/**
 * Resolve the DESKTOP installation identity that is actually enrolled in the
 * client-health registry (US-004).
 *
 * WHY THIS EXISTS
 * ---------------
 * `POST /v1/sync-manifest/upload` is fenced on enrolment: hq-pro's
 * `processSyncManifestUploadRequest` calls `isInstallationEnrolled(personUid,
 * upload.installationId)`, which is
 * `clientHealthStore.getSnapshot(personUid, installationId) !== null`. An
 * installation id that no client-health heartbeat has ever reported gets a
 * hard **403 INSTALLATION_NOT_ENROLLED** — the manifest row can never join the
 * heartbeat row, so the whole audit is silently dead for that host.
 *
 * WHO ENROLS A DESKTOP HOST
 * -------------------------
 * Not hq-cloud: the sync engine sends no client-health heartbeat at all. The
 * HQ Sync menubar app does, from Rust
 * (`hq-desktop-app/apps/sync/src-tauri/src/commands/client_health.rs`). It
 * pins its identity in `~/.hq/client-health.json` (`state_file_path()`), whose
 * `ClientHealthState` is `#[serde(rename_all = "camelCase")]` — so the JSON
 * key is `installationId`. The value is seeded on first use from
 * `~/.hq/menubar.json`'s `machineId` when that is wire-shaped, else a fresh
 * v4 UUID.
 *
 * That is NOT the same thing as `getOrCreateMachineId(hqRoot)`: machine-id
 * resolves `HQ_MACHINE_ID` → `<hqRoot>/.hq/machine-id` → menubar `machineId` →
 * autogen, and tier 2 wins before menubar ever gets a look-in. On a real
 * install the two diverge (observed: enrolled `e1bff370-…` from menubar vs
 * `<hqRoot>/.hq/machine-id` `e3ef5a5a-…`), which is exactly the 403.
 *
 * It is also NOT `cli-client-health.json`. That file is the hq-CLI's own
 * separate enrolled installation (`hq-cli/src/utils/client-health.ts`,
 * `CLIENT_HEALTH_STATE_FILE`); the CLI and the desktop are two distinct
 * installations of one person and each enrols under its own id. The runner
 * stamps `source: "desktop"`, so it must carry the DESKTOP id.
 *
 * DISCIPLINE
 * ----------
 * Strictly READ-ONLY. This module never creates, mints, migrates or rewrites
 * the client-health state file. Minting an id here would (a) be unenrolled by
 * construction, and (b) risk clobbering the heartbeat's own identity, which
 * would orphan every previously-reported snapshot. It never throws: a missing,
 * unreadable, malformed or non-conforming file is simply "no enrolled identity
 * known", and the caller skips the upload.
 */
/**
 * The desktop app's client-health state file. Note the absence of the `cli-`
 * prefix: `cli-client-health.json` is a DIFFERENT file owned by hq-cli for its
 * own separately-enrolled installation.
 */
export declare const DESKTOP_CLIENT_HEALTH_STATE_FILE = "client-health.json";
export interface ReadDesktopInstallationIdOptions {
    /** The runner's state dir (`HQ_STATE_DIR`-aware). */
    stateDir: string;
    /** Injected home dir. Tests pin it; production reads `os.homedir()`. */
    homeDir?: string;
}
/**
 * The enrolled desktop installation id for this host, or `undefined` when no
 * client-health heartbeat has ever pinned one.
 *
 * Never throws and never writes.
 */
export declare function readDesktopInstallationId(options: ReadDesktopInstallationIdOptions): string | undefined;
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