`zit add DIR` and `zit rm DIR` were hard errors that told the user to name individual files. That made the two most common invocations -- `zit add .` and adding a source subtree -- dead ends, and it was the last place where the CLI asked the user to do work the repository already knows how to do.

What changed:

- `add DIR` now expands to every untracked file beneath the directory. It reuses the ALREADY SHIPPED `extras.sweep` of the checkout root rather than introducing a second walker: the same walk, the same exclusions, the same no-follow symlink posture `addremove` and `clean` use. The sweep is lazy and memoized for the whole invocation, so `zit add a b c` over three directories still performs exactly one enumeration. Because the sweep already subtracts the tracked set and the depth-0 control names, neither can be re-inserted or re-reported by the directory path. - `rm DIR` expands over the TRACKED keys via `ManagedSet.iterate`, never over the disk, so a directory the user has already deleted is still forgettable. Keys are copied into the arena before the first removal, because `iterate()`'s slice and its backing bytes are invalidated by `remove` -- the same discipline `addremove` uses for its remove set. Ascending order is preserved and every expanded key still passes the per-key control-file guard (B-rm-7). - One containment predicate, `pathUnderDir`, serves both verbs, so the boundary case cannot diverge between them: `src2/c` is not under `src`, because containment requires the separator immediately after the directory's bytes. - No new diagnostic class. `zit rm .` with nothing tracked resolves to the existing not-tracked message rather than inventing an empty-expansion error; `zit add .` on a tree holding only control files adds nothing and succeeds. - The `add` and `rm` help text and exit-status wording now describe recursion instead of the removed directory error.

Test evidence: the B-add-5 and B-rm-5 contract tests were rewritten to pin the new behavior (a named symlink is still rejected; a directory now recurses; `.` at the root is never reported as outside the repository), and a new P3-F4 block of end-to-end tests covers nested trees, prefix-boundary siblings, multiple directory arguments sharing one sweep, --dry-run, --hard, and rm of a directory that no longer exists on disk. `zig build test` passes in this worktree after absorbing the sibling packaging commit (3645c03e2d), and the commit is proved against a clean `fossil open` checkout running `zig build` then `zig build test`. check-in: 281c0ed815 user: dmestas tags: release-0.1