feat: solution for 'Повторный экзамен: Structured output — Union событий API'

README.md

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+# Structured Log Parser
+
+This project demonstrates how to parse raw log lines into typed events using **Pydantic v2** and **LangChain**'s structured output.  
+It supports two event types:
+
+| Event | Fields |
+|-------|--------|
+| `HttpOkEvent` | `kind="ok"`, `status=200`, `path`, `duration_ms` |
+| `HttpErrorEvent` | `kind="error"`, `status` (4xx/5xx), `path`, `error_message` |
+
+The parser uses a LangChain prompt to convert each log line into a JSON object that matches one of the schemas. The output is then validated with Pydantic.
+
+## Features
+
+- **Discriminated Union**: `ApiEvent` is a union of `HttpOkEvent` and `HttpErrorEvent` with a `kind` discriminator.
+- **Structured Output**: Uses LangChain's `PydanticOutputParser` to enforce schema.
+- **Batch Parsing**: Handles multiple log lines in a single run.
+- **CLI**: Accepts example logs, a file, or custom text and prints a table of parsed events.
+
+## Installation
+
+```bash
+# Clone the repo
+git clone https://github.com/yourusername/structured-log-parser.git
+cd structured-log-parser
+
+# Create a virtual environment (optional but recommended)
+python -m venv .venv
+source .venv/bin/activate  # On Windows: .venv\Scripts\activate
+
+# Install dependencies
+pip install -r requirements.txt
+```
+
+## Usage
+
+### 1. Using the built‑in example
+
+```bash
+python -m src.main --example
+```
+
+### 2. Parsing a log file
+
+```bash
+python -m src.main --file path/to/log.txt
+```
+
+### 3. Parsing custom text
+
+```bash
+python -m src.main --text "2026-08-31 12:00:01 INFO /api/users 200 123ms"
+```
+
+The output will be a Markdown‑style table:
+
+```
+| kind | path          | status | duration_ms / error_message |
+|------|---------------|--------|-----------------------------|
+| ok   | /api/users    | 200    | 123 ms                      |
+| error| /api/orders   | 404    | Not Found                   |
+| error| /api/payments | 500    | Internal Server Error       |
+| ok   | /api/products | 200    | 45 ms                       |
+```
+
+## Environment Variables
+
+The project uses OpenAI's API. Set the following variable before running:
+
+```bash
+export OPENAI_API_KEY="sk-..."
+```
+
+Alternatively, create a `.env` file in the project root:
+
+```
+OPENAI_API_KEY=sk-...
+```
+
+The `python-dotenv` package will load it automatically.
+
+## Project Structure
+
+```
+src/
+├── __init__.py
+├── main.py          # CLI entry point
+├── cli.py           # Argument parsing and table rendering
+├── parser.py        # Log parsing logic
+└── models.py        # Pydantic event models
+```
+
+## License
+
+MIT License