/**
 * How large is the context this session is carrying, and is it over budget?
 *
 * 91% of what an AIDLC project spends on inference is cache traffic — re-reading
 * the same conversation prefix, turn after turn. Measured over 20,920 attributed
 * ledger records, the average carried prefix grows monotonically through the
 * lifecycle: 80k tokens in ideation, 164k in requirements, 259k in implementation,
 * 395k in deployment, 791k in maintenance. The `complete` phase does comparable
 * work at 76k for one reason — it runs in its own session.
 *
 * So a phase boundary is a free context reset, and this is how a phase skill checks
 * whether it should have taken one.
 *
 * **Reads the transcript, not the ledger.** The question is asked at a phase
 * boundary, which is exactly when no capture has run recently and the ledger is
 * stale or empty — and it must answer on a machine where no cost hook was ever
 * installed, because this project already has a lesson about a capability whose
 * arming was manual and was therefore inert on arrival.
 *
 * Only token counts are read. No transcript content — no prompt text, no file
 * body, no tool output — is copied anywhere, so nothing here can leak a secret into
 * a report (NFR-4).
 *
 * Requirements: context-budget/AC-16, AC-17, AC-18, AC-19; NFR-4
 * Design: design.md Part 4 (D4.3, D4.4)
 *
 * @module
 */
import type { CostConfig } from './types.js';
import type { ProviderEnv } from './providers/provider.js';
export interface ContextReading {
    /**
     * Resident prefix at the most recent API call, in tokens — everything the model
     * had to be *given*. Null when no usage-bearing transcript line was found for
     * this project, which is an ordinary state (a fresh session that has not yet made
     * a call), not a failure.
     */
    residentTokens: number | null;
    /** Model of that call, for context. Null when unknown. */
    model: string | null;
    /** ISO timestamp of that call. Null when unknown. */
    at: string | null;
    /** The budget in force, from config or the measured default. */
    budgetTokens: number;
    /** True when `residentTokens` exceeds the budget. Always false when unmeasured. */
    overBudget: boolean;
    /** Transcripts belonging to this project that were considered. */
    transcriptsScanned: number;
    /**
     * Transcripts that could not be read through to the end.
     *
     * Counted rather than swallowed. A silent fail-soft here would report `unmeasured`
     * with no reason on a machine where every transcript is unreadable, which looks
     * identical to a fresh session — and "an unmeasured reading with no explanation" is
     * the shape of failure this project has already paid for once. SOC 2 CC7.2 asks the
     * same thing of any failure path: record it with enough context to notice.
     */
    transcriptsUnreadable: number;
}
/** The budget in force: config when set to a positive number, else the measured default. */
export declare function contextBudget(config: CostConfig | null): number;
/**
 * Read resident context for this project's most recent API call.
 *
 * Scopes to this repository via `projectClaudeCodeRecords`, which resolves each
 * transcript's `cwd` to a git common dir rather than comparing path prefixes — the
 * transcript root holds every project this machine has ever worked on, and a
 * prefix match once put 711 entries of another repository's work into this one's
 * ledgers.
 */
export declare function readContext(projectRoot: string, config: CostConfig | null, env?: ProviderEnv): Promise<ContextReading>;
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