Fix and decompose the command line interface

[ESultanik]

main() was a single 165-line function mixing argument definition, logging setup, three subcommands, and handle cleanup. It is now build_parser() (with three focused _add_*_arguments helpers), configure_logging, and one do_encrypt / do_decrypt / do_test / do_version per action. Every function is under 50 lines and within the branch limits.

Defects fixed

• -5/--best was silently identical to -4. The five levels were separate store_true flags with -4 defaulting to True, so the dispatching elif chain reached -4 before it could consider -5, making 16-nibble-grams unreachable. One store_const destination makes every level distinct:

  -1 -> (1,)              -4 -> (1, 2, 4, 8)
  -2 -> (1, 2)            -5 -> (1, 2, 4, 8, 16)   <-- previously identical to -4
  -3 -> (1, 2, 4)
  

• -t reported every byte combination as missing. It probed tuple((c,) for c in combination) — a tuple of int-tuples — against an alphabet keyed by tuples of bytes, so membership could never match. It also rendered results with chr() of values 0–15, i.e. control characters, and accumulated the message by repeated string concatenation. Now probes the right shape, renders hex nibbles, and caps the listing at 64 entries with a count of the remainder (four secrets means 65,536 of them).

• Non-gzipped ciphertexts raised an uncaught BadGzipFile traceback. The decrypt path now uses auto_unzip, which accepts either, and - for stdin works as the help has always claimed.

• --same-length / --length-checksum / --dictionary were three overlapping booleans, one of which defaulted to True and was never read. Now one store_const mode.

• exit(main()) becomes sys.exit(main()); exit comes from site and is absent under -S.

• LenticryptError is caught and logged as a message rather than a traceback.

argparse.FileType removed

Replaced by taking paths and opening them after parsing. FileType is deprecated — both ty and Python warn it "may leave files open" — because it opens eagerly during parsing, so a file could be opened and leaked when a later argument failed to validate. Opening in the action that uses the file, under an ExitStack, removes both the deprecation and the handle-tracking bookkeeping. This clears 135 PendingDeprecationWarnings from the test run.

Help text

Three stale strings corrected: -e cited "the -l argument" for truncation when it meant --same-length (-l is --log-level), --dictionary cited a nonexistent -c option, and -t claimed its report goes to stdout when it goes to the logger on stderr. --dictionary's claim about reducing ciphertext size is now qualified — measured, it only wins above roughly 8 KiB of plaintext.

Verification

Two xfail markers removed. Both had tested replicas of the buggy logic rather than the real code, so they were retargeted at build_parser and missing_combinations before being unmarked. 13 new CLI tests cover mode and level selection, every compression level round-tripping end to end, and both gzipped and plain ciphertexts.

173 passed / 3 xfailed. ruff and ty clean on __main__.py.

🤖 Generated with Claude Code

https://claude.ai/code/session_01367hFob9sd4xpDmVT4uoFy