/**
 * GC Runner — Core garbage collection logic for autonomous transcript cleanup.
 *
 * Performs disk-pressure-aware pruning of ephemeral transcript and temp files
 * under `~/.claude/projects/` using the five-tier threshold model from T751.
 *
 * Retention policy (per ADR-047 and docs/specs/memory-architecture-spec.md §8):
 * - `.temp/` files: 24h normal, 1h emergency
 * - Transcript directories (agent-*.jsonl, tool-results/): 7d normal, 1d emergency
 * - `.cleo/logs/`: 30d normal, 7d emergency
 * - `.cleo/agent-outputs/*.md` (committed artifacts): NEVER auto-pruned
 *
 * Circuit breaker: if `ANTHROPIC_API_KEY` is absent AND no local model configured,
 * skip extraction and only delete transcripts older than 30 days.
 *
 * @see ADR-047 — Autonomous GC and Disk Safety
 * @see docs/specs/memory-architecture-spec.md §8
 * @task T731
 * @epic T726
 */
/**
 * Disk usage percentage thresholds.
 *
 * Values mirror the five-tier model recommended by T751 research §3.2:
 * - OK:        < 70% — routine cleanup by age policy only
 * - WATCH:    70-85% — log + schedule next GC sooner
 * - WARN:     85-90% — log + set escalation flag for next CLI invocation
 * - URGENT:   90-95% — auto-prune oldest transcripts immediately
 * - EMERGENCY: ≥ 95% — auto-prune all transcripts > 1d, pause new writes
 */
export declare const DISK_THRESHOLDS: {
    readonly WATCH: 70;
    readonly WARN: 85;
    readonly URGENT: 90;
    readonly EMERGENCY: 95;
};
/** Human-readable tier labels. */
export type DiskTier = 'ok' | 'watch' | 'warn' | 'urgent' | 'emergency';
/**
 * Result of a single GC run.
 */
export interface GCResult {
    /** Disk usage percentage at time of GC run (0–100). */
    diskUsedPct: number;
    /** Disk tier classification. */
    threshold: DiskTier;
    /** Files pruned during this run. */
    pruned: Array<{
        path: string;
        bytes: number;
    }>;
    /** Total bytes freed. */
    bytesFreed: number;
    /** Whether escalation flag was set (disk ≥ WARN). */
    escalationSet: boolean;
    /** Human-readable escalation reason (set when escalationSet=true). */
    escalationReason: string | null;
    /** ISO-8601 timestamp of run completion. */
    completedAt: string;
}
/**
 * Options for a GC run.
 */
export interface GCRunOptions {
    /**
     * Absolute path to the `.cleo/` directory (used for state file and disk check).
     * Defaults to `~/.cleo`.
     */
    cleoDir?: string;
    /**
     * Override the default `~/.claude/projects/` scan directory.
     * Primarily used in tests to point at a temp directory.
     */
    projectsDir?: string;
    /**
     * Paths from a previous crashed run to resume deletion from.
     * Written to `pendingPrune` in gc-state.json BEFORE starting deletion.
     */
    resumeFrom?: string[];
    /**
     * Dry-run mode: compute what would be pruned, but make zero filesystem changes.
     */
    dryRun?: boolean;
}
/**
 * Classify a disk usage percentage into a tier.
 *
 * @param pct - Disk usage percentage (0–100)
 * @returns DiskTier
 */
export declare function classifyDiskTier(pct: number): DiskTier;
/**
 * Compute retention threshold in milliseconds based on disk tier.
 *
 * Higher disk pressure → shorter retention → more aggressive pruning.
 *
 * @param tier - Current disk tier
 * @returns Maximum age in milliseconds for transcript retention
 */
export declare function retentionMs(tier: DiskTier): number;
/**
 * Get the size of a path in bytes (file or directory recursively).
 * Returns 0 if the path does not exist.
 *
 * @param targetPath - Path to measure
 * @returns Size in bytes
 */
export declare function getPathBytes(targetPath: string): Promise<number>;
/**
 * Idempotently delete a path (file or directory).
 *
 * Silently ignores ENOENT — safe to call if path was already deleted.
 * Uses `force: true` to suppress errors on missing paths.
 *
 * @param targetPath - Path to delete
 */
export declare function idempotentRm(targetPath: string): Promise<void>;
/**
 * Execute a GC run: check disk pressure, determine retention threshold,
 * prune eligible transcript files, update gc-state.json.
 *
 * This function is idempotent and safe to call multiple times. Crash recovery
 * is implemented via the `pendingPrune` field in gc-state.json:
 * 1. Write paths to `pendingPrune` BEFORE starting deletion
 * 2. Remove each path from `pendingPrune` AFTER successful deletion
 * 3. Clear `pendingPrune` when the job completes
 *
 * @param opts - GC run options
 * @returns GC run results
 */
export declare function runGC(opts?: GCRunOptions): Promise<GCResult>;
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