What if you could reverse a template engine?

I've been building software for over 20 years across banking, healthcare, financial SaaS, and media. At Stuff , one of New Zealand's largest news platforms, I worked on systems that consumed and produced structured content at scale. In banking and healthcare, I dealt with legacy systems that predate REST APIs entirely: fixed-format financial reports, statement exports, internal tools that print structured text to stdout because that was the interface in 2003 and nobody has touched it since. Back in 2012 I worked as a remote contractor for SITA, a Canadian company in the aviation industry, parsing CSV flight fare data and loading it into a database. Hundreds of files, each with a slightly different layout depending on the source system, each needing to be mapped to the same schema. We wrote a lot of custom parsing code in Java for what was, in the end, just structured text with a consistent shape. The problem of "here is some structured text, I need the data inside it" is one of the mos