Running task in an environment without the default feature crashes

[sdvillal]

Checks

• I have checked that this issue has not already been reported.

• I have confirmed this bug exists on the latest version of pixi, using pixi --version.

Reproducible example

Commands I ran and their output:

# these work and print "hi"
pixi run test
pixi run -e test test

# this crashes
pixi run -e test-no-default test

pixi.toml file that reproduces my issue:

[workspace]
channels = ["conda-forge"]
name = "pixi-default-thing"
platforms = ["osx-arm64"]
version = "0.1.0"

[environments]
test = ["a-feature"]
test-no-default = { features = ["a-feature"], no-default-feature = true }

[tasks]
test.cmd = "echo Hi"

[feature.a-feature.dependencies]

pixi info output:

System
------------
       Pixi version: 0.63.2
        TLS backend: rustls
           Platform: osx-arm64
   Virtual packages: __unix=0=0
                   : __osx=26.2=0
                   : __archspec=1=m1
          Cache dir: /Users/santi/Library/Caches/rattler/cache
       Auth storage: /Users/santi/.rattler/credentials.json
   Config locations: /Users/santi/.pixi/config.toml

Global
------------
            Bin dir: /Users/santi/.pixi/bin
    Environment dir: /Users/santi/.pixi/envs
       Manifest dir: /Users/santi/.pixi/manifests/pixi-global.toml

Workspace
------------
               Name: pixi-default-thing
            Version: 0.1.0
      Manifest file: /Users/santi/pixi-default-thing/pixi.toml
       Last updated: 21-01-2026 06:00:13

Environments
------------
        Environment: default
           Features: a-feature, default
           Channels: conda-forge
   Dependency count: 1
       Dependencies: python
   Target platforms: osx-arm64
    Prefix location: /Users/santi/pixi-default-thing/.pixi/envs/default
              Tasks: test

        Environment: test
           Features: a-feature, default
           Channels: conda-forge
   Dependency count: 1
       Dependencies: python
   Target platforms: osx-arm64
    Prefix location: /Users/santi/pixi-default-thing/.pixi/envs/test
              Tasks: test

        Environment: test-no-default
           Features: a-feature
           Channels: conda-forge
   Dependency count: 1
       Dependencies: python
   Target platforms: osx-arm64
    Prefix location: /Users/santi/pixi-default-thing/.pixi/envs/test-no-default

As seen in aqlaboratory/openfold-3#34

Issue description

SSIA

Happens in osx and linux, across pixi versions

Expected behavior

Task runs also in environments without default

[ruben-arts]

Tasks are also part of features, this is important to make it possible to create flexible task setups.

You can read [tasks] as [feature.default.tasks], more info here: https://pixi.prefix.dev/latest/workspace/multi_environment/#feature-environment-set-definitions

The fix for your example would be to add test to [feature.a-feature.tasks]. Or make a special feature for the tasks you want to share. You can add this back to the default feature by redefining that too:

[feature.test.tasks]
test = "echo HI"

[environments]
default = ["test"]
test = ["a-feature", "test"]
test-no-default = { features = ["a-feature", "test"], no-default-feature = true }