docs: events, storage, and component field notes

[amsraman]

Fourth batch of upstreaming Reflex Build's AI-builder knowledge base (#6775, #6777, and the recharts batch). Events/storage/component gaps:

• event_triggers: on_key_down/on_key_up sections (keyboard triggers were previously undocumented) and a Global Keyboard Events section for rx.window_event_listener (also undocumented)
• memo: Using with rx.foreach (lambda + keyword args; the key prop forwarding — verified against reflex_base source)
• text_area: Submitting on Enter (enter_key_submit, Shift+Enter behavior, and a verified warning that it can't be combined with on_key_down — raises ValueError)
• special_events: set_clipboard with state Vars, backend rx.download(data=...) example, auto_scroll cross-link
• page_load_events: loading/error handling pattern (yield-for-immediate-loading-state, try/except/finally)
• browser_storage: local-storage positional-default callout

Notably, three knowledge-base claims were checked against source and rejected rather than upstreamed (rx.get_clipboard doesn't exist; .temporal doesn't guarantee ordering; sync isn't default-on). Pre-commit clean.

🤖 Generated with Claude Code

[codspeed-hq]

Merging this PR will not alter performance

✅ 26 untouched benchmarks
⏩ 8 skipped benchmarks¹

---

_{Comparing docs/events-storage-field-notes (7939967) with main (7e80931)²}

Footnotes

1. 8 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

2. No successful run was found on main (fed116f) during the generation of this report, so 7e80931 was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩

[greptile-apps]

Greptile Summary

This PR adds six documentation sections across event triggers, browser storage, special events, page-load events, text area, and memo — the fourth batch of upstreaming knowledge from the Reflex Build AI-builder knowledge base.

• event_triggers.md documents on_key_down/on_key_up with working demos and a new Global Keyboard Events section for rx.window_event_listener.
• text_area.md covers enter_key_submit with a live demo, Var-toggling note, and a source-verified warning that combining it with on_key_down raises a ValueError.
• memo.md adds a rx.foreach example using rx.RestProp to forward key without triggering the 0.9.3 deprecation warning (fixed per prior review thread).
• special_events.md adds an rx.auto_scroll cross-link, a Var-based rx.set_clipboard demo, and a backend rx.download(data=…) example.
• page_load_events.md adds an async loading/error pattern using a loading flag, yield, and try/except/finally.
• browser_storage.md adds a positional-default callout for all three storage types.

Confidence Score: 5/5

Safe to merge — all changes are documentation additions with no functional code changes; examples have been verified against source.

All six files contain only documentation additions. The examples are consistent with the described behaviors, and the three knowledge-base claims that could not be verified were explicitly excluded. The one minor inaccuracy — max_age listed as a sample keyword arg for all three storage types when it is Cookie-only — is trivially correctable and does not affect correctness elsewhere.

docs/api-reference/browser_storage.md — the positional-default callout lists max_age as an example keyword for LocalStorage and SessionStorage, where it does not apply.

Important Files Changed

Filename	Overview
docs/api-reference/browser_storage.md	Adds a positional-default callout for rx.Cookie/LocalStorage/SessionStorage; max_age listed as an example keyword arg for all three types even though it is Cookie-only.
docs/api-reference/event_triggers.md	Adds on_key_down/on_key_up sections and a Global Keyboard Events section for rx.window_event_listener; examples look accurate and consistent.
docs/api-reference/special_events.md	Adds auto_scroll cross-link under rx.scroll_to, a Var-based rx.set_clipboard demo, and a backend rx.download(data=...) demo; all additions are accurate and runnable.
docs/events/page_load_events.md	Adds a loading/error handling pattern with async handler, loading flag, yield, and try/except/finally; pattern is idiomatic and correct.
docs/library/forms/text_area.md	Documents enter_key_submit prop with a live demo, Var-toggling note, and a verified warning about the on_key_down conflict; all claims align with the stated source check.
docs/library/other/memo.md	Adds rx.foreach section using the rx.RestProp pattern (fixed from the prior review thread) so key forwards correctly without triggering a deprecation warning.

_{Reviews (3): Last reviewed commit: "docs: correct the enter_key_submit / on_..." | Re-trigger Greptile}

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Avoid documenting deprecated key forwarding

When users copy this rx.foreach example, the later key=... is passed to a memo that has no rx.RestProp. The runtime explicitly treats that as legacy and calls _warn_legacy_base_props when rest_param is None (packages/reflex-base/src/reflex_base/components/memo.py:1630-1643), with the deprecation message saying to declare rx.RestProp for base props (packages/reflex-base/src/reflex_base/components/memo.py:1869-1878). This doc therefore recommends a pattern that immediately emits a deprecation warning and is scheduled for removal; include and pass a RestProp while still not declaring key as an explicit prop, or call out the warning.

Useful? React with 👍 / 👎.

[chatgpt-codex-connector]

Don't suggest on_key_down can replace enter_key_submit

In the case where a textarea also needs custom key handling, this fallback tells users to implement the Enter-submit behavior with a normal Reflex on_key_down, but the built-in implementation needs the raw JS event to call e.preventDefault() and e.target.form.requestSubmit() (packages/reflex-components-core/src/reflex_components_core/el/elements/forms.py:870-877), while the public key event only sends the key and modifier Vars to state handlers (packages/reflex-base/src/reflex_base/event/__init__.py:1028-1045). Following this advice still lets Enter insert a newline, and using .prevent_default would suppress all key input rather than only Enter, so the docs should point to a custom JS custom_attrs handler or another supported pattern.

Useful? React with 👍 / 👎.

[amsraman]

Verified and fixed. Confirmed against the Reflex source: on_key_down uses key_event, which passes only (key, {alt/ctrl/meta/shift}) to the Python handler — the raw event is consumed and never forwarded, so preventDefault() / requestSubmit() aren't reachable and the newline would still be inserted. Corrected the note: a Python on_key_down handler can't stop the newline, and replicating Enter-to-submit with custom key handling needs a client-side handler (e.g. rx.call_script), not a plain on_key_down. Thanks for the catch.