GeezerVison

Before: when a check failed, the text output printed the offending commit message, branch or tag name exactly as written. Escape sequences in it went straight to the reader's terminal (OSC 52 can write the clipboard, ESC[2K can erase what was printed), and a message body line starting with :: was printed at the start of a line, where a GitHub Actions runner reads it as a workflow command (::error, ::add-mask::).

After: in text output, control characters other than newline and tab are shown as \xNN escapes, a line that starts with :: (after any indentation) gets a backslash in front (\::error ...), and the older ##[command] form is broken up the same way (#\#[). The text is still readable, but it can no longer control the terminal or the runner. --format json output is unchanged; the JSON encoder already escapes it.

Before / after

msg.txt was written with:

$ printf 'Bad subject \033]52;c;ZWNobyBwd25lZA==\007\033[2Khidden\n\n::error file=README.md,line=1::Spoofed annotation\n::add-mask::[email protected]\n' > msg.txt

Before (main)

$ cchk msg.txt -m --no-banner | cat -v
CC001 message check failed ==> Bad subject ^[]52;c;ZWNobyBwd25lZA==^G^[[2Khidden

::error file=README.md,line=1::Spoofed annotation
::add-mask::[email protected]
The commit message should follow Conventional Commits. See https://www.conventionalcommits.org
Suggest: Use <type>(<scope>): <description>, where <type> is one of: feat, fix, docs, style, refactor, test, chore, ci
Docs: https://commit-check.com/rules/#cc001

$ cchk msg.txt -m --compact | cat -v
[FAIL] CC001 message: Bad subject ^[]52;c;ZWNobyBwd25lZA==^G^[[2Khidden

After (this branch)

$ cchk msg.txt -m --no-banner | cat -v
CC001 message check failed ==> Bad subject \x1b]52;c;ZWNobyBwd25lZA==\x07\x1b[2Khidden

\::error file=README.md,line=1::Spoofed annotation
\::add-mask::[email protected]
The commit message should follow Conventional Commits. See https://www.conventionalcommits.org
Suggest: Use <type>(<scope>): <description>, where <type> is one of: feat, fix, docs, style, refactor, test, chore, ci
Docs: https://commit-check.com/rules/#cc001

$ cchk msg.txt -m --compact | cat -v
[FAIL] CC001 message: Bad subject \x1b]52;c;ZWNobyBwd25lZA==\x07\x1b[2Khidden

cchk msg.txt -m --format json prints byte-identical output on both.

How

A new printable() helper in commit_check/util.py escapes C0/C1 control characters and DEL (keeping \n and \t), puts a backslash before the :: of any line whose first non-blank characters are ::, and turns ##[ into #\#[. Indenting alone would not be enough: the Actions runner calls TrimStart() before looking for ::, and it finds ##[ anywhere in a line. _print_failure applies it to the value (full and --compact output), the error and the suggestion, since a suggestion can quote a fixed value built from the commit text. Every text-mode failure goes through _print_failure. Tests cover the helper case by case and both output paths.

Text output visible to users changes, so commit-check.com may need an update after release.