fix(agent): warm up opencode on startup

tests/runtime/opencode.test.ts

@@ -1,4 +1,5 @@
 import { describe, expect, it } from "bun:test";
+import { type OpencodeClient } from "@opencode-ai/sdk/v2";
 
 import { OpencodeRuntimeAdapter } from "../../src/runtime/opencode.js";
 
@@ -60,3 +61,27 @@ describe("OpencodeRuntimeAdapter.revertToUserMessage", () => {
     });
   });
 });
+
+describe("OpencodeRuntimeAdapter.ensureClient", () => {
+  it("retries bootstrap after a failed startup attempt", async () => {
+    let attempts = 0;
+    const client = {
+      global: { health: async () => ({ data: { healthy: true } }) },
+    } as unknown as OpencodeClient;
+    const runtime = Object.assign(Object.create(OpencodeRuntimeAdapter.prototype), {
+      clientPromise: null,
+      closeServer: null,
+      bootstrapClient: async () => {
+        attempts += 1;
+        if (attempts === 1) {
+          throw new Error("startup failed");
+        }
+        return client;
+      },
+    }) as OpencodeRuntimeAdapter;
+
+    await expect(runtime.ensureClient()).rejects.toThrow("startup failed");
+    await expect(runtime.ensureClient()).resolves.toBe(client);
+    expect(attempts).toBe(2);
+  });
+});