Multiline commit messages
The Shell tool sends commands as a single string. Heredoc syntax (<<'EOF') inside $(cat ...) is fragile and can fail silently — the literal $(cat <<'EOF' ... ends up as the commit message instead of the intended text.
Rule
Prefer single-quoted strings with embedded newlines over $(cat <<'EOF' ...):
git commit -s -m 'short summary line
Longer body paragraph explaining why the change exists.
Additional context if needed.'
Why heredocs are fragile
The Shell tool passes the command as a single string argument. When you write:
git commit -m "$(cat <<'EOF'
message
EOF
)"
the EOF delimiter, newlines, and nested quoting can interact unpredictably, and the result is the raw $(cat <<'EOF' ... text appearing as the commit message.
Single-quoted strings with literal newlines are simple, portable, and always work. If the message itself must contain a single quote, close and reopen the quote ('\'') or fall back to a temp file passed via -F.
Sign off
Every commit still needs its Signed-off-by trailer — see git-staging. Pass -s on the same git commit invocation.