ergasia: 6 low-severity audit findings (wave-1 batch)

[forkwright]

Findings

correctness

• crates/ergasia/src/extract/pipeline.rs:182 — calculate_archive_size returns 0 on read_dir failure, making the disk check trivially pass (low)

resilience

• crates/ergasia/src/extract/seven_zip.rs:31 — collect_files recurses into subdirectories without depth limit, enabling stack overflow from crafted 7z archive (low)
• crates/ergasia/src/session.rs:184 — Concurrent delete_torrent calls for the same DownloadId race and produce a mislabelled error (low)

testing

• crates/ergasia/src/extract/rar.rs:66 — extract_rar actual extraction logic is untested; only volume-detection is covered (low)
• crates/ergasia/src/extract/seven_zip.rs:6 — extract_7z (and its collect_files traversal) has zero tests (low)
• crates/ergasia/src/session.rs:34 — TorrentSession — all download-management methods have zero tests (low)

Note

These are batched low/info findings; split any out if it gets prioritized.