The compactor
A small model, always running, that turns yesterday's verbatim turns into keyed notes.
Subtractive memory needs something doing the subtracting. That is the compactor — a cheap, fast, Haiku-class model that runs continuously beside the presence's route, independent of it. The route talks to you; the compactor tidies what falls behind.
What it does
- Extracts keywords from turns leaving the recent window and attaches notes to them — the raw salience signal.
- Condenses older verbatim turns into compressed notes: the words go, the meaning and its keys stay.
- Ages the fading tier — decrements timers, drops what expired.
- Resolves contradictions — folds a newer value onto an existing keyword.
What it never touches
| Protected | Why |
|---|---|
| recent turns | Recency is unconditional. The compactor only works behind the window, never inside it. |
| pinned content | A salient keyword is not rewritten or summarised away — only updated by a real contradiction. |
| standing instructions | Permanently pinned by preferences; outside the compactor's reach entirely. |
Why a small model
Three reasons it is deliberately not the main route:
- It runs constantly. Compaction on every presence, all the time, has to be cheap or it dominates cost.
- It is bounded work."Extract keys, compress, age timers" doesn't need frontier reasoning — it needs reliability.
- It must not interfere. A separate model can never slow or block your reply; compaction is always asynchronous.
Because it is route-independent, changing your routedoesn't change how memory is compacted. The presence's mind can change; its housekeeping stays constant.
Timing
Compaction is eventual, not instantaneous. A fact mentioned twice within the same window is recent on its own merit — it doesn't need the compactor to be known. The pin is reconciled shortly after, not in the reply path.
reply sent — immediate ↳ keywords extracted — seconds later ↳ older turns condensed — as the window advances ↳ timers aged, expiries dropped — continuously
So a fact you set and immediately ask about is always known; the seven-day decay is a property of the fading tier, not a delay in the compactor.