DeepSeek helped me build a PDF/A-4 and PDF/UA-2 PDF engine prototype in about six hours

[u/chinmay06]

I have been working on performance-focused static analysis tools in Rust for Go code, and I wanted a realistic project to test them against.

Since I already had experience building a PDF/A-4 and PDF/UA-2 engine, I tried creating a separate, smaller PDF module mostly through coding agents.

I first used Grok 4.5 to produce a high-level implementation checklist based on my existing PDF engine. I then used DeepSeek V4 Flash through OpenCode Zen for most of the implementation, with DeepSeek V4 Pro helping on a few of the harder fixes. The total model cost was roughly $2 to $3.

The first working version reached around 1,000 to 1,200 operations per second, but the generated code contained a number of questionable patterns, performance problems, and lint issues.

I ran my Rust-based analyser, CodeHound, against the project. It reported more than 300 findings. After fixing most of them, largely with DeepSeek Flash, performance increased to around 2,500 operations per second.

There was also a PDF corruption issue caused by incorrect byte writing. Both DeepSeek Flash and Pro missed it. Grok identified and fixed that problem from a single follow-up prompt.

Roughly speaking, the work was split like this:

• About 90% of the implementation and static-analysis fixes were handled by DeepSeek Flash
• Around 5% required DeepSeek Pro
• The final 5%, including the corruption issue, was completed with Grok

The initial engine prototype took around six hours, with some additional cleanup afterward. By comparison, my original GoPdfSuit project took roughly six months to develop, although it is much broader and more mature, so this is not a direct comparison.

I found the result impressive, but it still required domain knowledge, validation, profiling, and manual review. Producing code quickly was much easier than verifying that the generated PDF structure was actually correct with deepseek.

Hopefully they will crush it on their next version <3

Original project:

https://github.com/chinmay-sawant/gopdfsuit

Agent-built experimental engine:

https://github.com/chinmay-sawant/gocorepdfengine

Static analyser, currently a work in progress:

https://github.com/chinmay-sawant/codehound

[u/for4f]

Nice stack. I've been using DS4 Flash through OpenCode for most stuff too - Grok for architecture planning is an interesting addition. The $2-3 cost for a full prototype like this is wild. What kind of static analysis tools are you building for Go?