/**
 * Which config.yaml a page was looking at when it loaded, so a save that would
 * overwrite somebody else's edit can be refused instead of landing.
 *
 * The Settings page PUTs a whole config document it read at load time, and the
 * gateway merges that document over whatever is on disk now. Between those two
 * moments an operator can hand-edit the file, and a key they added is a key the
 * page never had — the merge keeps it, but a key they *changed* loses to the
 * page's stale copy, silently. The revision closes that window: it is taken from
 * the file, not from the in-memory config, because the file is what the merge
 * reads and therefore what a conflict is actually about.
 */
export declare const CONFIG_REVISION_HEADER = "X-Jinn-Config-Revision";
/**
 * A revision for config.yaml as it is on disk right now. Hashing the bytes rather
 * than reading an mtime keeps it honest across a rename-based atomic write, whose
 * mtime moves for a write that changed nothing.
 *
 * A file that is not there yet has the empty revision, which is a real value and
 * not an error: `jinn setup` has not run, and the first PUT is allowed to create
 * the file. It stops being empty the moment the file exists.
 */
export declare function currentConfigRevision(configPath?: string): string;
/**
 * Whether a PUT is writing over a config it has not seen.
 *
 * A request with no header is not stale — it opted out, and that is deliberate:
 * partial PUTs that touch one key (the Talk voice-setup card) never read the
 * document they are merging into, so there is no revision they could send and
 * nothing they could clobber by not sending one.
 */
export declare function isStaleConfigRevision(headers: Record<string, string | string[] | undefined>, current: string): boolean;
/** What the operator is told when their save would have overwritten a hand edit. */
export declare const CONFIG_CONFLICT_BODY: {
    readonly error: "config.yaml changed on disk after this page loaded it — saving now would overwrite that change";
    readonly code: "CONFIG_CONFLICT";
    readonly remedy: "Reload the config to pick up the change on disk, then reapply your edit and save again.";
};
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