/**
 * Budget-Aware Principle Selection
 *
 * Phase: PRI-75 Prompt Injection SDK Migration Phase 2
 *
 * Pure functions for selecting and formatting principles within a character budget.
 * No I/O dependencies — suitable for any host.
 */
import type { PrinciplePriority } from '../runtime-v2/types/principle-enums.js';
/**
 * Minimal principle shape required for injection selection.
 * Accepts both evolution-types.Principle and principle-tree-schema.Principle.
 */
export interface InjectablePrinciple {
    id: string;
    text: string;
    /** Priority level. Defaults to 'P1' if not set by the source. */
    priority?: PrinciplePriority;
    /** ISO date string. Required for recency ordering in selectPrinciplesForInjection. */
    createdAt: string;
}
/**
 * Result of principle selection for injection.
 */
export interface PrincipleSelectionResult {
    /** Selected principles in injection order (priority-first, then recency) */
    selected: InjectablePrinciple[];
    /** Total character count of selected principles' formatted output */
    totalChars: number;
    /** Number of principles by priority tier */
    breakdown: {
        p0: number;
        p1: number;
        p2: number;
    };
    /** Whether at least one P0 principle was included */
    hasP0: boolean;
    /** Whether the selection was truncated due to budget */
    wasTruncated: boolean;
}
/**
 * Format a single principle for injection.
 * Returns the formatted string including ID and text.
 *
 * Format: "- [ID] text" (matches existing prompt.ts format)
 */
export declare function formatPrinciple(p: InjectablePrinciple): string;
/**
 * Select principles for prompt injection within a character budget.
 *
 * Algorithm:
 *  1. Sort all principles by priority (P0 > P1 > P2), then by recency
 *  2. Iterate through sorted principles, accumulating character count
 *  3. Stop when adding the next principle would exceed budgetChars
 *  4. Ensure at least one P0 principle is included (even if it exceeds budget)
 *
 * @param principles - All available principles to select from
 * @param budgetChars - Maximum character budget for formatted output
 * @returns Selection result with chosen principles and metadata
 */
export declare function selectPrinciplesForInjection(principles: InjectablePrinciple[], budgetChars: number): PrincipleSelectionResult;
/**
 * Default character budget for principle injection.
 * 4000 characters is ~800 tokens, leaving ample room for other prompt sections
 * within the 10K character injection limit.
 */
export declare const DEFAULT_PRINCIPLE_BUDGET = 4000;
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