Method check

src/agent/read-ledger.ts:95–101

* Pure gate decision for ONE existing file about to be mutated. * `currentMtimeMs` is the file's mtime on disk right now (caller stats it). * Non-existent files never reach this check (creation is always allowed).

(absPath: string, currentMtimeMs: number)

   * Non-existent files never reach this check (creation is always allowed).
   */
  check(absPath: string, currentMtimeMs: number): GateVerdict {
    const recorded = this.seen.get(absPath);
    if (recorded === undefined) return { ok: false, kind: 'unread', path: absPath };
    // Allow a small clock-precision slack (some filesystems round mtime).
    if (currentMtimeMs > recorded + 1) return { ok: false, kind: 'stale', path: absPath };
    return { ok: true };
  }

  size(): number {
    return this.seen.size;