OpenBMB/ChatDev · error · ValueError

missing closing delimiter

Error message

missing closing delimiter

What it means

After finding the opening '---', _parse_frontmatter scans for a matching closing '---' line; if none exists before EOF it raises ValueError('missing closing delimiter'). The YAML frontmatter block is unterminated.

Source

Thrown at entity/configs/node/skills.py:58

            continue
        if not isinstance(raw_description, str) or not raw_description.strip():
            continue
        discovered.append((raw_name.strip(), raw_description.strip()))
    return discovered


def _parse_frontmatter(skill_file: Path) -> Mapping[str, object]:
    text = skill_file.read_text(encoding="utf-8")
    if not text.startswith("---"):
        raise ValueError("missing frontmatter")
    lines = text.splitlines()
    end_idx = None
    for idx in range(1, len(lines)):
        if lines[idx].strip() == "---":
            end_idx = idx
            break
    if end_idx is None:
        raise ValueError("missing closing delimiter")
    payload = "\n".join(lines[1:end_idx])
    data = yaml.safe_load(payload) or {}
    if not isinstance(data, Mapping):
        raise ValueError("frontmatter must be a mapping")
    return data


@dataclass
class AgentSkillSelectionConfig(BaseConfig):
    name: str

    FIELD_SPECS = {
        "name": ConfigFieldSpec(
            name="name",
            display_name="Skill Name",
            type_hint="str",
            required=True,
            description="Discovered skill name from the default repo-level skills directory.",

View on GitHub (pinned to 4fb2db0ea9)

Solutions

1. Add a closing '---' line after the YAML block on its own line
2. Verify the file is complete (not truncated by a failed write or partial download)
3. Run a quick lint: file must contain at least two lines equal to '---'

Example fix

# before
---
name: my-skill
# after
---
name: my-skill
---

lines = text.splitlines()
assert any(l.strip() == '---' for l in lines[1:]), 'unterminated frontmatter'

try:
    _discover_default_skills(skills_dir)
except ValueError as e:
    if 'closing delimiter' in str(e):
        # quarantine file, log, continue
        ...

When it happens

Trigger: A skill markdown file with an opening '---' but no second '---' line terminating the frontmatter block.

Common situations: Truncated files; authors forgetting the closing delimiter; copy-paste that drops the last line; a horizontal-rule '---' being confused with delimiters mid-document after the real block was never closed.

Related errors

• missing frontmatter
• frontmatter must be a mapping
• skill name is required
• expected list of skill entries
• expected skill entry mapping or string

AI-assisted analysis of OpenBMB/ChatDev@4fb2db0ea9 (2026-08-27). Data as JSON: /api/errors/50b32421d85737cd. Report an issue: GitHub.