Supermaven completions behave strangely when writing over them

[alexkirsz]

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• Completed

Describe the bug / provide steps to reproduce it

In Zed's Supermaven completion, if you start writing over a suggested completion in a way that doesn't match the completion, the completion isn't properly discarded and replaced. This causes weird behavior where partial completions stay on screen, even though they no longer make sense/would be invalid.

For instance:

Screen.Recording.2024-10-25.at.09.03.41.mov

Compare this to VS Code's implementation, which:

1. Properly discards/replaces suggestions as they are invalidated; and
2. When a suggestion cannot be reconciled with the current line, it is proposed at the very end of the line instead.

Screen.Recording.2024-10-25.at.09.05.53.mov

Environment

Zed: v0.158.2 (Zed)
OS: macOS 14.6.1
Memory: 32 GiB
Architecture: aarch64

If applicable, add mockups / screenshots to help explain present your vision of the feature

No response

If applicable, attach your Zed.log file to this issue.

Zed.log