Added validation to each phase

DESIGN.md

@@ -36,6 +36,7 @@ OpenTofu Client → HTTP Backend Protocol → QEMU Management Server
 - **Role**: Built-in OpenTofu HTTP backend (no custom code required)
 - **Responsibilities**: State serialization, HTTP communication, locking protocol
 - **Configuration**: Points to custom QEMU management server endpoints
+- **Integration**: Works with existing OpenTofu workflows and tooling with no additional code required
 
 #### 2. QEMU Management Server
 - **Role**: Core application implementing HTTP backend protocol
@@ -44,10 +45,11 @@ OpenTofu Client → HTTP Backend Protocol → QEMU Management Server
   - QEMU process lifecycle management
   - Resource allocation and conflict resolution
   - State persistence and recovery
+  - Exposing a web interface for monitoring, management and debugging
 
 #### 3. State Storage Layer
 - **Role**: Persistent storage for OpenTofu state and VM metadata
-- **Options**: SQLite (simple), PostgreSQL (production), file-based (development)
+- **Options**: SQLite
 - **Responsibilities**: State persistence, backup, recovery
 
 #### 4. QEMU Process Manager
@@ -69,6 +71,9 @@ OpenTofu Client → HTTP Backend Protocol → QEMU Management Server
 - Add proper error handling and logging
 - Create basic configuration system
 
+**Validation:**
+- We should be able to run OpenTofu against the resulting service, and get valid responses indicating success (even if nothing is created or run)
+
 ### Phase 2: QEMU Integration
 **Deliverables:**
 - QEMU process lifecycle management
@@ -82,6 +87,9 @@ OpenTofu Client → HTTP Backend Protocol → QEMU Management Server
 - Add QEMU Machine Protocol (QMP) integration
 - Create resource conflict detection
 
+**Validation:**
+- We should be able to run OpenTofu against the resulting service, and get valid responses indicating success (even if nothing is created or run yet)
+
 ### Phase 3: State Processing and VM Management
 **Deliverables:**
 - State diff processing to determine required changes
@@ -95,6 +103,12 @@ OpenTofu Client → HTTP Backend Protocol → QEMU Management Server
 - Add network and storage allocation
 - Build recovery and cleanup mechanisms
 
+**Validation:**
+- Boot a VM from OpenTofu configuration until network connectivity is established (ping response)
+- Verify VM configuration changes are applied correctly through state diff processing
+- Test graceful VM shutdown and resource cleanup
+- Validate network and storage allocation/deallocation
+
 ### Phase 4: Production Readiness
 **Deliverables:**
 - Comprehensive error handling and recovery
@@ -108,6 +122,15 @@ OpenTofu Client → HTTP Backend Protocol → QEMU Management Server
 - Performance testing and optimization
 - Security hardening and authentication
 
+**Validation:**
+- **Performance**: Deploy 10+ concurrent VMs and validate system stability under load
+- **Monitoring**: Verify metrics endpoints expose VM count, memory usage, and error rates
+- **Recovery**: Kill QEMU processes and validate automatic cleanup and state consistency
+- **Backup/Restore**: Create state backup, simulate data loss, and restore from backup
+- **Security**: Test authentication mechanisms and validate unauthorized access is blocked
+- **Error Handling**: Inject failures (disk full, network issues) and verify graceful degradation
+- **Resource Limits**: Exceed configured limits (max VMs, memory) and validate enforcement
+
 ## Technical Specifications
 
 ### HTTP Backend Protocol Implementation