feat: solution for '8. Самописный поисковый агент на основе deep agents from scratch'
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# Replace the placeholder values with your actual API keys
OPENAI_API_KEY=your-openai-api-key
SERPAPI_API_KEY=your-serpapi-key
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# Deep Agent Search
# Deep Search Agent
This project demonstrates a simple search agent built with **LangChain**'s `DeepAgent` and the **OpenAI** language model. The agent can answer user queries and perform web searches when needed.
A minimal implementation of a deep search agent built from scratch using the LangChain framework and OpenAI API.
The agent decides whether to answer a query directly or perform a web search using SerpAPI.
## Prerequisites
- Node.js 18+ (ES modules support)
- An OpenAI API key. Set it in your environment:
- Node.js 18+ (ESM support)
- An OpenAI API key
- A SerpAPI key (free tier available)
## Setup
```bash
export OPENAI_API_KEY="your-api-key-here"
```
# Clone the repository
git clone https://github.com/your-username/deep-search-agent.git
cd deep-search-agent
## Installation
```bash
# Install dependencies
npm install
# Create a .env file with your API keys
cp .env.example .env
# Edit .env and replace the placeholders with your actual keys
```
## Usage
### CLI
Run the agent interactively:
Run the agent with a query:
```bash
npm start
npm start -- "What is the capital of France?"
```
You will be prompted to enter a question. The agent will respond.
The agent will output either a direct answer or the results of a web search.
### Programmatic
## How It Works
```js
import { ask } from "./src/index.js";
1. **Planner** Uses an LLM to decide if the query requires a web search or can be answered directly.
2. **Executor** If a search is needed, the agent calls the SerpAPI tool and returns the results.
3. **Memory** Stores conversation context (optional for future extensions).
async function main() {
const answer = await ask("Who wrote 'Pride and Prejudice'?");
console.log(answer);
}
## Extending
main();
```
## Testing
A simple test script is provided:
```bash
npm test
```
It queries the agent with a sample question and prints the answer.
## Project Structure
- `src/agent.js` Configures the `DeepAgent` with OpenAI LLM and the search tool.
- `src/index.js` Exposes the `ask` function and a CLI demo.
- `test.js` Quick test script.
- `package.json` Project metadata and dependencies.
## Dependencies
- `langchain` Core LangChain library.
- `langchain-openai` OpenAI wrapper for LangChain.
- `langchain-community` Community tools, including the web search tool.
- Add more tools (e.g., Wikipedia, Calculator) and update the planner prompt accordingly.
- Replace the planner with a more sophisticated planner (e.g., chain of thought).
- Persist memory to a database for longterm context.
## License
MIT
MIT License
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**What was implemented**
- Added the required dependencies (`langchain-openai` and `langchain-community`) to `package.json`.
- Reimplemented the search agent using LangChains `DeepAgent` instead of the previous custom logic.
- Configured the OpenAI LLM through the `langchain-openai` wrapper, reading the key from `OPENAI_API_KEY`.
- Integrated the builtin `SearchTool` from `langchain-community` so the agent can perform web searches automatically.
- Exposed a simple `ask()` helper that invokes the agent and returns the output, and a CLI demo in `src/index.js`.
**Что реализовано**
- Добавлены пакеты `langchain-openai` и `langchain-community` в `package.json`.
- Создан класс `DeepAgent` в `src/index.js`, реализующий шаблон «Deep Agents from Scratch».
- Внутри агента реализован **планировщик** (`LLMChain` + `PromptTemplate`), который принимает запрос пользователя и возвращает JSON‑объект с типом действия (`search` или `answer`).
- В зависимости от плана агент либо вызывает инструмент `SerpAPI` для веб‑поиска, либо возвращает готовый ответ.
- Добавлена простая память (`BufferMemory`) для хранения истории диалога.
- В `main()` инициализируются LLM, инструмент поиска, память и агент, а затем агент обрабатывает запрос, переданный в командной строке.
**Why the main parts satisfy the requirements**
- **LangChain usage** `DeepAgent` is instantiated directly (`src/agent.js`), meeting the “use LangChains Deep Agent API” constraint.
- **OpenAI API via langchain-openai** The LLM is created with `new OpenAI({...})` from `langchain-openai`, ensuring all calls go through that package.
- **Dependencies added** `langchain-openai` and `langchain-community` are listed in `package.json`, satisfying the dependency requirement.
- **No reliance on old code** The previous custom agent logic is completely replaced; only the new LangChain components are used.
- **Search capability** `SearchTool` is passed to the agent, allowing it to decide when to query the web, fulfilling the “search agent” goal.
**Почему это соответствует требованиям**
- **LangChain**: все взаимодействия с LLM и инструментами построены через `langchain`‑объекты (`OpenAI`, `SerpAPI`, `LLMChain`, `PromptTemplate`).
- **OpenAI API**: используется `OpenAI` из `langchain-openai` с ключом из переменной окружения `OPENAI_API_KEY`.
- **Deep Agent**: класс `DeepAgent` полностью соответствует шаблону «Deep Agents from Scratch» – отдельный планировщик, исполнитель и память.
- **Поиск**: при выборе `search` агент вызывает `SerpAPI.run(query)` и возвращает результат.
- **Ответ**: при выборе `answer` агент просто возвращает строку из плана.
**Key code excerpts**
**Ключевые фрагменты кода**
`package.json`
```json
"dependencies": {
"langchain": "^0.0.112",
"langchain-openai": "^0.0.112",
"langchain-community": "^0.0.112"
"langchain": "^0.0.0",
"langchain-openai": "^0.0.0",
"langchain-community": "^0.0.0",
"dotenv": "^16.0.0"
}
```
`src/agent.js`
`src/index.js` планировщик
```js
import { DeepAgent } from "langchain/agents";
import { OpenAI } from "langchain-openai";
import { SearchTool } from "langchain-community/tools/search";
const llm = new OpenAI({ temperature: 0, modelName: "gpt-3.5-turbo" });
const searchTool = new SearchTool();
const agent = new DeepAgent({
llm,
tools: [searchTool],
verbose: true
this.planner = new LLMChain({
llm: this.llm,
prompt: new PromptTemplate({
inputVariables: ["input"],
template: `You are a helpful assistant. Given the user query: "{input}"
Decide whether you need to perform a web search or can answer directly.
Respond in JSON format:
{
"type": "search" | "answer",
"query": "<search query>" | null,
"answer": "<answer>" | null
}
If you choose "search", provide the search query in "query". If you choose "answer", provide the answer in "answer".`,
}),
});
```
`src/index.js` (invocation)
`src/index.js` выполнение плана
```js
export async function ask(query) {
const result = await agent.invoke({ input: query });
return result.output;
if (plan.type === "search" && plan.query) {
const searchTool = this.tools.find((t) => t.name === "SerpAPI");
const searchResult = await searchTool.run(plan.query);
return searchResult;
} else if (plan.type === "answer" && plan.answer) {
return plan.answer;
}
```
**Honest limitations**
- The implementation assumes `OPENAI_API_KEY` is set; no fallback or user prompt is provided.
- No custom error handling beyond the basic try/catch in the CLI demo.
- The agent uses the default `SearchTool`; if a different search provider is needed, additional configuration would be required.
**Ограничения**
- Планировщик возвращает JSON, но не проверяет корректность ключей `type`, `query`, `answer` более глубоко.
- В случае ошибки в ответе LLM (невалидный JSON) агент выбрасывает исключение.
- Параметры модели и инструмента заданы статически; для гибкой конфигурации можно добавить CLI‑параметры.
Overall, the project now fully complies with the assignment: it uses LangChain, integrates OpenAI via the dedicated package, and rebuilds the search agent with the Deep Agent API.
Таким образом, проект теперь содержит полноценного Deep Agent, использующего LangChain и OpenAI API, способного выполнять поисковые запросы и выдавать ответы.
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{
"name": "deep-agent-search",
"name": "deep-search-agent",
"version": "1.0.0",
"description": "A simple search agent built with LangChain DeepAgent and OpenAI",
"description": "A deep search agent built from scratch using LangChain and OpenAI",
"main": "src/index.js",
"type": "module",
"scripts": {
"start": "node src/index.js",
"test": "node test.js"
"start": "node src/index.js"
},
"dependencies": {
"langchain": "^0.0.112",
"langchain-openai": "^0.0.112",
"langchain-community": "^0.0.112"
"langchain": "^0.0.0",
"langchain-openai": "^0.0.0",
"langchain-community": "^0.0.0",
"dotenv": "^16.0.0"
}
}
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import agent from "./agent.js";
import { OpenAI } from "langchain-openai";
import { SerpAPI } from "langchain-community/tools/serpapi";
import { PromptTemplate, LLMChain } from "langchain";
import { BufferMemory } from "langchain/memory";
import dotenv from "dotenv";
/**
* Ask the agent a question and return the response.
*
* @param {string} query - The user query to send to the agent.
* @returns {Promise<string>} - The agent's answer.
*/
export async function ask(query) {
const result = await agent.invoke({ input: query });
return result.output;
dotenv.config();
class DeepAgent {
constructor(llm, tools, memory) {
this.llm = llm;
this.tools = tools;
this.memory = memory;
// Planner: decides whether to search or answer directly
this.planner = new LLMChain({
llm: this.llm,
prompt: new PromptTemplate({
inputVariables: ["input"],
template: `You are a helpful assistant. Given the user query: "{input}"
Decide whether you need to perform a web search or can answer directly.
Respond in JSON format:
{
"type": "search" | "answer",
"query": "<search query>" | null,
"answer": "<answer>" | null
}
If you choose "search", provide the search query in "query". If you choose "answer", provide the answer in "answer".`,
}),
});
}
/**
* Simple CLI demo: read a query from stdin and print the agent's answer.
*/
if (import.meta.url === `file://${process.argv[1]}`) {
const readline = await import("readline");
const rl = readline.createInterface({
input: process.stdin,
output: process.stdout
});
async run(userInput) {
// Store user input in memory (optional)
await this.memory.saveContext({ input: userInput }, { output: "" });
rl.question("Enter your question: ", async (question) => {
// Planning step
const plannerOutput = await this.planner.call({ input: userInput });
let plan;
try {
const answer = await ask(question);
console.log("\nAgent response:\n", answer);
} catch (err) {
console.error("Error:", err);
} finally {
rl.close();
plan = JSON.parse(plannerOutput.output);
} catch (e) {
throw new Error("Planner output is not valid JSON");
}
});
// Execution step
if (plan.type === "search" && plan.query) {
const searchTool = this.tools.find((t) => t.name === "SerpAPI");
if (!searchTool) {
throw new Error("Search tool not found");
}
const searchResult = await searchTool.run(plan.query);
return searchResult;
} else if (plan.type === "answer" && plan.answer) {
return plan.answer;
} else {
throw new Error("Invalid plan produced by planner");
}
}
}
async function main() {
// Initialize LLM
const openai = new OpenAI({
temperature: 0,
modelName: "gpt-3.5-turbo",
openAIApiKey: process.env.OPENAI_API_KEY,
});
// Initialize search tool
const searchTool = new SerpAPI({
apiKey: process.env.SERPAPI_API_KEY,
engine: "google",
});
// Memory (optional)
const memory = new BufferMemory({ memoryKey: "chat_history" });
// Create agent
const agent = new DeepAgent(openai, [searchTool], memory);
// Get query from command line arguments
const query = process.argv.slice(2).join(" ");
if (!query) {
console.log("Please provide a query as a command line argument.");
process.exit(1);
}
console.log(`Query: ${query}`);
try {
const result = await agent.run(query);
console.log("\nResult:");
console.log(result);
} catch (err) {
console.error("Error:", err.message);
}
}
main();