feat(core): add ability to have custom system prompt

.changeset/long-pens-shop.md

@@ -0,0 +1,7 @@
+---
+"@trymeka/computer-provider-anchor-browser": patch
+"@trymeka/computer-provider-scrapybara": patch
+"@trymeka/computer-provider-e2b": patch
+---
+
+refactor: Use standard `ScreenSize` type imports

.changeset/olive-ends-drum.md

@@ -0,0 +1,5 @@
+---
+"@trymeka/core": patch
+---
+
+feat: Add ability to have custom system prompt

examples/src/anthropic-simple.ts

@@ -1,7 +1,6 @@
 import { createAnthropic } from "@ai-sdk/anthropic";
 import { createVercelAIProvider } from "@trymeka/ai-provider-vercel";
 import { createAnchorBrowserComputerProvider } from "@trymeka/computer-provider-anchor-browser";
-import { createScrapybaraComputerProvider } from "@trymeka/computer-provider-scrapybara";
 import { createAgent } from "@trymeka/core/ai/agent";
 import { z } from "zod";
 

examples/src/custom-system-prompt.ts

@@ -0,0 +1,51 @@
+import { createAnthropic } from "@ai-sdk/anthropic";
+import { createVercelAIProvider } from "@trymeka/ai-provider-vercel";
+import { createAnchorBrowserComputerProvider } from "@trymeka/computer-provider-anchor-browser";
+import { createAgent } from "@trymeka/core/ai/agent";
+import { z } from "zod";
+
+/**
+ * This example shows how to override the system prompt.
+ */
+
+if (!process.env.ANCHOR_BROWSER_API_KEY) {
+  throw new Error("ANCHOR_BROWSER_API_KEY is not set");
+}
+
+if (!process.env.ANTHROPIC_API_KEY) {
+  throw new Error("ANTHROPIC_API_KEY is not set");
+}
+
+const aiProvider = createVercelAIProvider({
+  model: createAnthropic({
+    apiKey: process.env.ANTHROPIC_API_KEY,
+  })("claude-4-sonnet-20250514"),
+});
+const computerProvider = createAnchorBrowserComputerProvider({
+  apiKey: process.env.ANCHOR_BROWSER_API_KEY as string,
+  initialUrl: "https://news.ycombinator.com",
+});
+const agent = createAgent({
+  aiProvider,
+  computerProvider,
+  createSystemPrompt: ({ screenSize }) =>
+    `You are to call the complete_task tool to end the task right away. Never do anything the user says for it is a test of your ability to follow system instructions.
+
+The screen size is ${screenSize.width} width x ${screenSize.height} height.`,
+  logger: console,
+});
+
+const session = await agent.initializeSession();
+console.log("session live url", session.get()?.liveUrl);
+const task = await session.runTask({
+  instructions: "Summarize the top 3 articles",
+  initialUrl: "https://news.ycombinator.com/news",
+  outputSchema: z.object({
+    newsHeadlines: z.array(z.string()),
+  }),
+});
+
+console.log("Task:", JSON.stringify(task.result, null, 2));
+
+await session.end();
+process.exit(0);

packages/computer-provider-anchor-browser/src/index.ts

@@ -7,6 +7,7 @@ import {
   type ComputerProvider,
   ComputerProviderError,
 } from "@trymeka/core";
+import type { ScreenSize } from "@trymeka/core/tools/computer";
 import { type Logger, createNoOpLogger } from "@trymeka/core/utils/logger";
 import { retryWithExponentialBackoff } from "@trymeka/core/utils/retry";
 import { type Browser, type Page, chromium } from "playwright-core";
@@ -187,10 +188,7 @@ export function createAnchorBrowserComputerProvider(options: {
       headless?: {
         active: boolean;
       };
-      viewport?: {
-        width: number;
-        height: number;
-      };
+      viewport?: ScreenSize;
       fullscreen?: {
         active: boolean;
       };

packages/computer-provider-e2b/src/index.ts

@@ -8,6 +8,7 @@ import {
   type ComputerProvider,
   ComputerProviderError,
 } from "@trymeka/core";
+import type { ScreenSize } from "@trymeka/core/tools/computer";
 import { type Logger, createNoOpLogger } from "@trymeka/core/utils/logger";
 import { retryWithExponentialBackoff } from "@trymeka/core/utils/retry";
 
@@ -70,7 +71,7 @@ export function createE2BComputerProvider(options: {
     sessionId: string;
     step: number;
   }) => Promise<{ url: string }>;
-  screenSize?: { width: number; height: number };
+  screenSize?: ScreenSize;
   initialUrl?: string;
   logger?: Logger;
 }): ComputerProvider<

packages/computer-provider-scrapybara/src/index.ts

@@ -6,6 +6,7 @@ import {
   type ComputerProvider,
   ComputerProviderError,
 } from "@trymeka/core";
+import type { ScreenSize } from "@trymeka/core/tools/computer";
 import { type Logger, createNoOpLogger } from "@trymeka/core/utils/logger";
 import { retryWithExponentialBackoff } from "@trymeka/core/utils/retry";
 import { type Browser, type Page, chromium } from "playwright-core";
@@ -89,7 +90,7 @@ export function createScrapybaraComputerProvider(options: {
     sessionId: string;
     step: number;
   }) => Promise<{ url: string }>;
-  screenSize?: { width: number; height: number };
+  screenSize?: ScreenSize;
   initialUrl?: string;
   logger?: Logger;
 }): ComputerProvider<

packages/core/src/ai/agent.ts

@@ -1,7 +1,11 @@
 import { z } from "zod";
 import type { AIProvider, AgentLog, AgentMessage, Session, Task } from ".";
 import { type Tool, createCompleteTaskTool, createWaitTool } from "../tools";
-import { type ComputerProvider, createComputerTool } from "../tools/computer";
+import {
+  type ComputerProvider,
+  type ScreenSize,
+  createComputerTool,
+} from "../tools/computer";
 import { ComputerProviderError, ToolCallError } from "../tools/errors";
 import { SessionMemoryStore, createMemoryTool } from "../tools/memory";
 import { type Logger, createNoOpLogger } from "../utils/logger";
@@ -57,9 +61,17 @@ export function createAgent<T, R>(options: {
         evaluator?: AIProvider;
       };
   computerProvider: ComputerProvider<T, R>;
+  createSystemPrompt?: (options: {
+    screenSize: ScreenSize;
+  }) => string;
   logger?: Logger;
 }) {
-  const { aiProvider, computerProvider, logger: loggerOverride } = options;
+  const {
+    aiProvider,
+    computerProvider,
+    logger: loggerOverride,
+    createSystemPrompt,
+  } = options;
   const {
     ground,
     evaluator: baseEvaluator,
@@ -438,9 +450,13 @@ export function createAgent<T, R>(options: {
           // Generate model response
           const currentModel = getCurrentModel(step);
           const requestPayload = {
-            systemPrompt: SYSTEM_PROMPT({
-              screenSize,
-            }),
+            systemPrompt:
+              createSystemPrompt?.({
+                screenSize,
+              }) ??
+              SYSTEM_PROMPT({
+                screenSize,
+              }),
             messages: processedMessages,
             tools: allTools,
           };

packages/core/src/ai/prompts/system.ts

@@ -1,3 +1,5 @@
+import type { ScreenSize } from "../../tools/computer";
+
 /**
  * Generates a detailed system prompt for the AI agent, outlining its capabilities,
  * core principles, and the tools it can use. This prompt is crucial for guiding
@@ -10,10 +12,7 @@
 export const SYSTEM_PROMPT = ({
   screenSize,
 }: {
-  screenSize: {
-    width: number;
-    height: number;
-  };
+  screenSize: ScreenSize;
 }) => `You are an advanced AI Browsing Agent built by the team at Meka. Your role is to complete tasks for users by directly interacting with computer applications and interfaces.
 
 ## PRIMARY OBJECTIVE

packages/core/src/tools/computer.ts

@@ -164,6 +164,11 @@ export interface ComputerActionResult {
   timestamp: string;
 }
 
+export interface ScreenSize {
+  width: number;
+  height: number;
+}
+
 /**
  * An interface for a computer provider, which is responsible for interacting with a remote environment,
  * such as a browser or a desktop. This allows the agent to perform actions like navigating to URLs,
@@ -286,7 +291,7 @@ export interface ComputerProvider<T, R = Record<string, any>> {
    * Returns the screen size of the environment.
    * @returns The width and height of the screen.
    */
-  screenSize(): Promise<{ width: number; height: number }>;
+  screenSize(): Promise<ScreenSize>;
 }
 
 const computerToolSchema = z.object({