/**
 * writeSnapshot — write-side stage for Causal memory.
 *
 * Captures the current run's `(query, finalContent)` pair from
 * `scope.newMessages` (populated by the Agent's PrepareFinal stage),
 * embeds the query for retrieval, and persists a `SnapshotEntry` to
 * the store. Future turns can match new questions against past
 * queries via cosine similarity to replay decision evidence.
 *
 * Reads from scope:  `identity`, `turnNumber`, `newMessages`
 * Writes to store:   one `SnapshotEntry` per call, id = `snap-{turn}`
 *
 * Why per-turn (not per-iteration)?
 *   Causal memory captures TURN outcomes — "user asked X, agent said Y."
 *   Mid-iteration state isn't useful for cross-run replay.
 *
 * Turn derivation — collisions are impossible by construction:
 *   The effective turn is `max(scope.turnNumber, maxStoredTurn + 1)` where
 *   `maxStoredTurn` is the highest `snap-{n}` already live in THIS
 *   conversation's namespace (`identityNamespace(identity)` — the durable
 *   conversation anchor across `run()` calls, Agent instances, and
 *   processes). Rationale:
 *     - Hosts that track `turnNumber` correctly keep their numbering
 *       (`turnNumber: 5` → `snap-5`, gaps preserved).
 *     - Hosts with a stale counter (the Agent seeds `turnNumber = 1` on
 *       every run) still get a fresh, ordered id — turn 2 of the same
 *       conversation lands `snap-2` instead of silently replacing
 *       `snap-1`.
 *   Causal snapshots are decision evidence (audit/replay data): when
 *   "stale counter" and "deliberate same-turn rewrite" are
 *   indistinguishable, never destroying a prior turn's evidence wins.
 *   TTL-expired snapshots are ignored by the scan (same as every read).
 *
 * Empty-newMessages handling:
 *   When `newMessages` is empty (no final answer produced — e.g.
 *   pause-resume mid-flight), the stage no-ops. Re-runs after resume
 *   capture the snapshot then.
 *
 * @see ./types.ts          for the SnapshotEntry shape this writes
 * @see ./loadSnapshot.ts   for the read-side counterpart
 */
import type { TypedScope } from 'footprintjs';
import type { MemoryStore } from '../store/index.js';
import type { Embedder } from '../embedding/index.js';
import type { MemoryState } from '../stages/index.js';
export interface WriteSnapshotConfig {
    /** The store to persist the snapshot to. */
    readonly store: MemoryStore;
    /**
     * Embedder used to vectorize the query for later cosine-search.
     * Required — Causal memory's value comes from semantic retrieval
     * across past runs.
     */
    readonly embedder: Embedder;
    /**
     * Stable id for the embedder. Stored on the entry so a later
     * embedder swap doesn't cross-pollute similarity scores.
     * Default: `'unknown-embedder'` — pass an explicit id when you
     * may swap embedder instances over time.
     */
    readonly embedderId?: string;
    /**
     * TTL in milliseconds — drop snapshots after this duration. Useful
     * for compliance ("delete causal trace after 30 days").
     */
    readonly ttlMs?: number;
    /**
     * Tier to tag the snapshot with — typical: `'hot'` for current,
     * `'warm'`/`'cold'` for archived. Read stages can filter by tier.
     */
    readonly tier?: 'hot' | 'warm' | 'cold';
}
export declare function writeSnapshot(config: WriteSnapshotConfig): (scope: TypedScope<MemoryState>) => Promise<void>;
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