feat(config): add global prompt setting injected into all LLM calls

Add GLOBAL_PROMPT config field that appends user-defined instructions to
every LLM system message across all 9 call sites (legacy engine, agent
specialist, reflexion, critic, and debate orchestrator).

Configured via admin dashboard (auto-rendered from CONFIG_FIELDS metadata)
or GLOBAL_PROMPT env var. Example use: "请始终使用中文回复".

Changes:
- Add GLOBAL_PROMPT to Zod schema, AppConfig interface, and buildConfig
- Add CONFIG_FIELDS metadata (group: openai, type: text)
- Add getEffectiveValue switch case
- Add withGlobalPrompt() helper in src/utils/global-prompt.ts
- Inject into all LLM call sites via withGlobalPrompt wrapper

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-opencode)

src/config/__tests__/config-manager.test.ts

@@ -28,6 +28,7 @@ const SCHEMA_KEYS = [
   'OPENAI_MODEL',
   'CUSTOM_SUMMARY_PROMPT',
   'CUSTOM_LINE_COMMENT_PROMPT',
+  'GLOBAL_PROMPT',
   'FEISHU_WEBHOOK_URL',
   'FEISHU_WEBHOOK_SECRET',
   'PORT',

src/config/config-manager.ts

@@ -46,6 +46,7 @@ const envSchema = z.object({
   OPENAI_MODEL: z.string().default('gpt-4o-mini'),
   CUSTOM_SUMMARY_PROMPT: z.string().optional(),
   CUSTOM_LINE_COMMENT_PROMPT: z.string().optional(),
+  GLOBAL_PROMPT: z.string().optional(),
 
   // Feishu
   FEISHU_WEBHOOK_URL: z.preprocess(
@@ -118,6 +119,7 @@ export interface AppConfig {
     model: string;
     customSummaryPrompt: string | undefined;
     customLineCommentPrompt: string | undefined;
+    globalPrompt: string | undefined;
   };
   feishu: {
     webhookUrl: string | undefined;
@@ -271,6 +273,7 @@ class ConfigManager {
         model: env.OPENAI_MODEL,
         customSummaryPrompt: env.CUSTOM_SUMMARY_PROMPT,
         customLineCommentPrompt: env.CUSTOM_LINE_COMMENT_PROMPT,
+        globalPrompt: env.GLOBAL_PROMPT,
       },
       feishu: {
         webhookUrl: env.FEISHU_WEBHOOK_URL,

src/config/config-schema.ts

@@ -159,6 +159,14 @@ export const CONFIG_FIELDS: ConfigFieldMeta[] = [
     type: 'text',
     sensitive: false,
   },
+  {
+    envKey: 'GLOBAL_PROMPT',
+    group: 'openai',
+    label: '全局提示词',
+    description: '附加到所有 LLM 调用的系统提示词中（例如："请始终使用中文回复"）',
+    type: 'text',
+    sensitive: false,
+  },
 
   // ── 飞书 ────────────────────────────────────────────────────────────────
   {

src/controllers/config.ts

@@ -50,6 +50,8 @@ function getEffectiveValue(
       return current.openai.customSummaryPrompt;
     case 'CUSTOM_LINE_COMMENT_PROMPT':
       return current.openai.customLineCommentPrompt;
+    case 'GLOBAL_PROMPT':
+      return current.openai.globalPrompt;
     // Feishu
     case 'FEISHU_WEBHOOK_URL':
       return current.feishu.webhookUrl;

src/review/agents/critic-agent.ts

@@ -1,5 +1,7 @@
 import OpenAI from 'openai';
 import { logger } from '../../utils/logger';
+import { withGlobalPrompt } from '../../utils/global-prompt';
+import config from '../../config';
 import { Finding, ReviewContext } from '../types';
 
 export interface CritiqueResult {
@@ -76,7 +78,7 @@ ${context.diff.slice(0, 3000)}
         messages: [
           {
             role: 'system',
-            content: '你是严格的代码审查质量评估专家，以高标准评估findings的质量。',
+            content: withGlobalPrompt('你是严格的代码审查质量评估专家，以高标准评估findings的质量。', config.openai.globalPrompt),
           },
           { role: 'user', content: prompt },
         ],
@@ -165,7 +167,7 @@ ${context.diff.slice(0, 2000)}
         messages: [
           {
             role: 'system',
-            content: '你是代码审查质量评估专家。',
+            content: withGlobalPrompt('你是代码审查质量评估专家。', config.openai.globalPrompt),
           },
           { role: 'user', content: prompt },
         ],

src/review/agents/debate-orchestrator.ts

@@ -1,5 +1,7 @@
 import OpenAI from 'openai';
 import { logger } from '../../utils/logger';
+import { withGlobalPrompt } from '../../utils/global-prompt';
+import config from '../../config';
 import { Finding, FindingSeverity } from '../types';
 import { SpecialistAgent } from './specialist-agent';
 
@@ -108,7 +110,7 @@ export class DebateOrchestrator {
         messages: [
           {
             role: 'system',
-            content: `你是${agentName}，从你的专业角度独立评估代码问题。`,
+            content: withGlobalPrompt(`你是${agentName}，从你的专业角度独立评估代码问题。`, config.openai.globalPrompt),
           },
           { role: 'user', content: prompt },
         ],
@@ -185,7 +187,7 @@ ${otherOpinions
         messages: [
           {
             role: 'system',
-            content: `你是${agentName}，根据同行意见重新评估，但也要坚持你的专业判断。`,
+            content: withGlobalPrompt(`你是${agentName}，根据同行意见重新评估，但也要坚持你的专业判断。`, config.openai.globalPrompt),
           },
           { role: 'user', content: prompt },
         ],

src/review/agents/reflexion-agent.ts

@@ -1,6 +1,8 @@
 import { createHash } from 'node:crypto';
 import OpenAI from 'openai';
 import { logger } from '../../utils/logger';
+import { withGlobalPrompt } from '../../utils/global-prompt';
+import config from '../../config';
 import { LearningSystem } from '../learning/learning-system';
 import { findingResponseSchema } from '../schema/finding-schema';
 import { ToolRegistry } from '../tools/registry';
@@ -147,7 +149,7 @@ ${context.diff.slice(0, 3000)}
         messages: [
           {
             role: 'system',
-            content: `你是${this.agentName}，根据批评反馈改进审查结果。`,
+            content: withGlobalPrompt(`你是${this.agentName}，根据批评反馈改进审查结果。`, config.openai.globalPrompt),
           },
           { role: 'user', content: prompt },
         ],

src/services/ai-review.ts

@@ -1,6 +1,7 @@
 import OpenAI from 'openai';
 import config from '../config';
 import { logger } from '../utils/logger';
+import { withGlobalPrompt } from '../utils/global-prompt';
 import { PullRequestFile, giteaService } from './gitea';
 
 // 创建OpenAI客户端
@@ -206,7 +207,7 @@ export const aiReviewService = {
           {
             role: 'system',
             content:
-              '你是一个专业的代码审查助手，擅长识别代码中的严重问题和bug。你会查看代码的完整上下文，而不是为了评论而评论。如无明显问题，应给予简短肯定。',
+              withGlobalPrompt('你是一个专业的代码审查助手，擅长识别代码中的严重问题和bug。你会查看代码的完整上下文，而不是为了评论而评论。如无明显问题，应给予简短肯定。', config.openai.globalPrompt),
           },
           { role: 'user', content: summaryPrompt },
         ],
@@ -278,7 +279,7 @@ export const aiReviewService = {
             {
               role: 'system',
               content:
-                '你是一个谨慎的代码审查助手，只对有明显bug或严重问题的代码行提供评论。大多数情况下，如果代码没有严重问题，你应该返回空数组。请以JSON格式返回结果。',
+                withGlobalPrompt('你是一个谨慎的代码审查助手，只对有明显bug或严重问题的代码行提供评论。大多数情况下，如果代码没有严重问题，你应该返回空数组。请以JSON格式返回结果。', config.openai.globalPrompt),
             },
             { role: 'user', content: filePrompt },
           ],

src/utils/global-prompt.ts

@@ -0,0 +1,12 @@
+/**
+ * Helper to inject the global prompt into LLM system messages.
+ *
+ * If globalPrompt is non-empty, it is appended to the original system content
+ * separated by a blank line.  Otherwise the original content is returned as-is.
+ */
+export function withGlobalPrompt(systemContent: string, globalPrompt: string | undefined): string {
+  if (!globalPrompt || globalPrompt.trim() === '') {
+    return systemContent;
+  }
+  return `${systemContent}\n\n${globalPrompt}`;
+}