fix(reload): exclude marimo package from modulefinder crawl

[Bartok9]

This pull request was authored by a coding agent.

AI-assisted; human-reviewed line-by-line. Submitted under Daniel's standing Top10 merge-culture campaign instruction for Bartok9.

Summary

Closes #10225.

modulefinder.ModuleFinder cannot walk namespace packages. marimo ships several (marimo/_dependencies, etc.). Pip installs hide this because marimo lives under site-packages and is already excluded as third-party; editable installs do not, so dependency analysis fails quietly and autoreload misses chains.

Change

• _is_marimo_internal_module_name for marimo / marimo.*
• _get_excluded_modules always adds "marimo" and filters internal names
• Unit tests for exclusion behavior (including empty-module map baseline)

Tests

pytest tests/_runtime/reload/test_module_watcher.py::TestGetExcludedModules

Pre-Review Checklist

• Discussed via issue modulefinder crashes on marimo's own namespace packages (breaks autoreload for editable installs) #10225
• AI-generated code reviewed line-by-line by the human campaign owner
• No visual changes

Merge Checklist

• CONTRIBUTING read
• Tests added
• Docs N/A (internal reload)

[Bartok9]

I have read the CLA Document and I hereby sign the CLA

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Project	Deployment	Actions	Updated (UTC)
marimo-docs	Ready	Preview, Comment	Jul 22, 2026 4:37pm

[Bartok9]

I have read the CLA Document and I hereby sign the CLA

[dmadisetti]

Thanks! Can you clean up the comments to be more general? Aside from that LGTM

[Bartok9]

Thanks for the review! Cleaned up the comments to be more general — dropped the issue-specific detail and namespace-package explanation, kept the docstring to a one-liner and trimmed the root-package note. Ready for another look.

[Copilot]

Pull request overview

This PR addresses autoreload dependency discovery failing for editable installs when modulefinder.ModuleFinder encounters marimo’s namespace-package layout, by ensuring marimo modules are excluded from the dependency crawl (issue #10225).

Changes:

• Add _is_marimo_internal_module_name() to identify marimo / marimo.* module names.
• Update _get_excluded_modules() to exclude marimo internal modules (in addition to site-packages modules).
• Add unit tests covering marimo exclusion behavior.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
marimo/_runtime/reload/module_watcher.py	Adds marimo-internal module detection and expands excluded-module computation to prevent modulefinder crashes on marimo’s package tree.
tests/_runtime/reload/test_module_watcher.py	Adds tests validating marimo exclusion behavior for editable-install scenarios.

Comments suppressed due to low confidence (1)

marimo/_runtime/reload/module_watcher.py:127

• _get_excluded_modules() now unconditionally adds "marimo", which makes the function return a non-empty set even when the provided modules dict contains only user modules (this breaks the existing test_get_excluded_modules_empty expectation and changes the semantics from "exclude third-party/marimo modules present" to "always exclude marimo"). If the intent is only to avoid crawling marimo when it's actually loaded (the production call passes sys.modules, where marimo will be present), gate this addition on whether any marimo module names are present in modules.

    sys_modules: dict[str, types.ModuleType],
) -> dict[str, types.ModuleType]:
    """Returns the set of modules used by the graph that have been modified"""

[Bartok9]

Thanks @mscolnick — and sorry the approval got dismissed.

CI red was real: TestGetExcludedModules::test_get_excluded_modules_empty still expected set() while _get_excluded_modules now always adds bare "marimo" for modulefinder. Fixed the unit expectation and rebased onto current main (2d89acf63) so the matrix can go green again. Ready when you have a moment for a re-check.

[Bartok9]

I have read the CLA Document and I hereby sign the CLA

[github-actions]

🚀 Development release published. You may be able to view the changes at https://marimo.app?v=0.23.15-dev63