fix: prevent double response with responded guard in spawn handlers

vite.config.ts

@@ -67,15 +67,20 @@ function apiSavePlugin() {
 
             let stdout = ''
             let stderr = ''
+            let responded = false
             child.stdout.on('data', (d: Buffer) => stdout += d.toString())
             child.stderr.on('data', (d: Buffer) => stderr += d.toString())
 
-            child.on('error', (err) => {
+            child.on('error', () => {
+              if (responded) return
+              responded = true
               res.writeHead(503)
               res.end(JSON.stringify({ error: 'opencode 未安装，请运行 npm install' }))
             })
 
             child.on('close', async (code) => {
+              if (responded) return
+              responded = true
               if (code !== 0) {
                 res.writeHead(500)
                 res.end(JSON.stringify({ error: 'opencode exited with code ' + code, stderr }))
@@ -131,12 +136,17 @@ function apiSavePlugin() {
         try {
           const child = spawn('npx', ['opencode', 'session', 'list', '--format', 'json'], { timeout: 5000 })
           let stdout = ''
+          let responded = false
           child.stdout.on('data', (d: Buffer) => stdout += d.toString())
           child.on('error', () => {
+            if (responded) return
+            responded = true
             res.writeHead(200, { 'Content-Type': 'application/json' })
             res.end('[]')
           })
           child.on('close', () => {
+            if (responded) return
+            responded = true
             res.writeHead(200, { 'Content-Type': 'application/json' })
             res.end(stdout || '[]')
           })