Editing metainfo

Create a validated copy by default:

btpc edit payload.torrent --output edited.torrent --comment "reviewed"

Use --in-place only when atomic replacement is intended. Top-level fields such as comment and creator preserve info hashes. Changes inside the info dictionary, including private state, source, and file attributes, change applicable hashes. Top-level-only edits preserve the exact original info byte slice, even when its source encoding is noncanonical. Canonical serialization remains an explicit output choice. Hybrid real-file attribute edits update both v1 and v2 file representations atomically; padding attributes remain v1-only.

Python uses one three-state parameter per optional field: UNCHANGED preserves, None removes, and a typed value replaces.