Completion does not activate for imports/arguments without a non-space prefix

[tomshafer]

Moved over from main marimo repo. I’m no expert in TypeScript or CodeMirror, but GPT 5.6 identified a small change (few lines plus tests) that fixes this issue.

Describe the bug

Completion works as expected for from dataclasses import d<pause/ctl+space> (completion options appear), but does not activate at all for from dataclasses import <pause/ctl+space>. The same can be true for function argument completion, depending whether the user has backspaced through characters. This is an important feature for experimenting with APIs and I miss it when I use marimo.

Will you submit a PR?

• Yes

Environment

Details

{
  "marimo": "0.23.14",
  "editable": false,
  "location": "/Users/tomshafer/Library/Caches/uv/archive-v0/_LjD0vyGeI3lEH5m/lib/python3.14/site-packages/marimo",
  "OS": "Darwin",
  "OS Version": "25.5.0",
  "Processor": "arm",
  "Python Version": "3.14.2",
  "Locale": "C/en_US",
  "Binaries": {
    "Browser": "149.0.7827.201",
    "Node": "v26.3.1",
    "uv": "0.11.26 (396ef7ce4 2026-06-30 aarch64-apple-darwin)"
  },
  "Dependencies": {
    "click": "8.4.2",
    "docutils": "0.23",
    "itsdangerous": "2.2.0",
    "jedi": "0.19.2",
    "markdown": "3.10.2",
    "narwhals": "2.23.0",
    "packaging": "26.2",
    "psutil": "7.2.2",
    "pygments": "2.20.0",
    "pymdown-extensions": "10.21.3",
    "pyyaml": "6.0.3",
    "starlette": "1.3.1",
    "tomlkit": "0.15.0",
    "typing-extensions": "4.16.0",
    "uvicorn": "0.51.0",
    "websockets": "16.1"
  },
  "Optional Dependencies": {
    "loro": "1.13.1",
    "python-lsp-ruff": "2.3.1",
    "python-lsp-server": "1.14.0",
    "ruff": "0.15.21"
  },
  "Experimental Flags": {}
}

Code to reproduce

# /// script
# dependencies = [
#     "marimo",
# ]
# requires-python = ">=3.14"
# ///

import marimo

__generated_with = "0.23.14"
app = marimo.App(width="medium")


@app.cell
def _():
    import marimo as mo

    return


@app.cell
def _():
    from dataclasses import 

    return


if __name__ == "__main__":
    app.run()

[mscolnick]

Closed by #69