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Cole Miller 2a15bf630d
Require multibuffer excerpts to be ordered and nonoverlapping (#52364)
TODO:
- [x] merge main
- [x] nonshrinking `set_excerpts_for_path`
- [x] Test-drive potential problem areas in the app
- [x] prepare cloud side
- [x] test collaboration
- [ ] docstrings
- [ ] ???

## Context

### Background

Currently, a multibuffer consists of an arbitrary list of
anchor-delimited excerpts from individual buffers. Excerpt ranges for a
fixed buffer are permitted to overlap, and can appear in any order in
the multibuffer, possibly separated by excerpts from other buffers.
However, in practice all code that constructs multibuffers does so using
the APIs defined in the `path_key` submodule of the `multi_buffer` crate
(`set_excerpts_for_path` etc.) If you only use these APIs, the resulting
multibuffer will maintain the following invariants:

- All excerpts for the same buffer appear contiguously in the
multibuffer
- Excerpts for the same buffer cannot overlap
- Excerpts for the same buffer appear in order
- The placement of the excerpts for a specific buffer in the multibuffer
are determined by the `PathKey` passed to `set_excerpts_for_path`. There
is exactly one `PathKey` per buffer in the multibuffer

### Purpose of this PR

This PR changes the multibuffer so that the invariants maintained by the
`path_key` APIs *always* hold. It's no longer possible to construct a
multibuffer with overlapping excerpts, etc. The APIs that permitted
this, like `insert_excerpts_with_ids_after`, have been removed in favor
of the `path_key` suite.

The main upshot of this is that given a `text::Anchor` and a
multibuffer, it's possible to efficiently figure out the unique excerpt
that includes that anchor, if any:

```
impl MultiBufferSnapshot {
    fn buffer_anchor_to_anchor(&self, anchor: text::Anchor) -> Option<multi_buffer::Anchor>;
}
```

And in the other direction, given a `multi_buffer::Anchor`, we can look
at its `text::Anchor` to locate the excerpt that contains it. That means
we don't need an `ExcerptId` to create or resolve
`multi_buffer::Anchor`, and in fact we can delete `ExcerptId` entirely,
so that excerpts no longer have any identity outside their
`Range<text::Anchor>`.

There are a large number of changes to `editor` and other downstream
crates as a result of removing `ExcerptId` and multibuffer APIs that
assumed it.

### Other changes

There are some other improvements that are not immediate consequences of
that big change, but helped make it smoother. Notably:

- The `buffer_id` field of `text::Anchor` is no longer optional.
`text::Anchor::{MIN, MAX}` have been removed in favor of
`min_for_buffer`, etc.
- `multi_buffer::Anchor` is now a three-variant enum (inlined slightly):

```
enum Anchor {
    Min,
    Excerpt {
        text_anchor: text::Anchor,
        path_key_index: PathKeyIndex,
        diff_base_anchor: Option<text::Anchor>,
    },
    Max,
}
```

That means it's no longer possible to unconditionally access the
`text_anchor` field, which is good because most of the places that were
doing that were buggy for min/max! Instead, we have a new API that
correctly resolves min/max to the start of the first excerpt or the end
of the last excerpt:


```
impl MultiBufferSnapshot {
    fn anchor_to_buffer_anchor(&self, anchor: multi_buffer::Anchor) -> Option<text::Anchor>;
}
```
- `MultiBufferExcerpt` has been removed in favor of a new
`map_excerpt_ranges` API directly on `MultiBufferSnapshot`.

## Self-Review Checklist

<!-- Check before requesting review: -->
- [x] I've reviewed my own diff for quality, security, and reliability
- [x] Unsafe blocks (if any) have justifying comments
- [x] The content is consistent with the [UI/UX
checklist](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist)
- [x] Tests cover the new/changed behavior
- [x] Performance impact has been considered and is acceptable

Release Notes:

- N/A

---------

Co-authored-by: Conrad Irwin <conrad.irwin@gmail.com>
Co-authored-by: Piotr Osiewicz <24362066+osiewicz@users.noreply.github.com>
Co-authored-by: Jakub Konka <kubkon@jakubkonka.com>
Co-authored-by: Conrad <conrad@zed.dev>
2026-04-01 17:25:32 +00:00
.cargo livekit: Use our build of libwebrtc.a (#51433) 2026-03-16 10:47:36 +01:00
.cloudflare docs: Document context servers (#21170) 2024-11-25 11:05:14 -05:00
.config Increase timeout for test_random_blocks (#50724) 2026-03-04 12:25:12 -05:00
.factory Add humanizer skill for AI writing pattern detection (#50021) 2026-02-24 14:58:52 -06:00
.github Remove slash-commands-example extension (#52835) 2026-03-31 18:27:38 +02:00
.zed eval: Remove deprecated eval crate and workflow (#52733) 2026-03-30 13:33:29 +00:00
assets agent_settings: Add always_play_sound_when_agent_done setting (#52284) 2026-04-01 17:15:01 +00:00
ci Move Nightly release to gh-workflow (#41349) 2025-10-28 13:57:23 -06:00
crates Require multibuffer excerpts to be ordered and nonoverlapping (#52364) 2026-04-01 17:25:32 +00:00
docs agent_settings: Add always_play_sound_when_agent_done setting (#52284) 2026-04-01 17:15:01 +00:00
extensions Remove slash-commands-example extension (#52835) 2026-03-31 18:27:38 +02:00
legal Update legal docs to reflect new terms of service (#50530) 2026-03-02 12:36:31 -08:00
nix nix: Fix screen-casting when building Zed with nix (#52690) 2026-03-30 07:50:20 +02:00
script Add .tar.bz2 archive support for ACP agent server downloads (#52188) 2026-03-25 07:54:23 +00:00
tooling Remove slash-commands-example extension (#52835) 2026-03-31 18:27:38 +02:00
.git-blame-ignore-revs Add PR 50413 to .git-blame-ignore-revs (#50421) 2026-03-01 00:50:33 +01:00
.gitattributes windows: Make sure zed.sh using the correct line ending (#37650) 2025-09-05 16:25:55 +00:00
.gitignore docs: Improve Git documentation accuracy and structure (#47419) 2026-01-23 08:43:24 -08:00
.mailmap Update .mailmap (#47413) 2026-01-22 23:57:26 +05:30
.prettierrc ci: Add check for formatting default.json (#30034) 2025-05-06 18:55:26 +00:00
.rules Update AI docs for retired hosted models (#49486) 2026-02-18 10:36:38 -06:00
AGENTS.md ai: Symlink an AGENTS.md file to .rules (#45939) 2026-01-19 15:29:42 +01:00
Cargo.lock language_model: Refactor crate structure and dependencies (#52857) 2026-04-01 17:44:25 +02:00
Cargo.toml gpui: Implement audible system bell (#47531) 2026-04-01 02:50:01 +00:00
CLAUDE.md Initial .rules file for agent with symlinks for other rules file paths (#29014) 2025-04-17 23:41:23 +00:00
clippy.toml Revert "Revert scheduler update (#46659)" (#46671) 2026-01-14 07:19:13 +00:00
CODE_OF_CONDUCT.md Remove community content from docs and point to zed.dev (#19895) 2024-10-29 09:44:58 -04:00
compose.yml Remove Postgres and stripe-mock from Docker Compose (#48313) 2026-02-04 03:42:58 +00:00
CONTRIBUTING.md Add Zed Feature Process document (#50747) 2026-03-06 14:14:53 -08:00
debug.plist WIP 2023-12-14 09:25:14 -07:00
default.nix nix: Use flake-parts, partitions, and treefmt-nix (#45321) 2026-02-02 14:26:42 +00:00
Dockerfile-collab Bump Rust version to 1.94 (#51086) 2026-03-30 09:06:59 +00:00
Dockerfile-collab.dockerignore ci: Move collab to Dockerfile-collab (#18515) 2024-09-30 16:14:26 -04:00
Dockerfile-cross.dockerignore Add remote server cross compilation (#19136) 2024-10-12 23:23:56 -07:00
Dockerfile-distros Support More Linux (#18480) 2024-09-30 17:46:21 -04:00
Dockerfile-distros.dockerignore Support More Linux (#18480) 2024-09-30 17:46:21 -04:00
flake.lock nix: Update flake.lock (#52766) 2026-03-31 16:14:26 +02:00
flake.nix Try to improve nix caching (#48297) 2026-02-03 20:31:02 -07:00
GEMINI.md Add missing GEMINI.md rule file for gemini-cli (#38885) 2025-10-02 09:47:29 -04:00
LICENSE-AGPL Update license year (#24191) 2025-02-04 09:02:59 -05:00
LICENSE-APACHE Update license year (#24191) 2025-02-04 09:02:59 -05:00
LICENSE-GPL Licenses: change license fields in Cargo.toml to AGPL-3.0-or-later. (#5535) 2024-01-27 13:51:16 +01:00
livekit.yaml Add LiveKit server to Docker Compose (#7907) 2024-02-16 10:49:48 -05:00
lychee.toml ci: Check for broken links (#30844) 2025-06-06 09:39:35 +00:00
Procfile Update instructions for local collaboration (#35689) 2025-08-06 11:10:28 -07:00
Procfile.all Add agent thread sharing (#46140) 2026-01-06 12:49:51 -08:00
Procfile.web Remove PostgREST (#41299) 2025-10-27 13:27:59 -04:00
README.md Add sponsor button to main Zed repo (#46807) 2026-01-14 10:38:51 -06:00
renovate.json Remove workspace-hack (#40216) 2025-10-17 18:58:14 +00:00
REVIEWERS.conl Remove past reviewer (#51767) 2026-03-17 16:34:35 +00:00
rust-toolchain.toml Bump Rust version to 1.94 (#51086) 2026-03-30 09:06:59 +00:00
rustfmt.toml nix: Use flake-parts, partitions, and treefmt-nix (#45321) 2026-02-02 14:26:42 +00:00
shell.nix nix: Use flake-parts, partitions, and treefmt-nix (#45321) 2026-02-02 14:26:42 +00:00
typos.toml eval: Remove deprecated eval crate and workflow (#52733) 2026-03-30 13:33:29 +00:00

Zed

Zed CI

Welcome to Zed, a high-performance, multiplayer code editor from the creators of Atom and Tree-sitter.


Installation

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Other platforms are not yet available:

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