/** Emits a development diagnostic when Lit's development signal is present. Callers retain
* their own bounded deduplication state when warnings belong to one document generation. */
export declare function devWarn(message:string):void;
/**
* Dev-mode-only: emits `message` at most once per `key` for the page. Shares the exact gate and
* dedupe store `warnUnknownAttributes` uses below, so a diagnostic added by a component behaves
* like the attribute diagnostic: silent in production, silent when Lit itself is not in dev mode,
* and never repeated for the same key however many instances exist.
*/
export declare function devWarnOnce(key:string,message:string):void;
/**
* Dev-mode-only: warns once per (tag, attribute-name) when `host` carries an attribute that
* isn't in `observedAttributes`, isn't in `knownUnobservedAttributes`, and isn't in the
* always-exempt global/data/aria set. No-op when Lit's own dev-mode signal isn't present
* (production, or a dev environment where Lit itself is not in dev mode).
*
* `knownUnobservedAttributes` exists because "not observed" is not the same as "not ours". Two
* shapes of genuinely-owned attribute never reach `observedAttributes`:
*
* - **Self-reflected read-only state.** `<lr-animated-image>` publishes its live `playing` state
*   with `toggleAttribute('playing', ...)`, `<lr-menu-item>` does the same for `submenu-open`,
*   `<lr-app-rail>` for its derived `mode`. Nothing observes them because setting them from
*   markup means nothing -- they are output, not input. Left undeclared, a component reports its
*   *own* attribute as unknown, in every consumer app, the moment that state turns on.
* - **CSS-only public attributes.** `<lr-page>`'s documented `disable-sticky` is consumed purely
*   by `:host([disable-sticky~="header"])` selectors, so it needs no reactive property. Left
*   undeclared, correct authored markup draws a warning telling the author it is wrong.
*
* Both cases are false positives against real, documented API, which is corrosive in a way a
* missed warning is not: a diagnostic that cries wolf about a component's own output teaches
* consumers to tune out the ones that matter.
*/
export declare function warnUnknownAttributes(host:Element,observedAttributes:readonly string[],knownUnobservedAttributes?:readonly string[]):void;