/**
 * v2.3.0 Part C.3 — `peek_inbox_version` MCP tool handler.
 *
 * Pure observation. Returns the current mailbox shape for an agent:
 * `{mailbox_id, epoch, last_seq, total_messages_count, total_unread_count}`.
 * Callers use this to detect "anything new arrived since my last
 * observation" WITHOUT consuming messages (distinct from
 * `get_messages`'s default consume-once semantic). Intended for the
 * Phase 4s ambient-wake pattern — wake on a cheap peek, drain via
 * `get_messages` only when `total_unread_count > 0` or `epoch`
 * differs from the cached one.
 *
 * The wake signal is `total_unread_count`, NOT `last_seq` (v2.3.0
 * Codex HIGH #2 contract at src/db.ts:3014-3021). `seq` is assigned
 * on FIRST OBSERVATION — i.e., the recipient's get_messages drain
 * path at src/db.ts:3181-3199 runs UPDATE messages SET seq = ...
 * WHERE seq IS NULL — so `last_seq` doesn't advance on delivery
 * and won't reflect pre-first-observation new mail. Watching
 * `last_seq` alone will miss every fresh arrival.
 *
 * Auth model: same as `get_messages`. The dispatcher's enforceAuth
 * step handles token verification before we're called; this handler
 * trusts that gate.
 *
 * Epoch semantics (per Codex Q9 2026-04-19): a client's cached
 * `last_seen_seq` is only comparable if its cached epoch matches the
 * server's current epoch. Mismatch = DB was backed-up/restored; the
 * client MUST reset its local last_seen to 0 and drain from scratch.
 */
import type { PeekInboxVersionInput } from "../types.js";
export declare function handlePeekInboxVersion(input: PeekInboxVersionInput): {
    content: {
        type: "text";
        text: string;
    }[];
};
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