Closes
https://linear.app/zed-industries/issue/Z-2368/use-a-different-icon-for-the-assistant-panel
Closes
https://linear.app/zed-industries/issue/Z-2363/ship-the-assistant-only-on-preview
Closes
https://linear.app/zed-industries/issue/Z-2331/scrolling-makes-it-hard-to-read
Closes
https://linear.app/zed-industries/issue/Z-2306/allow-undo-and-collaboration-in-assistant

This pull request is a significant overhaul of the assistant panel,
which now uses a simple `Buffer` as opposed to a `MultiBuffer` to show
messages. Specifically, we track the start of each message with an
anchor located right after the newline (or `Anchor::MIN` for the first
message). When the anchor becomes invalid (that is, the newline is
deleted), we merge the message with the preceding ones. Crucially,
messages don't actually get deleted so that, if the newline anchor
becomes valid again (such as when undoing/redoing), we can restore the
messages as well.

As part of this overhaul, we are also improving the scrolling behavior
to maintain the viewport stable only when editing or moving the cursor,
but otherwise leave the scroll position unchanged when manually
scrolling up or down.

Note that with these changes, we are limiting access to the assistant to
users on preview (and dev), as we want to polish the behavior a little
more before shipping to the general public. Users on stable will still
be able to see the default settings/keybindings of the assistant, but I
think that's okay, as they won't be able to do anything with them.

Release Notes:

- Added support for undo/redo in the assistant (preview-only)
- Improved the scrolling behavior of the assistant when it was
generating responses. Now Zed will keep the viewport stable only when
editing or moving the cursor, but otherwise leave the scroll position
unchanged when manually scrolling up or down (preview-only)
- Changed the icon of the assistant panel (preview-only)

**Note for @JosephTLyons: given that we're feature flagging this, let's
make sure things on stable look reasonable and work correctly. Things to
look out for: ensure a stock installation works, changing the settings
on stable works, changing the keybinding on stable works.**

I accidentally added the information about folder-specific settings to
the user settings default file - just fixing that.

Release Notes:

- N/A

Release Notes:

- Improved comment extension for cases where cursor was placed before
start of comment marker

This rewrites and simplifies the git status system by attaching the git
status to each individual entry. This also improves the git testing
infrastructure to cover more cases and be more accurate to how file
events actually occur. This also fixes several other bugs in the worktree and the buffer, and stops any randomly generated actions from happening inside a `.git` folder. Hopefully, we can undo this change soon once our randomized testing is more robust.

Release Notes:

- Will require a DB migration

TODO:
- [x] Pass randomized tests
- [x] Get ready for merging

Fixes Z-1618. In the current state, this only works for line comments
such as `//` (and whatever's set in `{language}.toml` as a
line_comment).

Release Notes:

- Comments are now extended on new line.

This pull request introduces a new assistant panel to Zed that lets
users interact with OpenAI using their API key:

![CleanShot 2023-06-07 at 09 39
10@2x](https://github.com/zed-industries/zed/assets/482957/ba2a5830-9aeb-4c45-a182-a44d6a72675f)

After setting the key up, it will be saved to the keychain and
automatically loaded the next time the assistant panel is opened. The
key can be reset using `assistant: reset key`.

![CleanShot 2023-06-07 at 09 39
23@2x](https://github.com/zed-industries/zed/assets/482957/a6808bb0-0098-45ae-a2e3-f4d88472e626)

From there, users can type messages in a multi-buffer and hit
`cmd-enter` (`assistant: assist`) to stream assistant responses using
the OpenAI API. Responses can be canceled by hitting `escape`.

![CleanShot 2023-06-07 at 09 40
16@2x](https://github.com/zed-industries/zed/assets/482957/749779da-850e-4ad5-af04-74a3ca39f7ad)

Users can quote a selection from the active editor by hitting `cmd->`
(`assistant: quote selection`), which will embed the selected piece of
text in a Markdown fenced code block. Conversations with the assistant
are ephemeral at the moment, but can be easily copy/pasted:

![CleanShot 2023-06-07 at 09 50
33@2x](https://github.com/zed-industries/zed/assets/482957/b3386c10-4c51-4419-a0e0-517112ef6521)

Release Notes:

- Added a new assistant panel feature that enables interacting with
OpenAI using an API key. This replaces the previous experimental `ai:
assist` command that would work on any buffer. The experience is similar
to the one offered by ChatGPT with the added ability to edit, delete or
enhance previous messages. When hitting `cmd-enter`, the assistant will
start streaming responses from OpenAI. A response stream can be canceled
using `escape`. Moreover, the active editor's selection can be quoted in
the assistant panel using `cmd->`, which will automatically embed the
selected piece of text in a Markdown fenced code block.

Fixes
https://linear.app/zed-industries/issue/Z-2208/outline-view-doesnt-differentiate-between-overloaded-functions
Fixes
https://linear.app/zed-industries/issue/Z-2205/elixir-syntax-highlighting-not-working-properly-for-doc-attributes-and

This PR improves syntax highlighting and outline view in Elixir. It's
common to overload elixir functions, with many different versions of the
function for different patterns of parameters, so I updated the outline
view to show functions' parameters in Elixir. But if we showed functions
the same way in the *breadcrumbs*, it would take up too much space.

So I added a new capture in languages' `outline` queries called
`@context.extra`, which is included in the outline view, but not in
breadcrumbs.

Release Notes:

- Improved syntax highlighting of doc attributes and special macros in
Elixir
- Updated the outline view in Elixir to display function parameters, to
allow differentiating between function overloads.

Introduce a new capture in the outline query called 'context.extra', which
causes text to appear in the outline, but not in the breadcrumbs.

### Before

![Screen Shot 2023-06-06 at 2 32 46
PM](https://github.com/zed-industries/zed/assets/326587/036f1da3-19c6-4979-adc6-c3133f8d63dc)

### After

![Screen Shot 2023-06-06 at 2 32 08
PM](https://github.com/zed-industries/zed/assets/326587/6d4729db-b76a-4052-847e-fd9de346f194)

Release Notes:

* Improved the syntax highlighting of fenced code blocks in markdown.

This time I've added a `components` section to rust-toolchain.toml file
to explicitly require a rustfmt component. Fingers crossed.

This PR adds live reloading of Tree-sitter queries when running in debug
mode, similar to what we do for the themes. This way, you can change a
highlighting query or an outline query, and immediately see the result
in the app.

Release Notes:

- N/A

Reverts zed-industries/zed#2573

Add rust-toolchain.toml

Release Notes:

- N/A

Per conversation with Antonio, I've suggested enabling full LTO; right
now we use a crate-local ThinLTO, which does not inline function calls
across crates.

| Configuration    | Current main (788f97e) | Thin LTO  | Full LTO  |
|------------------|------------------------|-----------|-----------|
| Size in bytes    | 158806721              | 155868753 | 111115553 |
| % of `main` size | 100%                   | 98.14%    | 69.96%    |
| Size in bytes (no debug info) | 129186657 | 127942929 | 108281345 |

Previously, all static assets were embedded into Zed using a single
`RustEmbed` struct called `Assets`, which was in a crate of its own,
also called `assets`. Many crates depended on this crate. The problem
with this situation was that changing *any* static asset file caused
almost every crate in the codebase to need recompilation (because of
recursive dependencies on `assets`).

Now, most of the assets are embedded only into the top-level `zed`
crate. A few assets (such as settings JSON files and AI prompts) are
needed in lower-level crates such as `settings` and `ai`. For these,
I've created separate `RustEmbed` structs in those specific crates,
which embed those specific sub-folders of `assets`.

The result is that now, when you change a theme file, the only crate
that needs to recompile is `zed`.

Release Notes:

- N/A

Co-Authored-By: Nathan Sobo <nathan@zed.dev>

Co-Authored-By: Nathan Sobo <nathan@zed.dev>

Previously, project-specific settings were not discoverable. This PR
adds a `Zed > Preferences > Local Settings` application menu command
that creates a `.zed/settings.json` at the root of your current
worktree. This command works in both local and remote projects.

Limitations:

* Currently, if you have an empty project open, the command just shows a
notification that there are no folders open.
* The JSON-schema-based autocomplete is the same in local settings files
as in your main settings, even though not all settings can be locally
customized.

Release Notes:

- Added an application menu command - `Zed > Preferences > Local
Settings` for creating a folder-specific settings file.

Co-Authored-By: Nathan Sobo <nathan@zed.dev>

Co-Authored-By: Nathan Sobo <nathan@zed.dev>

Following https://github.com/zed-industries/zed/pull/2559 the project
panel entries become pretty wide again. This PR tries to mitigate that
and just make some general improvements to visual density in the project
panel.

- Reduces padding around items
- Removes top margin
- Slightly reduces the height of each item
- Fixes an issue where ignored files had the wrong color chevron

Release Notes:

- Improved density of the project panel and tidied up some visual
issues.

Z-1012

Release notes:
- Adjust indent of files in subdirectories.

Co-Authored-By: Julia Risley <julia@zed.dev>

Co-Authored-By: Julia Risley <julia@zed.dev>

This makes a difference when an edit spans two excerpts and the selection
start won't necessarily be the same as the selection end after the edit.