fix: ignore fenced code blocks when checking PR bodies

.github/scripts/check_pr_body.py

@@ -22,6 +22,7 @@ E2E_PREFIX: Final = "tests/e2e/"
 PLACEHOLDER_TOKENS: Final = ("<blah>",)
 NO_CAVEATS_PATTERN: Final = re.compile(r"^(none|n/?a)[.!]?$", re.IGNORECASE)
 HTML_COMMENT_PATTERN: Final = re.compile(r"<!--.*?-->", re.DOTALL)
+FENCE_PATTERN: Final = re.compile(r"^\s{0,3}(?:```|~~~)")
 HEADING_PATTERN: Final = re.compile(r"^#{2,6}\s+(?P<title>.+?)\s*$")
 BULLET_PATTERN: Final = re.compile(r"^\s*(?:[-*+]|\d+[.)])\s+(?P<text>.*)$")
 LABEL_PATTERN: Final = re.compile(r"^[^-*+].*:\s*$")
@@ -46,6 +47,17 @@ def strip_html_comments(body: str) -> str:
     return HTML_COMMENT_PATTERN.sub("", body.replace("\r\n", "\n"))
 
 
+def mask_fenced_blocks(body: str) -> str:
+    def step(acc: tuple[tuple[str, ...], bool], line: str) -> tuple[tuple[str, ...], bool]:
+        lines, in_fence = acc
+        if FENCE_PATTERN.match(line):
+            return (*lines, ""), not in_fence
+        return (*lines, "" if in_fence else line), in_fence
+
+    masked, _ = reduce(step, body.split("\n"), ((), False))
+    return "\n".join(masked)
+
+
 def split_sections(body: str) -> tuple[Section, ...]:
     lines: Final = tuple(body.split("\n"))
     headings: Final = tuple(
@@ -119,7 +131,7 @@ def check_qa_runbook(sections: tuple[Section, ...], changed_files: tuple[str, ..
 
 
 def check_body(body: str, changed_files: tuple[str, ...]) -> tuple[Violation, ...]:
-    sections: Final = split_sections(strip_html_comments(body))
+    sections: Final = split_sections(mask_fenced_blocks(strip_html_comments(body)))
     bullet_violations: Final = tuple(
         violation
         for section in sections

tests/test_litellm/test_github_check_pr_body.py

@@ -104,6 +104,25 @@ def test_empty_body_passes(checker):
     assert checker.check_body("", ()) == ()
 
 
+def test_ellipsis_inside_code_fence_is_not_a_placeholder(checker):
+    body = "## Screenshots / Proof of Fix\n\n```\n$ curl http://localhost:4000/health\n...\n{\"status\": \"ok\"}\n```\n"
+    assert checker.check_body(body, ()) == ()
+
+
+def test_headings_inside_code_fence_do_not_split_sections(checker):
+    body = (
+        "## Screenshots / Proof of Fix\n\nThe old body looked like this:\n\n```\n## TLDR\n\n- <blah>\n- ...\n\n"
+        "## Caveats (if any)\n\nA long prose paragraph that would fail the bullet rule if parsed.\n```\n"
+    )
+    assert checker.check_body(body, ()) == ()
+
+
+def test_ellipsis_outside_fences_still_fails(checker):
+    violations = checker.check_body("## TLDR\n\nProblem this solves:\n\n- ...\n", ())
+    assert len(violations) == 1
+    assert "placeholder" in violations[0].detail
+
+
 def test_multiline_html_comment_spanning_section_is_stripped(checker):
     body = "## QA runbook\n\n<!-- Only needed when your PR edits tests/e2e; delete this section otherwise\n\nExample:\n\n- step one\n-->\n"
     violations = checker.check_body(body, ("litellm/main.py",))