/** Pure: the lineage-ROOT id from a chunk of transcript JSONL — Claude Code's
 *  snake_case `session_id`. Returns the first match, or null. */
export declare function rootIdFromChunk(chunk: string): string | null;
/** Pure: the session (own) id from a transcript FILENAME, or null. */
export declare function idFromTranscriptName(name: string): string | null;
/** Pure: among transcript candidates `{id, mtime, root}`, the one to FOLLOW —
 *  the newest whose lineage `root` matches `myRoot` and whose own `id` differs
 *  from the id we currently tail — or null when none qualifies.
 *
 *  Same-lineage only (root match) so a sibling agent sharing the cwd is never
 *  adopted. Newest so a multi-step fork chain (A→B→C, all rooted at A) jumps
 *  straight to the live tip rather than to an intermediate frozen file. */
export declare function forkTarget(candidates: {
    id: string;
    mtime: number;
    root: string | null;
}[], tailId: string, myRoot: string): string | null;
/** Read the lineage-root of a transcript file (bounded head read — the snake
 *  `session_id` appears on the early carried/user records). null on any error.
 *  Head-only because a live transcript can be many MB and we only need one id. */
export declare function rootIdOfFile(file: string, maxBytes?: number): string | null;
/**
 * Scan the directory of `myFile` for a live fork of the session rooted at
 * `myRoot` that we currently tail as `tailId`. Returns the new id, or null.
 *
 * Only files strictly NEWER than `myFile` are parsed for their root: the fork
 * post-dates the freeze of the file we read, and while the agent works normally
 * ITS file is the newest, so the common no-fork case costs one readdir + a stat
 * per sibling and never opens a transcript. `[]`/no match → null.
 */
export declare function detectFork(myFile: string, tailId: string, myRoot: string, 
/** Ids we have already tailed and left. A dead transcript's mtime should never
 *  advance, but if it ever did (an external touch, a manual resume) we must not
 *  oscillate back onto it — so a followed id is excluded from then on. */
seen?: ReadonlySet<string>): string | null;