feat: add provider abstraction for review backends

src/providers/openai.js

@@ -0,0 +1,29 @@
+// OpenAI chat provider adapter.
+// Wraps src/openai/client.js + src/openai/responses.js into the provider interface.
+
+import { createOpenAIClient } from "../openai/client.js";
+import { sendOpenAIResponse } from "../openai/responses.js";
+
+/**
+ * Chat provider backed by OpenAI Responses API.
+ * Implements { send(input, config) => Promise<{ content: string }> }.
+ */
+export const openaiProvider = {
+  /**
+   * @param {object} input - validated tool input (post-budget check).
+   * @param {object} config - full config from loadConfig().
+   * @returns {Promise<{ content: string }>}
+   */
+  async send(input, config) {
+    const client = createOpenAIClient(config);
+
+    const result = await sendOpenAIResponse(client, {
+      input: [{ role: "system", content: input }],
+      model: config.openaiModel,
+      temperature: config.temperature,
+      maxOutputTokens: config.maxOutputTokens,
+    });
+
+    return { content: result.content };
+  },
+};