Argument suggestion should take what the user already provided into account

[etiennebacher]

When pressing TAB to get argument suggestions, I think the suggestions should take the number of arguments that were already passed into account.

For example, cos() takes a single argument (x) so cos(1, <TAB>) should know that the user already provided one argument and it shouldn't suggest introducing x = as shown in the video:

Screencast.from.2026-08-27.16-03-28.webm

Note that this also happens in RStudio.

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Positron Version: 2026.09.0 build 150
Code - OSS Version: 1.130.0
Commit: 9684f4d
Date: 2026-08-24T16:15:08-06:00
Electron: 42.6.0
Chromium: 148.0.7778.280
Node.js: 24.18.0
V8: 14.8.178.38-electron.0
OS: Linux x64 6.17.0-1030-oem

[jonvanausdeln]

@etiennebacher , thanks for the report, and for the video.

You are right, and this one is already on our radar in a small way. The R language server's test suite carries a TODO describing exactly this case, on match(1, ): it should not offer x once the first argument is filled. So the behavior you are seeing is known rather than intended, it just never had an issue tracking it.

I have opened #15772 to track it, feel free to add anything additional