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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⚙️ Run configuration

Configuration used: Organization UI

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📥 Commits

Reviewing files that changed from the base of the PR and between 1b855b4 and 59d446b.

📒 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

🚧 Files skipped from review as they are similar to previous changes (4)

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

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📝 Walkthrough

Walkthrough

Crew.akickoff now supports asynchronous before- and after-kickoff callbacks. Kickoff preparation awaits asynchronous callbacks. Tool argument validation now consistently uses the localized ToolUsageError.

Changes

Async kickoff callbacks

Layer / File(s)	Summary
Async kickoff preparation lib/crewai/src/crewai/crews/utils.py, lib/crewai/src/crewai/crew.py	Adds aprepare_kickoff, preserves kickoff setup, and awaits 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 asynchronous 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 TaskExecution
  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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Merge Risk: ⚪ Minimal · up to 59d44

Async kickoff callbacks are now awaited for both preparation and completion paths, with coverage for async, synchronous, mixed, and empty callback configurations. No concrete merge-blocking risk remains.

🚥 Pre-merge checks | ✅ 3 | ❌ 2

❌ Failed checks (2 warnings)

Check name	Status	Explanation	Resolution
Out of Scope Changes check	⚠️ Warning	The tool_usage.py change alters ToolUsageError behavior and is unrelated to async kickoff callback support described in issue #6481.	Remove the unrelated tool_usage.py change from this pull request, or link it to a separate issue and submit it separately.
Docstring Coverage	⚠️ Warning	Docstring coverage is 64.29% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 14 functions across 4 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (3 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly identifies issue #6481 and the main change: async support for before and after kickoff callbacks in akickoff.
Description check	✅ Passed	The description explains the issue, root cause, implementation, affected files, and test results. It does not use every template heading, but it contains the required information in equivalent section…
Linked Issues check	✅ Passed	The changes satisfy issue #6481 by adding async before-callback support through aprepare_kickoff, awaiting async after-callback results, and adding tests for async, mixed, and empty callback cases.

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