jj: add jj current change ID

[Jujutsu](https://github.com/martinvonz/jj) is a new VCS that is change-based.

I want to do several PRs to add various parts of its informations to starship, starting with the 
simplest one, the current change ID.

.github/config-schema.json

@@ -868,6 +868,19 @@
  }
  ]
  },
+ "jj_change": {
+ "default": {
+ "change_id_length": 7,
+ "disabled": true,
+ "format": "[\\($change_id\\)]($style) ",
+ "style": "bold purple"
+ },
+ "allOf": [
+ {
+ "$ref": "#/definitions/JujutsuChangeConfig"
+ }
+ ]
+ },
  "jobs": {
  "default": {
  "disabled": false,
@@ -3939,6 +3952,30 @@
  },
  "additionalProperties": false
  },
+ "JujutsuChangeConfig": {
+ "type": "object",
+ "properties": {
+ "change_id_length": {
+ "default": 7,
+ "type": "integer",
+ "format": "uint",
+ "minimum": 0.0
+ },
+ "disabled": {
+ "default": true,
+ "type": "boolean"
+ },
+ "format": {
+ "default": "[\\($change_id\\)]($style) ",
+ "type": "string"
+ },
+ "style": {
+ "default": "bold purple",
+ "type": "string"
+ }
+ },
+ "additionalProperties": false
+ },
  "JobsConfig": {
  "type": "object",
  "properties": {

docs/.vuepress/public/presets/toml/bracketed-segments.toml

@@ -85,6 +85,9 @@ format = '\[[$symbol$branch]($style)\]'
 [java]
 format = '\[[$symbol($version)]($style)\]'
 
+[jj_change]
+format = '\[[$change_id]($style)\]'
+
 [julia]
 format = '\[[$symbol($version)]($style)\]'
 

docs/.vuepress/public/presets/toml/gruvbox-rainbow.toml

@@ -9,6 +9,7 @@ $directory\
 [](fg:color_yellow bg:color_aqua)\
 $git_branch\
 $git_status\
+$jj_change\
 [](fg:color_aqua bg:color_blue)\
 $c\
 $rust\
@@ -124,6 +125,10 @@ symbol = " "
 style = "bg:color_blue"
 format = '[[ $symbol( $version) ](fg:color_fg0 bg:color_blue)]($style)'
 
+[jj_change]
+style = "bg:color_purple"
+format = '[[ $change_id ](fg:color_fg0 bg:color_purple)]($style)'
+
 [kotlin]
 symbol = ""
 style = "bg:color_blue"

docs/.vuepress/public/presets/toml/jetpack.toml

@@ -22,6 +22,7 @@ $git_state\
 $git_metrics\
 $git_status\
 $hg_branch\
+$jj_change\
 $pijul_channel\
 $docker_context\
 $package\
@@ -263,6 +264,9 @@ format = " hs [$symbol($version )]($style)"
 symbol = "∪ "
 format = " java [${symbol}(${version} )]($style)"
 
+[jj_change]
+format = " jj [$change_id]($style)"
+
 [julia]
 symbol = "◎ "
 format = " jl [$symbol($version )]($style)"

docs/.vuepress/public/presets/toml/pastel-powerline.toml

@@ -7,6 +7,7 @@ $directory\
 [](fg:#DA627D bg:#FCA17D)\
 $git_branch\
 $git_status\
+$jj_change\
 [](fg:#FCA17D bg:#86BBD8)\
 $c\
 $elixir\
@@ -112,6 +113,10 @@ symbol = " "
 style = "bg:#86BBD8"
 format = '[ $symbol ($version) ]($style)'
 
+[jj_change]
+style = "bg:#FCA17D"
+format = '[ $change_id ]($style)'
+
 [julia]
 symbol = " "
 style = "bg:#86BBD8"

docs/config/README.md

@@ -281,6 +281,7 @@ $git_state\
 $git_metrics\
 $git_status\
 $hg_branch\
+$jj_change\
 $pijul_channel\
 $docker_context\
 $package\
@@ -2445,6 +2446,39 @@ number_threshold = 4
 symbol_threshold = 0
 ```
 
+## Jujutsu Change
+
+The `jj_change` module shows the current change ID in a [Jujutsu](martinvonz.github.io/jj/) repository.
+When active (`disabled = false`), the module will be shown when your current directory is a Jujutsu directory.
+
+### Options
+
+| Option | Default | Description |
+| ------------------ | ------------------------ | -------------------------------------------------------------------------------------------- |
+| `change_id_length` | `7` | Minimum size of the unique prefix to use. Pass `0` to always use the shortest possible size. |
+| `format` | `'[$change_id]($style)'` | The format for the module. |
+| `style` | `'bold purple'` | The style for the module. |
+| `disabled` | `true` | Disables the `jj_change` module. |
+
+### Variables
+
+| Variable | Example | Description |
+| --------- | -------- | ----------------------------------- |
+| change_id | `mvlssa` | The current change ID |
+| style\* | | Mirrors the value of option `style` |
+
+*: This variable can only be used as a part of a style string
+
+### Example
+
+```toml
+# ~/.config/starship.toml
+
+[jj_change]
+change_id_length = 12
+disabled = false
+```
+
 ## Julia
 
 The `julia` module shows the currently installed version of [Julia](https://julialang.org/).

src/configs/jj_change.rs

@@ -0,0 +1,29 @@
+use serde::{Deserialize, Serialize};
+
+#[derive(Clone, Deserialize, Serialize)]
+#[cfg_attr(
+ feature = "config-schema",
+ derive(schemars::JsonSchema),
+ schemars(deny_unknown_fields)
+)]
+#[serde(default)]
+pub struct JujutsuChangeConfig<'a> {
+ pub change_id_length: usize,
+
+ pub disabled: bool,
+ pub format: &'a str,
+ pub style: &'a str,
+}
+
+impl Default for JujutsuChangeConfig<'_> {
+ fn default() -> Self {
+ Self {
+ // Copy the git default
+ change_id_length: 7,
+
+ disabled: true,
+ format: "[\\($change_id\\)]($style) ",
+ style: "bold purple",
+ }
+ }
+}

src/configs/mod.rs

@@ -45,6 +45,7 @@ pub mod helm;
 pub mod hg_branch;
 pub mod hostname;
 pub mod java;
+pub mod jj_change;
 pub mod jobs;
 pub mod julia;
 pub mod kotlin;
@@ -196,6 +197,8 @@ pub struct FullConfig<'a> {
  #[serde(borrow)]
  java: java::JavaConfig<'a>,
  #[serde(borrow)]
+ jj_change: jj_change::JujutsuChangeConfig<'a>,
+ #[serde(borrow)]
  jobs: jobs::JobsConfig<'a>,
  #[serde(borrow)]
  julia: julia::JuliaConfig<'a>,

src/configs/starship_root.rs

@@ -47,6 +47,7 @@ pub const PROMPT_ORDER: &[&str] = &[
  "git_metrics",
  "git_status",
  "hg_branch",
+ "jj_change",
  "pijul_channel",
  "docker_context",
  "package",

src/context.rs

@@ -52,6 +52,10 @@ pub struct Context<'a> {
  /// Private field to store Git information for modules who need it
  repo: OnceCell<Repo>,
 
+ /// Private field indicating whether a JJ repo was found. Useful to skip computing JJ modules
+ /// when unnecessary because a previous one already checked.
+ found_jj_repo: OnceCell<bool>,
+
  /// The shell the user is assumed to be running
  pub shell: Shell,
 
@@ -168,6 +172,7 @@ impl<'a> Context<'a> {
  logical_dir,
  dir_contents: OnceCell::new(),
  repo: OnceCell::new(),
+ found_jj_repo: OnceCell::new(),
  shell,
  target,
  width,
@@ -363,6 +368,15 @@ impl<'a> Context<'a> {
  })
  }
 
+ pub fn found_jj_repo(&self) -> bool {
+ *self
+ .found_jj_repo
+ .get_or_init(|| match self.exec_cmd("jj", &["root"]) {
+ Some(out) => out.stdout.lines().next().is_some_and(|s| !s.is_empty()),
+ None => false,
+ })
+ }
+
  pub fn dir_contents(&self) -> Result<&DirContents, std::io::Error> {
  self.dir_contents.get_or_try_init(|| {
  let timeout = self.root_config.scan_timeout;

src/module.rs

@@ -52,6 +52,7 @@ pub const ALL_MODULES: &[&str] = &[
  "hg_branch",
  "hostname",
  "java",
+ "jj_change",
  "jobs",
  "julia",
  "kotlin",