[Bug] Error: Could not find source file

Reproducible in vscode.dev or in VS Code Desktop?

• Not reproducible in vscode.dev or VS Code Desktop

Reproducible in the monaco editor playground?

• Not reproducible in the monaco editor playground

Monaco Editor Playground Code

monaco.editor.create(document.getElementById("container"), {
    model: monaco.editor.createModel(
        "import * as t from 'test';\nt.X.toExponential();", 
        "typescript",
        monaco.Uri.parse("root")
    )
});

monaco.languages.typescript.typescriptDefaults.setCompilerOptions({
  ...monaco.languages.typescript.typescriptDefaults.getCompilerOptions(),
  moduleResolution: monaco.languages.typescript.ModuleResolutionKind.Classic
});

const parsed = monaco.Uri.parse("/test.ts?id=123");
monaco.editor.createModel(
    "export const X = 1;", 
    "javascript",
    parsed
);
console.log(parsed)

Reproduction Steps

1. Paste the code
2. Open browser debug tool
3. Press "Run" button
4. Hover over import statement to make worker work

Actual (Problematic) Behavior

There's an error caused by adding query param (with equal sign or Russian word as example) to URI.
The problem is in method getValidSourceFile.
This file exists in the list of models, I checked this via program.getSourceFiles(), but its fileName doesn't correspond due to encoding equal sign to %3D, so the method returns undefined and console shows this error:

Uncaught (in promise) Error: Could not find source file: 'file:///test.ts?id%3D123'. at Ve (/vs/language/typescript/tsWorker.js:255:8493) at Object.On [as getSyntacticDiagnostics] (/vs/language/typescript/tsWorker.js:255:13349) at lm.getSyntacticDiagnostics (/vs/language/typescript/tsWorker.js:33955:2559) at S.fmr (workerMain.js:22:33695) at f._handleMessage (workerMain.js:22:17684) at Object.handleMessage (workerMain.js:22:17309) at w._handleRequestMessage (workerMain.js:22:14120) at w._handleMessage (workerMain.js:22:13570) at w.handleMessage (workerMain.js:22:13458) at f.onmessage (workerMain.js:22:17401)

Expected Behavior

File should be returned from the list of model regardless encoding/decoding issues in URI.

Additional Context

No response

Start with the Monaco Editor Playground reproduction and inspect the getValidSourceFile path used by the TypeScript worker. Verify behavior with the provided model URI containing a query parameter, and consider the issue complete when the existing model is returned despite URI encoding differences and the diagnostic request no longer reports “Could not find source file.”