sinelaw/fresh · error · ValueError

empty path

Error message

empty path

What it means

validate_path in the remote agent service canonicalizes any path before file operations (read, write, sudo_write, stat, ls, rm). It raises ValueError('empty path') when the argument is falsy (None or ""), because a canonicalized empty path is meaningless and would otherwise resolve to the process CWD and allow unintended operations.

Solutions

1. Provide a non-empty absolute (or workspace-relative) path in the request.
2. On the client side, validate the path is a non-empty string before sending the command.
3. If the path is meant to be optional, handle that in the command layer before calling validate_path instead of passing ""/None.
4. Catch ValueError from the command and return a clear client error indicating the missing path parameter.

Example fix

// before
result = agent.cmd_read("")

// after
path = request.get("path") or ""
if not path:
    raise BadRequest("'path' is required and must be non-empty")
result = agent.cmd_read(path)

if not isinstance(p, str) or not p:
    raise ValueError("path must be a non-empty string")

def is_valid_path(p) -> bool:
    return isinstance(p, str) and bool(p)

try:
    canonical = validate_path(p)
except ValueError as e:
    if str(e) == "empty path":
        return error_response(400, "'path' is required and must be non-empty")
    raise

When it happens

Trigger: Any of the remote agent commands cmd_read, cmd_write, cmd_sudo_write, cmd_stat, cmd_ls, cmd_rm invoked with p=None or p="" — e.g. a client request whose 'path' field is missing, null, or an empty string reaches agent.py:50.

Common situations: API clients omitting the path field in the JSON request body; frontends sending empty inputs from unfilled form fields; protocol/serialization bugs dropping empty strings; defaults where None is used for 'not provided'.

Understand the failure class

Background: "must not be empty", "cannot be empty" — required-field validation errors across open-source libraries — this error's family across 41 libraries.

Related errors

• project path does not exist
• ${built.error}
• folder name must not be empty
• sudo tee failed
• empty script: pass a file, or pipe the source on stdin

AI-assisted analysis of sinelaw/fresh@67894ca546 (2026-09-13). Data as JSON: /api/errors/adc55a69b97efa95. Report an issue: GitHub.

Appendix: source

Thrown at crates/fresh-editor/src/services/remote/agent.py:50

    with write_lock:
        sys.stdout.write(line)
        sys.stdout.flush()


def b64(data):
    """Encode bytes to base64 string."""
    return base64.b64encode(data).decode("ascii")


def unb64(s):
    """Decode base64 string to bytes."""
    return base64.b64decode(s)


def validate_path(p):
    """Validate and canonicalize a path."""
    if not p:
        raise ValueError("empty path")
    expanded = os.path.expanduser(p)
    if not os.path.isabs(expanded):
        expanded = os.path.abspath(expanded)
    return os.path.realpath(expanded)


# === File Operations ===


def cmd_read(id, p):
    """Read file contents, streaming in chunks for large files."""
    path = validate_path(p["path"])
    off = p.get("off", 0)
    length = p.get("len")

    with open(path, "rb") as f:
        if off:
            f.seek(off)

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