That was my experience with Claude when my vibe-coded project was small.
But now that I've been working on it a month and there's a lot of documentation, it's pretty clearly ignoring parts of the documentation and parts of the code. It will come up with some ridiculous statement about how something works, and I'll challenge it, and it'll admit I'm right.
It definitely reads more documentation than any programmer I've ever worked with (myself included) but because it doesn't have a memory other than the documentation, it still makes mistakes like that.
I haven't turned on "memory" or tried it with Codex, so I don't know how that'll change soon, though.
Yeah the biggest task these days that I do manually is curating the documentation. AGENTS.md in every major directory, and a variety of reference docs that are explicitly referenced in those files.
# See DOC-ITEM-NAME
DOC-ITEM-NAME.md
When referencing documents, always use the exact syntax See <TAG> - this is enforced by a lint on precommit
And those doc items are basically all of the values, architectural, strategic, and tactical items. It's a poor man's in-repo RAG but it's shockingly effective, especially if you keep them small. I may migrate some/all of them to skills over time, but I usually update them biweekly, and I only allow agents to make small edits or propose new notes. And typically I go through and delete or curate any agent edits before merge.
Depending on language I've seen this scale past multiple millions of lines of code, as long as you pair it with all of the linting and tooling that you can possibly build.
But now that I've been working on it a month and there's a lot of documentation, it's pretty clearly ignoring parts of the documentation and parts of the code. It will come up with some ridiculous statement about how something works, and I'll challenge it, and it'll admit I'm right.
It definitely reads more documentation than any programmer I've ever worked with (myself included) but because it doesn't have a memory other than the documentation, it still makes mistakes like that.
I haven't turned on "memory" or tried it with Codex, so I don't know how that'll change soon, though.