feat: support user system prompt (#147)

* feat: add support for userSystemPrompt

* feat: udpate chat-cli to support user system prompt

apps/server/src/agent/agent/GeminiAgent.prompt.ts

@@ -169,4 +169,9 @@ export function getSystemPrompt(): string {
   return systemPrompt
 }
 
+export function buildSystemPrompt(userSystemPrompt?: string): string {
+  if (!userSystemPrompt) return systemPrompt
+  return `${systemPrompt}\n\n---\n\n## User Preferences:\n\n${userSystemPrompt}`
+}
+
 export { systemPrompt }

apps/server/src/agent/agent/GeminiAgent.ts

@@ -24,7 +24,7 @@ import { Sentry } from '../../common/sentry/instrument.js'
 import type { BrowserContext } from '../../http/types.js'
 import { AgentExecutionError } from '../errors.js'
 import { KlavisClient } from '../klavis/index.js'
-import { getSystemPrompt } from './GeminiAgent.prompt.js'
+import { buildSystemPrompt } from './GeminiAgent.prompt.js'
 import {
   AIProvider,
   VercelAIContentGenerator,
@@ -198,7 +198,9 @@ export class GeminiAgent {
     ).contentGenerator = contentGenerator
 
     const client = geminiConfig.getGeminiClient()
-    client.getChat().setSystemInstruction(getSystemPrompt())
+    client
+      .getChat()
+      .setSystemInstruction(buildSystemPrompt(resolvedConfig.userSystemPrompt))
     await client.setTools()
 
     // Disable chat recording to prevent disk writes

apps/server/src/agent/agent/types.ts

@@ -17,6 +17,7 @@ export const AgentConfigSchema = VercelAIConfigSchema.extend({
   browserosId: z.string().optional(),
   enabledMcpServers: z.array(z.string()).optional(),
   customMcpServers: z.array(CustomMcpServerSchema).optional(),
+  userSystemPrompt: z.string().optional(),
 })
 
 export type AgentConfig = z.infer<typeof AgentConfigSchema>

apps/server/src/http/routes/chat.ts

@@ -112,6 +112,7 @@ export function createChatRoutes(deps: ChatRouteDeps) {
           browserosId,
           enabledMcpServers: request.browserContext?.enabledMcpServers,
           customMcpServers: request.browserContext?.customMcpServers,
+          userSystemPrompt: request.userSystemPrompt,
         })
 
         const sseStream = {

apps/server/src/http/types.ts

@@ -43,6 +43,7 @@ export const ChatRequestSchema = VercelAIConfigSchema.extend({
   message: z.string().min(1, 'Message cannot be empty'),
   contextWindowSize: z.number().optional(),
   browserContext: BrowserContextSchema.optional(),
+  userSystemPrompt: z.string().optional(),
 })
 
 export type ChatRequest = z.infer<typeof ChatRequestSchema>

scripts/dev/chat-cli.ts

@@ -7,9 +7,10 @@
  *   bun --env-file=.env.dev tests/agent-cli.ts --provider=openai --model=gpt-4o "your message here"
  *
  * Options:
- *   --provider  AI provider (default: google)
- *   --model     Model name (default: gemini-2.5-flash)
+ *   --provider  AI provider (default: browseros)
+ *   --model     Model name (default: default)
  *   --port      Server port (default: $BROWSEROS_SERVER_PORT or 9100)
+ *   --system-prompt  Custom system prompt to append
  *   --show-full-output  Show full tool output (default: truncated to 50 chars)
  */
 
@@ -19,6 +20,7 @@ interface ChatRequest {
   provider: string
   model: string
   apiKey?: string
+  userSystemPrompt?: string
 }
 
 function parseArgs(): {
@@ -26,13 +28,15 @@ function parseArgs(): {
   provider: string
   model: string
   port: string
+  userSystemPrompt?: string
   showFullOutput: boolean
 } {
   const args = process.argv.slice(2)
-  let provider = 'google'
-  let model = 'gemini-2.5-flash'
+  let provider = 'browseros'
+  let model = 'default'
   let port = process.env.BROWSEROS_SERVER_PORT || '9100'
   let showFullOutput = false
+  let userSystemPrompt: string | undefined
   let message = ''
 
   for (const arg of args) {
@@ -42,6 +46,8 @@ function parseArgs(): {
       model = arg.split('=')[1]
     } else if (arg.startsWith('--port=')) {
       port = arg.split('=')[1]
+    } else if (arg.startsWith('--system-prompt=')) {
+      userSystemPrompt = arg.split('=').slice(1).join('=')
     } else if (arg === '--show-full-output') {
       showFullOutput = true
     } else if (!arg.startsWith('--')) {
@@ -50,22 +56,23 @@ function parseArgs(): {
   }
 
   if (!message) {
-    console.error('Usage: bun tests/test-agent-cli.ts [options] "your message"')
+    console.error('Usage: bun scripts/dev/chat-cli.ts [options] "your message"')
     console.error('Options:')
     console.error(
       '  --provider=<provider>  AI provider (anthropic, openai, google, etc.)',
     )
     console.error('  --model=<model>        Model name')
     console.error(
-      '  --port=<port>          Server port (default: $AGENT_PORT or 9200)',
+      '  --port=<port>          Server port (default: $BROWSEROS_SERVER_PORT or 9100)',
     )
+    console.error('  --system-prompt=<prompt>  Custom system prompt to append')
     console.error(
       '  --show-full-output     Show full tool output (default: truncated)',
     )
     process.exit(1)
   }
 
-  return { message, provider, model, port, showFullOutput }
+  return { message, provider, model, port, userSystemPrompt, showFullOutput }
 }
 
 function truncateOutput(obj: unknown, maxLen = 50): unknown {
@@ -90,6 +97,7 @@ async function chat(config: {
   provider: string
   model: string
   port: string
+  userSystemPrompt?: string
   showFullOutput: boolean
 }) {
   const conversationId = crypto.randomUUID()
@@ -99,6 +107,7 @@ async function chat(config: {
     message: config.message,
     provider: config.provider,
     model: config.model,
+    userSystemPrompt: config.userSystemPrompt,
   }
 
   console.log('\n--- Request ---')