[civilwarinfrance]

make_legal_content("caption\n") currently returns the trailing newline unchanged because its fast path only checks the first character and internal blank lines. Consequently, strict Subtitle.to_srt() and compose() emit three newlines after that cue instead of the usual two.

Check the last character before taking the fast path, so this input uses the existing boundary-newline normalization. Legal multiline content and horizontal whitespace are preserved; non-strict output is unchanged.

Validation on macOS with Python 3.9.6:

• The new regression file has 11 failures and 11 passing controls on the unchanged baseline; all 22 cases pass after the fix. It checks exact LF/CRLF output from to_srt() and compose(), non-strict controls, Unicode, and whitespace preservation.
• Full tests and doctests: 73 passed, with 100% statement and branch coverage for srt.py.
• Both configured Black checks, Pytype and Bandit pass.
• The configured Pylint command reports the same three diagnostics before and after this change: a removed C0330 option and two existing positional-argument warnings. The full OS/Python CI matrix was not run locally.

AI assistance: This patch, tests and description were prepared with Codex (GPT-6).