/**
 * Cost ledger: append-only NDJSON with closed-schema validation.
 *
 * Write semantics mirror transition-log.ts: O_APPEND single-line writes,
 * whole-line atomicity under concurrent writers. Readers skip torn or
 * malformed lines with a stderr warning.
 *
 * Privacy (SR1/FR2.4): validateEntry enforces a closed key set with
 * numeric/enum/identifier values only — free-form text cannot enter the
 * ledger regardless of origin (provider, sync, or --manual).
 *
 * Design: design.md §2.1, §4.5
 */
import type { CostEntry, CostFidelity } from './types.js';
/**
 * Validate a candidate ledger entry against the closed schema.
 *
 * @returns null when valid, otherwise a reason string (safe to log).
 */
export declare function validateEntry(entry: unknown): string | null;
/**
 * Thrown by `appendEntry` when the closed schema refuses an entry.
 *
 * A type rather than a message to parse: sync must tell a refusal from a failed
 * write, and once caught both as "validation-rejected" with the reason dropped —
 * 124 records a run, every run, with nothing saying why
 * (cost-sync-silent-rejections/AC-3, AC-4).
 */
export declare class InvalidCostEntryError extends Error {
    /** `validateEntry`'s fixed reason — never a field value, so safe to print (SR1). */
    readonly reason: string;
    constructor(reason: string);
}
/**
 * Append one validated entry to a ledger file. Throws `InvalidCostEntryError` on
 * an invalid entry, and lets a write error through as Node raised it — callers
 * decide whether that is a logged rejection (hook path) or an error surfaced to
 * the user (manual path).
 */
export declare function appendEntry(ledgerPath: string, entry: CostEntry): void;
/**
 * Read all valid entries from a ledger file. Missing file → empty array.
 * Malformed or schema-invalid lines are skipped with a stderr warning
 * (line number only — never line content, per SR1).
 */
export declare function readEntries(ledgerPath: string): CostEntry[];
/**
 * Replace a ledger file's contents with `entries`, atomically.
 *
 * The ledger is append-only for *capture*, which is what makes concurrent hook
 * firings safe. Reconciliation is a different caller: when `aidlc cost sync`
 * moves a record out of unattributed.ndjson into an instance ledger, leaving the
 * original behind would keep reporting money as unattributed that is now
 * attributed. Append-only cannot express a move.
 *
 * Temp-plus-rename so a crash leaves either the old file or the new one, never a
 * truncated one — and callers must append to the destination BEFORE rewriting the
 * source, so an interruption duplicates a record rather than losing it.
 */
export declare function rewriteLedger(ledgerPath: string, entries: CostEntry[]): void;
/** Ledger path for an instance. */
export declare function ledgerPath(projectRoot: string, instance: string): string;
/** Path of the unattributed ledger. */
export declare function unattributedPath(projectRoot: string): string;
/**
 * Newest cursor recorded for a session across the given ledger files
 * (instance ledgers plus unattributed — design §2.4). "Newest" is by entry
 * timestamp; ties resolved by later coverage.to.
 */
export declare function newestCursor(session_id: string, ledgerPaths: string[]): string | null;
/** A cost entry with its counted weight after precedence reduction. */
export interface WeightedEntry {
    entry: CostEntry;
    /** 0..1 — fraction of this entry's units that count toward totals. */
    weight: number;
}
/**
 * Apply read-time fidelity precedence: each entry's weight is the fraction
 * of its coverage window not overlapped by higher-fidelity coverage for the
 * same session. `session_id: null` entries always count in full. `unknown`
 * entries carry no units and get weight 0.
 *
 * Linear sweep over per-session sorted window lists — O(n log n).
 */
export declare function applyPrecedence(entries: CostEntry[]): WeightedEntry[];
/** Sum weighted units per model (tokens) and total credits. */
export interface UsageTotals {
    tokens: Map<string, {
        input: number;
        output: number;
        cacheRead: number;
        cacheWrite: number;
    }>;
    credits: number;
    fidelityWeights: Record<CostFidelity, number>;
}
export declare function totalUsage(weighted: WeightedEntry[]): UsageTotals;
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