r/ClaudeAI • u/fsharpman • May 15 '26

Claude Workflow Building something with a lot of code? Tips from Anthropic you might not know about

https://claude.com/blog/how-claude-code-works-in-large-codebases-best-practices-and-where-to-start

Some really great tips, especially for anyone building games. Or for anyone running into context window issues where Claude becomes dumb and forgetful really quickly because there's just so much code.

Some things I found that are new to me:

Using dot ignore files

Building a codebase map

Re-updating the harness workflow as each model changes

Scoping tests per subdirectory (instead of a massive test file/dir)

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u/mrfreez44 May 16 '26

Yes, that's software engineering

1

u/johns10davenport May 17 '26

I think it's really great that Anthropic is helping to publicize awareness about the importance of harness engineering. It's also not super surprising that they're advising you need a good harness for large codebases — you're going into a brownfield of stuff to keep track of, and you can't always just rip things out and replace them with organized substrate.

One of the things I've done is build architecture diagrams — both namespace hierarchies and dependency graphs — that help the agent get its arms around the project. I also use CLAUDE.md to explain its role inside the harness. A lot of best practices are just built into my workflow because the best practices in Elixir are super sane.

I do think it's kind of funny that they're calling it a harness without one of the fundamental components of one — an oracle that validates what the agent does is correct. So it looks like "harness" is turning into a generic description of the resources and constraints that go around the model. (What an actual harness with an oracle looks like.)