scripts: read-list.sh hangs forever when a bare --comments is the final argument

[kyle-sexton]

Context

Found by the repo-wide /code-tidying:batch-simplify sweep (62 groups / 986 files, branch claude/repo-code-tidying-batch-twhddw). The sweep's doctrine files latent defects instead of fixing them mid-sweep, because the fix changes observable behavior; this issue is that filing.

scripts/lib/read-list.sh:69-71 — shift 2 || true never shifts when only one positional remains (bash leaves params untouched when n > $#), so the option loop re-reads --comments indefinitely. Empirically confirmed: timeout 3 exits 124. No current caller invokes it this way (all seven pass a mode).

Proposed work

• Validate the option's argument before shift 2 and fail with the usage error instead of looping.

Acceptance criteria

• Invoking read-list.sh with --comments as the last argument exits non-zero with a usage message instead of hanging.

References

• scripts/lib/read-list.sh:69-71

Filed by the /code-tidying:batch-simplify closeout (Phase 8).

[kyle-sexton]

This was generated by AI during work-loop.

Already fixed on main. scripts/lib/read-list.sh drains a bare --comments with shift $(($# > 1 ? 2 : 1)) and returns 2 via the existing "mode is required" path (landed with #3363).

Verified this session:

timeout 3 bash -c 'source scripts/lib/read-list.sh; arr=(); read_list::into arr /etc/hosts --comments; echo rc:$?'
# -> read-list: --comments is required (inline|leading); there is no default
# rc:2

No hang (would have been exit 124). Closing.