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fix(rules): ignore footer lines in body max length #4813

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8 changes: 8 additions & 0 deletions @commitlint/rules/src/body-max-line-length.test.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,7 @@ import { bodyMaxLineLength } from "./body-max-line-length.js";

const short = "a";
const long = "ab";
const longFooter = `Signed-off-by: ${"a".repeat(110)}`;
const url = "https://example.com/URL/with/a/very/long/path";

const value = short.length;
Expand All @@ -13,6 +14,7 @@ const messages = {
empty: "test: subject",
short: `test: subject\n${short}`,
long: `test: subject\n${long}`,
longFooter: `test: subject\n\n${short}\n\n${longFooter}`,
shortMultipleLines: `test:subject\n${short}\n${short}\n${short}`,
longMultipleLines: `test:subject\n${short}\n${long}\n${short}`,
urlStandalone: `test:subject\n${short}\n${url}\n${short}`,
Expand Down Expand Up @@ -57,6 +59,12 @@ test("with long should fail", async () => {
expect(actual).toEqual(expected);
});

test("with long footer should succeed", async () => {
const [actual] = bodyMaxLineLength(await parsed.longFooter, undefined, value);
const expected = true;
expect(actual).toEqual(expected);
});

test("with short with multiple lines should succeed", async () => {
const [actual] = bodyMaxLineLength(await parsed.shortMultipleLines, undefined, value);
const expected = true;
Expand Down
41 changes: 39 additions & 2 deletions @commitlint/rules/src/body-max-line-length.ts
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Original file line number Diff line number Diff line change
@@ -1,12 +1,49 @@
import { maxLineLength } from "@commitlint/ensure";
import toLines from "@commitlint/to-lines";
import { SyncRule } from "@commitlint/types";

const TRAILER_TOKEN = /^[A-Za-z0-9]+(?:-[A-Za-z0-9]+)+:\s\S/;

function withoutTrailingFooter(body: string, footer?: string | null): string {
const footerStart = footer ? body.length - footer.length : -1;
const input =
footer &&
footerStart >= 0 &&
body.endsWith(footer) &&
(footerStart === 0 || body[footerStart - 1] === "\n")
? body.slice(0, footerStart).replace(/(\r?\n)+$/, "")
: body;

const lines = toLines(input);
let last = lines.length - 1;

while (last >= 0 && lines[last] === "") {
last--;
}

let first = last;

while (first >= 0 && lines[first] !== "") {
first--;
}

const footerLines = lines.slice(first + 1, last + 1);

if (footerLines.length === 0 || !footerLines.every((line) => TRAILER_TOKEN.test(line))) {
return input;
Comment on lines +5 to +33

@qodo-code-review qodo-code-review Bot Jun 4, 2026

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1. trailer_token excludes valid footers 📎 Requirement gap ≡ Correctness

withoutTrailingFooter() only treats the last paragraph as a footer if every line matches
TRAILER_TOKEN, but the regex requires a hyphenated token and will miss valid trailers like
Fixes:/Refs:/BREAKING CHANGE:. As a result, some footer lines can still be checked by
body-max-line-length, violating the requirement that footer line-length is not enforced by the
body rule.
Agent Prompt 
## Issue description
`body-max-line-length` is intended to ignore footer/trailer lines so they are not validated against the body max length. The current trailer detection regex (`TRAILER_TOKEN`) only matches hyphenated tokens (e.g., `Signed-off-by:`), which means other valid trailer/footer tokens (e.g., `Fixes:`, `Refs:`, `BREAKING CHANGE:`) may remain in the body input and still trigger `body-max-line-length` failures.

## Issue Context
Compliance requires that footer lines are not validated by `body-max-line-length` (they should be governed separately, e.g. by `footer-max-line-length`). The current implementation gates footer stripping on `TRAILER_TOKEN`, so missed trailer formats can violate that requirement.

## Fix Focus Areas
- @commitlint/rules/src/body-max-line-length.ts[5-37]

ⓘ Copy this prompt and use it to remediate the issue with your preferred AI generation tools

}

return lines.slice(0, first).join("\n");
}
Comment on lines +24 to +37

@qodo-code-review qodo-code-review Bot Jun 4, 2026

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Action required

2. Multi-trailer body not removed 🐞 Bug ≡ Correctness

withoutTrailingFooter() removes a detected trailer paragraph via lines.slice(0, first), but when
the body contains only multiple trailer lines (no blank separator), first becomes -1 and the
function returns all but the last trailer line. This can still trigger bodyMaxLineLength failures
for long trailer lines in commits that contain only trailers (e.g., Signed-off-by +
Co-authored-by).
Agent Prompt 
## Issue description
`withoutTrailingFooter()` can detect that the entire body is made of trailer lines, but when there is no blank line separator, `first` ends up as `-1` and `lines.slice(0, first)` drops only the last trailer line (because `slice(0, -1)` keeps all-but-last). This leaves remaining trailer lines in the body, so `body-max-line-length` can still fail on long trailer lines.

## Issue Context
This happens when the commit has no body and contains multiple trailers (e.g., `Signed-off-by: ...` followed by `Co-authored-by: ...`) that are present in `parsed.body` (trailers are commonly handled via raw parsing / `git interpret-trailers`).

## Fix Focus Areas
- @commitlint/rules/src/body-max-line-length.ts[24-37]

### Suggested change
Special-case `first < 0` to remove the entire input (return empty string) when the last paragraph is detected as trailers.

### Add regression test
Add a test where the commit message has *no body* and *multiple* trailer lines, and ensure `bodyMaxLineLength` returns `true` when the trailers exceed the body limit (since they should be ignored).

ⓘ Copy this prompt and use it to remediate the issue with your preferred AI generation tools


export const bodyMaxLineLength: SyncRule<number> = (parsed, _when = undefined, value = 0) => {
const input = parsed.body;
const body = parsed.body;

if (!input) {
if (!body) {
return [true];
}

const input = withoutTrailingFooter(body, parsed.footer);

return [maxLineLength(input, value), `body's lines must not be longer than ${value} characters`];
};
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