| name | antigravity-hooks-middleware-dart |
| description | Intercept agent turns, validate tool execution, handle errors, or track compaction using HookRouter lifecycle hooks in Dart. |
Lifecycle Hooks & Agent Middleware in Dart
Guidelines for registering harness and client-side lifecycle hooks using HookRouter to inspect, decide, transform, and intercept agent steps.
1. Registering Lifecycle Hooks
- Hook Router Setup: Pass registered hooks to
LocalAgentConfig(hooks: [...]).
- Turn & Tool Interception:
PreTurnHook: Pre-validate prompts or reject turns before harness dispatch.PostTurnHook: Inspect output tokens, state, or trajectory results.PostToolCallHook: Inspect or log tool outputs post-execution.OnToolErrorHook: Catch tool execution failures (ToolExecutionException) and provide fallback responses.OnCompactionHook: Intercept context window compaction events.
- Stateless Factories: Use
.stateless() constructors (FunctionInspectHook.stateless, FunctionDecideHook.stateless, FunctionTransformHook.stateless) when context tracking is unneeded.
For complete hook implementations, inspect references/hooks_patterns.md.
2. Correlation & Telemetry Tracking
- Access
callId across ToolCall, ToolResult, and hook payloads to correlate tool operations across concurrent step turns.
- Monitor session lifecycle events via
OnSessionStartHook and OnSessionEndHook.
For code patterns, consult references/hooks_patterns.md.
Completion Criteria
