Checkpoint
One last thing before we move on. Same surface as a write step — but the lesson doesn't complete until this passes.
Finish the analysis loop: slice, rank, then pull the reading list. Group the (segment, input_id, correct) rows, print the per-slice table worst-first (f"{s:<8} {acc:.0%} (n={n})"), then print f"worst slice: {name}" and the failing input ids from that slice as "failures to read: [...]" — because the table produces guesses and the examples produce fixes.