fix: decorator invalidation for caching

[dmadisetti]

📝 Summary

Closes #8155

ast.Function.body does not include parent decorator information. As such hashing the ast produced invalid cache hits when inner decorators changed. As a work around, we artificially append the decorator statements into the function body for module hashing. Additionally, to prevent cache invalidations between:

@app.function
@mo.cache # observed ast from imported module
def fn(): ...

and

@mo.cache # observed ast from kernel
def fn(): ...

we scan the decorators and remove all prior (and including) the caching wrap.

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Project	Deployment	Actions	Updated (UTC)
marimo-docs	Ready	Preview, Comment	Feb 9, 2026 8:45pm

[Copilot]

Pull request overview

Updates marimo’s caching/hash computation so that changes to decorator expressions (including decorator-factory arguments and referenced variables) properly invalidate caches, addressing cases where ast.FunctionDef.body omits decorator information.

Changes:

• Introduce get_hashable_ast() to include decorator AST (as synthetic statements) when building hashable modules, with support for skipping cache decorators and any outer decorators.
• Switch cache/base block hashing and hash_function() to use get_hashable_ast() instead of strip_function().
• Add unit and E2E tests covering decorator-parameter hashing and decorator ref tracking.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
marimo/_ast/transformers.py	Adds get_hashable_ast() and decorator handling to ensure decorator changes participate in hashing.
marimo/_save/save.py	Uses get_hashable_ast(..., skip_decorators={...}) for cached function base-block hashing.
marimo/_save/hash.py	Updates hash_function() to hash via get_hashable_ast() rather than the removed helper.
tests/_ast/test_transformers.py	Renames/updates transformer tests and adds coverage for decorator inclusion/skipping.
tests/_save/test_hash.py	Adds regression/E2E tests to confirm decorator param/ref changes affect cache hashes as intended.

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