can1357/oh-my-pi · error · NameError

UsageError: Line magic function '%{name}' not found.

Error message

UsageError: Line magic function '%{name}' not found.

What it means

The runner dispatches line magics by name through __omp_magic, which looks up the name in the registered line-magic table. Unknown names raise NameError formatted like IPython's UsageError: "Line magic function '%name' not found." to mimic IPython behavior.

Source

Thrown at packages/coding-agent/src/eval/py/runner.py:831

def _run_shell_body(body: str, *, shell_arg: str) -> int:
    # stdin=DEVNULL: children must not inherit the runner's stdin, which is
    # the host's NDJSON control channel (a reading child would steal frames,
    # and inheriting the pipe deadlocks nested interpreters on Windows).
    proc = subprocess.Popen(
        [shell_arg, "-c", body],
        stdin=subprocess.DEVNULL,
        stdout=subprocess.PIPE,
        stderr=subprocess.STDOUT,
    )
    _stream_process_output(proc)
    proc.wait()
    return proc.returncode


def __omp_magic(name: str, args: str) -> Any:
    fn = _LINE_MAGICS.get(name)
    if fn is None:
        raise NameError(f"UsageError: Line magic function '%{name}' not found.")
    return fn(args)


def __omp_magic_cell(name: str, args: str, body: str) -> Any:
    fn = _CELL_MAGICS.get(name)
    if fn is None:
        raise NameError(f"UsageError: Cell magic function '%%{name}' not found.")
    return fn(args, body)


class _ShellResult(list):
    """Result of ``!cmd`` — list of stripped output lines."""

    def __init__(self, lines: list[str], returncode: int) -> None:
        super().__init__(lines)
        self.returncode = returncode

    @property

View on GitHub (pinned to 9690622007)

Solutions

1. Check the runner's registered line magics and use an equivalent supported one
2. Replace unsupported IPython magics with plain Python code (e.g. time.perf_counter() instead of %timeit)
3. Remove or comment the magic line when porting IPython code
4. Register a custom magic with @line_magic if extending the runner

Example fix

// before
%timeit compute()
// after
import time
t0 = time.perf_counter(); compute(); print(time.perf_counter() - t0)

# only invoke magics known to the runner
KNOWN_LINE_MAGICS = {"set_env", "run", "time"}  # from runner docs
if name not in KNOWN_LINE_MAGICS:
    ...

try:
    __omp_magic(name, args)
except NameError as e:
    if "Line magic function" in str(e):
        print(f"{name!r} is not supported; use plain Python instead")

When it happens

Trigger: Evaluating code that invokes %some_magic where some_magic was never registered via @line_magic in the runner — e.g. %matplotlib, %timeit, or any IPython-specific magic not implemented here.

Common situations: Running notebooks/code written for real IPython inside this eval runner, typos in a magic name, or assuming IPython-only magics (%,%%, ?, !) are supported.

Related errors

• UsageError: Cell magic function '%%{name}' not found.
• Usage: %set_env KEY VALUE
• Usage: %run <path>
• Command aborted
• Command timed out

AI-assisted analysis of can1357/oh-my-pi@9690622007 (2026-08-31). Data as JSON: /api/errors/bb308b82c13502e6. Report an issue: GitHub.