Design Specifications

This section contains detailed design specifications for system components following Sphinx-Needs methodology.

Design Documents:

• High-Level Architecture Design Specification
  • Overview
  • Component Design Specifications
  • Data Flow Architecture
  • QEMU Emulation Architecture
  • Threading Architecture
  • Build System Integration
  • Development Workflow Design
  • Logging and Diagnostics
  • Error Recovery Strategy
  • Performance Targets
  • Traceability
• JSON-Based Configuration Manager Design
  • Architecture Design
  • Data Structure Design
  • NVS Access Layer (Config Manager)
  • Web Interface Design
  • Best Practices & Development Guide
  • Traceability
• Configuration Webpage Design Specification
  • Architecture Overview
  • Data Flow Architecture
  • Schema-Driven Form Generation
  • Configuration Data Mapping
  • User Interface States
  • Reset Countdown Modal
  • Error Handling
  • Page Initialization Sequence
  • Traceability
• Web Server Design Specification
  • Architecture Overview
  • Static File Embedding
  • URI Routing and Handlers
  • Configuration API Design
  • Configuration Manager Integration
  • WiFi Manager Integration
  • Captive Portal Implementation
  • Server Configuration and Lifecycle
  • Adding New Pages and Endpoints
  • CORS and Security
  • Testing and Debugging
  • Traceability

Overview

Design specifications define how the system implements requirements. They are:

• Traceable - Each design spec links to parent requirements

• Detailed - Include architecture, data structures, APIs, and algorithms

• Testable - Provide basis for implementation and verification

• Versioned - Tracked in Git alongside code

Design Hierarchy

Design specifications are organized by scope:

1. High-Level Architecture (SPEC_ARCH_*) - System-wide design decisions

   • Layered architecture and component organization

   • Threading model and memory management

   • Build system and QEMU integration

   • Network architecture (WiFi, HTTP)

   • Performance targets and development workflow

2. Component-Specific Designs - Detailed component specifications

   • SPEC_CFG_JSON_* - Configuration Manager (JSON-based system)

   • SPEC_WEB_* - Web Server HTTP interface and REST API

   • Additional component designs to be added as needed

Each design specification uses Sphinx-Needs :spec: directive and links to parent requirements using :links: attribute.

Document Standards

All design documents follow this structure:

• Metadata: Version, date, author, requirements coverage

• Architecture: High-level design decisions and patterns

• Data Structures: Internal data layouts and formats

• API Design: Public interfaces and contracts

• Implementation: Detailed algorithms and approaches

• Traceability: Requirement coverage matrix

Design vs. Code

Design documents are separate from code to avoid bloat:

• Design docs (docs/12_design/): Architecture, algorithms, rationale

• Code comments: Implementation notes, requirement IDs

• API docs (Doxygen): Function signatures, parameter descriptions

This separation enables:

• Professional documentation tooling (Sphinx-Needs traceability matrices)

• Design review without code complexity

• Version control for design decisions

• Scalability for large projects

Traceability Chain

The complete traceability chain:

Requirements (docs/11_requirements/)
     ↓ :links: attribute
Design Specs (docs/12_design/)
     ↓ @file comments with REQ/SPEC IDs
Implementation (main/, components/)
     ↓ test suite references
Tests (to be added)

See the Traceability section for visualizations of the complete chain.