nteract/papermill

Literal annotation results in unrecognized parameter

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#906 opened on Aug 10, 2026

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bughelp wanted

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Description

🐛 Bug

Papermill 2.7.0

Tagging a cell as parameters and inserting the following definition results in Papermill complaining about unknown parameter if swallow is passed using parameters (CLI argument or keyword argument to execute()):

# previous cell: from typing import Literal
swallow: Literal["african", "european", "unknown"] = "unknown"

This works:

swallow: str = "unknown"

Contributor guide

Research direction
Investigate how Papermill extracts parameter annotations from notebook cells. Check the code that parses type hints, specifically how it handles `Literal` from `typing`. Reproduce the bug and trace the execution path to identify why `Literal["african", "european", "unknown"]` is not recognized. Look at existing tests for parameter parsing and add a test case for `Literal`.
Tech stack
python
Domain
backend
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
GitPythonJupyter Notebooks
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
75