Write Bats Test

Goal

Cover new or changed shell behavior with a bats-core test that matches the
existing convention in tests/.

When to use

When setup.sh or skills/deepworkplan/shared/context.sh gains or changes
behavior (a new flag, a new detection branch, a new output field).

Steps

1. Read the existing tests to match style and helpers:
   tests/setup-sh.bats, tests/context-sh.bats.
2. Add @test cases for the new behavior. Use a throwaway HOME/temp dir for
   any filesystem effect so the suite never touches the developer's ~/.claude.
3. Keep assertions on observable contract: emitted JSON fields from
   context.sh, created symlink names from setup.sh, exit codes.
4. Run bats tests/ and iterate until green.

Validation

bats tests/ passes, including the new cases, and the suite leaves no artifacts
outside its temp dirs.

Notes

Tests must run on bash 3.2. Prefer testing the public contract (flags,
symlink names, JSON keys) over internal implementation so refactors don't churn
the suite.