Description
Description of Problem
Per #249531 (comment), it would be helpful to clarify the difference between custom instructions (*.instructions.md files which contain instructions either for all files, or specific files matching an applyTo file glob in the instructions) and codeGen instructions (added via .vscode/settings.json).
There seems to at least be overlap between the two and it's not totally clear why you'd use custom instruction files because when you prompt the model for new code (new files) it can't attach any additional instructions because it doesn't know the file extensions yet.
Therefore, it seems like all of these instructions should just go in the codeGen instructions files, but then you end up attaching a huge amount of additional context to all prompts unnecessarily.
Feature Proposal
I'd say in the most ideal scenario, we stick with the instructions files, but we somehow insert these additional instructions in between an initial prompt and when the model either creates the files or identifies the files to be worked on.
Example Scenario
Prompt: create a new component that manages users
Model: plans and creates new files manage-users.component.ts, manage-users.component.html, manage-users.component.scss, manage-users.component.spec.ts
System: Recognizes edits being made to files that match custom instructions files applyTo field, provides these custom instruction file to model
Model: begins adding code to file with custom instructions in context