# 🔥🕊️ Rise of the Phoenix: Event Loop Refactor

[fede-kamel]

🔨 Modularizing Event Loop Logic

Commit: 8cb8422
Author: Fede Kamelhar
Date: May 25, 2025
Message: Modularizing Event Loop

⸻

✨ What’s Included

1. Extracted Tool Execution Logic

Moved all logic related to handling tool_use into a dedicated private function: _handle_tool_execution().

Benefit:
Improves readability, simplifies event_loop_cycle(), and separates concerns for better maintainability and testing.

New function:

def _handle_tool_execution(...) -> Tuple[StopReason, Message, EventLoopMetrics, Dict[str, Any]]:

if stop_reason == "tool_use":
    return _handle_tool_execution(...)

2. Centralized Retry Configuration

Introduced constants for retry settings, replacing hardcoded values:

MAX_ATTEMPTS = 6
INITIAL_DELAY = 4
MAX_DELAY = 240  # 4 minutes

Benefit:
Easier tuning of retry behavior and removal of magic numbers.

3. Type Hint Improvements

Refined function signatures for stronger typing:
• initialize_state() now accepts a Dict[str, Any] instead of **kwargs.
• callback_handler is now typed as Callable[..., Any].

Benefit:
Improves IDE support, readability, and static analysis.

⸻

4. Small Refactors & Cleanup
   • Replaced inline retry configuration with named constants.
   • Removed redundant state handling and improved control flow.
   • Added a detailed docstring to _handle_tool_execution().

5. Updated Tests

Updated test_initialize_state() to use the new function signature:

kwargs = strands.event_loop.event_loop.initialize_state(kwargs)

Benefit:
Keeps tests aligned with refactored API for better coverage and accuracy.

[awsarron]

Hi @fede-dash, great to see you here! Thank you for your contribution ❤️

Would it be possible to separate out the formatting changes from this PR? We're using ruff with hatch fmt for formatting and linting (https://github.com/strands-agents/sdk-python/blob/main/CONTRIBUTING.md) so it seems the black rules that were applied in this PR don't match with what we have configured in the project (https://github.com/strands-agents/sdk-python/blob/main/pyproject.toml).

The event_loop improvements and modularization are great, would love to get those merged.

[fede-kamel]

Comments addressed

[awsarron]

Thanks for the updates!

hatch run test-lint is showing these errors:

cmd [1] | ruff check
All checks passed!
cmd [2] | mypy -p src
src/strands/event_loop/event_loop.py:213: error: Argument 1 to "EventLoopException" has incompatible type "str"; expected "Exception"  [arg-type]
src/strands/event_loop/event_loop.py:224: error: Argument 6 to "_handle_tool_execution" has incompatible type "ToolConfig | None"; expected "ToolConfig"  [arg-type]
Found 2 errors in 1 file (checked 51 source files)

Other than that, looks great. I gave it a test locally as well ☺️

[fede-kamel]

lints passing now - will do that moving forward

❯ hatch run test-lint
cmd [1] | ruff check
All checks passed!
cmd [2] | mypy -p src
Success: no issues found in 51 source files

[awsarron]

Thank you @fede-dash 🚀 !!

[fede-kamel]

🔥🕊️ Always will be!