Summary

Phase 4 of the ecosystem-wide directory structure standardization. network_system has a 1031-line root CMakeLists.txt, a single monolithic tests/unit_tests.cpp, and an ambiguous relationship between libs/network-*/ modular protocol libraries and the src/ source tree. Decompose the CMake configuration, split the test file, and document the libs/ vs src/ boundary.

Part of kcenon/common_system#657 (master EPIC).

Status

EPIC complete. All four sub-issues merged on 2026-05-01.

Child Issues

• tests: split unit_tests.cpp with TCP messaging fixture #1088 — tests: split unit_tests.cpp with TCP messaging fixture (PR test: split unit_tests.cpp with TCP messaging fixture #1092, b3d8bd28)
• docs: augment PROJECT_STRUCTURE.md with libs/ vs src/ boundary #1089 — docs: augment PROJECT_STRUCTURE.md with libs/ vs src/ boundary (PR docs: augment PROJECT_STRUCTURE.md with libs/ vs src/ boundary #1093, 33313aec)
• build: decompose root CMakeLists.txt into cmake/*.cmake modules #1090 — build: decompose root CMakeLists.txt into cmake/*.cmake modules (PR refactor(build): decompose root CMakeLists.txt into cmake/ modules #1096)
• samples: merge samples/ into examples/ canonical directory #1091 — samples: merge samples/ into examples/ canonical directory (PR refactor: merge samples/ into examples/ canonical directory #1094, 4ac841f0)

Acceptance Criteria

• Per-protocol test files run in parallel without port conflicts (tests: split unit_tests.cpp with TCP messaging fixture #1088)
• PROJECT_STRUCTURE.md updated and the existing README link still resolves (docs: augment PROJECT_STRUCTURE.md with libs/ vs src/ boundary #1089)
• cmake modules match the canonical network_system_*.cmake naming (build: decompose root CMakeLists.txt into cmake/*.cmake modules #1090)
• Single canonical examples directory, single BUILD_EXAMPLES flag (samples: merge samples/ into examples/ canonical directory #1091)
• All downstream consumers (pacs) build unchanged (verified by Phase 4 CI matrix)

Outcome

• Root CMakeLists.txt: 1031 → ~118 lines (orchestrator only)
• tests/unit_tests.cpp: 962 lines removed, replaced by 6 per-concern files + shared TCP fixture
• samples/ directory removed, examples/ is now the single canonical examples tree
• BUILD_SAMPLES flag retired, BUILD_EXAMPLES is the single switch
• docs/PROJECT_STRUCTURE.md documents the libs/ vs src/ boundary and resolves the src/protocol/ vs src/protocols/ ambiguity (both current, distinct roles)