TypeScript 7 VS Code extension: closing JSX tags are not inserted in content-mapped files, although tsc --lsp provides them #64564

In a content-mapped file, typing > after an opening JSX tag does not insert the closing tag, while the same keystroke in a .tsx file does. The language server supports it: textDocument/_vs_onAutoInsert for the content-mapped file returns the closing tag. The extension never sends that request for content-mapped files.

Repro: https://gist.github.com/leonidaz/a09cfe652d708cda59e20a112e879307, a 47-line identity content mapper (.foo files contain TSX and are returned unchanged as .tsx). TypeScript 7 extension 1.0.1, typescript@7.1.0-dev.20260930.4 through js/ts.tsdk.path, VS Code 1.140.0, macOS.

In VS Code

Type <b> between <div> and </div>:

The server log shows one textDocument/_vs_onAutoInsert, sent while typing in the .tsx file, and none for the .foo file.

The server supports it

npm run ask sends tsc --lsp the request the extension sends on >, right after <b> in card.foo and in control.tsx (both contain export const card = <div><b></div>;):

card.foo: {"_vs_textEditFormat":2,"_vs_textEdit":{"range":{"start":{"line":0,"character":28},"end":{"line":0,"character":28}},"newText":"$0</b>"}}
control.tsx: {"_vs_textEditFormat":2,"_vs_textEdit":{"range":{"start":{"line":0,"character":28},"end":{"line":0,"character":28}},"newText":"$0</b>"}}

Cause

packages/vscode-typescript/src/client.ts says content-mapped files are covered (L76-L78):

These augment the static jsTs document selector so the extension's custom language-feature providers (hover, multi-document highlight, on-auto-insert) also cover content-mapped files.

but registerSelectorScopedFeatures() registers only multi-document highlight and hover (L375-L387), and on-auto-insert is registered once with the static selector (L317):

registerOnAutoInsertFeature(this.documentSelector, this.client),

The published 1.0.1 does the same.

Suggested fix

Register on-auto-insert in registerSelectorScopedFeatures() with the selector-scoped selector, like hover. Its requireActiveDocumentSetting condition already matches the active document against the selector it is given. Happy to open a PR.

For mappers that generate code rather than copy it, the server offers the tag only when the generated JSX is still unclosed at the mapped position and the span carries FeatureAutoInsert; that part already works.

Found while adding TypeScript 7 support for .tsrx files through a content mapper (tsrx-org/tsrx#135).