The Librarian

Find the right memory. Show the evidence.

Replay mode Inbox Use cases & plugin Developers

The Archive ✦ — conversations

The selected pagespages the Librarian brings

No pages on the desk yet.

THE DEMO ABOVE USES REAL RECORDED REACTOR ANSWERS.Explore how it works ↓

How the Librarian works

An assistant that remembers months of conversations, and says so when it doesn't.

The Archive

~200 conversations, ~1.6M characters per person. Far too much for Reactor, which may read only a few pages per question.

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The Search

Local code: hybrid search + reranking picks the few pages that matter, and spots decoys about other people.

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III

Margin notes

Code lines up timelines, computes day gaps, marks the newest value and flags "this is your friend's cat, not yours".

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Reactor

Reactor reads the small dossier, answers and cites its pages, or says "not written in the archive".

Use case Find the right memory. Show the evidence.

The Librarian lights the candles…

INSIDE THE LIBRARY

A good answer has a history.

Back to the demo ↑

01 / THE PROBLEM

A whole archive.
A handful of useful pages.

Months of conversation hide the small details that matter. Some facts change. Some mentions belong to someone else. Some answers were never there.

The Librarian finds the relevant evidence, checks its context, and gives Reactor just the pages it needs.

200conversations per test archive1.65Mcharacters, approximatelyA fewpages selected per question

The tiny Librarian searches an enormous heap of books for one glowing page. — A library of near misses. One detail that answers your question.

02 / FROM QUESTION TO ANSWER

The journey of a memory.

01 / 05

The Librarian receives a question through a pneumatic tube.

THE QUESTION

First, a question.

A single fact may be buried in months of conversation. Start with what you want to remember.

Every replay above starts with a real question from the benchmark.

03 / FIVE SPECIALISED LENSES

Different questions need different reading.

Personal facts

What the user said about themselves, rather than someone else.

Advice & recommendations

What the assistant actually recommended in an earlier conversation.

Across conversations

Bring scattered facts together, then count or compare.

Things that changed

Read the timeline carefully. The latest relevant value wins.

Dates & durations

Find the right events. Let code do the date arithmetic.

04 / FOR DEVELOPERS

Give your own assistant this memory.

The Librarian at a switchboard, patching the library into machines outside it.

HTTP API

Works today

POST /api/pack question → cited pages
POST /api/ask question → Reactor’s answer
POST /api/upload your own archive

MCP server

Works today

The same memory as a tool for any MCP client: librarian67.pages.dev/mcp
recall search timeline ask_reactor
Connect Claude Code, Claude Desktop or Cursor →

Source code

Public at submission

The retrieval filter, with its Python and HTTP API. We have a business use case, but we share the code with the community.

AND WHEN THE ANSWER ISN’T THERE?

A good memory knows its limits.

Reactor can abstain instead of inventing an answer. The selected pages and citations stay open to inspection.

Try the demo ↑