diff --git a/packages/ui-default/components/autocomplete/components/AutoComplete.tsx b/packages/ui-default/components/autocomplete/components/AutoComplete.tsx
index 276d3a3b3..699020bbd 100644
--- a/packages/ui-default/components/autocomplete/components/AutoComplete.tsx
+++ b/packages/ui-default/components/autocomplete/components/AutoComplete.tsx
@@ -233,6 +233,7 @@ const AutoComplete = forwardRef(function Impl<T>(props: AutoCompleteProps<T>, re
     setSelectedItems: (items) => {
       setSelected(items);
       setSelectedKeys(items.map((i) => itemKey(i)));
+      if (!multi && inputRef.current) inputRef.current.value = items.map((i) => itemKey(i)).join(',');
     },
     getQuery: () => inputRef.current?.value,
     setQuery: (query) => {
diff --git a/packages/ui-default/components/problemconfig/TestCasesTable.tsx b/packages/ui-default/components/problemconfig/TestCasesTable.tsx
index 2731d8414..908480dde 100644
--- a/packages/ui-default/components/problemconfig/TestCasesTable.tsx
+++ b/packages/ui-default/components/problemconfig/TestCasesTable.tsx
@@ -2,7 +2,7 @@ import { NumericInput, Tag } from '@blueprintjs/core';
 import { parseMemoryMB, parseTimeMS } from '@hydrooj/utils/lib/common';
 import type { SubtaskConfig } from 'hydrooj/src/interface';
 import { isEqual } from 'lodash';
-import React from 'react';
+import React, { useEffect, useRef } from 'react';
 import { useDispatch, useSelector } from 'react-redux';
 import i18n from 'vj/utils/i18n';
 import FileSelectAutoComplete from '../autocomplete/components/FileSelectAutoComplete';
@@ -29,7 +29,40 @@ export function TestCaseEntry({ index, subindex }) {
       casesKey,
       value,
     });
+    if ((casesKey === 'input' && (value as string).endsWith('.in') && !testcase.output)
+      || (casesKey === 'output' && (value as string).endsWith('.out') && !testcase.input)) {
+      const filename = (value as string).substring(0, (value as string).lastIndexOf('.'));
+      if (!testcase.output && (Files.map((f) => f.name).includes(`${filename}.out`) || Files.map((f) => f.name).includes(`${filename}.ans`))) {
+        dispatch({
+          type: 'CONFIG_SUBTASK_UPDATE',
+          id: index,
+          key: 'cases-edit',
+          casesId: subindex,
+          casesKey: 'output',
+          value: Files.map((f) => f.name).includes(`${filename}.out`) ? `${filename}.out` : `${filename}.ans`,
+        });
+      }
+      if (!testcase.input && Files.map((f) => f.name).includes(`${filename}.in`)) {
+        dispatch({
+          type: 'CONFIG_SUBTASK_UPDATE',
+          id: index,
+          key: 'cases-edit',
+          casesId: subindex,
+          casesKey: 'input',
+          value: `${filename}.in`,
+        });
+      }
+    }
   };
+  const refs = {
+    input: useRef(),
+    output: useRef(),
+  };
+  for (const type of ['input', 'output']) {
+    useEffect(() => {
+      refs[type].current?.setSelectedItems(testcase[type] ? [testcase[type]] : []);
+    }, [testcase[type]]);
+  }
   if (!testcase || Object.keys(testcase).length === 0) {
     return (
       <tr><td colSpan={5}>{i18n('Failed to parse testcase.')}</td></tr>
@@ -60,6 +93,7 @@ export function TestCaseEntry({ index, subindex }) {
       {['input', 'output'].map((t) => (
         <td key={t}>
           <FileSelectAutoComplete
+            ref={refs[t]}
             width="100%"
             data={Files}
             selectedKeys={[testcase[t]]}
diff --git a/packages/ui-default/components/problemconfig/reducer/config.ts b/packages/ui-default/components/problemconfig/reducer/config.ts
index d370d9500..522a14526 100644
--- a/packages/ui-default/components/problemconfig/reducer/config.ts
+++ b/packages/ui-default/components/problemconfig/reducer/config.ts
@@ -48,7 +48,7 @@ export default function reducer(state = { type: 'default', __loaded: false } as
       if (action.key.split('-')[0] === 'cases') {
         if (action.key === 'cases-add') subsubtasks.cases.push(action.value);
         else if (action.key === 'cases-edit') {
-          if (action.value === '') delete subsubtasks.cases[action.casesId][action.casesKey];
+          if (action.value === '' && !['input', 'output'].includes(action.casesKey)) delete subsubtasks.cases[action.casesId][action.casesKey];
           else subsubtasks.cases[action.casesId][action.casesKey] = action.value;
         } else if (action.key === 'cases-delete') {
           subsubtasks.cases = subsubtasks.cases.filter((k, v) => v !== action.value);
diff --git a/packages/vjudge/package.json b/packages/vjudge/package.json
index 884585bc7..b7220bdb6 100644
--- a/packages/vjudge/package.json
+++ b/packages/vjudge/package.json
@@ -1,6 +1,6 @@
 {
     "name": "@hydrooj/vjudge",
-    "version": "1.5.0-next.6",
+    "version": "1.5.0-next.7",
     "description": "Submit problems to remote oj",
     "main": "package.json",
     "repository": "https://github.com/hydro-dev/Hydro.git",
diff --git a/packages/vjudge/src/interface.ts b/packages/vjudge/src/interface.ts
index 4c8c944f4..0b623c72c 100644
--- a/packages/vjudge/src/interface.ts
+++ b/packages/vjudge/src/interface.ts
@@ -32,7 +32,7 @@ export interface IBasicProvider {
     }>;
     entryProblemLists?: string[];
     listProblem(page: number, resync: boolean, listId: string): Promise<string[]>;
-    submitProblem(id: string, lang: string, code: string, info: any, next: any, end: any): Promise<string>;
+    submitProblem(id: string, lang: string, code: string, info: any, next: any, end: any): Promise<string | void>;
     waitForSubmission(id: string, next: any, end: any): Promise<void>;
 }
 
diff --git a/packages/vjudge/src/providers/luogu.ts b/packages/vjudge/src/providers/luogu.ts
index 5a1751586..a2e8eb6f7 100644
--- a/packages/vjudge/src/providers/luogu.ts
+++ b/packages/vjudge/src/providers/luogu.ts
@@ -89,8 +89,6 @@ export default class LuoguProvider implements IBasicProvider {
     }
 
     async getProblem(id: string) {
-        logger.info(id);
-        // TODO
         return {
             title: id,
             data: {},
@@ -104,9 +102,16 @@ export default class LuoguProvider implements IBasicProvider {
         return [];
     }
 
-    async submitProblem(id: string, lang: string, code: string, info) {
+    async submitProblem(id: string, lang: string, code: string, info, next, end) {
         let enableO2 = 0;
         const comment = setting.langs[lang]?.comment;
+        if (code.length < 10) {
+            end({ status: STATUS.STATUS_COMPILE_ERROR, message: 'Code too short' });
+            return null;
+        }
+        if (!lang.startsWith('luogu.')) {
+            end({ status: STATUS.STATUS_COMPILE_ERROR, message: `Language not supported: ${lang}` });
+        }
         if (comment) {
             const msg = `Hydro submission #${info.rid}@${new Date().toLocaleString()}`;
             if (typeof comment === 'string') code = `${comment} ${msg}\n${code}`;
@@ -116,7 +121,7 @@ export default class LuoguProvider implements IBasicProvider {
             enableO2 = 1;
             lang = lang.slice(0, -2);
         }
-        lang = lang.includes('luogu.') ? lang.split('luogu.')[1] : '0';
+        lang = lang.split('luogu.')[1];
         const result = await this.post(`/fe/api/problem/submit/${id}${this.account.query || ''}`)
             .set('referer', `https://www.luogu.com.cn/problem/${id}`)
             .send({