diff --git a/e2e/specs/opencode-conversation.e2e.ts b/e2e/specs/opencode-conversation.e2e.ts
new file mode 100644
index 0000000..affc279
--- /dev/null
+++ b/e2e/specs/opencode-conversation.e2e.ts
@@ -0,0 +1,99 @@
+/**
+ * OpenCode real E2E conversation test.
+ *
+ * Tests the full stack with a real OpenCode server:
+ *   OpenCodeProvider → callOpenCode → OpenCodeClient → createOpencode (real server)
+ *
+ * Skipped automatically if the opencode binary is not found.
+ * Run with: npm run test:e2e:opencode
+ */
+
+import { describe, it, expect, afterAll } from 'vitest';
+import { execSync } from 'node:child_process';
+import { resetSharedServer } from '../../src/infra/opencode/client.js';
+import { OpenCodeProvider } from '../../src/infra/providers/opencode.js';
+
+function isOpencodeAvailable(): boolean {
+  try {
+    execSync('which opencode', { stdio: 'ignore' });
+    return true;
+  } catch {
+    return false;
+  }
+}
+
+const MODEL = process.env.OPENCODE_E2E_MODEL ?? 'minimax/MiniMax-M2.5-highspeed';
+const enabled = isOpencodeAvailable();
+
+describe.skipIf(!enabled)('OpenCode real E2E conversation', () => {
+  afterAll(() => {
+    resetSharedServer();
+  });
+
+  it('should complete a two-turn conversation with sessionId inheritance', async () => {
+    const provider = new OpenCodeProvider();
+    const agent = provider.setup({
+      name: 'coder',
+      systemPrompt: 'You are a concise assistant. Keep all responses under 20 words.',
+    });
+
+    // 1ターン目
+    const result1 = await agent.call('Say only the word "apple".', {
+      cwd: process.cwd(),
+      model: MODEL,
+    });
+
+    expect(result1.status).toBe('done');
+    expect(result1.sessionId).toBeDefined();
+
+    // 2ターン目: sessionId を引き継いで送る（conversationLoop と同じ）
+    const result2 = await agent.call('What fruit did I ask you about?', {
+      cwd: process.cwd(),
+      model: MODEL,
+      sessionId: result1.sessionId,
+    });
+
+    expect(result2.status).toBe('done');
+    // 同じセッションを再利用している
+    expect(result2.sessionId).toBe(result1.sessionId);
+    // 会話が引き継がれていれば "apple" に言及するはず
+    expect(result2.content.toLowerCase()).toContain('apple');
+  }, 120_000);
+
+  it('should complete a three-turn conversation without hanging', async () => {
+    const provider = new OpenCodeProvider();
+    const agent = provider.setup({
+      name: 'coder',
+      systemPrompt: 'You are a concise assistant. Keep all responses under 20 words.',
+    });
+
+    const results = [];
+    let prevSessionId: string | undefined;
+
+    const prompts = [
+      'Remember the number 42.',
+      'What number did I ask you to remember?',
+      'Double that number.',
+    ];
+
+    for (const prompt of prompts) {
+      const result = await agent.call(prompt, {
+        cwd: process.cwd(),
+        model: MODEL,
+        sessionId: prevSessionId,
+      });
+
+      expect(result.status).toBe('done');
+      results.push(result);
+      prevSessionId = result.sessionId;
+    }
+
+    // すべてのターンが同じセッションを使っている
+    expect(results[1].sessionId).toBe(results[0].sessionId);
+    expect(results[2].sessionId).toBe(results[0].sessionId);
+
+    // 会話が引き継がれている
+    expect(results[1].content).toMatch(/42/);
+    expect(results[2].content).toMatch(/84/);
+  }, 180_000);
+});
diff --git a/src/__tests__/opencode-client-cleanup.test.ts b/src/__tests__/opencode-client-cleanup.test.ts
index ab40943..4adb3d4 100644
--- a/src/__tests__/opencode-client-cleanup.test.ts
+++ b/src/__tests__/opencode-client-cleanup.test.ts
@@ -95,10 +95,6 @@ describe('OpenCodeClient stream cleanup', () => {
 
     expect(result.status).toBe('done');
     expect(stream.returnSpy).toHaveBeenCalled();
-    expect(disposeInstance).toHaveBeenCalledWith(
-      { directory: '/tmp' },
-      expect.objectContaining({ signal: expect.any(AbortSignal) }),
-    );
     expect(subscribe).toHaveBeenCalledWith(
       { directory: '/tmp' },
       expect.objectContaining({ signal: expect.any(AbortSignal) }),
@@ -141,10 +137,6 @@ describe('OpenCodeClient stream cleanup', () => {
     expect(result.status).toBe('error');
     expect(result.content).toContain('boom');
     expect(stream.returnSpy).toHaveBeenCalled();
-    expect(disposeInstance).toHaveBeenCalledWith(
-      { directory: '/tmp' },
-      expect.objectContaining({ signal: expect.any(AbortSignal) }),
-    );
     expect(subscribe).toHaveBeenCalledWith(
       { directory: '/tmp' },
       expect.objectContaining({ signal: expect.any(AbortSignal) }),
@@ -210,10 +202,6 @@ describe('OpenCodeClient stream cleanup', () => {
 
     expect(result.status).toBe('done');
     expect(result.content).toBe('done more');
-    expect(disposeInstance).toHaveBeenCalledWith(
-      { directory: '/tmp' },
-      expect.objectContaining({ signal: expect.any(AbortSignal) }),
-    );
     expect(subscribe).toHaveBeenCalledWith(
       { directory: '/tmp' },
       expect.objectContaining({ signal: expect.any(AbortSignal) }),
@@ -615,4 +603,137 @@ describe('OpenCodeClient stream cleanup', () => {
     expect(result1.status).toBe('done');
     expect(result2.status).toBe('done');
   });
+
+});
+
+describe('OpenCode conversation via provider (E2E)', () => {
+  beforeEach(async () => {
+    vi.clearAllMocks();
+    const { resetSharedServer } = await import('../infra/opencode/client.js');
+    resetSharedServer();
+  });
+
+  function makeClientMock(sessionId: string, responses: string[]) {
+    let turnIndex = 0;
+    const sessionCreate = vi.fn().mockResolvedValue({ data: { id: sessionId } });
+    const promptAsync = vi.fn().mockResolvedValue(undefined);
+    const subscribe = vi.fn().mockImplementation(() => {
+      const text = responses[turnIndex] ?? '';
+      const events: unknown[] = [];
+      if (text) {
+        events.push({
+          type: 'message.part.updated',
+          properties: { part: { id: `p-${turnIndex}`, type: 'text', text }, delta: text },
+        });
+      }
+      events.push({ type: 'session.idle', properties: { sessionID: sessionId } });
+      turnIndex += 1;
+      return Promise.resolve({ stream: new MockEventStream(events) });
+    });
+    return { sessionCreate, promptAsync, subscribe };
+  }
+
+  it('should carry sessionId across turns and reuse server', async () => {
+    const { OpenCodeProvider } = await import('../infra/providers/opencode.js');
+    const { resetSharedServer } = await import('../infra/opencode/client.js');
+    resetSharedServer();
+
+    const { sessionCreate, promptAsync, subscribe } = makeClientMock('conv-session', [
+      'Hello!',
+      'I remember our conversation.',
+    ]);
+
+    createOpencodeMock.mockResolvedValue({
+      client: {
+        instance: { dispose: vi.fn() },
+        session: { create: sessionCreate, promptAsync },
+        event: { subscribe },
+        permission: { reply: vi.fn() },
+      },
+      server: { close: vi.fn() },
+    });
+
+    const provider = new OpenCodeProvider();
+    const agent = provider.setup({ name: 'coder', systemPrompt: 'You are a helpful assistant.' });
+
+    // 1ターン目
+    const result1 = await agent.call('Hi', { cwd: '/tmp', model: 'opencode/big-pickle' });
+    expect(result1.status).toBe('done');
+    expect(result1.content).toBe('Hello!');
+    expect(result1.sessionId).toBe('conv-session');
+
+    // 2ターン目: conversationLoop と同様に前ターンの sessionId を引き継ぐ
+    const result2 = await agent.call('Do you remember me?', {
+      cwd: '/tmp',
+      model: 'opencode/big-pickle',
+      sessionId: result1.sessionId,
+    });
+    expect(result2.status).toBe('done');
+    expect(result2.content).toBe('I remember our conversation.');
+    expect(result2.sessionId).toBe('conv-session');
+
+    // サーバーは1回だけ起動（再利用）
+    expect(createOpencodeMock).toHaveBeenCalledTimes(1);
+    // sessionId を引き継いだので session.create は1回だけ
+    expect(sessionCreate).toHaveBeenCalledTimes(1);
+    // 両ターンでプロンプトが送られた
+    expect(promptAsync).toHaveBeenCalledTimes(2);
+    expect(subscribe).toHaveBeenCalledTimes(2);
+  });
+
+  it('should carry sessionId across three turns (multi-turn conversation)', async () => {
+    const { OpenCodeProvider } = await import('../infra/providers/opencode.js');
+    const { resetSharedServer } = await import('../infra/opencode/client.js');
+    resetSharedServer();
+
+    const { sessionCreate, promptAsync, subscribe } = makeClientMock('multi-session', [
+      'Turn 1 response',
+      'Turn 2 response',
+      'Turn 3 response',
+    ]);
+
+    createOpencodeMock.mockResolvedValue({
+      client: {
+        instance: { dispose: vi.fn() },
+        session: { create: sessionCreate, promptAsync },
+        event: { subscribe },
+        permission: { reply: vi.fn() },
+      },
+      server: { close: vi.fn() },
+    });
+
+    const provider = new OpenCodeProvider();
+    const agent = provider.setup({ name: 'coder' });
+
+    const results = [];
+    let prevSessionId: string | undefined;
+
+    for (let i = 0; i < 3; i++) {
+      const result = await agent.call(`message ${i + 1}`, {
+        cwd: '/tmp',
+        model: 'opencode/big-pickle',
+        sessionId: prevSessionId,
+      });
+      results.push(result);
+      prevSessionId = result.sessionId;
+    }
+
+    expect(results[0].status).toBe('done');
+    expect(results[1].status).toBe('done');
+    expect(results[2].status).toBe('done');
+    expect(results[0].content).toBe('Turn 1 response');
+    expect(results[1].content).toBe('Turn 2 response');
+    expect(results[2].content).toBe('Turn 3 response');
+
+    // サーバーは1回だけ起動
+    expect(createOpencodeMock).toHaveBeenCalledTimes(1);
+    // sessionId を引き継いでいるので session.create は1回のみ
+    expect(sessionCreate).toHaveBeenCalledTimes(1);
+    // 3ターン分のプロンプトが送られた
+    expect(promptAsync).toHaveBeenCalledTimes(3);
+    // すべてのターンで同じ sessionId
+    expect(results[0].sessionId).toBe('multi-session');
+    expect(results[1].sessionId).toBe('multi-session');
+    expect(results[2].sessionId).toBe('multi-session');
+  });
 });
diff --git a/src/infra/opencode/client.ts b/src/infra/opencode/client.ts
index a0cf429..748912a 100644
--- a/src/infra/opencode/client.ts
+++ b/src/infra/opencode/client.ts
@@ -62,7 +62,7 @@ interface SharedServer {
 let sharedServer: SharedServer | null = null;
 let initPromise: Promise<void> | null = null;
 
-async function acquireClient(model: string, apiKey?: string, signal?: AbortSignal): Promise<{ client: OpencodeClient; release: () => void }> {
+async function acquireClient(model: string, apiKey?: string): Promise<{ client: OpencodeClient; release: () => void }> {
   if (initPromise) {
     await initPromise;
   }
@@ -85,7 +85,6 @@ async function acquireClient(model: string, apiKey?: string, signal?: AbortSigna
     const port = await getFreePort();
     const { client, server } = await createOpencode({
       port,
-      signal,
       config: {
         model,
         small_model: model,
@@ -94,7 +93,15 @@ async function acquireClient(model: string, apiKey?: string, signal?: AbortSigna
       timeout: OPENCODE_SERVER_START_TIMEOUT_MS,
     });
 
-    sharedServer = { client, close: server.close, model, apiKey, queue: [] };
+    const closeServer = (): void => {
+      try {
+        server.close();
+      } catch {
+        // Ignore close errors
+      }
+    };
+
+    sharedServer = { client, close: closeServer, model, apiKey, queue: [] };
     log.debug('OpenCode server started', { model, port });
 
     return { client, release: () => releaseClient() };
@@ -380,7 +387,7 @@ export class OpenCodeClient {
         const parsedModel = parseProviderModel(options.model, 'OpenCode model');
         const fullModel = `${parsedModel.providerID}/${parsedModel.modelID}`;
 
-        const acquired = await acquireClient(fullModel, options.opencodeApiKey, streamAbortController.signal);
+        const acquired = await acquireClient(fullModel, options.opencodeApiKey);
         opencodeApiClient = acquired.client;
         release = acquired.release;
 
@@ -707,22 +714,6 @@ export class OpenCodeClient {
         if (options.abortSignal) {
           options.abortSignal.removeEventListener('abort', onExternalAbort);
         }
-        if (opencodeApiClient) {
-          const disposeAbortController = new AbortController();
-          const disposeTimeoutId = setTimeout(() => {
-            disposeAbortController.abort();
-          }, 3000);
-          try {
-            await opencodeApiClient.instance.dispose(
-              { directory: options.cwd },
-              { signal: disposeAbortController.signal },
-            );
-          } catch {
-            // Ignore dispose errors during cleanup.
-          } finally {
-            clearTimeout(disposeTimeoutId);
-          }
-        }
         release?.();
         if (!streamAbortController.signal.aborted) {
           streamAbortController.abort();
diff --git a/vitest.config.e2e.provider.ts b/vitest.config.e2e.provider.ts
index a35d436..8ca9ea4 100644
--- a/vitest.config.e2e.provider.ts
+++ b/vitest.config.e2e.provider.ts
@@ -10,6 +10,7 @@ export default defineConfig({
       'e2e/specs/pipeline.e2e.ts',
       'e2e/specs/github-issue.e2e.ts',
       'e2e/specs/structured-output.e2e.ts',
+      'e2e/specs/opencode-conversation.e2e.ts',
     ],
   },
 });