# Objective Fixes #56544 The settings reference documents `format_on_save` as defaulting to `on`, but `assets/settings/default.json` ships `"format_on_save": "off"`. The reporter in #56544 hit exactly that: a fresh config, a C file, save, and nothing happens. The reason the documented default looks right to many people is that Zed enables it per language for twelve languages (Astro, Dart, EEx, Elixir, Elm, Go, GraphQL, HEEx, Kotlin, Rust, Starlark, Zig). Save formats a Rust buffer and not a C one, and neither the reference nor the reporter's mental model had anywhere to hang that difference. Checking that one entry made me wonder how many others were stale, so I compared every `Setting:`/`Default:` pair on the page against the corresponding path in `default.json`. Six more were wrong. ## Solution | Setting | Documented | Ships as | | --- | --- | --- | | `format_on_save` | `on` | `off` | | `auto_indent` | `true`, "`boolean` values" | `syntax_aware`, a three-way enum | | `diagnostics_max_severity` | `null` | `all` | | `terminal.cursor_shape` | `null` (defaults to block) | `block` | | `terminal.alternate_scroll` | `off` | `on` | | `edit_predictions.disabled_globs` | 7 globs | 10 globs | | `git.gutter_debounce` | `null` | `0` | Two of these needed more than a value swap: `auto_indent` stopped being a boolean when it became `AutoIndentMode` (`crates/settings_content/src/language.rs:411`), so the options list now covers `syntax_aware`, `preserve_indent` and `none`, and the description no longer reads as a yes/no toggle. `format_on_save` gets a sentence naming the twelve languages, so the difference between saving a Rust buffer and a C one has somewhere to hang. `diagnostics_max_severity` and `terminal.cursor_shape` were self-contradicting rather than merely stale: each section's own prose already described the real default while the `Default:` line said `null`. ## Testing `cd docs && npx prettier --check src/` passes, as required by `docs/AGENTS.md`. The change is prose and adds no `{#action}` or `{#kb}` references, so it does not depend on the action metadata that `check_docs` generates. The `[\`languages\`](#languages)` link resolves to the single `## Languages` heading on the same page. Every value in the table above was read out of `assets/settings/default.json` on `main`, and I confirmed `default.json` is authoritative for each by following the resolved-settings path (the `user_content.<x>.unwrap()` style accessors) rather than trusting the file alone. ## Notes for review Found while auditing, deliberately left out of this PR — happy to take any of them in a follow-up, or here if you would rather: - Two Rust doc comments carry the same wrong defaults and feed the settings.json schema tooltips, so the in-editor hover still disagrees with the site: `crates/settings_content/src/language.rs` says `/// Default: on` for `format_on_save`, and `crates/settings_content/src/editor.rs` says `/// Default: warning` for `diagnostics_max_severity` while also saying "Shows all diagnostics if not specified". Fixing those is a source change rather than a docs one. - `docs/src/diagnostics.md` and `docs/src/visual-customization.md` still present `diagnostics_max_severity: null`, and the latter also shows `cursor_shape: null` for the editor where `default.json` ships `bar`. Same defect class, different pages and a different presentation (defaults listings rather than a reference), so I kept this PR to the reference page. - The reference's `diagnostics_max_severity` options omit `off`, which is a live variant (`DiagnosticSeverityContent` in `crates/settings_content/src/project.rs`). That is a missing option rather than a wrong default, so it is not in scope here. - Neither the Format On Save nor the Autosave section mentions that `"autosave": {"after_delay": {...}}` disables format on save outright (`crates/workspace/src/pane.rs`), even though `default.json` carries that warning as a comment. - The twelve-language list is a maintenance cost: it has to be edited whenever a language gains or loses a default. `default.json` sets per-language defaults for `tab_size`, `soft_wrap`, `allow_rewrap`, `hard_tabs` and others too, and none of them are called out anywhere. A single general statement about per-language defaults overriding top-level ones would cover all of them and never go stale. I kept the explicit list because it is what actually answers #56544, but I will happily swap it for the general version if you prefer. ## Self-Review Checklist: - [x] I've reviewed my own diff for quality, security, and reliability - [x] Unsafe blocks (if any) have justifying comments - [x] The content adheres to Zed's UI standards ([UX/UI](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist) and [icon](https://github.com/zed-industries/zed/blob/main/crates/icons/README.md) guidelines) - [x] Tests cover the new/changed behavior - [x] Performance impact has been considered and is acceptable Release Notes: - N/A
Zed Docs
Welcome to Zed's documentation.
This is built on push to main and published automatically to https://zed.dev/docs.
To preview the docs locally you will need to install mdBook (cargo install mdbook@0.4.40), generate the action metadata, and then serve:
script/generate-action-metadata
mdbook serve docs
The first command dumps an action manifest to crates/docs_preprocessor/actions.json. Without it, the preprocessor cannot validate keybinding and action references in the docs and will report errors. You only need to re-run it when actions change.
If you use Nix, the development shell provides a pinned mdbook (0.4.40) and a
prebuilt docs preprocessor, so you can build the docs without installing anything
or compiling the preprocessor on every run:
nix develop -c mdbook build docs
(When actions.json has not been generated, action/keybinding validation is
skipped with a warning rather than failing the build.)
It's important to note the version number above. For an unknown reason, as of 2025-04-23, running 0.4.48 will cause odd URL behavior that breaks things.
Before committing, verify that the docs are formatted in the way Prettier expects with:
cd docs && pnpm dlx prettier@3.5.0 . --write && cd ..
Preprocessor
We have a custom mdBook preprocessor for interfacing with our crates (crates/docs_preprocessor).
If for some reason you need to bypass the docs preprocessor, you can comment out [preprocessor.zed-docs-preprocessor] from the book.toml.
Images and videos
To add images or videos to the docs, upload them to another location (e.g., zed.dev, GitHub's asset storage) and then link out to them from the docs.
Putting binary assets such as images in the Git repository will bloat the repository size over time.
Internal notes:
- We have a Cloudflare router called
docs-proxythat intercepts requests tozed.dev/docsand forwards them to the "docs" Cloudflare Pages project. - The CI uploads a new version to the Cloudflare Pages project from
.github/workflows/deploy_docs.ymlon every push tomain.
Table of Contents
The table of contents files (theme/page-toc.js and theme/page-doc.css) were initially generated by mdbook-pagetoc.
Since all this preprocessor does is generate the static assets, we don't need to keep it around once they have been generated.
Referencing Keybindings and Actions
When referencing keybindings or actions, use the following formats:
Keybindings
{#kb scope::Action} - e.g., {#kb zed::OpenSettings}.
This will output a code element like: <code>Cmd + , | Ctrl + ,</code>. We then use a client-side plugin to show the actual keybinding based on the user's platform.
By using the action name, we can ensure that the keybinding is always up-to-date rather than hardcoding the keybinding.
Keymap Overlays
{#kb:keymap_name scope::Action} - e.g., {#kb:jetbrains editor::GoToDefinition}.
This resolves the keybinding from a keymap overlay (e.g., JetBrains) first, falling back to the default keymap if the overlay doesn't define a binding for that action. This is useful for sections where the documentation expects a special base keymap to be configured.
Supported overlays: jetbrains.
Actions
{#action scope::Action} - e.g., {#action zed::OpenSettings}.
This will render a human-readable version of the action name, e.g., "zed: open settings", and will allow us to implement things like additional context on hover, etc.
Creating New Templates
Templates are functions that modify the source of the docs pages (usually with a regex match and replace).
You can see how the actions and keybindings are templated in crates/docs_preprocessor/src/main.rs for reference on how to create new templates.
Consent Banner
We pre-bundle the c15t package because the docs pipeline does not include a JS bundler. If you need to update c15t and rebuild the bundle, use:
mkdir c15t-bundle && cd c15t-bundle
npm init -y
npm install c15t@<version> esbuild
echo "import { getOrCreateConsentRuntime } from 'c15t'; window.c15t = { getOrCreateConsentRuntime };" > entry.js
npx esbuild entry.js --bundle --format=iife --minify --outfile=c15t@<version>.js
cp c15t@<version>.js ../theme/c15t@<version>.js
cd .. && rm -rf c15t-bundle
Replace <version> with the new version of c15t you are installing. Then update book.toml to reference the new bundle filename.
References
- Template Trait:
crates/docs_preprocessor/src/templates.rs - Example template:
crates/docs_preprocessor/src/templates/keybinding.rs - Client-side plugins:
docs/theme/plugins.js
Postprocessor
A postprocessor is implemented as a sub-command of docs_preprocessor that wraps the built-in HTML renderer and applies post-processing to the HTML files, to add support for page-specific title and meta tag description values.
An example of the syntax can be found in git.md, as well as below:
---
title: Some more detailed title for this page
description: A page-specific description
---
# Editor
The above code will be transformed into (with non-relevant tags removed):
<head>
<title>Editor | Some more detailed title for this page</title>
<meta name="description" contents="A page-specific description" />
</head>
<body>
<h1>Editor</h1>
</body>
If no front matter is provided, or if one or both keys aren't provided, the title and description will be set based on the default-title and default-description keys in book.toml respectively.
Implementation details
Unfortunately, mdBook does not support post-processing like it does pre-processing, and only supports defining one description to put in the meta tag per book rather than per file.
So in order to apply post-processing (necessary to modify the HTML head tags) the global book description is set to a marker value #description# and the HTML renderer is replaced with a sub-command of docs_preprocessor that wraps the built-in HTML renderer and applies post-processing to the HTML files, replacing the marker value and the <title>(.*)</title> with the contents of the front matter if there is one.
Known limitations
The front matter parsing is extremely simple, which avoids needing to take on an additional dependency, or implement full YAML parsing.
- Double quotes and multi-line values are not supported, i.e. Keys and values must be entirely on the same line, with no double quotes around the value.
The following will not work:
---
title: Some
Multi-line
Title
---
neither this:
---
title: "Some title"
---
- The front matter must be at the top of the file, with only white-space preceding it.
- The contents of the
titleanddescriptionwill not be HTML escaped. They should be simple ASCII text with no unicode or emoji characters.