Threads
What you are working on right now, as opposed to everything you have ever done.
An origin says where it was written. A memory says one fact. A thread is what sits between them: one piece of work, the debugging run, the feature, the conversation.
Without it, every retrieval competes against a project's entire history, and something you decided twenty minutes ago ranks no higher than something from March.
You do not manage them
Threads open by themselves on the first thing a tool records, stay joinable for a couple of hours of quiet, and take their name from the first thing said in them. Two hours because that is what a working thread actually looks like, lunch, a meeting, a context switch and back.
Different tools get different threads. Cursor open alongside a browser chat is two pieces of work, and treating them as one would boost each into the other's results.
Browser chats are threads
A chat carries its own conversation id, so reopening that tab next week rejoins the same thread rather than starting a fifth.
What they change
Retrieval boosts the current thread rather than filtering to it. Current work wins ties; older context still appears when it is genuinely the better answer. Starting fresh never hides what the project already knows.
Picking up where you left off
Ask any connected tool what you were working on, and it can load a thread's history in the order it happened, which is a different question from "what is relevant to this query", and one ordinary search cannot answer.
The dashboard's Threads view shows the same thing, newest first.