chore: import upstream snapshot with attribution

examples/provider-custom/basic/vercelAiSdkExample.js

@@ -0,0 +1,85 @@
+// Example from @Codeshark-NET https://github.com/promptfoo/promptfoo/issues/922
+// @ts-check
+import { anthropic } from '@ai-sdk/anthropic';
+import { generateObject } from 'ai';
+import promptfoo from 'promptfoo';
+import { promptSchema } from './schemaValidation.mjs';
+
+class CustomProvider {
+  constructor(options) {
+    // Provider ID can be overridden by the config file (e.g. when using multiple of the same provider)
+    this.providerId = options.id || 'custom provider';
+
+    // options.config contains any custom options passed to the provider
+    this.config = options.config;
+  }
+
+  id() {
+    return this.providerId;
+  }
+
+  async callApi(prompt, context) {
+    const cache = await promptfoo.default.cache.getCache();
+
+    // Create a unique cache key based on the prompt and context
+    const cacheKey = `api:${this.providerId}:${prompt}}`; // :${JSON.stringify(context)
+
+    // Check if the response is already cached
+    const cachedResponse = await cache.get(cacheKey);
+    if (cachedResponse) {
+      return {
+        // Required
+        output: JSON.parse(cachedResponse),
+
+        // Optional
+        tokenUsage: {
+          total: 0, // No tokens used because it's from the cache
+          prompt: 0,
+          completion: 0,
+        },
+
+        cost: 0, // No cost because it's from the cache
+      };
+    }
+
+    // If not cached, make the function call
+    const model = anthropic('claude-haiku-4-5-20251001');
+    const { object, usage } = await generateObject({
+      model,
+      messages: JSON.parse(prompt),
+      maxTokens: 4096,
+      temperature: 0.4,
+      maxRetries: 0,
+      schema: promptSchema,
+      mode: 'tool',
+    });
+
+    const inputCost = 0.00025 / 1000; //config.cost ?? model.cost.input;
+    const outputCost = 0.00125 / 1000; // config.cost ?? model.cost.output;
+    const totalCost =
+      inputCost * usage.promptTokens + outputCost * usage.completionTokens || undefined;
+
+    // Store the response in the cache
+    try {
+      await cache.set(cacheKey, JSON.stringify(object));
+    } catch (error) {
+      console.error('Failed to store response in cache:', error);
+    }
+
+    return {
+      // Required
+      output: object,
+
+      // Optional
+      tokenUsage: {
+        total: usage.totalTokens,
+        prompt: usage.promptTokens,
+        completion: usage.completionTokens,
+      },
+
+      cost: totalCost,
+    };
+  }
+}
+
+export default CustomProvider;