/**
 * Cross-database cleanup hooks for brain.db → tasks.db soft FK enforcement.
 *
 * SQLite does not support foreign key constraints across database connections.
 * This module provides application-layer guards that maintain referential
 * integrity between brain.db and tasks.db after destructive operations.
 *
 * Implements the recommendations from T030 audit (XFKB-001 through XFKB-005).
 *
 * @task T033
 * @epic T029
 */
/**
 * Clean up brain.db references after a task is deleted from tasks.db.
 *
 * Handles:
 * - XFKB-001/002: Nullify brain_decisions.context_epic_id / context_task_id
 * - XFKB-003: Delete brain_memory_links rows where task_id matches
 * - XFKB-005: Delete brain_page_nodes with id='task:<taskId>' and cascade brain_page_edges
 *
 * This is a best-effort cleanup — brain.db is a cognitive store and minor
 * staleness is preferable to failing task deletions due to brain.db errors.
 *
 * @remarks
 * Best-effort: failures in brain.db cleanup do not propagate to the caller.
 * A background reconciliation pass can clean up any residual stale refs.
 *
 * @param taskId - The ID of the task being deleted from tasks.db
 * @param cwd - Optional working directory
 *
 * @example
 * ```ts
 * await cleanupBrainRefsOnTaskDelete('T042');
 * ```
 */
export declare function cleanupBrainRefsOnTaskDelete(taskId: string, cwd?: string): Promise<void>;
/**
 * Clean up brain.db references after a session is deleted from tasks.db.
 *
 * Handles:
 * - XFKB-004: Nullify brain_observations.source_session_id where it matches
 *
 * @remarks
 * Best-effort: failures do not propagate. brain.db may not be initialised.
 *
 * @param sessionId - The ID of the session being deleted from tasks.db
 * @param cwd - Optional working directory
 *
 * @example
 * ```ts
 * await cleanupBrainRefsOnSessionDelete('ses_20260321_abc');
 * ```
 */
export declare function cleanupBrainRefsOnSessionDelete(sessionId: string, cwd?: string): Promise<void>;
/**
 * Verify a task ID exists in tasks.db before writing a cross-DB reference to brain.db.
 * Returns true if the task exists, false otherwise.
 *
 * Provides write-guard for XFKB-001/002/003 on brain.db insert.
 *
 * @remarks
 * Used as a write-guard before inserting cross-DB references into brain.db.
 *
 * @param taskId - Task ID to verify
 * @param tasksDb - The tasks.db drizzle instance
 * @returns True if the task exists in tasks.db
 *
 * @example
 * ```ts
 * if (await taskExistsInTasksDb('T042', db)) { /* safe to reference *\/ }
 * ```
 */
export declare function taskExistsInTasksDb(taskId: string, tasksDb: Awaited<ReturnType<typeof import('./sqlite.js').getDb>>): Promise<boolean>;
/**
 * Verify a session ID exists in tasks.db before writing a cross-DB reference to brain.db.
 * Returns true if the session exists, false otherwise.
 *
 * Provides write-guard for XFKB-004 on brain.db insert.
 *
 * @remarks
 * Used as a write-guard before inserting cross-DB references into brain.db.
 *
 * @param sessionId - Session ID to verify
 * @param tasksDb - The tasks.db drizzle instance
 * @returns True if the session exists in tasks.db
 *
 * @example
 * ```ts
 * if (await sessionExistsInTasksDb('ses_abc', db)) { /* safe to reference *\/ }
 * ```
 */
/**
 * Reconcile orphaned cross-DB references in brain.db.
 *
 * Scans brain.db for references to tasks/sessions that no longer exist in
 * tasks.db and cleans them up:
 * - brain_decisions with stale context_task_id or context_epic_id → nullify
 * - brain_observations with stale source_session_id → nullify
 * - brain_memory_links with stale task_id → delete row
 *
 * This is the background reconciliation pass mentioned in the module doc.
 * Safe to run at any frequency — idempotent.
 *
 * @param cwd - Optional working directory
 * @returns Counts of orphaned references cleaned up
 */
export declare function reconcileOrphanedRefs(cwd?: string): Promise<{
    decisionsFixed: number;
    observationsFixed: number;
    linksRemoved: number;
}>;
/**
 * Verify a session ID through the caller's shared tasks database handle.
 *
 * @param sessionId - Session ID to verify.
 * @param tasksDb - Shared tasks database handle.
 * @returns True when the session exists.
 */
export declare function sessionExistsInTasksDb(sessionId: string, tasksDb: Awaited<ReturnType<typeof import('./sqlite.js').getDb>>): Promise<boolean>;
/**
 * Verify a session ID through fresh read-only connections and the caller's live handle.
 *
 * This is the bounded fallback for callers whose shared project handle either
 * closed during the primary query or returned a stale empty result. It does not
 * evict the dual-scope cache, so other domains retaining the shared handle stay
 * live while the probe runs. The live handle is checked last because it can own
 * a committed, unlinked SQLite file that is no longer reachable by path.
 *
 * @param sessionId - Session ID to verify.
 * @param tasksDb - Shared tasks handle whose native path anchors the probe when available.
 * @param cwd - Project root used to resolve the project-scope cleo.db.
 * @returns True when the session is present in any live project session table.
 * @throws Error when no database candidate can be read, distinguishing unavailable validation from absence.
 * @task T12034
 */
export declare function sessionExistsInTasksDbFresh(sessionId: string, tasksDb: Awaited<ReturnType<typeof import('./sqlite.js').getDb>> | null, cwd?: string): Promise<boolean>;
/**
 * Verify a task ID through fresh read-only connections and the caller's live handle.
 *
 * Checks both the active legacy tasks table and its consolidated prefixed
 * counterpart so callers remain correct during the E3-to-E6 transition.
 *
 * @param taskId - Task ID to verify.
 * @param tasksDb - Shared tasks handle used only when no project root is available.
 * @param cwd - Project root used to resolve the authoritative project database.
 * @returns True when the task exists in either supported project table.
 * @throws Error when no database candidate can be read, distinguishing unavailable validation from absence.
 * @task T12034
 */
export declare function taskExistsInTasksDbFresh(taskId: string, tasksDb: Awaited<ReturnType<typeof import('./sqlite.js').getDb>> | null, cwd?: string): Promise<boolean>;
/**
 * Verify an agent exists in the global Agent Registry before creating cross-DB references.
 * Returns true if the agent_id exists in the global cleo.db agent_registry_agents table.
 *
 * Provides write-guard for agent_instances and agent_error_log in tasks.db
 * that reference agents whose identity lives in the global Agent Registry.
 *
 * @param agentId - Agent slug (e.g. 'cleo-db-lead') to verify
 * @param cwd - Optional working directory
 * @returns True if the agent exists in the global Agent Registry
 *
 * @task T238
 */
export declare function agentExistsInAgentRegistryDb(agentId: string, cwd?: string): Promise<boolean>;
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