Why LLM debugging fails on fragmented repository context

After spending a lot of time debugging large repositories with ChatGPT/Claude, I kept noticing the same failure pattern: the model was not necessarily "bad at coding" - it was operating on a broken map of the repository. Typical workflow looks something like: search manually across many files paste fragmented snippets omit surrounding implementation paths lose imports/dependencies/state flow ask the model to reason across missing context At that point the model starts interpolating architecture that may not actually exist.