import type { DevtoolsLogLevel } from "./types.js";
/** Default measured window for the log ring; older lines are evicted, never grown. */
export declare const LOG_BUS_CAPACITY = 200;
/** Warnings and errors also land in their own ring, so an error is never pushed out by info traffic. */
export declare const LOG_BUS_SEVERE_CAPACITY = 64;
/** Longest kept message; a longer one is cut once, at write time. */
export declare const LOG_BUS_MESSAGE_MAX = 400;
/** One captured line: when, how bad, which system said it, and what it said. */
export interface LogBusEntry {
    at: number;
    level: DevtoolsLogLevel;
    /** Owning system tag, e.g. `needs`, `nav`, `render/culling`, `console`. */
    system: string;
    message: string;
}
/** Lifetime totals per level, plus how many lines the ring dropped. */
export interface LogBusCounts {
    log: number;
    info: number;
    warn: number;
    error: number;
}
/** Read-out of the log bus: newest-window entries, the warning/error ring, totals, and evictions. */
export interface LogBusSnapshot {
    entries: readonly LogBusEntry[];
    severe: readonly LogBusEntry[];
    counts: LogBusCounts;
    dropped: number;
    capacity: number;
}
/** Tunables for the log ring: capacity, the severity ring's capacity, and the clock. */
export interface LogBusOptions {
    capacity?: number;
    severeCapacity?: number;
    now?: () => number;
}
/**
 * A fixed-capacity ring of log lines tagged by owning system. `write` reuses a
 * preallocated slot — no array growth, no splice, no per-write object — so a hot
 * path can call it and only the message string (already built by the caller)
 * costs an allocation.
 *
 * @capability devtools-log-bus a bounded, per-system-tagged log ring a system writes to and a report reads
 */
export interface LogBus {
    write(level: DevtoolsLogLevel, system: string, message: string): void;
    /** Oldest-to-newest entries currently held. Allocates once per read. */
    list(): readonly LogBusEntry[];
    /** Warnings and errors only, oldest first. */
    severe(): readonly LogBusEntry[];
    counts(): LogBusCounts;
    dropped(): number;
    snapshot(): LogBusSnapshot;
    /** Empty every ring and counter, keeping the allocation. */
    reset(): void;
}
/** Create the bounded log bus the devtools log facade writes through. */
export declare function createLogBus(options?: LogBusOptions): LogBus;