diff --git a/src/agents/runtime/proxy.test.ts b/src/agents/runtime/proxy.test.ts
new file mode 100644
index 00000000000..a89ef58b946
--- /dev/null
+++ b/src/agents/runtime/proxy.test.ts
@@ -0,0 +1,94 @@
+import { afterEach, describe, expect, it, vi } from "vitest";
+import type { Context, Model, Usage } from "../../llm/types.js";
+import { streamProxy } from "./proxy.js";
+
+const usage: Usage = {
+  input: 1,
+  output: 2,
+  cacheRead: 0,
+  cacheWrite: 0,
+  totalTokens: 3,
+  cost: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0, total: 0 },
+};
+
+const model: Model = {
+  id: "test-model",
+  provider: "test",
+  api: "openai-responses",
+  maxTokens: 1024,
+};
+
+const context: Context = {
+  messages: [{ role: "user", content: "hello" }],
+};
+
+function responseFromText(text: string): Response {
+  return new Response(
+    new ReadableStream({
+      start(controller) {
+        controller.enqueue(new TextEncoder().encode(text));
+        controller.close();
+      },
+    }),
+    { status: 200 },
+  );
+}
+
+describe("streamProxy", () => {
+  afterEach(() => {
+    vi.unstubAllGlobals();
+  });
+
+  it("flushes a final SSE frame without a trailing newline", async () => {
+    vi.stubGlobal(
+      "fetch",
+      vi.fn(async () =>
+        responseFromText(
+          `data: ${JSON.stringify({
+            type: "done",
+            reason: "stop",
+            usage,
+          })}`,
+        ),
+      ),
+    );
+
+    const stream = streamProxy(model, context, {
+      authToken: "token",
+      proxyUrl: "https://proxy.example",
+    });
+    const events = [];
+    for await (const event of stream) {
+      events.push(event);
+    }
+
+    expect(events.at(-1)?.type).toBe("done");
+    await expect(stream.result()).resolves.toMatchObject({
+      role: "assistant",
+      stopReason: "stop",
+      usage,
+    });
+  });
+
+  it("returns an error result when EOF arrives without a terminal event", async () => {
+    vi.stubGlobal(
+      "fetch",
+      vi.fn(async () => responseFromText(`data: ${JSON.stringify({ type: "start" })}`)),
+    );
+
+    const stream = streamProxy(model, context, {
+      authToken: "token",
+      proxyUrl: "https://proxy.example",
+    });
+    const events = [];
+    for await (const event of stream) {
+      events.push(event);
+    }
+
+    expect(events.at(-1)?.type).toBe("error");
+    await expect(stream.result()).resolves.toMatchObject({
+      stopReason: "error",
+      errorMessage: "Proxy stream ended before terminal event",
+    });
+  });
+});
diff --git a/src/agents/runtime/proxy.ts b/src/agents/runtime/proxy.ts
index d7ca996fd04..e624963ed36 100644
--- a/src/agents/runtime/proxy.ts
+++ b/src/agents/runtime/proxy.ts
@@ -189,6 +189,24 @@ export function streamProxy(
       reader = response.body!.getReader();
       const decoder = new TextDecoder();
       let buffer = "";
+      let terminalEventSeen = false;
+
+      const processSseLine = (line: string) => {
+        if (!line.startsWith("data: ")) {
+          return;
+        }
+        const data = line.slice(6).trim();
+        if (!data) {
+          return;
+        }
+        const proxyEvent = JSON.parse(data) as ProxyAssistantMessageEvent;
+        const event = processProxyEvent(proxyEvent, partial);
+        if (!event) {
+          return;
+        }
+        terminalEventSeen = event.type === "done" || event.type === "error";
+        stream.push(event);
+      };
 
       while (true) {
         const { done, value } = await reader.read();
@@ -205,22 +223,20 @@ export function streamProxy(
         buffer = lines.pop() || "";
 
         for (const line of lines) {
-          if (line.startsWith("data: ")) {
-            const data = line.slice(6).trim();
-            if (data) {
-              const proxyEvent = JSON.parse(data) as ProxyAssistantMessageEvent;
-              const event = processProxyEvent(proxyEvent, partial);
-              if (event) {
-                stream.push(event);
-              }
-            }
-          }
+          processSseLine(line);
         }
       }
 
       if (options.signal?.aborted) {
         throw new Error("Request aborted by user");
       }
+      buffer += decoder.decode();
+      if (buffer.trim()) {
+        processSseLine(buffer);
+      }
+      if (!terminalEventSeen) {
+        throw new Error("Proxy stream ended before terminal event");
+      }
 
       stream.end();
     } catch (error) {
diff --git a/src/plugin-sdk/agent-core.test.ts b/src/plugin-sdk/agent-core.test.ts
new file mode 100644
index 00000000000..9c3e6af3cb4
--- /dev/null
+++ b/src/plugin-sdk/agent-core.test.ts
@@ -0,0 +1,12 @@
+import { readFileSync } from "node:fs";
+import { resolve } from "node:path";
+import { describe, expect, it } from "vitest";
+
+describe("plugin-sdk/agent-core", () => {
+  it("keeps public declaration imports package-relative", () => {
+    const source = readFileSync(resolve(process.cwd(), "src/plugin-sdk/agent-core.ts"), "utf8");
+
+    expect(source).toContain("../../packages/agent-core/src/index.js");
+    expect(source).not.toContain("../agents/runtime/index.js");
+  });
+});
diff --git a/src/plugin-sdk/agent-core.ts b/src/plugin-sdk/agent-core.ts
index dc1ce0f0faa..d3f1c8b56ab 100644
--- a/src/plugin-sdk/agent-core.ts
+++ b/src/plugin-sdk/agent-core.ts
@@ -1 +1,23 @@
-export * from "../agents/runtime/index.js";
+import {
+  Agent as CoreAgent,
+  type AgentOptions as CoreAgentOptions,
+} from "../../packages/agent-core/src/agent.js";
+import type { CompleteSimpleFn, StreamFn } from "../../packages/agent-core/src/llm.js";
+import type { AgentCoreRuntimeDeps } from "../../packages/agent-core/src/runtime-deps.js";
+import { completeSimple, streamSimple } from "./llm.js";
+
+export const openClawAgentCoreRuntime = {
+  completeSimple: completeSimple as unknown as CompleteSimpleFn,
+  streamSimple: streamSimple as unknown as StreamFn,
+} satisfies AgentCoreRuntimeDeps;
+
+export class Agent extends CoreAgent {
+  constructor(options: CoreAgentOptions = {}) {
+    super({ runtime: openClawAgentCoreRuntime, ...options });
+  }
+}
+
+// OpenClaw-owned reusable agent core
+export * from "../../packages/agent-core/src/index.js";
+// Proxy utilities
+export * from "../agents/runtime/proxy.js";