/**
 * src/lanes/ndjson.ts — incremental NDJSON stream parser into ChildResult.
 *
 * Ported from the harness NDJSON buffering / `processLine` (child-runner.ts
 * cr:396-433), mirroring the stdin-spike event order:
 *   session -> agent_start -> turn_start -> message_start -> message_update*
 *   -> turn_end -> agent_end -> agent_settled.
 *
 * Semantics (per the spike verdict):
 *   - message_update + assistantMessageEvent.text_delta streams output;
 *   - message_end + role assistant sets final output / stopReason / model;
 *   - agent_end + messages array refines output from the last assistant msg;
 *   - agent_settled marks the TERMINAL SUCCESS marker (the last NDJSON line).
 *
 * Pure module: zero @earendil-works/* imports, zero child_process, zero fs.
 */
import type { ChildResult } from "../core/types.js";
export interface NdjsonParserOptions {
    /** Incremental update callback (result mutated before each emit). */
    onUpdate?: (result: ChildResult, info?: NdjsonUpdateInfo) => void;
}
/** Why onUpdate fired, so consumers (LanePool) can classify the update. */
export interface NdjsonUpdateInfo {
    kind: "text" | "turn" | "action";
    /** Streamed delta for kind="text". */
    text?: string;
    /** `name(args)` toolCall summary for kind="action". */
    action?: string;
}
/** Max chars of serialized toolCall arguments kept in an action summary. */
export declare const TOOL_CALL_ARGS_MAX_CHARS = 80;
/**
 * Summarize one assistant content toolCall part as `name(args)` with the
 * serialized arguments truncated (~80 chars). Accepts both the pi nested
 * shape `{ type: "toolCall", toolCall: { name, arguments } }` and a flat
 * `{ type: "toolCall", name, arguments }` fallback.
 */
export declare function toolCallSummary(part: Record<string, unknown>): string;
/**
 * Streaming NDJSON line parser. Feed chunked stdout via `push`, then `flush`
 * after close to drain any trailing unterminated line.
 */
export declare class NdjsonStreamParser {
    readonly result: ChildResult;
    private buffer;
    private finalText;
    /** Previous assistant message_end usage snapshot (delta accumulation base). */
    private lastUsage?;
    /** True once any usage-bearing event was applied (agent_end fallback guard). */
    private sawUsage;
    private readonly onUpdate?;
    /** True once `agent_settled` has been observed (terminal success marker). */
    settled: boolean;
    constructor(result: ChildResult, options?: NdjsonParserOptions);
    /**
     * Accumulate one usage snapshot with DELTA semantics (B4 anti-
     * double-counting). The child pi re-encodes the whole conversation each
     * turn, so consecutive message_end usage snapshots are CUMULATIVE for
     * input/cache: summing them directly would re-count the growing context
     * (benchmark pi-small-dense §1.4/§3.2). Run totals therefore accumulate
     * `max(0, current - previous)` per field, which equals the LAST cumulative
     * snapshot for monotonic counters. `contextTokens` keeps the OTHER
     * semantics — current context size — as the LAST totalTokens snapshot
     * (overwritten, never summed; pi9 activity.ts:111-119).
     */
    private applyUsageDelta;
    /** True once the terminal `agent_settled` marker was parsed. */
    get hasSettled(): boolean;
    push(chunk: string): void;
    /** Drain any trailing unterminated (non-empty) buffer line. */
    flush(): void;
    private processLine;
}