Trust, but verify the robot | KOM Cloud Service

Sunday was about speed. Monday was about trust. When the robot is answering in a third of a second and some Mastery pools hold a single attempt, the scariest thing is not a hard challenge. It is a change I made last night that quietly broke something I solved last week.

Day 8 before breakfast

The robot was on Day 8 by 07:59. A little too eager, actually: it started the day before I had said go, so that turned into a rule on the spot. Before any new backlog day, the robot asks me first, and an announced plan I have not answered is not a yes.

Day 8 itself went well. Lost in Translation, the script lane, was a pile of polyglot files (PHP, HTA, WSF) with 615 questions, and the Single Solve went 615 for 615 in one round. Entity Relations in warmups was HTML character references like N, which Python’s standard library reads in one call, with one trap: &hyphen; is a Unicode hyphen, not the plain ASCII one. What’s in the Box? was about zip archives storing full folder paths, so two files can share a name and live in different rooms.

A day of proving it

Then I spent most of the day doing something that does not show up on any board. I made the robot prove itself. Four separate reviewers read the whole codebase cold and ranked what they found, and every change after that had to show it broke nothing we had already solved. The checks that guard a scarce Mastery got their own review, five rounds of it. Round five still came back with problems, and I said what I meant: “We can’t let it go unfixed.” So we fixed them.

Swift Justice

The Day 8 binary was a good trick. The config blob the binary lane always hides was sitting inside a 67 MB statically linked Swift program, written out as base64 text. A raw scan for its magic header found nothing at all. The engine learned to search for the base64 and hex spellings of the header too.

At 21:21 the Mastery ran. 400 out of 400, CORRECT, 5.9 seconds of server time. 9th on the board. The leader was at 2.1 seconds, so there was plenty left to chase.

Calls I made on Monday

Call challenges by their names. Percent Chance, Node by Node, Routine Check. Not ids, not lane numbers. I want to read the logs like a scoreboard.
Once we hold 1st on a board, leave it alone. Reruns are for places we can still gain.
Time Trials prepare the Mastery. Big Time Trial pools are there to learn from. What gets protected is a correct, timed Mastery on the board.
And to the robot, on changes and builds: “you make the call on anything moving forward.”

At 23:07 it started Day 9. By 23:16 all five Single Solves were CORRECT. The script lane, All the World’s a Stager, went 695 for 695 on its very first try.

Tech tips

HTML entities as one family

Day 8’s warmups layer was HTML character references. Rather than parse H, H and H separately, hand the line to Python’s html.unescape(), which reads decimal, hex, zero padded and named forms in one call.

Base64 hidden in a string

Day 8’s Swift binary was 67 MB and stored its config as a Base64 string, so a scan for the raw magic bytes found nothing. The fix is to decode candidate text runs as Base64 at each of three alignments, plus URL-safe Base64 and hex, and scan the decoded bytes for the blob.

Decoys need three checks

Day 9’s Nim binary had two decoys carrying the same magic bytes: one in an error message, one followed by nothing but zeros. An empty blob even passes a CRC check, because CRC-32 of zero bytes is 0. The real blob was the Base64 one the Swift fix already knew how to find. What picks it: the magic, a matching checksum, and contents that actually parse.