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A randomized fuzzer (documents with ranks, names in every case and letter case, numbers, dates, non-breaking spaces, tabs, CRLF and hard line wraps; round trip, leak and over-masking checks) found the problems below. All of them except the hang were already on main. Each one has a test in tests/test_fuzz_findings.py: 56 of its tests fail on main, and the rest are guards against over-masking.

Names left unmasked

• A full name before a rank that has more words after it was not masked at all, e.g. Петренко Іван Іванович доповів капітану про виконання. The parser looked for name anchors only after the first rank in the line.
• A line break inside a name left part of it open (Петренка\nІвана Івановича, Петренка Івана\nІвановича, Шановний Віталію\nРомановичу!). When a name with a patronymic, or a rank and its name, crosses the break, the two lines are now parsed together, and the break is put back after masking.
• Initials and a surname on adjacent lines. In a run like Ю.А. Зінченко Н.І. Савчук, only the middle pair used to be masked. The masker now picks the set of matches that covers the most names.
• Fixed for initials: double surnames in capitals (ПЕТРЕНКО-КОВАЛЬ І.М.) and surnames with an apostrophe (ПИЛИП'ЮК О.І.).
• Fixed in names: a capitals heading before a name (ВИТЯГ З НАКАЗУ Коваль …), an adjective surname in the genitive (Рапорт Білого Ярослава Миколайовича), and the vocative Любове.

Unmasking did not restore the original

• A rank masked as генерал-майор медичної служби was not restored. Rank boundaries in the unmasker now exclude a hyphen.
• A rank with a non-breaking space or tab between its words lost the separator when its mask had a different number of words. The mask now keeps the word count.
• A rank broken across lines came back with a space instead of the line break.
• An open rank … медичної служби (one without a name next to it) could become the mask of another rank.
• In Мороз Ольги Богданівни Л.А. Мороз, the patronymic before the initials was masked as a surname and then masked again.
• Masks inside one line were recorded in parse order, not text order, so Іване and Івану (both masked as Ігорю) were restored the wrong way round.
• In a brigade name broken across lines, the end of the name disappeared from the masked text.

Masks

• Naval ranks now get naval masks (капітан 1-го рангу used to become майор).
• Білої now gets the same synthetic stem as Біла and Білій.

Checks

• pytest: 1620 passed. mypy: 0 errors. flake8: clean.
• Fuzzer, 4000 documents over 8 seeds: no round-trip failures, no leaks, no timeouts. The only flags are cases where a mask happens to equal another person's real name, which is a documented limitation.
• CLI round trips on both example files pass for plain, --encrypt and --re-mask 2.
• Against main, the only mask change in input_example.txt is a naval rank. In the generated documents, the changes are the fixes listed above.

Changes are under ## [Unreleased] in CHANGELOG.md. The version is not bumped, per the release-time bump rule.

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