Add initial GigaChat CLI implementation with environment setup

- Created .env_example for environment variable configuration.
- Added .gitignore to exclude sensitive files and directories.
- Implemented gigachat_cli.py for command-line interaction with the GigaChat API.
- Updated README.md with setup instructions and usage examples.
- Included requirements.txt for necessary dependencies.

.env_example

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+GIGACHAT_CREDENTIALS=

.gitignore

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+.env
+.venv/
+__pycache__/
+

README.md

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+# GigaChat CLI Tester
+
+Simple command-line helper for sending prompts to the GigaChat API.
+
+## Prerequisites
+
+- Python 3.9+
+- GigaChat credentials (set `GIGACHAT_CREDENTIALS`). Get them from [GigaChat Studio](https://developers.sber.ru/studio).
+
+## Setup
+
+```bash
+python -m venv .venv
+.venv\Scripts\activate  # PowerShell: .venv\Scripts\Activate.ps1
+pip install -r requirements.txt
+```
+
+## Usage
+
+Send a single prompt:
+
+```bash
+python gigachat_cli.py "Explain how AI works in a few words"
+```
+
+Interactive mode:
+
+```bash
+python gigachat_cli.py
+```
+
+Specify a different model:
+
+```bash
+python gigachat_cli.py --model GigaChat-Pro
+```

gigachat_cli.py

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+import argparse
+import base64
+import os
+import sys
+import uuid
+from typing import Optional
+
+from dotenv import load_dotenv
+from gigachat import GigaChat
+
+
+DEFAULT_MODEL = "GigaChat"
+
+
+def build_client(credentials: Optional[str], scope: Optional[str], model: Optional[str] = None) -> GigaChat:
+    # verify_ssl_certs=False is sometimes needed depending on the environment,
+    # but we will start with default.
+    kwargs = {"verify_ssl_certs": False}
+    if credentials:
+        kwargs["credentials"] = credentials
+    if scope:
+        kwargs["scope"] = scope
+    if model:
+        kwargs["model"] = model
+        
+    return GigaChat(**kwargs)
+
+
+def generate_text(client: GigaChat, model: str, prompt: str) -> str:
+    # GigaChat client handles the model parameter in the constructor usually.
+    # If we need to change model dynamically, we might need to rebuild client or check documentation
+    # but for now, we rely on client being initialized with correct model or default.
+    # The `chat` method only accepts string prompt in some versions.
+    response = client.chat(prompt)
+    return response.choices[0].message.content or ""
+
+
+def cli() -> None:
+    load_dotenv()
+    
+    parser = argparse.ArgumentParser(
+        description="Send prompts to the GigaChat API and print the response."
+    )
+    parser.add_argument(
+        "prompt",
+        nargs="?",
+        help="Optional prompt to send immediately. If omitted, the program enters interactive mode.",
+    )
+    parser.add_argument(
+        "--model",
+        default=DEFAULT_MODEL,
+        help=f"GigaChat model to use (default: {DEFAULT_MODEL}).",
+    )
+    args = parser.parse_args()
+
+    credentials = os.getenv("GIGACHAT_CREDENTIALS")
+    scope = os.getenv("GIGACHAT_SCOPE")
+    
+    if not credentials:
+        print(
+            "Missing environment variable GIGACHAT_CREDENTIALS. "
+            "Get your credentials from https://developers.sber.ru/studio and export them (or set in .env).",
+            file=sys.stderr,
+        )
+        sys.exit(1)
+
+    try:
+        client = build_client(credentials, scope, args.model)
+    except Exception as e:
+        print(f"Failed to initialize GigaChat client: {e}", file=sys.stderr)
+        sys.exit(1)
+
+    if args.prompt:
+        prompt = args.prompt.strip()
+        if not prompt:
+            print("Prompt is empty. Nothing to send.", file=sys.stderr)
+            sys.exit(1)
+        print_response(client, args.model, prompt)
+        return
+
+    print(
+        f"GigaChat CLI (model: {args.model}). Enter an empty line to exit.",
+        file=sys.stderr,
+    )
+    while True:
+        try:
+            prompt = input("> ").strip()
+        except (EOFError, KeyboardInterrupt):
+            print("\nExiting.", file=sys.stderr)
+            break
+
+        if not prompt:
+            print("Goodbye!", file=sys.stderr)
+            break
+
+        print_response(client, args.model, prompt)
+
+
+def print_response(client: GigaChat, model: str, prompt: str) -> None:
+    try:
+        text = generate_text(client, model, prompt)
+    except Exception as exc:
+        # It might be a specific GigaChat error related to auth
+        print(f"Request failed: {exc}", file=sys.stderr)
+        return
+
+    if not text:
+        print("(No text returned by the model.)", file=sys.stderr)
+        return
+
+    print(text)
+
+
+if __name__ == "__main__":
+    cli()

requirements.txt

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+gigachat
+python-dotenv