Yes, at least up to the point of the context limit of the underlying model. If you needed to go beyond that, you would break the work up into separate "plans" (a plan is a set of tasks with an attached context and conversation).

The general workflow is to load some relevant context (could be a few files, an entire directory, a glob pattern, a URL, or piped in data), then send a prompt. Quick example:

  plandex new
  plandex load components/some-component.ts lib/api.ts package.json https://react.dev/reference/react/hooks
  plan tell "Update the component in components/some- 
  components.ts to load data from the 'fetchFooBars' 
  function in 'lib/api.ts' and then display it in a 
  datagrid. Use a suitable datagrid library."

From there the plan will start streaming. Existing files will be updated and new files created as needed.

One thing I like about it for large codebases compared to IDE-based tools I've tried is that it gives me precise control over context. A lot of tools try to index the whole codebase and it's pretty opaque--you never really know what the model is working with.