/**
 * Lean-change rules for spawn prompts and the `cleo lean` verbs (T13422, T13663).
 *
 * The core rules of the `ct-lean` skill (adapted from Ponytail 5.1.0,
 * DietrichGebert, MIT), emitted at every spawn tier so workers that never load
 * the skill still get them. The skill holds the full text; this block is the
 * part a worker needs on every task.
 *
 * The rules run at a level (`off`, `lite`, `full`, `ultra`). The level
 * resolves from `CLEO_LEAN_LEVEL`, then the session-scoped level written by
 * `cleo lean level <l> --session`, then the `lean.level` config key, then
 * `full`.
 *
 * @task T13422
 * @task T13663
 */
import type { LeanLevel, LeanLevelSource } from '@cleocode/contracts';
/** Every lean level, in increasing strictness. */
export declare const LEAN_LEVELS: readonly LeanLevel[];
/** One-paragraph lean-change rule (level `full`); the full rules are in the `ct-lean` skill. */
export declare const LEAN_CHANGE_LINE = "Make the smallest complete change: skip anything nobody asked for (name it in one line); reuse a helper, contract or chokepoint already in the repo before writing new code; add no abstraction, option or dependency for later; fix a bug once at its root after grepping every caller; finish every caller, test and fixture the change breaks; leave one small test for new non-trivial logic. Never cut validation, data-loss error handling, security, privacy, evidence gates, type safety or the package boundary. End with one line on what you skipped or did not check. Full rules: the `ct-lean` skill.";
/**
 * Whether `value` (trimmed, any case) names a lean level.
 *
 * @param value - e.g. `process.env.CLEO_LEAN_LEVEL`.
 */
export declare function isLeanLevel(value: string | undefined | null): boolean;
/**
 * The lean rule paragraph for a level, or `null` for `off`.
 *
 * @param level - the resolved level.
 */
export declare function leanChangeLine(level?: LeanLevel): string | null;
/**
 * Build the `## Lean Change (ct-lean)` spawn-prompt block, or `null` at level `off`.
 *
 * @param level - the resolved level (default `full`).
 */
export declare function buildLeanChangeBlock(level?: LeanLevel): string | null;
/** A resolved lean level and where it came from. */
export interface ResolvedLeanLevel {
    /** The effective level. */
    readonly level: LeanLevel;
    /** Which layer set it. */
    readonly source: LeanLevelSource;
}
/**
 * Resolve the effective level from its layers: env, then session, then
 * config, then `full`. Unknown values are ignored.
 *
 * @param layers - the raw value of each layer.
 * @returns the level and its source.
 */
export declare function resolveLeanLevel(layers: {
    readonly env?: string | null;
    readonly session?: string | null;
    readonly config?: string | null;
}): ResolvedLeanLevel;
/** The session-scoped level file (gitignored by `.cleo/.gitignore`, deny-by-default). */
export declare function leanSessionFile(projectRoot: string): string;
/**
 * The session-scoped level, when it was set for `sessionId`. A level set in
 * another session is ignored, so it ends with the session that set it.
 *
 * @param projectRoot - the project root.
 * @param sessionId - the current CLEO session id, if known.
 */
export declare function readSessionLeanLevel(projectRoot: string, sessionId: string | null | undefined): LeanLevel | undefined;
/**
 * Set the level for one session only.
 *
 * @param projectRoot - the project root.
 * @param sessionId - the session the level belongs to.
 * @param level - the level.
 */
export declare function writeSessionLeanLevel(projectRoot: string, sessionId: string, level: LeanLevel): Promise<void>;
/**
 * `lean.level` from the merged global + project config, or `undefined` when
 * unset, invalid or unreadable.
 *
 * @param projectRoot - the project root.
 */
export declare function configuredLeanLevel(projectRoot: string): Promise<LeanLevel | undefined>;
/**
 * The effective level for a project and session: `CLEO_LEAN_LEVEL`, then the
 * session level, then `lean.level`, then `full`.
 *
 * @param opts - project root, session id and environment.
 */
export declare function effectiveLeanLevel(opts: {
    readonly projectRoot: string;
    readonly sessionId?: string | null;
    readonly env?: Readonly<Record<string, string | undefined>>;
}): Promise<ResolvedLeanLevel>;
/** Where `cleo lean level <l>` writes the level. */
export type LeanLevelScope = 'session' | 'project' | 'global';
/**
 * Persist a level: for one session (`session`, needs `sessionId`), or as the
 * `lean.level` key of the project or global config.
 *
 * @param opts - project root, level, scope and (for `session`) the session id.
 * @returns the level and scope written.
 * @throws Error when `scope` is `session` and no session id is given.
 */
export declare function setLeanLevel(opts: {
    readonly projectRoot: string;
    readonly level: LeanLevel;
    readonly scope: LeanLevelScope;
    readonly sessionId?: string | null;
}): Promise<{
    readonly level: LeanLevel;
    readonly scope: LeanLevelScope;
}>;
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