Signature help should be triggered when entering placeholders following trigger chars

[sam-mccall]

When a completion provider returns a snippet like atan2(${1:y}, ${2:x}), the user should see signature help when editing the parameters.
VSCode could trigger signature help automatically when entering these placeholders (given that ( and , are trigger characters) but does not do so.
Other editors do this and provide noticeably a better signature-help flow with the same language servers (e.g. Neovim+nvim-cmp+lsp_signature.nvim).

This is a near-dupe of #78806 which is locked, I believe the resolution wasn't right.
It was suggested that providers should attach a command to the completion item to trigger signature help. However this doesn't really achieve the goal: will only fire when first entering the first parameter placeholder for the first time, it will not trigger when tabbing to other parameters, or when returning to the first one.

Moreover that idea requires changes to LSP, various language servers and other plugins, which means it may be a long time until it is available to users (3 years so far), and doesn't seem necessary.

[sam-mccall]

Correction: if signature help is opened (e.g. with the command), tabbing to a second parameter does seem to keep the signature help open and refresh it.
However the signature help window often disappears while editing (inlay hint updates seem to do this) and doesn't reappear when moving to an eligible tabstop.

[vscodenpa]

This feature request is now a candidate for our backlog. The community has 60 days to upvote the issue. If it receives 20 upvotes we will move it to our backlog. If not, we will close it. To learn more about how we handle feature requests, please see our documentation.

Happy Coding!

[vscodenpa]

This feature request has not yet received the 20 community upvotes it takes to make to our backlog. 10 days to go. To learn more about how we handle feature requests, please see our documentation.

Happy Coding!

[vscodenpa]

🙁 In the last 60 days, this feature request has received less than 20 community upvotes and we closed it. Still a big Thank You to you for taking the time to create this issue! To learn more about how we handle feature requests, please see our documentation.

Happy Coding!