Concretization failed errors emit ANSI escape sequences that screen readers cannot parse

Concretization failure output contains ANSI escape sequences that screen readers cannot parse

When spack concretize or spack install cannot resolve a spec, the CLI prints a multi‑line dependency conflict trace that uses ANSI color codes for version constraints, conflict markers, and tree connectors. In monochrome terminals or under screen readers these escape sequences appear as raw characters (e.g., ^[[31m), obscuring the root‑cause message.

Likely explanation

The error trace is formatted for interactive human reading; color and tree‑drawing characters are added to make the structure visible in a typical terminal. Screen readers or headless CI environments that do not interpret ANSI escapes receive the raw control codes instead of the underlying text.

Confirmed facts

• Spack ties color emission to terminal capability; the --color=never flag suppresses color but does not restructure the dense dependency trace.
• No --error-format=json or YAML option is documented for concretization failures; spack spec --format applies only to successful specs.
• Headless CI defaults to an 80‑column width, causing line‑wrapping that further degrades readability independent of ANSI codes.

Steps to verify

1. Run the failing command with spack --color=never and pipe the output through cat -v or od -c to confirm that no ESC bracket sequences are present.
2. Inspect the installed Spack version with spack --version and check that the --color flag is recognized.
3. Execute the command in a headless environment with TERM=dumb NO_COLOR=1 and verify that the output remains linear and free of escape characters.

Missing diagnostic detail

Please provide the Spack version and the terminal environment variables TERM, NO_COLOR, and whether the command runs in a CI context, as these factors influence ANSI emission and flag support.