[Init] Initial commit - NetMesh terminal manager

infrastructure/ai/sdk/providers.ts

@@ -0,0 +1,706 @@
+import { createOpenAI } from '@ai-sdk/openai';
+import { createAnthropic } from '@ai-sdk/anthropic';
+import { createGoogle } from '@ai-sdk/google';
+import type { ProviderConfig, ProviderStyle } from '../types';
+import { resolveOpenAIApi, resolveProviderStyle } from '../types';
+import { normalizeAnthropicSdkBaseURL } from '../anthropicCompatBaseUrl';
+import { normalizeOllamaSdkBaseURL } from '../ollamaCompatBaseUrl';
+
+export { normalizeOllamaSdkBaseURL };
+import {
+  applyOpenAIChatContinuationToBody,
+  extractProviderContinuationFromRawChunk,
+  mergeProviderContinuation,
+  rawOpenAIChatChunkHasToolCalls,
+  repairOpenAIChatToolResultPairsInBody,
+  type OpenAIChatAssistantFields,
+} from '../providerContinuation';
+
+export interface ProviderRequestContext {
+  getOpenAIChatAssistantFields?: () => Array<OpenAIChatAssistantFields | undefined>;
+  streamIdleTimeoutMs?: number;
+}
+
+/**
+ * Bridge API subset used for SDK fetch adapter.
+ */
+interface BridgeAPI {
+  aiFetch(
+    url: string,
+    method: string,
+    headers: Record<string, string>,
+    body?: string,
+    providerId?: string,
+  ): Promise<{
+    ok: boolean;
+    status: number;
+    data: string;
+    error?: string;
+  }>;
+  aiChatStream(
+    requestId: string,
+    url: string,
+    headers: Record<string, string>,
+    body: string,
+    providerId?: string,
+    idleTimeoutMs?: number,
+  ): Promise<{ ok: boolean; statusCode?: number; statusText?: string; error?: string; aborted?: boolean }>;
+  onAiStreamData(requestId: string, cb: (data: string) => void): () => void;
+  onAiStreamEnd(requestId: string, cb: () => void): () => void;
+  onAiStreamError(requestId: string, cb: (error: string) => void): () => void;
+  aiChatCancel(requestId: string): Promise<boolean>;
+}
+
+function getBridge(): BridgeAPI | null {
+  const w = window as unknown as { netcatty?: BridgeAPI };
+  return w.netcatty ?? null;
+}
+
+/**
+ * Detect whether a request is likely a streaming request.
+ * AI SDK streaming requests use POST with `"stream": true` in the body.
+ */
+function isStreamingRequest(init?: RequestInit): boolean {
+  if (!init?.body) return false;
+  try {
+    const bodyStr = typeof init.body === 'string' ? init.body : null;
+    if (!bodyStr) return false;
+    const parsed = JSON.parse(bodyStr);
+    return parsed.stream === true;
+  } catch {
+    return false;
+  }
+}
+
+function mergeOpenAIChatAssistantFields(
+  current: OpenAIChatAssistantFields | undefined,
+  incoming: OpenAIChatAssistantFields | undefined,
+): OpenAIChatAssistantFields | undefined {
+  return mergeProviderContinuation(
+    { openAIChatAssistantFields: current },
+    { openAIChatAssistantFields: incoming },
+  )?.openAIChatAssistantFields;
+}
+
+function createOpenAIChatStreamFieldCapture(
+  requestContext?: ProviderRequestContext,
+): (data: string) => void {
+  const assistantFields = requestContext?.getOpenAIChatAssistantFields?.();
+  if (!assistantFields) return () => undefined;
+
+  let streamFieldIndex: number | undefined;
+  let pendingFields: OpenAIChatAssistantFields | undefined;
+
+  const ensureStreamFieldSlot = (): number => {
+    if (streamFieldIndex !== undefined) return streamFieldIndex;
+    streamFieldIndex = assistantFields.length;
+    assistantFields.push(undefined);
+    return streamFieldIndex;
+  };
+
+  const flushPendingFields = (fieldIndex: number) => {
+    if (!pendingFields) return;
+    assistantFields[fieldIndex] = mergeOpenAIChatAssistantFields(
+      assistantFields[fieldIndex],
+      pendingFields,
+    );
+    pendingFields = undefined;
+  };
+
+  return (data: string) => {
+    const continuation = extractProviderContinuationFromRawChunk(data);
+    const fields = continuation?.openAIChatAssistantFields;
+    if (fields) {
+      pendingFields = mergeOpenAIChatAssistantFields(pendingFields, fields);
+      if (streamFieldIndex !== undefined) {
+        flushPendingFields(streamFieldIndex);
+      }
+    }
+
+    if (rawOpenAIChatChunkHasToolCalls(data)) {
+      flushPendingFields(ensureStreamFieldSlot());
+    }
+  };
+}
+
+function createOpenAIChatToolCallNormalizer(requestId: string): (data: string) => string {
+  const toolCallIdsByChoiceAndIndex = new Map<string, string>();
+  const toolCallNamesByChoiceAndIndex = new Map<string, string>();
+  const pendingToolCallsByChoiceAndIndex = new Map<string, Record<string, unknown>>();
+  // Full concatenation of every arguments fragment seen for a tool call key,
+  // so a tool call the SDK has not seen yet can be forwarded self-describing.
+  const argumentsSeenByKey = new Map<string, string>();
+  // Keys forwarded inside choices array position 0 — the only element the
+  // AI SDK reads. Tool calls living at position > 0 are invisible to it.
+  const sdkVisibleKeys = new Set<string>();
+  const requestIdToken = requestId.replace(/[^a-zA-Z0-9_-]/g, '_');
+
+  return (data: string): string => {
+    if (!data || data.trim() === '[DONE]') return data;
+
+    let parsed: unknown;
+    try {
+      parsed = JSON.parse(data);
+    } catch {
+      return data;
+    }
+
+    if (!parsed || typeof parsed !== 'object' || !Array.isArray((parsed as Record<string, unknown>).choices)) {
+      return data;
+    }
+
+    let changed = false;
+    const normalizedChoices = ((parsed as Record<string, unknown>).choices as unknown[]).map((choice, choicePosition) => {
+      if (!choice || typeof choice !== 'object') return choice;
+      const choiceRecord = choice as Record<string, unknown>;
+      const delta = choiceRecord.delta;
+      if (!delta || typeof delta !== 'object') return choice;
+
+      const deltaRecord = delta as Record<string, unknown>;
+      if (!Array.isArray(deltaRecord.tool_calls)) return choice;
+
+      const choiceIndex = typeof choiceRecord.index === 'number' ? choiceRecord.index : choicePosition;
+      let deltaChanged = false;
+      const normalizedToolCalls: unknown[] = [];
+      for (const [toolCallPosition, toolCall] of deltaRecord.tool_calls.entries()) {
+        if (!toolCall || typeof toolCall !== 'object') {
+          normalizedToolCalls.push(toolCall);
+          continue;
+        }
+        const toolCallRecord = toolCall as Record<string, unknown>;
+        const toolCallIndex = typeof toolCallRecord.index === 'number' ? toolCallRecord.index : toolCallPosition;
+        const key = `${choiceIndex}:${toolCallIndex}`;
+        const recordFn = toolCallRecord.function;
+        const recordArguments = recordFn && typeof recordFn === 'object'
+          ? (recordFn as Record<string, unknown>).arguments
+          : undefined;
+        if (typeof recordArguments === 'string') {
+          argumentsSeenByKey.set(key, (argumentsSeenByKey.get(key) ?? '') + recordArguments);
+        }
+        const existingId = toolCallIdsByChoiceAndIndex.get(key);
+        const pendingToolCall = pendingToolCallsByChoiceAndIndex.get(key);
+        const candidateToolCall = pendingToolCall
+          ? mergeOpenAIChatToolCallDeltas(pendingToolCall, toolCallRecord)
+          : toolCallRecord;
+
+        if (existingId) {
+          const rememberedName = toolCallNamesByChoiceAndIndex.get(key);
+          const needsFullArguments = choicePosition === 0 && !sdkVisibleKeys.has(key);
+          let normalizedToolCall = normalizeOpenAIChatToolCall(
+            toolCallRecord,
+            existingId,
+            rememberedName,
+          );
+          if (needsFullArguments) {
+            normalizedToolCall = injectFullOpenAIChatToolCallArguments(
+              normalizedToolCall,
+              argumentsSeenByKey.get(key),
+            );
+          }
+          if (choicePosition === 0) {
+            sdkVisibleKeys.add(key);
+          }
+          if (
+            normalizedToolCall.id === toolCallRecord.id &&
+            normalizedToolCall.type === toolCallRecord.type &&
+            normalizedToolCall.function === toolCallRecord.function &&
+            (!rememberedName || hasFunctionName(toolCallRecord))
+          ) {
+            normalizedToolCalls.push(toolCall);
+          } else {
+            changed = true;
+            deltaChanged = true;
+            normalizedToolCalls.push(normalizedToolCall);
+          }
+          continue;
+        }
+
+        if (!hasFunctionName(candidateToolCall)) {
+          pendingToolCallsByChoiceAndIndex.set(key, candidateToolCall);
+          changed = true;
+          deltaChanged = true;
+          continue;
+        }
+
+        const toolCallId = typeof candidateToolCall.id === 'string' && candidateToolCall.id
+          ? candidateToolCall.id
+          : `call_netcatty_${requestIdToken}_${choiceIndex}_${toolCallIndex}`;
+        toolCallIdsByChoiceAndIndex.set(key, toolCallId);
+        const candidateFunction = candidateToolCall.function;
+        if (candidateFunction && typeof candidateFunction === 'object') {
+          toolCallNamesByChoiceAndIndex.set(
+            key,
+            (candidateFunction as Record<string, unknown>).name as string,
+          );
+        }
+        pendingToolCallsByChoiceAndIndex.delete(key);
+        let normalizedToolCall = normalizeOpenAIChatToolCall(candidateToolCall, toolCallId);
+        if (choicePosition === 0 && !sdkVisibleKeys.has(key)) {
+          normalizedToolCall = injectFullOpenAIChatToolCallArguments(
+            normalizedToolCall,
+            argumentsSeenByKey.get(key),
+          );
+        }
+        if (choicePosition === 0) {
+          sdkVisibleKeys.add(key);
+        }
+
+        if (
+          candidateToolCall === toolCallRecord &&
+          toolCallId === toolCallRecord.id &&
+          normalizedToolCall.type === toolCallRecord.type &&
+          normalizedToolCall.function === toolCallRecord.function
+        ) {
+          normalizedToolCalls.push(toolCall);
+          continue;
+        }
+
+        changed = true;
+        deltaChanged = true;
+        normalizedToolCalls.push(normalizedToolCall);
+      }
+
+      if (!deltaChanged) return choice;
+      return {
+        ...choiceRecord,
+        delta: {
+          ...deltaRecord,
+          tool_calls: normalizedToolCalls,
+        },
+      };
+    });
+
+    if (!changed) return data;
+    return JSON.stringify({
+      ...(parsed as Record<string, unknown>),
+      choices: normalizedChoices,
+    });
+  };
+}
+
+function mergeOpenAIChatToolCallDeltas(
+  current: Record<string, unknown>,
+  incoming: Record<string, unknown>,
+): Record<string, unknown> {
+  const currentFn = current.function;
+  const incomingFn = incoming.function;
+  const currentFunction = currentFn && typeof currentFn === 'object'
+    ? currentFn as Record<string, unknown>
+    : undefined;
+  const incomingFunction = incomingFn && typeof incomingFn === 'object'
+    ? incomingFn as Record<string, unknown>
+    : undefined;
+  const mergedFunction: Record<string, unknown> = {
+    ...(currentFunction ?? {}),
+    ...(incomingFunction ?? {}),
+  };
+  if (
+    typeof currentFunction?.name === 'string' &&
+    currentFunction.name &&
+    incomingFunction?.name === ''
+  ) {
+    mergedFunction.name = currentFunction.name;
+  }
+  const currentArgs = currentFunction?.arguments;
+  const incomingArgs = incomingFunction?.arguments;
+  if (typeof currentArgs === 'string' && typeof incomingArgs === 'string') {
+    mergedFunction.arguments = currentArgs + incomingArgs;
+  }
+
+  return {
+    ...current,
+    ...incoming,
+    function: mergedFunction,
+  };
+}
+
+function normalizeOpenAIChatToolCall(
+  toolCall: Record<string, unknown>,
+  toolCallId: string,
+  rememberedName?: string,
+): Record<string, unknown> {
+  const normalized = { ...toolCall, id: toolCallId };
+  if (
+    normalized.type === '' ||
+    normalized.type == null ||
+    (typeof normalized.type === 'string' && normalized.type !== 'function')
+  ) {
+    normalized.type = 'function';
+  }
+  const fn = normalized.function;
+  if (fn && typeof fn === 'object') {
+    const fnRecord = fn as Record<string, unknown>;
+    if (!hasFunctionName({ function: fnRecord })) {
+      const normalizedFunction = { ...fnRecord };
+      if (rememberedName) {
+        normalizedFunction.name = rememberedName;
+      } else if (fnRecord.name === '' || fnRecord.name === null) {
+        delete normalizedFunction.name;
+      }
+      normalized.function = normalizedFunction;
+    }
+  } else if (rememberedName) {
+    normalized.function = { name: rememberedName };
+  }
+  return normalized;
+}
+
+function injectFullOpenAIChatToolCallArguments(
+  toolCall: Record<string, unknown>,
+  fullArguments: string | undefined,
+): Record<string, unknown> {
+  if (fullArguments === undefined) return toolCall;
+  const fn = toolCall.function;
+  const fnRecord = fn && typeof fn === 'object' ? fn as Record<string, unknown> : undefined;
+  if (fnRecord?.arguments === fullArguments) return toolCall;
+  return {
+    ...toolCall,
+    function: { ...(fnRecord ?? {}), arguments: fullArguments },
+  };
+}
+
+function hasFunctionName(toolCall: Record<string, unknown>): boolean {
+  const fn = toolCall.function;
+  return Boolean(
+    fn &&
+    typeof fn === 'object' &&
+    typeof (fn as Record<string, unknown>).name === 'string' &&
+    (fn as Record<string, unknown>).name,
+  );
+}
+
+/**
+ * Extract headers as a plain Record<string, string> from various header formats.
+ */
+function extractHeaders(headers?: HeadersInit): Record<string, string> {
+  const result: Record<string, string> = {};
+  if (!headers) return result;
+
+  if (headers instanceof Headers) {
+    headers.forEach((value, key) => {
+      result[key] = value;
+    });
+  } else if (Array.isArray(headers)) {
+    for (const [key, value] of headers) {
+      result[key] = value;
+    }
+  } else {
+    Object.assign(result, headers);
+  }
+  return result;
+}
+
+/**
+ * Create a fetch function compatible with the Vercel AI SDK that routes
+ * requests through the Electron IPC bridge to avoid CORS.
+ *
+ * - Non-streaming requests: uses `window.netcatty.aiFetch()` and returns a `Response`.
+ * - Streaming requests: uses `window.netcatty.aiChatStream()` and returns a
+ *   `Response` with a `ReadableStream` body.
+ * - Falls back to `globalThis.fetch` if the bridge is unavailable.
+ */
+/** Placeholder API key used by the renderer; main process replaces it with the real key. */
+export const API_KEY_PLACEHOLDER = '__IPC_SECURED__';
+
+function toSafeStatusText(message: string, fallback: string): string {
+  const normalized = message
+    .replace(/[\r\n\t]+/g, ' ')
+    .replace(/\s+/g, ' ')
+    .trim();
+  if (!normalized) return fallback;
+  const byteStringSafe = Array.from(normalized, (char) => {
+    const code = char.charCodeAt(0);
+    if (code < 0x20 || code === 0x7f || code > 0xff) return '?';
+    return char;
+  }).join('');
+  return byteStringSafe.slice(0, 120) || fallback;
+}
+
+export function createBridgeFetchForSDK(
+  providerId?: string,
+  requestContext?: ProviderRequestContext,
+): typeof globalThis.fetch {
+  return async (
+    input: string | URL | Request,
+    init?: RequestInit,
+  ): Promise<Response> => {
+    const bridge = getBridge();
+    if (!bridge) {
+      return globalThis.fetch(input, init);
+    }
+
+    // Resolve URL string
+    let url: string;
+    let resolvedInit = init;
+
+    if (input instanceof Request) {
+      url = input.url;
+      // Merge Request properties with init overrides
+      if (!resolvedInit) {
+        resolvedInit = {
+          method: input.method,
+          headers: extractHeaders(input.headers),
+          body: input.body ? await new Response(input.body).text() : undefined,
+        };
+      }
+    } else {
+      url = input instanceof URL ? input.toString() : input;
+    }
+
+    const method = resolvedInit?.method || 'GET';
+    const headers = extractHeaders(resolvedInit?.headers);
+    const body =
+      resolvedInit?.body != null ? String(resolvedInit.body) : undefined;
+    const requestBody = body != null
+      ? repairOpenAIChatToolResultPairsInBody(applyOpenAIChatContinuationToBody(
+          body,
+          requestContext?.getOpenAIChatAssistantFields?.() ?? [],
+        ))
+      : undefined;
+
+    // Streaming path
+    if (isStreamingRequest(resolvedInit)) {
+      const requestId = `sdk_${Date.now()}_${Math.random().toString(36).slice(2, 8)}`;
+      const captureOpenAIChatFields = createOpenAIChatStreamFieldCapture(requestContext);
+      const normalizeOpenAIChatToolCalls = createOpenAIChatToolCallNormalizer(requestId);
+
+      // Set up IPC event listeners BEFORE starting the stream to avoid
+      // missing early events.
+      const encoder = new TextEncoder();
+      let streamController: ReadableStreamDefaultController<Uint8Array> | null = null;
+      const pendingChunks: Uint8Array[] = [];
+      let pendingClose = false;
+      let pendingError: Error | null = null;
+      let cleanedUp = false;
+
+      const enqueueChunk = (chunk: Uint8Array) => {
+        if (streamController) {
+          streamController.enqueue(chunk);
+          return;
+        }
+        pendingChunks.push(chunk);
+      };
+      const closeStream = () => {
+        if (streamController) {
+          try { streamController.close(); } catch { /* already closed */ }
+          return;
+        }
+        pendingClose = true;
+      };
+      const errorStream = (error: Error) => {
+        if (streamController) {
+          try { streamController.error(error); } catch { /* already errored */ }
+          return;
+        }
+        pendingError = error;
+      };
+      const flushPendingStreamEvents = (controller: ReadableStreamDefaultController<Uint8Array>) => {
+        for (const chunk of pendingChunks.splice(0)) {
+          controller.enqueue(chunk);
+        }
+        if (pendingError) {
+          controller.error(pendingError);
+          return;
+        }
+        if (pendingClose) {
+          controller.close();
+        }
+      };
+
+      const unsubData = bridge.onAiStreamData(requestId, (data: string) => {
+        const normalizedData = normalizeOpenAIChatToolCalls(data);
+        captureOpenAIChatFields(normalizedData);
+        // Re-wrap as SSE so the SDK can parse it
+        enqueueChunk(encoder.encode(`data: ${normalizedData}\n\n`));
+      });
+      const unsubEnd = bridge.onAiStreamEnd(requestId, () => {
+        closeStream();
+        cleanup();
+      });
+      const unsubError = bridge.onAiStreamError(
+        requestId,
+        (error: string) => {
+          errorStream(new Error(error));
+          cleanup();
+        },
+      );
+
+      const cleanup = () => {
+        if (cleanedUp) return;
+        cleanedUp = true;
+        unsubData();
+        unsubEnd();
+        unsubError();
+      };
+
+      // Handle abort
+      if (resolvedInit?.signal) {
+        resolvedInit.signal.addEventListener(
+          'abort',
+          () => {
+            bridge.aiChatCancel(requestId).catch(() => {});
+            errorStream(new DOMException('Aborted', 'AbortError'));
+            cleanup();
+          },
+          { once: true },
+        );
+      }
+
+      // Start the stream — resolves once HTTP response headers arrive,
+      // returning the real status code.
+      const result = await bridge.aiChatStream(
+        requestId,
+        url,
+        headers,
+        requestBody || '',
+        providerId,
+        requestContext?.streamIdleTimeoutMs,
+      );
+
+      if (!result.ok) {
+        cleanup();
+        // Cancel during proxy lookup / request start must stay an AbortError,
+        // not a synthetic 502 that the AI SDK treats as a provider failure.
+        if (result.aborted || resolvedInit?.signal?.aborted) {
+          throw new DOMException('Aborted', 'AbortError');
+        }
+        const errorMessage = result.error || 'Stream request failed';
+        const jsonBody = JSON.stringify({ error: { message: errorMessage } });
+        return new Response(jsonBody, {
+          status: 502,
+          statusText: toSafeStatusText(errorMessage, 'Bad Gateway'),
+          headers: { 'content-type': 'application/json' },
+        });
+      }
+
+      // If the server returned a non-2xx status, return the error details
+      // as a JSON body in OpenAI-compatible format so the AI SDK's
+      // failedResponseHandler can extract the message properly.
+      // Also set a safe ASCII statusText as fallback for non-OpenAI SDK providers.
+      const statusCode = result.statusCode ?? 200;
+      if (statusCode < 200 || statusCode >= 300) {
+        cleanup();
+        const errorDetail = result.statusText || `HTTP ${statusCode}`;
+        const jsonBody = JSON.stringify({ error: { message: errorDetail } });
+        return new Response(jsonBody, {
+          status: statusCode,
+          statusText: toSafeStatusText(errorDetail, `Error ${statusCode}`),
+          headers: { 'content-type': 'application/json' },
+        });
+      }
+
+      const stream = new ReadableStream<Uint8Array>({
+        start(controller) {
+          streamController = controller;
+          flushPendingStreamEvents(controller);
+        },
+      });
+
+      return new Response(stream, {
+        status: statusCode,
+        statusText: result.statusText ?? 'OK',
+        headers: { 'content-type': 'text/event-stream' },
+      });
+    }
+
+    // Non-streaming path
+    const result = await bridge.aiFetch(url, method, headers, requestBody, providerId);
+
+    return new Response(result.data, {
+      status: result.status,
+      statusText: result.ok ? 'OK' : 'Error',
+      headers: { 'content-type': 'application/json' },
+    });
+  };
+}
+
+/**
+ * Create a Vercel AI SDK model instance from a ProviderConfig.
+ *
+ * API keys are NOT sent to the SDK in plaintext. Instead, a placeholder
+ * token is used so the SDK builds proper auth headers, and the main
+ * process replaces the placeholder with the real decrypted key before
+ * making the HTTP request.
+ */
+/**
+ * Apply per-vendor URL and apiKey quirks on top of the style-based
+ * wire-protocol routing. Exported so it can be unit-tested without spinning
+ * up the Vercel AI SDK clients.
+ *
+ * The URL fallback fires regardless of style — the user picked this
+ * providerId for a reason, even if they overrode the wire format. The
+ * ollama `'ollama'` throwaway apiKey is only for unauthenticated local
+ * OpenAI-compat servers: Anthropic/Google need a real key, and Ollama
+ * Cloud must keep the IPC placeholder so the main process can inject
+ * the decrypted cloud key.
+ */
+export function resolveProviderEndpoint(
+  config: ProviderConfig,
+  style: ProviderStyle,
+  safeApiKey: string | undefined,
+): { baseURL: string | undefined; apiKey: string | undefined } {
+  let baseURL = config.baseURL;
+  let apiKey = safeApiKey;
+  if (config.providerId === 'ollama') {
+    baseURL = normalizeOllamaSdkBaseURL(baseURL || 'http://localhost:11434/v1');
+    if (style === 'openai' && !apiKey) {
+      apiKey = 'ollama';
+    }
+  } else if (config.providerId === 'openrouter') {
+    baseURL = baseURL || 'https://openrouter.ai/api/v1';
+  }
+  // @ai-sdk/anthropic expects baseURL to include /v1 (then appends /messages).
+  // Bare Claude Code style hosts get /v1 so chat matches probe/discovery.
+  // Custom path prefixes (e.g. …/anthropic) are left alone — they already
+  // complete the SDK base and must not become …/anthropic/v1.
+  if (style === 'anthropic' && baseURL) {
+    baseURL = normalizeAnthropicSdkBaseURL(baseURL);
+  }
+  return { baseURL, apiKey };
+}
+
+export function createModelFromConfig(
+  config: ProviderConfig,
+  requestContext?: ProviderRequestContext,
+) {
+  // Use placeholder API key — the main process will inject the real key
+  const safeApiKey = config.apiKey ? API_KEY_PLACEHOLDER : undefined;
+  const customFetch = createBridgeFetchForSDK(config.id, requestContext);
+  const modelId = config.defaultModel || '';
+  const style = resolveProviderStyle(config);
+  const { baseURL, apiKey } = resolveProviderEndpoint(config, style, safeApiKey);
+
+  switch (style) {
+    case 'openai': {
+      const openai = createOpenAI({
+        apiKey,
+        baseURL,
+        fetch: customFetch,
+      });
+      // Chat Completions stays the default so OpenAI-compatible proxies keep
+      // working. Responses is opt-in for relays that cache better on /v1/responses.
+      return resolveOpenAIApi(config) === 'responses'
+        ? openai.responses(modelId)
+        : openai.chat(modelId);
+    }
+
+    case 'anthropic':
+      return createAnthropic({
+        apiKey,
+        baseURL,
+        fetch: customFetch,
+      })(modelId);
+
+    case 'google':
+      return createGoogle({
+        apiKey,
+        baseURL,
+        fetch: customFetch,
+      })(modelId);
+
+    default: {
+      const _exhaustive: never = style;
+      throw new Error(`Unsupported provider style: ${_exhaustive}`);
+    }
+  }
+}