fix(mcp): enable JSON response mode for HTTP transport

Avoid SSE stream response for finite HTTP MCP tool calls by enabling enableJsonResponse option on transport.

src/router/mcp.test.ts

@@ -0,0 +1,51 @@
+import { describe, expect, it, mock } from 'bun:test'
+
+process.env.MCP_SECRET = 'test-secret'
+
+mock.module('@/utils/archive', () => ({
+  archiveVideo: async (input: string) => {
+    // Integration delay simulation to test async handler waiting
+    await Bun.sleep(50)
+    return { success: true, message: 'Video archived successfully.', videoId: input }
+  },
+  addToSizeWhitelist: async () => ({ success: true, message: 'Whitelisted.' }),
+  getVideoMetadata: async () => ({ success: true, metadata: {} }),
+  extractVideoId: (input: string) => input
+}))
+
+// Dynamic import required so mock.module executes before mcp module is imported
+const { default: app } = await import('./mcp')
+
+describe('HTTP MCP Transport', () => {
+  it('returns JSON response for delayed tool call without streaming SSE', async () => {
+    const startTime = Date.now()
+    const response = await app.handle(
+      new Request('http://localhost/api/mcp/', {
+        method: 'POST',
+        headers: {
+          'Authorization': 'Bearer test-secret',
+          'Accept': 'application/json, text/event-stream',
+          'Content-Type': 'application/json',
+          'Mcp-Protocol-Version': '2025-03-26'
+        },
+        body: JSON.stringify({
+          jsonrpc: '2.0',
+          id: 1,
+          method: 'tools/call',
+          params: {
+            name: 'archive_video',
+            arguments: { videoId: 'dQw4w9WgXcQ' }
+          }
+        })
+      })
+    )
+
+    const duration = Date.now() - startTime
+    expect(duration).toBeLessThan(1000)
+    expect(response.status).toBe(200)
+    expect(response.headers.get('content-type')).toContain('application/json')
+
+    const body = await response.json()
+    expect(body.result.content[0].text).toContain('Video archived successfully.')
+  })
+})

src/router/mcp.ts

@@ -83,7 +83,7 @@ function createMcpServer() {
 }
 
 async function handleMcpStreamRequest(request: Request): Promise<Response> {
-  const transport = new WebStandardStreamableHTTPServerTransport()
+  const transport = new WebStandardStreamableHTTPServerTransport({ enableJsonResponse: true })
   const mcpServer = createMcpServer()
   await mcpServer.connect(transport)
   return await transport.handleRequest(request)