unknown): boolean {
+  return (
+    error instanceof AIError &&
+    (error.status === 408 || error.status === 429 || error.status >= 500)
+  );
+}
+
+function abortError(): Error {
+  return new DOMException("The operation was aborted", "AbortError");
+}
+
+async function delay(ms: number, signal?: AbortSignal): Promise<void> {
+  if (signal?.aborted) throw signal.reason ?? abortError();
+  await new Promise<void>((resolve, reject) => {
+    const timer = setTimeout(resolve, ms);
+    signal?.addEventListener(
+      "abort",
+      () => {
+        clearTimeout(timer);
+        reject(signal.reason ?? abortError());
+      },
+      { once: true },
+    );
+  });
+}
+
 export function createAIClient(options: AIClientOptions): AIClient {
   if (!options.providers.length) throw new Error("WRN-AI-NO-PROVIDERS");
+  const duplicate = options.providers.find(
+    (provider, index) =>
+      options.providers.findIndex((other) => other.name === provider.name) !== index,
+  );
+  if (duplicate) throw new Error(`WRN-AI-DUPLICATE-PROVIDER:${duplicate.name}`);
+  const circuits = new Map<string, { failures: number; openedAt?: number }>();
   const select = (name?: string) =>
     name ? options.providers.filter((provider) => provider.name === name) : options.providers;
+  const attempts = Math.max(1, options.retry?.attempts ?? 1);
+  const failureThreshold = Math.max(1, options.circuitBreaker?.failureThreshold ?? 5);
+  const resetAfterMs = Math.max(0, options.circuitBreaker?.resetAfterMs ?? 30_000);
+
   const generate: AIClient["generate"] = async (prompt, callOptions = {}) => {
     const providers = select(callOptions.provider);
     if (!providers.length)
       throw new AIError(`Unknown AI provider: ${callOptions.provider}`, 0, "provider_error");
     let last: unknown;
     for (const provider of providers) {
-      try {
-        await options.onAttempt?.(provider.name);
-        return await provider.generate(prompt, callOptions);
-      } catch (error) {
-        last = error;
-        await options.onAttempt?.(provider.name, error);
-        if (options.fallback === false || callOptions.provider) throw error;
+      const circuit = circuits.get(provider.name) ?? { failures: 0 };
+      if (circuit.openedAt !== undefined && Date.now() - circuit.openedAt < resetAfterMs) {
+        await options.onAttempt?.({ provider: provider.name, attempt: 0, outcome: "circuit-open" });
+        last = new AIError(`Circuit is open for provider: ${provider.name}`, 0, "circuit_open");
+        if (callOptions.provider) throw last;
+        continue;
       }
+      if (circuit.openedAt !== undefined) {
+        circuit.failures = 0;
+        circuit.openedAt = undefined;
+      }
+      for (let attempt = 1; attempt <= attempts; attempt++) {
+        if (callOptions.signal?.aborted) throw callOptions.signal.reason ?? abortError();
+        const started = Date.now();
+        await options.onAttempt?.({ provider: provider.name, attempt, outcome: "start" });
+        try {
+          const result = await provider.generate(prompt, callOptions);
+          circuits.set(provider.name, { failures: 0 });
+          await options.onAttempt?.({
+            provider: provider.name,
+            attempt,
+            outcome: "success",
+            durationMs: Date.now() - started,
+            usage: result.usage,
+          });
+          return result;
+        } catch (error) {
+          last = error;
+          circuit.failures++;
+          if (circuit.failures >= failureThreshold) circuit.openedAt = Date.now();
+          circuits.set(provider.name, circuit);
+          await options.onAttempt?.({
+            provider: provider.name,
+            attempt,
+            outcome: "error",
+            durationMs: Date.now() - started,
+            error: safeError(error),
+          });
+          const retryable = (options.retry?.retry ?? defaultRetry)(error);
+          if (!retryable || attempt === attempts || callOptions.signal?.aborted) break;
+          const backoff = Math.min(
+            options.retry?.maxDelayMs ?? 5_000,
+            (options.retry?.baseDelayMs ?? 100) * 2 ** (attempt - 1),
+          );
+          await delay(backoff, callOptions.signal);
+        }
+      }
+      if (options.fallback === false || callOptions.provider) throw last;
     }
     throw last;
   };
+
   return {
     generate,
     async generateObject<T>(
@@ -114,6 +296,16 @@ export function createAIClient(options: AIClientOptions): AIClient {
         validate?: (value: unknown) => value is T;
       } = {},
     ) {
+      const candidates = select(callOptions.provider);
+      if (
+        candidates.length &&
+        candidates.every((provider) => provider.capabilities?.structuredOutput === false)
+      )
+        throw new AIError(
+          "Selected provider does not support structured output",
+          0,
+          "capability_error",
+        );
       const result = await generate(prompt, callOptions);
       let value: unknown;
       try {
@@ -129,11 +321,27 @@ export function createAIClient(options: AIClientOptions): AIClient {
         );
       return { ...result, value: value as T };
     },
+    async executeTools(result, tools, toolOptions = {}) {
+      const registry = new Map(tools.map((tool) => [tool.name, tool]));
+      const output: Array<{ call: AIToolCall; value: unknown }> = [];
+      for (const call of result.toolCalls ?? []) {
+        if (toolOptions.signal?.aborted) throw toolOptions.signal.reason ?? abortError();
+        const tool = registry.get(call.name);
+        if (!tool) throw new AIError(`Unknown AI tool: ${call.name}`, 0, "tool_error");
+        if (tool.validate && !tool.validate(call.arguments))
+          throw new AIError(`Invalid arguments for AI tool: ${call.name}`, 0, "tool_error");
+        output.push({
+          call,
+          value: await tool.execute(call.arguments, { signal: toolOptions.signal }),
+        });
+      }
+      return output;
+    },
     async *stream(prompt, callOptions = {}) {
       const providers = select(callOptions.provider);
       let last: unknown;
       for (const provider of providers) {
-        if (!provider.stream) continue;
+        if (!provider.stream || provider.capabilities?.streaming === false) continue;
         try {
           yield* provider.stream(prompt, callOptions);
           return;
@@ -146,5 +354,10 @@ export function createAIClient(options: AIClientOptions): AIClient {
       const result = await generate(prompt, callOptions);
       yield result.value;
     },
+    capabilities(provider) {
+      return Object.fromEntries(
+        select(provider).map((item) => [item.name, { ...item.capabilities }]),
+      );
+    },
   };
 }