Prompt is different if I run `devbox shell` under `nix-shell`.

Start by reproducing the reported prompt difference with devbox shell directly and after nix-shell -p cowsay, using the supplied devbox.json and init.sh. Read the shell entry points and tests for environment or prompt initialization; the issue does not name specific files. Done means both invocation paths preserve the configured zsh prompt, with a regression test covering the difference.

What happened?

I expect the same prompt wether I run devbox shell directly or run nix-shell first, and then devbox shell. I have no idea whether anything else is broken. But the prompt is not the one I've configured for zsh.

Running zsh as my shell in a recently updated NixOS 25.11.

Steps to reproduce

1. New terminal
2. devbox shell
3. See prompt is the same as the parent shell
4. exit
5. nix-shell -p cowsay
6. devbox shell
7. See different prompt

Command

shell

devbox.json

{
  "$schema": "https://raw.githubusercontent.com/jetify-com/devbox/0.16.0/.schema/devbox.schema.json",
  "packages": ["cowsay@latest"],
  "shell": {
    "init_hook": [
        "source ./init.sh"
    ]
  }
}

init.sh

echo init.sh called
export INIT_SH_CALLED=yes

Devbox version

0.16.0

Nix version

nix (Nix) 2.31.2

What system does this bug occur on?

Linux (x86-64)

Debug logs

20:04:52 peter@sky:/work/hr/devbox/test[2]» DEVBOX_DEBUG=1 devbox shell
time=2026-01-19T20:05:06.055+01:00 level=DEBUG source=go.jetify.com/devbox/internal/devconfig/config.go:126 msg="searching for config file (including parent directories)" path=.
time=2026-01-19T20:05:06.067+01:00 level=DEBUG source=go.jetify.com/devbox/internal/devconfig/config.go:147 msg="trying config file" path=devbox.json
time=2026-01-19T20:05:06.068+01:00 level=DEBUG source=go.jetify.com/devbox/internal/devconfig/config.go:134 msg="config file found" path=/home/peter/work/hr/devbox/test/devbox.json dur=12.623981ms
time=2026-01-19T20:05:06.068+01:00 level=DEBUG source=go.jetify.com/devbox/internal/devpkg/package.go:204 msg="package doesn't need patching" pkg=cowsay mode=auto
time=2026-01-19T20:05:06.068+01:00 level=DEBUG source=go.jetify.com/devbox/internal/devconfig/config.go:126 msg="searching for config file (including parent directories)" path=.
time=2026-01-19T20:05:06.068+01:00 level=DEBUG source=go.jetify.com/devbox/internal/devconfig/config.go:147 msg="trying config file" path=devbox.json
time=2026-01-19T20:05:06.068+01:00 level=DEBUG source=go.jetify.com/devbox/internal/devconfig/config.go:134 msg="config file found" path=/home/peter/work/hr/devbox/test/devbox.json dur=71.934µs
time=2026-01-19T20:05:06.068+01:00 level=DEBUG source=go.jetify.com/devbox/internal/devpkg/package.go:204 msg="package doesn't need patching" pkg=cowsay mode=auto
time=2026-01-19T20:05:06.069+01:00 level=DEBUG source=go.jetify.com/devbox/nix/nix.go:143 msg="nix command starting" cmd.args="nix --extra-experimental-features ca-derivations --option experimental-features 'nix-command flakes fetch-closure' --version --debug"
time=2026-01-19T20:05:06.122+01:00 level=DEBUG source=go.jetify.com/devbox/nix/nix.go:143 msg="nix command exited" cmd.args="nix --extra-experimental-features ca-derivations --option experimental-features 'nix-command flakes fetch-closure' --version --debug" cmd.path=/run/current-system/sw/bin/nix cmd.pid=1145016 cmd.code=0 cmd.dur=53.816497ms
time=2026-01-19T20:05:06.123+01:00 level=DEBUG source=go.jetify.com/devbox/internal/devconfig/config.go:126 msg="searching for config file (including parent directories)" path=.
time=2026-01-19T20:05:06.123+01:00 level=DEBUG source=go.jetify.com/devbox/internal/devconfig/config.go:147 msg="trying config file" path=devbox.json
time=2026-01-19T20:05:06.123+01:00 level=DEBUG source=go.jetify.com/devbox/internal/devconfig/config.go:134 msg="config file found" path=/home/peter/work/hr/devbox/test/devbox.json dur=183.755µs
time=2026-01-19T20:05:06.123+01:00 level=DEBUG source=go.jetify.com/devbox/internal/devpkg/package.go:204 msg="package doesn't need patching" pkg=cowsay mode=auto
time=2026-01-19T20:05:06.123+01:00 level=DEBUG source=go.jetify.com/devbox/internal/devpkg/package.go:204 msg="package doesn't need patching" pkg=cowsay mode=auto
time=2026-01-19T20:05:06.123+01:00 level=DEBUG source=go.jetify.com/devbox/internal/devpkg/package.go:204 msg="package doesn't need patching" pkg=cowsay mode=auto
time=2026-01-19T20:05:06.124+01:00 level=DEBUG source=go.jetify.com/devbox/internal/devpkg/package.go:204 msg="package doesn't need patching" pkg=cowsay mode=auto
time=2026-01-19T20:05:06.126+01:00 level=DEBUG source=go.jetify.com/devbox/internal/devbox/devbox.go:702 msg="current environment PATH" path=/nix/store/35yc81pz0q5yba14lxhn5r3jx5yg6c3l-bash-interactive-5.3p3/bin:/nix/store/35yc81pz0q5yba14lxhn5r3jx5yg6c3l-bash-interactive-5.3p3/bin:/nix/store/8q2582rd22xp8jlcg1xn1w219q5lx5xa-patchelf-0.15.2/bin:/nix/store/vr15iyyykg9zai6fpgvhcgyw7gckl78w-gcc-wrapper-14.3.0/bin:/nix/store/kzq78n13l8w24jn8bx4djj79k5j717f1-gcc-14.3.0/bin:/nix/store/q6wgv06q39bfhx2xl8ysc05wi6m2zdss-glibc-2.40-66-bin/bin:/nix/store/imad8dvhp77h0pjbckp6wvmnyhp8dpgg-coreutils-9.8/bin:/nix/store/xwydcyvlsa3cvssk0y5llgdhlhjvmqdm-binutils-wrapper-2.44/bin:/nix/store/dc9vaz50jg7mibk9xvqw5dqv89cxzla3-binutils-2.44/bin:/nix/store/2fgj127razzmajyjyc81fcjjfpj97akk-cowsay-3.8.4/bin:/nix/store/imad8dvhp77h0pjbckp6wvmnyhp8dpgg-coreutils-9.8/bin:/nix/store/av4xw9f56xlx5pgv862wabfif6m1yc0a-findutils-4.10.0/bin:/nix/store/20axvl7mgj15m23jgmnq97hx37fgz7bk-diffutils-3.12/bin:/nix/store/drc7kang929jaza6cy9zdx10s4gw1z5p-gnused-4.9/bin:/nix/store/x3zjxxz8m4ki88axp0gn8q8m6bldybba-gnugrep-3.12/bin:/nix/store/y2wdhdcrffp9hnkzk06d178hq3g98jay-gawk-5.3.2/bin:/nix/store/yi3c5karhx764ham5rfwk7iynr8mjf6q-gnutar-1.35/bin:/nix/store/d471xb7sfbah076s8rx02i68zpxc2r5n-gzip-1.14/bin:/nix/store/qm9rxn2sc1vrz91i443rr6f0vxm0zd82-bzip2-1.0.8-bin/bin:/nix/store/3fmzbq9y4m9nk235il7scmvwn8j9zy3p-gnumake-4.4.1/bin:/nix/store/rlq03x4cwf8zn73hxaxnx0zn5q9kifls-bash-5.3p3/bin:/nix/store/qrwznp1ikdf0qw05wia2haiwi32ik5n0-patch-2.8/bin:/nix/store/v0rfdwhg6w6i0yb6dbry4srk6pnj3xp0-xz-5.8.1-bin/bin:/nix/store/paj6a1lpzp57hz1djm5bs86b7ci221r0-file-5.45/bin:.:/home/peter/bin/local/hr:/home/peter/bin/local/format-hrpy-ruff:/home/peter/bin/local/format-hrpy-empty-lines:/home/peter/bin/local/format-hrpy:/home/peter/bin/local/aws:/home/peter/bin/local:/home/peter/bin:/home/peter/.local/bin:/home/peter/bin/modules/monitorfiles:/snap/bin:/usr/sbin:/sbin:/run/wrappers/bin:/home/peter/.nix-profile/bin:/nix/profile/bin:/home/peter/.local/state/nix/profile/bin:/etc/profiles/per-user/peter/bin:/nix/var/nix/profiles/default/bin:/run/current-system/sw/bin:/home/peter/.fzf/bin
time=2026-01-19T20:05:06.126+01:00 level=DEBUG source=go.jetify.com/devbox/internal/devbox/devbox.go:717 msg="nix environment PATH" path=/nix/store/3vs2fr2mazafcdwyza15bfhpmccx1k7z-patchelf-0.15.2/bin:/nix/store/r9wbjib6xxjkyb9yvjvrkl4sq61i2lyn-gcc-wrapper-15.2.0/bin:/nix/store/qarrb8yfby1yyypm32vabzgxgq3w41ma-gcc-15.2.0/bin:/nix/store/7ri1mm5y99nkr7657r77wycrvhg7z9x0-glibc-2.40-66-bin/bin:/nix/store/d75200gb22v7p0703h5jrkgg8bqydk5q-coreutils-9.8/bin:/nix/store/dwiyp91lmxq864plaas14jm14m87sg3f-binutils-wrapper-2.44/bin:/nix/store/cl88v2m1y5q3k6jlkq5jjf73nmfgl1px-binutils-2.44/bin:/nix/store/y5awi2qqhx6rx6j7fh6ik2k8aagdyy1z-cowsay-3.8.4/bin:/nix/store/d75200gb22v7p0703h5jrkgg8bqydk5q-coreutils-9.8/bin:/nix/store/wd99g2j010fdkry0ws1bhxzm52w82ssx-findutils-4.10.0/bin:/nix/store/20zvyjvxq9x2mkp7rbnvrwjjzq2n76hh-diffutils-3.12/bin:/nix/store/k06ssckzrzn9jjvvs4n62m6567zmbx6x-gnused-4.9/bin:/nix/store/qfmq7p42ak5yn389qvx7zpxkan5i4xiy-gnugrep-3.12/bin:/nix/store/nmxm04dhkaqg1q6hai70n9zmzb0q49a5-gawk-5.3.2/bin:/nix/store/k1lcfin159706lihwx5hhvl80dbij4jw-gnutar-1.35/bin:/nix/store/0hv4z5s3r1h4lmvn0427mlxjxgvg34nr-gzip-1.14/bin:/nix/store/p61ba9fdgx3358bpp18hv4rslf6n5bq6-bzip2-1.0.8-bin/bin:/nix/store/mkm3my2067305hdh7rzmi10npwr7y17f-gnumake-4.4.1/bin:/nix/store/lw117lsr8d585xs63kx5k233impyrq7q-bash-5.3p3/bin:/nix/store/clrf4mjwr8xcfpvway6w34wzvqc1hry4-patch-2.8/bin:/nix/store/j1zc5jh0vi9sbxj09ldj4xklgm6kpf8n-xz-5.8.1-bin/bin:/nix/store/s2k48fw3y698j4kcvmw0520m06ihv2z4-file-5.45/bin
time=2026-01-19T20:05:06.126+01:00 level=DEBUG source=go.jetify.com/devbox/internal/devbox/devbox.go:751 msg="PATH after plugins and config" path=/home/peter/work/hr/devbox/test/.devbox/nix/profile/default/bin:/nix/store/3vs2fr2mazafcdwyza15bfhpmccx1k7z-patchelf-0.15.2/bin:/nix/store/r9wbjib6xxjkyb9yvjvrkl4sq61i2lyn-gcc-wrapper-15.2.0/bin:/nix/store/qarrb8yfby1yyypm32vabzgxgq3w41ma-gcc-15.2.0/bin:/nix/store/7ri1mm5y99nkr7657r77wycrvhg7z9x0-glibc-2.40-66-bin/bin:/nix/store/d75200gb22v7p0703h5jrkgg8bqydk5q-coreutils-9.8/bin:/nix/store/dwiyp91lmxq864plaas14jm14m87sg3f-binutils-wrapper-2.44/bin:/nix/store/cl88v2m1y5q3k6jlkq5jjf73nmfgl1px-binutils-2.44/bin:/nix/store/y5awi2qqhx6rx6j7fh6ik2k8aagdyy1z-cowsay-3.8.4/bin:/nix/store/wd99g2j010fdkry0ws1bhxzm52w82ssx-findutils-4.10.0/bin:/nix/store/20zvyjvxq9x2mkp7rbnvrwjjzq2n76hh-diffutils-3.12/bin:/nix/store/k06ssckzrzn9jjvvs4n62m6567zmbx6x-gnused-4.9/bin:/nix/store/qfmq7p42ak5yn389qvx7zpxkan5i4xiy-gnugrep-3.12/bin:/nix/store/nmxm04dhkaqg1q6hai70n9zmzb0q49a5-gawk-5.3.2/bin:/nix/store/k1lcfin159706lihwx5hhvl80dbij4jw-gnutar-1.35/bin:/nix/store/0hv4z5s3r1h4lmvn0427mlxjxgvg34nr-gzip-1.14/bin:/nix/store/p61ba9fdgx3358bpp18hv4rslf6n5bq6-bzip2-1.0.8-bin/bin:/nix/store/mkm3my2067305hdh7rzmi10npwr7y17f-gnumake-4.4.1/bin:/nix/store/lw117lsr8d585xs63kx5k233impyrq7q-bash-5.3p3/bin:/nix/store/clrf4mjwr8xcfpvway6w34wzvqc1hry4-patch-2.8/bin:/nix/store/j1zc5jh0vi9sbxj09ldj4xklgm6kpf8n-xz-5.8.1-bin/bin:/nix/store/s2k48fw3y698j4kcvmw0520m06ihv2z4-file-5.45/bin
time=2026-01-19T20:05:06.126+01:00 level=DEBUG source=go.jetify.com/devbox/internal/devbox/devbox.go:769 msg="filtering out buildInput from PATH" path=/nix/store/y5awi2qqhx6rx6j7fh6ik2k8aagdyy1z-cowsay-3.8.4/bin input=/nix/store/y5awi2qqhx6rx6j7fh6ik2k8aagdyy1z-cowsay-3.8.4
time=2026-01-19T20:05:06.126+01:00 level=DEBUG source=go.jetify.com/devbox/internal/devbox/devbox.go:775 msg="PATH after filtering buildInputs" inputs="[/nix/store/y5awi2qqhx6rx6j7fh6ik2k8aagdyy1z-cowsay-3.8.4 /nix/store/6mk2k28339wgplwz7l32ilp66ldqlr6v-cowsay-3.8.4-man]" path=/home/peter/work/hr/devbox/test/.devbox/nix/profile/default/bin:/nix/store/3vs2fr2mazafcdwyza15bfhpmccx1k7z-patchelf-0.15.2/bin:/nix/store/r9wbjib6xxjkyb9yvjvrkl4sq61i2lyn-gcc-wrapper-15.2.0/bin:/nix/store/qarrb8yfby1yyypm32vabzgxgq3w41ma-gcc-15.2.0/bin:/nix/store/7ri1mm5y99nkr7657r77wycrvhg7z9x0-glibc-2.40-66-bin/bin:/nix/store/d75200gb22v7p0703h5jrkgg8bqydk5q-coreutils-9.8/bin:/nix/store/dwiyp91lmxq864plaas14jm14m87sg3f-binutils-wrapper-2.44/bin:/nix/store/cl88v2m1y5q3k6jlkq5jjf73nmfgl1px-binutils-2.44/bin:/nix/store/wd99g2j010fdkry0ws1bhxzm52w82ssx-findutils-4.10.0/bin:/nix/store/20zvyjvxq9x2mkp7rbnvrwjjzq2n76hh-diffutils-3.12/bin:/nix/store/k06ssckzrzn9jjvvs4n62m6567zmbx6x-gnused-4.9/bin:/nix/store/qfmq7p42ak5yn389qvx7zpxkan5i4xiy-gnugrep-3.12/bin:/nix/store/nmxm04dhkaqg1q6hai70n9zmzb0q49a5-gawk-5.3.2/bin:/nix/store/k1lcfin159706lihwx5hhvl80dbij4jw-gnutar-1.35/bin:/nix/store/0hv4z5s3r1h4lmvn0427mlxjxgvg34nr-gzip-1.14/bin:/nix/store/p61ba9fdgx3358bpp18hv4rslf6n5bq6-bzip2-1.0.8-bin/bin:/nix/store/mkm3my2067305hdh7rzmi10npwr7y17f-gnumake-4.4.1/bin:/nix/store/lw117lsr8d585xs63kx5k233impyrq7q-bash-5.3p3/bin:/nix/store/clrf4mjwr8xcfpvway6w34wzvqc1hry4-patch-2.8/bin:/nix/store/j1zc5jh0vi9sbxj09ldj4xklgm6kpf8n-xz-5.8.1-bin/bin:/nix/store/s2k48fw3y698j4kcvmw0520m06ihv2z4-file-5.45/bin
time=2026-01-19T20:05:06.127+01:00 level=DEBUG source=go.jetify.com/devbox/internal/devpkg/package.go:204 msg="package doesn't need patching" pkg=cowsay mode=auto
time=2026-01-19T20:05:06.127+01:00 level=DEBUG source=go.jetify.com/devbox/internal/devbox/devbox.go:794 msg="new path stack is" path_stack=DEVBOX_NIX_ENV_PATH_e28de54fefcf686f8937e591af1faa6afe770305218364c2070e0fb9097705b5:DEVBOX_INIT_PATH
time=2026-01-19T20:05:06.127+01:00 level=DEBUG source=go.jetify.com/devbox/internal/devbox/devbox.go:796 msg="computed environment PATH" path=/home/peter/work/hr/devbox/test/.devbox/nix/profile/default/bin:/nix/store/3vs2fr2mazafcdwyza15bfhpmccx1k7z-patchelf-0.15.2/bin:/nix/store/r9wbjib6xxjkyb9yvjvrkl4sq61i2lyn-gcc-wrapper-15.2.0/bin:/nix/store/qarrb8yfby1yyypm32vabzgxgq3w41ma-gcc-15.2.0/bin:/nix/store/7ri1mm5y99nkr7657r77wycrvhg7z9x0-glibc-2.40-66-bin/bin:/nix/store/d75200gb22v7p0703h5jrkgg8bqydk5q-coreutils-9.8/bin:/nix/store/dwiyp91lmxq864plaas14jm14m87sg3f-binutils-wrapper-2.44/bin:/nix/store/cl88v2m1y5q3k6jlkq5jjf73nmfgl1px-binutils-2.44/bin:/nix/store/wd99g2j010fdkry0ws1bhxzm52w82ssx-findutils-4.10.0/bin:/nix/store/20zvyjvxq9x2mkp7rbnvrwjjzq2n76hh-diffutils-3.12/bin:/nix/store/k06ssckzrzn9jjvvs4n62m6567zmbx6x-gnused-4.9/bin:/nix/store/qfmq7p42ak5yn389qvx7zpxkan5i4xiy-gnugrep-3.12/bin:/nix/store/nmxm04dhkaqg1q6hai70n9zmzb0q49a5-gawk-5.3.2/bin:/nix/store/k1lcfin159706lihwx5hhvl80dbij4jw-gnutar-1.35/bin:/nix/store/0hv4z5s3r1h4lmvn0427mlxjxgvg34nr-gzip-1.14/bin:/nix/store/p61ba9fdgx3358bpp18hv4rslf6n5bq6-bzip2-1.0.8-bin/bin:/nix/store/mkm3my2067305hdh7rzmi10npwr7y17f-gnumake-4.4.1/bin:/nix/store/lw117lsr8d585xs63kx5k233impyrq7q-bash-5.3p3/bin:/nix/store/clrf4mjwr8xcfpvway6w34wzvqc1hry4-patch-2.8/bin:/nix/store/j1zc5jh0vi9sbxj09ldj4xklgm6kpf8n-xz-5.8.1-bin/bin:/nix/store/s2k48fw3y698j4kcvmw0520m06ihv2z4-file-5.45/bin:/home/peter/work/hr/devbox/test/.devbox/virtenv/runx/bin:/nix/store/35yc81pz0q5yba14lxhn5r3jx5yg6c3l-bash-interactive-5.3p3/bin:/nix/store/8q2582rd22xp8jlcg1xn1w219q5lx5xa-patchelf-0.15.2/bin:/nix/store/vr15iyyykg9zai6fpgvhcgyw7gckl78w-gcc-wrapper-14.3.0/bin:/nix/store/kzq78n13l8w24jn8bx4djj79k5j717f1-gcc-14.3.0/bin:/nix/store/q6wgv06q39bfhx2xl8ysc05wi6m2zdss-glibc-2.40-66-bin/bin:/nix/store/imad8dvhp77h0pjbckp6wvmnyhp8dpgg-coreutils-9.8/bin:/nix/store/xwydcyvlsa3cvssk0y5llgdhlhjvmqdm-binutils-wrapper-2.44/bin:/nix/store/dc9vaz50jg7mibk9xvqw5dqv89cxzla3-binutils-2.44/bin:/nix/store/2fgj127razzmajyjyc81fcjjfpj97akk-cowsay-3.8.4/bin:/nix/store/av4xw9f56xlx5pgv862wabfif6m1yc0a-findutils-4.10.0/bin:/nix/store/20axvl7mgj15m23jgmnq97hx37fgz7bk-diffutils-3.12/bin:/nix/store/drc7kang929jaza6cy9zdx10s4gw1z5p-gnused-4.9/bin:/nix/store/x3zjxxz8m4ki88axp0gn8q8m6bldybba-gnugrep-3.12/bin:/nix/store/y2wdhdcrffp9hnkzk06d178hq3g98jay-gawk-5.3.2/bin:/nix/store/yi3c5karhx764ham5rfwk7iynr8mjf6q-gnutar-1.35/bin:/nix/store/d471xb7sfbah076s8rx02i68zpxc2r5n-gzip-1.14/bin:/nix/store/qm9rxn2sc1vrz91i443rr6f0vxm0zd82-bzip2-1.0.8-bin/bin:/nix/store/3fmzbq9y4m9nk235il7scmvwn8j9zy3p-gnumake-4.4.1/bin:/nix/store/rlq03x4cwf8zn73hxaxnx0zn5q9kifls-bash-5.3p3/bin:/nix/store/qrwznp1ikdf0qw05wia2haiwi32ik5n0-patch-2.8/bin:/nix/store/v0rfdwhg6w6i0yb6dbry4srk6pnj3xp0-xz-5.8.1-bin/bin:/nix/store/paj6a1lpzp57hz1djm5bs86b7ci221r0-file-5.45/bin:/home/peter/bin/local/hr:/home/peter/bin/local/format-hrpy-ruff:/home/peter/bin/local/format-hrpy-empty-lines:/home/peter/bin/local/format-hrpy:/home/peter/bin/local/aws:/home/peter/bin/local:/home/peter/bin:/home/peter/.local/bin:/home/peter/bin/modules/monitorfiles:/snap/bin:/usr/sbin:/sbin:/run/wrappers/bin:/home/peter/.nix-profile/bin:/nix/profile/bin:/home/peter/.local/state/nix/profile/bin:/etc/profiles/per-user/peter/bin:/nix/var/nix/profiles/default/bin:/run/current-system/sw/bin:/home/peter/.fzf/bin
Starting a devbox shell...
time=2026-01-19T20:05:06.129+01:00 level=DEBUG source=go.jetify.com/devbox/internal/devbox/shell.go:102 msg="using SHELL env var for shell binary path" shell=/run/current-system/sw/bin/zsh
time=2026-01-19T20:05:06.129+01:00 level=DEBUG source=go.jetify.com/devbox/internal/devbox/shell.go:86 msg="detected user shell" shell=/run/current-system/sw/bin/zsh initrc=/home/peter/.zshrc
time=2026-01-19T20:05:06.131+01:00 level=DEBUG source=go.jetify.com/devbox/internal/devbox/shell.go:346 msg="wrote devbox shellrc" path=/tmp/nix-shell-1144888-2476511810/devbox2324808265/.zshrc
time=2026-01-19T20:05:06.135+01:00 level=DEBUG source=go.jetify.com/devbox/internal/devbox/shell.go:247 msg="Executing shell %s with args: %v" /run/current-system/sw/bin/zsh=[/run/current-system/sw/bin/zsh]
init.sh called
(devbox) peter@sky:/work/hr/devbox/test/ >