SAM json schema: cannot change schema in template.yaml file

Problem

Cannot manually select a different json schema in SAM template.yaml.

Steps to reproduce the issue

1. Choose a different schema from the status bar:
   • 
2. the schema is ignored and the selection remains aws://sam.schema.json

Expected behavior

System details (run the AWS: About Toolkit command)

• OS:
• Visual Studio Code version:
• AWS Toolkit version:

[jpinkney-aws]

The way the VSCode-YAML API works is, given an intellisense action (hover, validation, completion, etc), it will query all the extensions that are currently registered to use it’s API and then ask them if this file is supported by their extension.

E.g. In our case, we see a SAM file in VSCode so we tell VSCode-YAML that we are the ones who should be providing the schema for this file.

Once VSCode-YAML see’s that an extension is ready and available to send a schema for the given file, it disables all other modes of settings the schema (modeline, yaml.schemas, etc) for that file.

This is by design, since theoretically an extension should be able to recognize their files and then provide support for them, that way users don’t have to manually specify schemas using the modeline or the yaml.schemas setting.

The problem here is we aren’t able to easily override the way the VSCode-YAML API works. So right now, the VSCode-YAML API sees that our extension will send back the schema for the given SAM file and then disables all other ways to set the schema

[hoffa]

For context, this is affecting https://github.com/aws/serverless-application-model/discussions/2645