Why every sentence gets a receipt

When we started Lanternfish, the question we kept hearing was not "can it find the answer?" It was "how do I know it is right?" A fluent answer with no trail behind it is worth very little to a team that has to act on it. So we built the product around one rule: every sentence ends with a receipt.

What a receipt is

A receipt is a small numbered mark at the end of a sentence. Select it and you land on the exact passage the sentence was built from: a paragraph in a document, a message in a thread, a field in a ticket. The original opens in a side panel with the matching text highlighted, so you can compare the claim with its source without leaving the answer.

Receipts are not a bibliography at the bottom of the page. A list of ten sources under an answer tells you where the writer looked. It does not tell you which source supports which claim. Putting the mark on the sentence is what turns checking into one click instead of ten minutes of searching.

What it costs us, and what it buys you

Citing every sentence is a constraint, and it has a cost. Some answers come back shorter than you might like, because a sentence that cannot be traced to a source does not get written. When Lanternfish needs a connecting sentence between two sourced facts, it marks that sentence as an inference, so you can see which parts are reading and which are reasoning.

We also say so when we find nothing. An empty answer usually means a connector is missing, or that the question names something nobody ever wrote down. We would rather tell you that than fill the gap with a guess that sounds confident.

What it buys you is trust you can pass along. A cited answer can be shared. When a colleague asks "where did that come from?", the reply is already attached. In reviews, in support threads and in planning meetings, people can argue about the decision instead of arguing about whether a number is real.

It also changes how people use the tool. Once checking is cheap, people check. The first few times you open a receipt, you are learning how far to trust the answer. After that you open them when the stakes are high, which is exactly the habit we hoped for.

What we are still working on

A receipt is only as good as the passage it points to. Long documents, scanned PDFs and threads with hundreds of replies are harder to pinpoint than a short note, and we keep improving how precisely a receipt lands. If one ever points somewhere it should not, flag it from the answer and we will look at it the same day.