feat(providers): add OpencodeExecutor for opencode-zen/go multi-format routing

open-sse/executors/opencode.ts

@@ -0,0 +1,61 @@
+import { BaseExecutor, type ExecuteInput, type ProviderCredentials } from "./base.ts";
+import { PROVIDERS } from "../config/constants.ts";
+import { getModelTargetFormat } from "../config/providerModels.ts";
+
+export class OpencodeExecutor extends BaseExecutor {
+  _requestFormat: string | null = null;
+
+  constructor(provider: string) {
+    super(provider, PROVIDERS[provider] || PROVIDERS.openai);
+  }
+
+  async execute(input: ExecuteInput) {
+    this._requestFormat = getModelTargetFormat(this.provider, input.model) || "openai";
+    try {
+      return await super.execute(input);
+    } finally {
+      this._requestFormat = null;
+    }
+  }
+
+  buildUrl(
+    model: string,
+    stream: boolean,
+    urlIndex = 0,
+    credentials: ProviderCredentials | null = null
+  ) {
+    void urlIndex;
+    void credentials;
+
+    const base = this.config.baseUrl;
+    switch (this._requestFormat) {
+      case "claude":
+        return `${base}/messages`;
+      case "openai-responses":
+        return `${base}/responses`;
+      case "gemini":
+        return `${base}/models/${model}:${stream ? "streamGenerateContent?alt=sse" : "generateContent"}`;
+      default:
+        return `${base}/chat/completions`;
+    }
+  }
+
+  buildHeaders(credentials: ProviderCredentials | null, stream = true) {
+    const headers: Record<string, string> = { "Content-Type": "application/json" };
+    const key = credentials?.apiKey || credentials?.accessToken;
+
+    if (key) {
+      headers["Authorization"] = `Bearer ${key}`;
+    }
+
+    if (this._requestFormat === "claude") {
+      headers["anthropic-version"] = "2023-06-01";
+    }
+
+    if (stream) {
+      headers["Accept"] = "text/event-stream";
+    }
+
+    return headers;
+  }
+}