ADR-004: PSR-14 Event System 

Status 

Accepted (2024-02)

Context 

Consumers need extension points for:

• Logging and monitoring.
• Request modification.
• Response processing.
• Cost tracking and rate limiting.

Decision 

Use TYPO3's PSR-14 event system with events:

• BeforeRequestEvent: Modify requests before sending.
• AfterResponseEvent: Process responses after receiving.

Events are dispatched by LlmServiceManager and provide:

• Full context (messages, options, provider).
• Mutable options (before request).
• Response data (after response).
• Timing information.

Consequences 

Positive:

• ●● Follows TYPO3 conventions.
• ●● Decoupled extension mechanism.
• ● Multiple listeners without modification.
• ● Testable event handlers.

Negative:

• ◑ Event overhead on every request.
• ◑ Listener ordering considerations.
• ◑ Debugging event flow complexity.

Net Score: +6.5 (Strong positive impact - standard TYPO3 integration with decoupled extensibility)