feat: add Daytona sandbox support

[lakshyaag]

Summary

Daytona

Add a new DaytonaREPL environment that runs Python code in Daytona sandboxes, following the same HTTP broker pattern as ModalREPL.

Changes

• rlm/environments/daytona_repl.py: Full DaytonaREPL implementation using HTTP broker pattern
• examples/daytona_repl_example.py: Example demonstrating basic code execution and LLM queries
• rlm/environments/__init__.py: Register "daytona" environment
• rlm/core/types.py: Add "daytona" to EnvironmentType
• pyproject.toml: Add daytona optional dependency
• examples/quickstart.py: Update to use Daytona environment by default

Key Implementation Details

• Uses daytona SDK for sandbox management
• Runs Flask broker on port 8080 inside the sandbox
• Uses Daytona preview URLs (sandbox.get_preview_link) for host-to-sandbox communication
• Supports llm_query(), llm_query_batched(), and FINAL_VAR()
• State persistence across code executions via dill serialization

Usage

# Install with daytona support
uv pip install -e ".[daytona]"
# Set API key
export DAYTONA_API_KEY=your_key
# Run example
python -m examples.daytona_repl_example

Example output

============================================================
Daytona REPL Example
============================================================

[1] Basic code execution (no LLM handler)
----------------------------------------
Daytona sandbox started with ID: 1e431a46-e584-432e-b64f-084878ab49e4
Executed: x = 1 + 2
Locals: {'x': '3'}
Executed: print(x * 2)
Stdout: 6
FINAL_VAR('answer'): 42

[2] Code execution with LLM handler
----------------------------------------
LM Handler started at ('127.0.0.1', 34369)
Daytona sandbox started with ID: af6c170a-058c-4c7f-807b-b08299ffd31b
Broker URL: https://8080-af6c170a-058c-4c7f-807b-b08299ffd31b.proxy.daytona.works
Executed: response = llm_query('What is 2+2?')
Response: Mock response to: What is 2+2?

Executed: responses = llm_query_batched([...])
Result: Got 3 responses
First response: Mock response to: Question 1

============================================================
Done!
============================================================

Test Plan

• Basic code execution works
• State persistence works across calls
• FINAL_VAR() extracts variables correctly
• LLM handler integration works (single and batched queries)
• Broker communication works over Daytona preview URLs
• Ruff passes all checks

[kmad]

This is great, thanks. What's the reasoning to change the quickstart to use Daytona by default? My sense is folks who just want to try it out are more likely to just have an OpenAI/ Anthropic key than a specific provider (Daytona, Modal, etc).

Maybe create a separate provider_example.py with a toggle between the various supported providers, including Daytona?

[lakshyaag]

You're right. The quickstart change should be reverted. I was using it as a local sanity check, seem to have committed it accidentally.

[alexzhang13]

Thanks for this, testing on my end rn.

[alexzhang13]

Tested on my end, thanks