Specification: Newline-safe worktree registration

Created: 2026-10-15 Status: Clarified Input: Continue finding repository bugs, publish confirmed fixes and merge after checks.

User story

Task cleanup may delete a leftover directory only after Git says that path is not a registered worktree. A registered checkout whose path contains a newline must still count as registered, so a failed git worktree remove cannot be followed by remove_dir_all.

Requirements

• FR-001: is_worktree_registered reports a checkout registered when git worktree list --porcelain -z lists that path, including when the path contains a newline or when a UTF-8 symlink's canonical bytes are not UTF-8.
• FR-002: A path Git does not list stays unregistered. When Git itself fails, the path stays registered (fail closed).
• FR-003: The comparison still accepts the caller's path or its canonical form. No IPC, persisted data, or cleanup policy change.

Acceptance scenarios

1. A worktree added at an absolute path containing a newline is registered.
2. The existing guard still reports a normal path unregistered before add, registered after add, and unregistered after remove.
3. A failed Git listing does not become "not registered".
4. A UTF-8 symlink whose canonical worktree path is not UTF-8 stays registered.

Success criteria

The server unit test creates a real Git worktree whose path contains a newline and requires is_worktree_registered to return true. Existing registration tests pass. Full repository verification passes.

Clarification

No user questions are required. The leftover-directory guard already refuses to delete a checkout Git still claims. The defect is the line-oriented parser hiding that claim. Sharing one porcelain parser with worktree listing is a later cleanup, not this correction.