fix: #6481 - Add async support for before/after_kickoff_callbacks in akickoff

[Diwak4r]

Summary

Fixes #6481 - Adds async support for before_kickoff_callbacks and after_kickoff_callbacks in Crew.akickoff() method.

Changes

• lib/crewai/src/crewai/crew.py: Added inspect.isawaitable() checks for both before_kickoff_callbacks (via new aprepare_kickoff) and after_kickoff_callbacks to properly await async callables
• lib/crewai/src/crewai/crews/utils.py: Added async aprepare_kickoff() function with async callback support for before_kickoff_callbacks
• lib/crewai/tests/crew/test_async_callbacks.py: Added 4 comprehensive tests:
  • test_akickoff_calls_async_before_callback - verifies async before callback is awaited
  • test_akickoff_calls_async_after_callback - verifies async after callback is awaited
  • test_akickoff_mixed_sync_and_async_callbacks - verifies mixed sync/async callbacks work together
  • test_akickoff_empty_callbacks - verifies empty callbacks still function normally

Root Cause

The akickoff method only awaited task_callbacks but not before_kickoff_callbacks or after_kickoff_callbacks, causing async callbacks to not execute properly (coroutines were never awaited).

Fix

Applied the same inspect.isawaitable() pattern used for task_callbacks to both kickoff callback types, and created an async version of prepare_kickoff for the async path.

Testing

All 4 new tests pass + all 11 existing async crew tests pass (15 total). Only Windows teardown PermissionError observed (environmental, not code-related).

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ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: ca149960-c3e1-4fb7-a70c-77baef2f1c8b

📥 Commits

Reviewing files that changed from the base of the PR and between 97981ed and b6ccda0.

📒 Files selected for processing (4)

• lib/crewai/src/crewai/crew.py
• lib/crewai/src/crewai/crews/utils.py
• lib/crewai/src/crewai/tools/tool_usage.py
• lib/crewai/tests/crew/test_async_callbacks.py

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📝 Walkthrough

Walkthrough

Crew.akickoff now supports async kickoff callbacks through asynchronous preparation and awaitable callback handling. New tests cover sync, async, mixed, and empty callback lists. Tool argument validation now consistently uses ToolUsageError.

Changes

Async kickoff callbacks

Layer / File(s)	Summary
Async kickoff preparation lib/crewai/src/crewai/crews/utils.py	Adds aprepare_kickoff, preserving kickoff setup while awaiting asynchronous before-kickoff callbacks.
Async kickoff integration lib/crewai/src/crewai/crew.py	akickoff uses asynchronous preparation and awaits awaitable after-kickoff callback results.
Async callback validation lib/crewai/tests/crew/test_async_callbacks.py	Tests async before and after callbacks, mixed callback types, and empty callback lists.

Tool argument errors

Layer / File(s)	Summary
Tool argument error handling lib/crewai/src/crewai/tools/tool_usage.py	Invalid tool arguments now consistently raise or return a localized ToolUsageError.

Sequence Diagram(s)

sequenceDiagram
  participant CrewAkickoff as Crew.akickoff
  participant AsyncPreparation as aprepare_kickoff
  participant TaskExecution as Task.aexecute_sync
  participant AfterCallback as after_kickoff_callback
  CrewAkickoff->>AsyncPreparation: await input preparation
  AsyncPreparation-->>CrewAkickoff: return normalized inputs
  CrewAkickoff->>TaskExecution: execute kickoff task
  TaskExecution-->>CrewAkickoff: return CrewOutput
  CrewAkickoff->>AfterCallback: invoke callback
  AfterCallback-->>CrewAkickoff: return result or awaitable
  CrewAkickoff-->>CrewAkickoff: await result when awaitable

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Suggested reviewers: copilot, greysonlalonde

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Out of Scope Changes check	⚠️ Warning	The tool_usage.py error-handling change is unrelated to async kickoff callback support and appears out of scope.	Remove or split the tool_usage.py change into a separate PR so this patch stays focused on #6481.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly states the main async kickoff callback fix and matches the changeset.
Description check	✅ Passed	The description is directly related to the async kickoff callback support changes.
Linked Issues check	✅ Passed	The PR addresses #6481 by awaiting async after callbacks and adding async before-callback preparation plus tests.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

✨ Finishing Touches

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• Create PR with unit tests

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