SqlProj Tasks Bug Bash - Duplicate errors under Problems tab

[zijchen]

Steps to Reproduce:

1. Create a database project, configure build as default configuration to create tasks.json
2. Add a table, but with a syntax error like this

   CREATE TABLE [dbo].[Table1] ( [Id] INT NOT NULL PRIMARY KY ) 

3. Build the project, in Terminal it says there is only 1 error
4. But under Problems tab it shows 2
   
5. If I fix the syntax error, manually or using Copilot, only 1 error disappears unless I build the project again

[ssreerama]

This duplication occurs because one error is captured by VS Code’s built-in problem matcher (which provides live updates as the task runs), while the other is captured by our custom build process and diagnostic parsing. Both use the same problem matcher pattern, but the first is automatically applied by VS Code to the task output, and the second is applied after the build completes when we parse the output ourselves.

To resolve this, we should remove the problemMatcher from the package.json contribution and handle all diagnostics programmatically in our extension code. However, this means we will lose the default live update feature in the Problems window during the build, since diagnostics will only appear after the build finishes and our code processes the output.

When we remove the problem matcher from package.json, VS Code stops showing live build errors automatically. To display errors in the Problems tab, we have to run the build again in our code, capture the output, and create diagnostics ourselves. This means the build runs twice once for the user and once for error reporting which can slow things down. There’s currently no way to get the build output directly from the VS Code task for custom diagnostics.