This PR adds a staff-only button to the edit prediction menu for
capturing your current editing session as edit prediction example file.

When you click that button, it opens a markdown tab with the example. By
default, the most recent change that you've made is used as the expected
patch, and all of the previous events are used as the editing history.

<img width="303" height="123" alt="Screenshot 2025-12-14 at 6 58 33 PM"
src="https://github.com/user-attachments/assets/600c7bf2-7cf4-4d27-8cd4-8bb70d0b20b0"
/>

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- N/A

Closes #ISSUE

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Imitating the approach of #41829. Prevents e.g. reverting a hunk and
having that excerpt yanked out from under the cursor.

Release Notes:

- git: Improved stability of excerpts when editing in the project diff.

The test `test_collaborating_with_completion` has a latent race
condition that hasn't manifested on CI yet but could cause hangs with
certain task orderings.

## The Bug

Commit `fd1494c31a` set up LSP request handlers AFTER typing the trigger
character:

```rust
// Type trigger first - spawns async tasks to send completion request
editor_b.update_in(cx_b, |editor, window, cx| {
    editor.handle_input(".", window, cx);
});

// THEN set up handlers (race condition!)
fake_language_server
    .set_request_handler::<lsp::request::Completion, _, _>(...)
    .next().await.unwrap();  // Waits for handler to receive a request
```

Whether this works depends on task scheduling order, which varies by
seed. If the completion request is processed before the handler is
registered, the request goes to `on_unhandled_notification` which claims
to handle it but sends no response, causing a hang.

## Changes

- Move handler setup BEFORE typing the trigger character
- Make `TestDispatcher::spawn_realtime` panic to prevent future
non-determinism from real OS threads
- Add `execution_hash()` and `execution_count()` to TestDispatcher for
debugging
- Add `DEBUG_SCHEDULER=1` logging for task execution tracing
- Document the investigation in `situation.md`

cc @localcc @SomeoneToIgnore (authors of related commits)

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---------

Co-authored-by: Kirill Bulatov <kirill@zed.dev>

This adds implementations of `std::iter::Sum` for `Pixels`, allowing the
use of `.sum()` on iterators of `Pixels` values.

### Changes
- Implement `Sum<Pixels>` for `Pixels` (owned values)
- Implement `Sum<&Pixels>` for `Pixels` (references)

This enables ergonomic patterns like:
```rust
let total: Pixels = pixel_values.iter().sum();
```

This change matches how normal hovers are handled (which early return
with `None` in this branch)

Release Notes:

- Fixed hover boxes for inlays blinking in and out without movement when
cursor blinking was enabled

Release Notes:

- N/A *or* Added/Fixed/Improved ...

When an external agent doesn't provide an icon, we were using different
fallback icons in all the places we display icons (settings view, thread
new menu, and the thread view toolbar itself).

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- N/A

Fix a bug where the branch picker would be dismissed before completing
the add remote flow, thus making Zed unable to add remote repositories
through the branch picker.

This bug was caused by the picker always being dismissed on the confirm
action, so the fix was stopping the branch modal from being dismissed
too early.

I also cleaned up the UI a bit and code.

1. Removed the loading field from the Branch delegate because it was
never used and the activity indicator will show remote add command if it
takes a while.
2. I replaced some async task spawning with the use of `cx.defer`.
3. Added a `add remote name` fake entry when the picker is in the name
remote state. I did this so the UI would be consistent with the other
states.
4. Added two regression tests. 
4.1 One to prevent this bug from occurring again:
https://github.com/zed-industries/zed/pull/44742
4.2 Another to prevent the early dismissal bug from occurring 
5. Made `init_branch_list_test` param order consistent with Zed's code
base

###### Updated UI
<img width="1150" height="298" alt="image"
src="https://github.com/user-attachments/assets/edead508-381c-4bd8-8a41-394dd5b7b781"
/>


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This fixes the build when Visual Studio 2026 is installed.

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Clarify the docs regarding how operators are affected when subword
motion in Vim is activated.

Ref:
https://github.com/zed-industries/zed/issues/23344#issuecomment-3186025873.

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---------

Co-authored-by: Kunall Banerjee <hey@kimchiii.space>

Depends on: https://github.com/zed-industries/zed/pull/44753

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- N/A

---------

Co-authored-by: Mikayla Maki <mikayla.c.maki@gmail.com>

Add the repository name when:

- there's more than one repository, and
- the name of the active repository doesn't match the name of the
project (to avoid stuttering with the adjacent project switcher button)

Release Notes:

- The branch name in the title bar now includes the name of the current
repository when needed to disambiguate.

- Edit prediction providers can now be configured through the settings
UI
- Cleaned up the status bar menu to only show _configured_ providers
- Added to the status bar icon button tooltip the name of the active
provider
- Only display the data collection functionality under "Privacy" for the
Zed models
- Moved the Codestral edit prediction provider out of the Mistral
section in the agent panel into the settings UI
- Refined and improved UI and states for configuring GitHub Copilot as
both an agent and edit prediction provider

#### Todos before merge:

- [x] UI: Unify with settings UI style and tidy it all up
- [x] Unify Copilot modal `impl`s to use separate window
- [x] Remove stop light icons from GitHub modal
- [x] Make dismiss events work on GitHub modal
- [ ] Investigate workarounds to tell if Copilot authenticated even when
LSP not running


Release Notes:

- settings_ui: Added a section for configuring edit prediction providers
under AI > Edit Predictions, including Codestral and GitHub Copilot.
Once you've updated you can use the following link to open it:
zed://settings/edit_predictions.providers

---------

Co-authored-by: Ben Kunkle <ben@zed.dev>

Release Notes:

- N/A

Just a small docs change

With the deprecation of `toggle_relative_line_numbers` the docs should
reflect that

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Enables rainbow bracket highlighting for angle brackets (< >) in C++.

<img width="401" height="46" alt="image"
src="https://github.com/user-attachments/assets/169afdaa-c8be-4b78-bf64-9cf08787eb47"
/>


Release Notes:

- Added rainbow bracket coloring for C++ angle brackets (`<>`)

This fixes an issue where a user could get confused by the branch picker
because it would only show the 10 most recent branches, instead of all
branches.

Release Notes:

- git: Show all branches in branch picker when search field is empty

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- N/A

---------

Co-authored-by: Max Brunsfeld <maxbrunsfeld@gmail.com>
Co-authored-by: Agus Zubiaga <agus@zed.dev>

We were panicking whenever something went wrong with an example in the
CLI. This can be very disruptive when running many examples, and e.g a
single request fails. Instead, if running more than one example, errors
will now be logged alongside instructions to explore and re-run the
example by itself.

<img width="1454" height="744" alt="CleanShot 2025-12-12 at 13 32 04@2x"
src="https://github.com/user-attachments/assets/87c59e64-08b9-4461-af5b-03af5de94152"></img>


You can still opt in to stop as soon as en error occurs with the new
`--failfast` argument.

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- N/A