Race condition in all singleton initializations

[DeFiVC]

What

All singletons use the pattern:

global _client
if _client is None:
    _client = CohereClient()
return _client

In a concurrent async context, multiple coroutines can read _client is None as True simultaneously and each create a new instance.

Why

While only one "wins" the assignment, the others may have partially initialized state.

Scope

• Use asyncio.Lock or module-level eager initialization

Acceptance Criteria

• Singleton initialization is thread/async-safe

Technical Context

• Files:
  • src/services/cohere_client.py, lines 148-151
  • src/services/embedding.py, lines 62-64
  • src/services/generation.py, lines 130-132
  • src/services/quiz_generator.py, lines 125-127
  • src/services/feedback_engine.py, lines 130-132
  • src/knowledge/vectorstore.py, lines 170-174

[mekeke111]

Hi maintainer I am a full stack developer I can handle this