libra sparse-checkout: subcommand/option not recognized (LBR-CLI-001)

[genedna]

Summary

git sparse-checkout is a high-FAIL area in the libra 0.23.49 full dual-track run (TC 1..3603, git control 2.55.0.782.g1630431f32 vs libra 0.23.49). 28 upstream tests FAIL under libra while passing under Git control.

Failure scenarios

1. subcommand/option not recognized (LBR-CLI-001) — libra reports Error-Code: LBR-CLI-001. Affects e.g. can move out-of-cone directory with --sparse; can move out-of-cone file with --sparse.

Impact

Users relying on git sparse-checkout semantics cannot depend on libra behaving like Git; the mismatch appears as option-rejection, exit-status, output, or reference/pathspec-resolution differences.

Acceptance criteria

1. Confirm intended libra behavior for each scenario above.
2. Where supported, align with Git's observable contract (exit status, output, reference/pathspec handling).
3. Where intentionally unsupported, classify explicitly and update compatibility documentation.
4. Re-run the referenced upstream tests after changes.

[genedna]

Failure scenario 1: subcommand/option not recognized (LBR-CLI-001)

This is one distinct failure pattern for git sparse-checkout, observed in 28 upstream test cases (confirmed FAIL in the libra 0.23.49 run).

Triggering scenarios: can move out-of-cone directory with --sparse; can move out-of-cone file with --sparse; conflicting entries written to worktree even if sparse.

Git behavior: the command/option is accepted and produces the documented output/exit status.

Libra behavior: Error-Code: LBR-CLI-001.

Why it matters: callers exercising this interface get an error or a different exit status/output from Git, breaking scripts and automation that depend on the Git contract.

[genedna]

Related issues

This issue is related to the following open issues (cross-linked):

• sparse index: support skip-worktree setup required by add --ignore-missing #490: sparse-checkout / --skip-worktree setup is required

Linked to improve discoverability, triage, and tracking of shared root causes.