Note other-file state persistence.

[wyattscarpenter]

📚 Context

One of the most relevant types of state persistence is absent from the current documentation, it seems.

🧠 Description of Changes

• content/develop/concepts/architecture/session-state.md

Revised:

💥 Impact

Size:

• [x] Small
• [ ] Not small

🌐 References

• https://discuss.streamlit.io/t/how-to-have-global-variable-outside-of-session-state/54885/2
• my own testing

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[sfc-gh-dmatthews]

Thanks for the suggestion. Since this comment isn't about Session State specifically, I'm thinking it would be better to note this elsewhere, such as with a general explanation of Streamlit's rerun model. I've got some other updates open, so I'll leave this open for a little bit until I can review a few other pages and see about working it in. 😄