feat: Kafka message bus for sending webhook events

Author: arcoraven

CLAUDE.md

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+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## Development Commands
+
+### Build and Test
+- `cargo build --release` - Build production binary
+- `cargo test` - Run all tests including Redis integration tests
+- `cargo nextest run -p twmq --profile ci` - Run specific component tests
+- `RUST_LOG=debug cargo run` - Run server with debug logging
+
+### Development Setup
+Redis is required for development:
+```bash
+docker run -d --name redis -p 6379:6379 redis:7-alpine
+```
+
+Required environment variables:
+```bash
+export APP__THIRDWEB__SECRET="your_secret_key"
+export APP__THIRDWEB__CLIENT_ID="your_client_id"
+```
+
+## Architecture Overview
+
+This is a **Rust workspace** with 7 crates providing blockchain transaction infrastructure:
+
+- **`server/`** - Main HTTP API server (Axum-based REST API with OpenAPI docs)
+- **`core/`** - Core blockchain functionality (chain management, transactions, UserOps)
+- **`aa-core/`** - Account Abstraction engine (ERC-4337 v0.6/v0.7 support)
+- **`aa-types/`** - Account Abstraction type definitions
+- **`executors/`** - Background job handlers (webhooks, transaction confirmation)
+- **`twmq/`** - Thirdweb Message Queue (Redis-backed job queue with lease-based concurrency)
+- **`thirdweb-core/`** - Thirdweb service integrations (Vault SDK, IAW)
+
+### Key Technologies
+- **Axum** for HTTP server
+- **Alloy** for Ethereum interactions
+- **Redis** for job queue and state
+- **Tokio** for async runtime
+- **Vault SDK** for secure key management
+
+## Configuration System
+
+Hierarchical configuration priority:
+1. Environment variables (`APP__` prefix)
+2. Environment-specific YAML (`server_development.yaml`, `server_production.yaml`)
+3. Base YAML (`server_base.yaml`)
+
+Configuration files located in `server/configuration/`
+
+## Transaction Types Supported
+
+- **EOA transactions** - Traditional wallet transactions
+- **Account Abstraction** - ERC-4337 smart accounts with gas sponsorship
+- **EIP-7702** - Delegated transaction execution
+
+## Key Development Areas
+
+### API Routes
+Located in `server/src/http/routes/` - follows RESTful patterns with OpenAPI documentation
+
+### Background Jobs
+Implemented in `executors/src/` - uses TWMQ for reliable job processing with Redis persistence
+
+### Blockchain Core
+`core/src/` contains chain management, transaction building, and UserOperation support
+
+### Account Abstraction
+`aa-core/src/` implements complete ERC-4337 flow including bundler integration
+
+## Error Handling
+
+Uses comprehensive error types with context. All errors are structured and logged with tracing spans.
+
+## Testing
+
+Integration tests require Redis. Tests cover job queue operations, transaction building, and API endpoints.
+
+## Production Features
+
+- Horizontal scaling via shared Redis backend
+- Graceful shutdown with job completion guarantees
+- Vault-backed private key management
+- Comprehensive metrics and health checks
+- Docker support with multi-stage builds