Starship

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

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

[custom.jj]
command = '''
jj log -r@ -n1 --ignore-working-copy --no-graph --color always  -T '
  separate(" ",
    bookmarks.map(|x| if(
        x.name().substr(0, 10).starts_with(x.name()),
        x.name().substr(0, 10),
        x.name().substr(0, 9) ++ "…")
      ).join(" "),
    tags.map(|x| if(
        x.name().substr(0, 10).starts_with(x.name()),
        x.name().substr(0, 10),
        x.name().substr(0, 9) ++ "…")
      ).join(" "),
    surround("\"","\"",
      if(
         description.first_line().substr(0, 24).starts_with(description.first_line()),
         description.first_line().substr(0, 24),
         description.first_line().substr(0, 23) ++ "…"
      )
    ),
    if(conflict, "conflict"),
    if(divergent, "divergent"),
    if(hidden, "hidden"),
  )
'
'''
when = "jj root"
symbol = "jj"

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

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:

---

Here's an alternate configuration. Importantly, by setting when to true and combining jj root && jj log ... directly into command, we can move from two (very expensive!) shell invocations down to one.

# custom module for jj status
[custom.jj]
ignore_timeout = true
description = "current jj status"
symbol = ""
when = true
command = '''
jj root > /dev/null && 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") ++ if(description.first_line().len() == 0,
      "(no description set)",
      if(description.first_line().substr(0, 29) == description.first_line(),
        description.first_line(),
        description.first_line().substr(0, 29) ++ "…",
      )
    ) ++ raw_escape_sequence("\x1b[0m"),
  )
'
'''

# disable git modules
[git_state]
disabled = true

[git_commit]
disabled = true

[git_metrics]
disabled = true

[git_branch]
disabled = true

# re-enable git_branch as long as we're not in a jj repo
[custom.git_branch]
when = true
command = "jj root >/dev/null 2>&1 || starship module git_branch"
description = "Only show git_branch if we're not in a jj repo"

Example screenshot: