/**
 * Trend-delta computation for log10x_top_patterns envelope.
 *
 * Produces a compact, pre-rendered TrendDelta per pattern row, driven
 * entirely from the existing state field + the 24h trend array already
 * fetched in Phase 2. No new Prometheus queries.
 *
 * Design contract:
 *   GROWING   → glyph ↗, scope 'wow', pct change from first half vs second half of trend array
 *   SHRINKING → glyph ↘, scope 'wow', signed negative pct
 *   STABLE    → glyph ─, scope 'wow', small pct near 0
 *   ACUTE     → glyph 🔥, scope 'h1', last 6 buckets vs prior 6 buckets
 *   NEW       → glyph 🆕, scope 'age', floor(firstSeenAgeSeconds / 86400) days
 *
 * Edge cases:
 *   - empty or single-point trend array  → value: 0, label: '—'
 *   - null firstSeenAgeSeconds for NEW   → value: 0, label: '—'
 */
import type { Badge } from './top-patterns-extras.js';
export type TrendDelta = {
    glyph: '↗' | '↘' | '─' | '🔥' | '🆕';
    value: number;
    unit: 'pct' | 'days';
    scope: 'wow' | 'h1' | 'age';
    /** Pre-rendered short label, e.g. '+45% WoW', '+220% 1h', '3d'. */
    label: string;
};
/**
 * How the age was sourced for a NEW pattern's display string.
 *   'engine_metric'          — firstSeenAgeSeconds came from the first-seen TSDB query
 *   'derived_from_trend_window' — age derived from trend array length × step seconds
 *   'unknown'                — neither source was available
 */
export type FirstSeenAgeSource = 'engine_metric' | 'derived_from_trend_window' | 'unknown';
/**
 * Build the pre-composed display string for a TrendDelta row.
 *
 * For GROWING/SHRINKING/STABLE/ACUTE: "${glyph} ${label}"
 * For NEW with known engine age: "🆕 Xh ago" / "🆕 Xd ago"
 * For NEW with unknown engine age but trend window available:
 *   derives max age from trendLength × stepSec and emits "🆕 <Nh ago" / "🆕 ~Nmin ago"
 * For NEW with no information: "🆕 (age unknown)"
 *
 * @param td             - The TrendDelta struct already computed by computeTrendDelta.
 * @param ageSeconds     - firstSeenAgeSeconds from the engine metric, or null.
 * @param trendLength    - Number of samples in the trend array (used for derivation).
 * @param stepSec        - Seconds per trend sample (e.g. 600 for 10-min buckets).
 */
export declare function fmtTrendDelta(td: TrendDelta, ageSeconds: number | null, trendLength: number, stepSec: number): {
    display: string;
    ageSource: FirstSeenAgeSource;
};
/** Map a Badge/State to its canonical glyph so glyph always matches state. */
export declare function glyphForState(state: Badge): TrendDelta['glyph'];
/**
 * Compute the trend delta for one pattern row.
 *
 * @param state        - The Badge/State already classified for this row.
 * @param trendArray   - Byte-rate values from the 24h trend query (up to 144 pts).
 * @param firstSeenAgeSeconds - Age in seconds, or null when unknown (used for NEW).
 */
export declare function computeTrendDelta(state: Badge, trendArray: number[], firstSeenAgeSeconds: number | null): TrendDelta;