Modernizing Legacy Code with Vibe Coding (2/2): PHP, Built Up Alongside the History of the Web

Fri, 16 Oct 2026 18:00:00 +0900

The risk in legacy PHP lies not in pointers but in aging runtime environments, implicit type conversions, authorization checks, and the database and external integrations. In most cases the right answer is not to abandon PHP, but to move it to a supported version and put verification and deployment practices in place first.

Dohyun Jung - Principal Consultant, ROBOCO

In Part 1, I covered how to modernize C/C++ applications that are more than 20 years old with vibe coding.¹ This post covers the legacy web, and PHP in particular.

Modernizing Legacy Code with Vibe Coding (1/2): 20-Year-Old C/C++ Applications

Fri, 16 Oct 2026 10:00:00 +0900

Agents struggle with legacy C/C++ not because the code is complex, but because they have no way to check whether what they did is correct. The first investment in modernization is not a language migration but a verification environment.

Dohyun Jung - Principal Consultant, ROBOCO

When I consult on vibe coding adoption, I often hear the same complaint: “Our project is too complex. The agent can’t do what we ask it to do.” At first, I assumed the cause was a specialized domain or poorly written prompts. But as the cases piled up, a common thread emerged. Most of the teams saying this were working on C/C++ codebases more than 20 years old.

Legacy-Modernization on ROBOCO

Modernizing Legacy Code with Vibe Coding (2/2): PHP, Built Up Alongside the History of the Web

Dohyun Jung - Principal Consultant, ROBOCO

Modernizing Legacy Code with Vibe Coding (1/2): 20-Year-Old C/C++ Applications

Dohyun Jung - Principal Consultant, ROBOCO