Chromy/plans/08-avoid-catching-baseexception.md

8. Avoid Catching BaseException in CLI Dispatch

Summary

Change CLI dispatch error handling so process-control exceptions such as KeyboardInterrupt and SystemExit are not swallowed.

Implementation Steps

• Change execute_command to catch Exception instead of BaseException.
• Keep mapped, expected errors handled through the existing command error mapping or its replacement.
• Print handled user-facing errors to stderr instead of stdout.
• Allow unmapped exceptions, KeyboardInterrupt, and SystemExit to propagate normally.
• Consider adding debug logging for unexpected exceptions after the logging plan exists.

Public Interface Changes

• Expected command errors still return a non-zero exit code.
• Handled error messages move from stdout to stderr.
• Interrupt and process-exit behavior becomes conventional.

Test Plan

• Test that a mapped exception returns 1 and writes to stderr.
• Test that KeyboardInterrupt is not caught by execute_command.
• Test that unmapped exceptions still propagate.

Assumptions

• Returning 1 for handled user errors remains acceptable until the exit-code conventions plan is implemented.