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docs/content/stories/epic1/1.4-error-handling.md

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+# Story 1.4: Error Handling and Error Bus
+
+## Metadata
+- **Story ID**: 1.4
+- **Title**: Error Handling and Error Bus
+- **Epic**: 1 - Core Kernel & Infrastructure
+- **Status**: Pending
+- **Priority**: High
+- **Estimated Time**: 4-5 hours
+- **Dependencies**: 1.1, 1.3
+
+## Goal
+Implement centralized error handling with an error bus that captures, logs, and optionally reports all application errors.
+
+## Description
+This story creates a complete error handling system with an error bus that captures all errors, logs them with context, and provides a foundation for future error reporting integrations (like Sentry).
+
+## Deliverables
+
+### 1. Error Bus Interface (`pkg/errorbus/errorbus.go`)
+- `ErrorPublisher` interface with `Publish(err error)` method
+- Error context support
+- Error categorization
+
+### 2. Channel-Based Error Bus (`internal/errorbus/channel_bus.go`)
+- Buffered channel for error publishing
+- Background goroutine consumes errors
+- Logs all errors with context (request ID, user ID, etc.)
+- Error aggregation
+- Optional: Sentry integration placeholder (Epic 6)
+
+### 3. Panic Recovery Middleware
+- Recovers from panics in HTTP handlers
+- Publishes panics to error bus
+- Returns appropriate HTTP error responses (500)
+- Preserves error context
+
+### 4. Integration
+- Integration with DI container
+- Integration with HTTP middleware stack
+- Integration with logger
+
+## Implementation Steps
+
+1. **Create Error Bus Interface**
+   - Create `pkg/errorbus/errorbus.go`
+   - Define ErrorPublisher interface
+
+2. **Implement Channel-Based Error Bus**
+   - Create `internal/errorbus/channel_bus.go`
+   - Implement buffered channel
+   - Implement background consumer
+   - Add error logging
+
+3. **Create Panic Recovery Middleware**
+   - Create middleware for Gin
+   - Recover from panics
+   - Publish to error bus
+   - Return error responses
+
+4. **Integrate with DI**
+   - Create provider function
+   - Register in container
+
+5. **Integrate with HTTP Server**
+   - Add panic recovery middleware
+   - Test error handling
+
+## Acceptance Criteria
+- [ ] Errors are captured and logged via error bus
+- [ ] Panics are recovered and logged
+- [ ] HTTP handlers return proper error responses
+- [ ] Error bus is injectable via DI
+- [ ] Error context (request ID, user ID) is preserved
+- [ ] Background error consumer works correctly
+- [ ] Error bus doesn't block request handling
+
+## Related ADRs
+- [ADR-0015: Error Bus Implementation](../../adr/0015-error-bus-implementation.md)
+- [ADR-0026: Error Reporting Service](../../adr/0026-error-reporting-service.md)
+
+## Implementation Notes
+- Use buffered channels to prevent blocking
+- Background goroutine should handle errors asynchronously
+- Preserve error context (stack traces, request IDs)
+- Consider error rate limiting in future
+- Placeholder for Sentry integration in Epic 6
+
+## Testing
+```bash
+# Test error bus
+go test ./internal/errorbus/...
+
+# Test panic recovery
+# Trigger panic in handler and verify recovery
+```
+
+## Files to Create/Modify
+- `pkg/errorbus/errorbus.go` - Error bus interface
+- `internal/errorbus/channel_bus.go` - Error bus implementation
+- `internal/server/middleware.go` - Panic recovery middleware
+- `internal/di/providers.go` - Add error bus provider
+