Starship - jj-vcs/jj GitHub Wiki

Configuring Starship to call jj

https://starship.rs/ is a cross-shell prompt.

Basic prompt

For some info about the jj change you are currently at you can use:

[custom.jj]
command = '''
jj log --revisions @ --limit 1 --ignore-working-copy --no-graph --color always  --template '
  separate(" ",
    bookmarks.map(|x| truncate_end(10, x.name(), "…")).join(" "),
    tags.map(|x| truncate_end(10, x.name(), "…")).join(" "),
    surround("\"", "\"", truncate_end(24, description.first_line(), "…")),
    if(conflict, "conflict"),
    if(divergent, "divergent"),
    if(hidden, "hidden"),
  )
'
'''
when = "jj --ignore-working-copy root"
symbol = "jj"

[custom.jjstate]
when = "jj --ignore-working-copy root"
command = '''
jj log -r@ -n1 --ignore-working-copy --no-graph -T "" --stat | tail -n1 | sd "(\d+) files? changed, (\d+) insertions?\(\+\), (\d+) deletions?\(-\)" ' ${1}m ${2}+ ${3}-' | sd " 0." ""
'''

[!TIP]

This is partially inspired by the Fish Shell prompt example. This is a quick solution, feel free to improve on it and share your improvements.

Example screenshot:

Alternative prompt

This prompt uses more emojis and also disables Git modules when JJ is found:

# custom module for jj status
[custom.jj]
description = "The current jj status"
when = "jj --ignore-working-copy root"
symbol = "🥋 "
command = '''
jj log --revisions @ --no-graph --ignore-working-copy --color always --limit 1 --template '
  separate(" ",
    change_id.shortest(4),
    bookmarks,
    "|",
    concat(
      if(conflict, "💥"),
      if(divergent, "🚧"),
      if(hidden, "👻"),
      if(immutable, "🔒"),
    ),
    raw_escape_sequence("\x1b[1;32m") ++ if(empty, "(empty)"),
    raw_escape_sequence("\x1b[1;32m") ++ coalesce(
      truncate_end(29, description.first_line(), "…"),
      "(no description set)",
    ) ++ raw_escape_sequence("\x1b[0m"),
  )
'
'''

# optionally disable git modules when JJ is found.
# note that you'll need to add ${custom.git_branch}, ${custom.git_commit} etc
# into format: https://starship.rs/config/#default-prompt-format
[git_status]
disabled = true

[custom.git_status]
when = "! jj --ignore-working-copy root" # Slow without `require_repo = true`
require_repo = true # Avoids `when` eval overhead in plain dirs
command = "starship module git_status"
style = "" # This disables the default "(bold green)" style
description = "Only show git_status if we're not in a jj repo"

[git_commit]
disabled = true

[custom.git_commit]
when = "! jj --ignore-working-copy root"
require_repo = true
command = "starship module git_commit"
style = ""
description = "Only show git_commit if we're not in a jj repo"


[git_metrics]
disabled = true

[custom.git_metrics]
when = "! jj --ignore-working-copy root"
require_repo = true
command = "starship module git_metrics"
description = "Only show git_metrics if we're not in a jj repo"
style = ""

[git_branch]
disabled = true

[custom.git_branch]
when = "! jj --ignore-working-copy root"
require_repo = true
command = "starship module git_branch"
description = "Only show git_branch if we're not in a jj repo"
style = ""

Example screenshot:

Performance tips

--ignore-working-copy. The commands above use a jj --ignore-working-copy flag. This tells jj not to update its snapshot of the working copy, and improves performance of the prompt.
detect_folders. The when = "jj --ignore-working-copy root" config requires a shell invocation, which has performance overhead. The overhead is small (~12 ms on a MacBook Pro with M2) but not zero. If you’d like to avoid it, use detect_folders instead (but note that the JJ prompt will only be shown in the root of the repo, then):
```
- when = "jj --ignore-working-copy root"
+ detect_folders = [".jj"]
```
Faster location of .jj directory: Instead of using jj --ignore-working-copy root to test for being in a jj workspace, the following is about 5-10x faster on my system: when = "while ! test -d .jj; do test $PWD = / && exit 1; cd -P ..; done; exit 0" Swap the exit 1 and exit 0 to invert the test for the custom.git* entries
Don't search for the .jj directory if not in a git repository
- require_repo = true will do this and is very fast (<1ms with a warm cache on my machine)
- everybody should set this for the custom.git* entries to speed things
- If you only use git colocated workspaces (default since 0.34) you can set this for the custom.jj entry as well.
  - Downside is you won't get jj prompts for non-colocated workspaces
  - Also there are 4 custom.git* entries, but only one custom.jj entry, so you get 80% of the performance benefit without this.
shell. Starship defaults to using the parent shell for custom modules. Depending on the shell in use, using a more minimal shell and avoiding shell init sourcing can be much faster.
```
+ shell = ["sh", "--norc", "--noprofile"]
```

Using starship-jj in Starship

starship-jj uses the jj-cli crate to have better performance than having multiple jj invocations in your starship.toml

https://gitlab.com/lanastara_foss/starship-jj

install via

  cargo install starship-jj --locked

and add it to your starship.toml

# Extend the default format config: https://starship.rs/config/#default-prompt-format
format="""
...
${custom.jj}\
...
"""

#...

[custom.jj]
command = "prompt"
format = "$output"
ignore_timeout = true
shell = ["starship-jj", "--ignore-working-copy", "starship"]
use_stdin = false
when = true