The empty-folder bug: when our system decided on nothing, and nothing screamed.
By Himanshu Bhagat · Engineering notes · 6 August 2026 · Education, not advice
In short. In our paper phase, the system kept deciding with nothing in front of it, and every light stayed green. We caught it in review, before a single live order had been placed. We publish notes like this because "we test carefully" is a claim, and a failure we caught is evidence.
A watchman patrolling the wrong warehouse
A night watchman files an "all quiet" report every hour, and he has been guarding the wrong building, an empty one two plots away. Every report was true. Every report was also about nothing. Our system did that in its paper phase. It is meant to read the morning's list of listed names and choose from it, and it was reading an empty room instead.
Why the silence is the dangerous part
An absence is not bad data. It is no data, and from the inside it looks exactly like a quiet market rather than a disconnected microphone. Any automated strategy can go on deciding confidently over an empty room while the reports read all clear, which is the version of this that costs real money. The danger is not the outage. It is the calm.
What changed
A pre-launch review asked what the last decision had actually looked at, and the answer came back empty. Our first fix was worse than the bug: written the obvious way, it would have released the very safeguard that halts buying on stale data. That version died in review as well.
Today, if the morning's data does not arrive, new buying halts, existing positions are still managed, the check against the broker's own records still runs, and the journal says so out loud. Silence is a counted, visible event now, not an assumption of peace.
The paper phase did exactly its job, and a fictional month is a cheap price for a real one. The bug cost us nothing except pride.
P.S. The watchman now checks the address every single night.
These notes are general education about how we build, not investment advice or a recommendation. Investments in the securities market are subject to market risks. See the disclaimer and risk disclosure.