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Issue Description

We've been using the v8 alpha-30 release to make use of ESLint v9 and have now switched to using the full release.
When using the projectService option for typescript-eslint's parser in v8.0.0, creating a new file causes the extension to produce the error:

Parsing error: [path-to-newly-created-file] was not found by the project service. Consider either including it in the tsconfig.json or including it in allowDefaultProject.

Requiring that the extension be restarted to force the project service to pick up the new file.
The alpha version (30) of v8 previously raised This rule requires the 'strictNullChecks' compiler option to be turned on to function correctly. on the newly created file, likely caused by the same issue (the project service was not aware of the new file as from the command line it will be started after the file is created).

Background

• The repo is an NX monorepo using a custom flat config.
• Each project contains a tsconfig.json that extends a base config, and references several additional tsconfig files (e.g tsconfig.lib.json/tsconfig.spec.json).
• Linting is run from the root of the workspace on all projects
• There is also a root level tsconfig.json (as well as the base config) that includes all files outside of nested projects (which theoretically negates the need for a defaultProject if I understand correctly).
• The ESLint configuration uses a function to return the config at runtime based on environment variables and dynamic values - this all works as expected when editing existing files.
• Running ESLint from the command line works as expected.

This issue was also opened on the vscode-eslint repo.

CC @dbaeumer

Reproduction Repository Link

https://github.com/tetarchus/project-service

Repro Steps

• Clone the repo
• Open the repo in VSCode
• Install dependencies
• Run npm run lint in the terminal and observe no errors
• Ensure that the vscode extension is installed and active
• Create a new file (can be anywhere, but libs/project-test/src/ is definitely covered by a tsconfig.json file)
• Add some basic content and save the file
• Observe that the extension shows an error line below the first word of the file - hovering to show the error (shown below) - also present in the Output logs.
• Run npm run lint in a terminal and observe there are still no errors
• Run the ESLint: Restart ESLint Server action and wait until complete
• Observe that the error no longer displays.

Versions