Peek feature (originally "any lookahead ability?")

Since as outside users of the ink-engine as middleware we are likely to find outselves parsing output from its stories as possible commands it would be nice to have a lookahead function (as parsers like to have :-) ). Is there any look ahead capacity? Rather then being forced to "eat" content from the ink-engine to look ahead?
Obviously I can build my own buffer but just wanted to know if any was available or planned.
Thank you.

No files, tests, or entry points are named. Start by reviewing the ink-engine output interface and the five-comment discussion to determine whether lookahead already exists; the work is complete when the supported behavior and its non-consuming semantics are documented or agreed upon.

Written by the indexing model from the issue text.