/**
 * Unused-key reconciler (B3) — decide which *defined* keys no source references.
 *
 * A key counts as used if ANY usage layer reaches it, biased hard toward "used"
 * so a live key is never flagged for deletion: exact static call, dynamic-prefix
 * coverage, the loose literal-pool harvest (any string literal equal to a key),
 * an explicit dynamic-key allowlist, or a runtime-observed key. What survives all
 * layers is reported — `confirmed` when no opaque `t(variable)` site could be
 * hiding it, else `suspect`. Separately, static render keys absent from the
 * defined set surface as `used-but-undefined` (a typo / stale rename that renders
 * its raw key at runtime).
 */
import type { KeyUsageSite, UsageScan } from './scan/types.js';
export interface UnusedKeyFinding {
    key: string;
    /** `confirmed`: no usage signal and no opaque sites. `suspect`: opaque `t(var)` sites exist. */
    tier: 'confirmed' | 'suspect';
}
export interface UsedButUndefinedFinding {
    key: string;
    sites: KeyUsageSite[];
}
export interface DynamicPrefixCoverage {
    prefix: string;
    /** Defined keys this prefix shields from the unused list (no other usage signal). */
    shieldedKeys: number;
}
export interface UnusedReport {
    /** Defined keys reached by no usage layer. */
    unused: UnusedKeyFinding[];
    /** Static render keys (`t('x')`) with no matching defined key. */
    usedButUndefined: UsedButUndefinedFinding[];
    /** Per-prefix blast radius, so a human sees what each dynamic family hides. */
    dynamicPrefixCoverage: DynamicPrefixCoverage[];
    /** Count of unresolved `t(variable)` sites — why `suspect` exists. */
    opaqueSiteCount: number;
}
export interface FindUnusedOptions {
    /** Key globs (`errors.*`) built dynamically — always treated as used. */
    dynamicKeys?: string[];
    /** Key globs excluded from the report entirely (intentionally retained, e.g. `legacy.*`). */
    ignoreKeys?: string[];
    /** Keys observed at runtime (e.g. from `createMissingKeyCollector`) — treated as used. */
    runtimeUsedKeys?: Iterable<string>;
}
export declare function findUnusedKeys(definedKeys: Iterable<string>, scan: UsageScan, options?: FindUnusedOptions): UnusedReport;