Glossary

This glossary gives one meaning to each technical term in the Library documentation. The first use of a term in a document also gives a short explanation when necessary.

Context and model terms

Term	Meaning in this project
Agent	Software that uses a model, tools, and stored state to do a task.
Artificial intelligence (AI)	Software that does tasks that usually need human reasoning or language skills.
Compaction	A process that replaces older conversation text with a shorter form. The shorter form can omit details.
Context	Information that the model can use for one request. Context can include instructions, messages, and retrieved text.
Context window	The maximum number of tokens that a model can accept for one request.
Model	Software that reads an input and produces an output. This project usually uses a language model.
Prompt	The complete input that an application sends to a model.
Token	A small unit of text that a model reads. A token can be a word, part of a word, or punctuation.
Token budget	The maximum number of tokens that one part of a prompt can use.

Library terms

Term	Meaning in this project
Backing store	Durable storage that keeps data when the process stops. SQLite is the Library backing store.
Book	The public name for one context record. A book is not a second database entity.
Catalog	The stored set of records and their descriptive data.
Collection	A named project boundary in one Library database. The code also uses namespace for this value.
Context event	One ordered message or item in a governed thread. SQLite keeps the complete event.
Context record	One indexed unit that retrieval can find. The public documentation calls this unit a book.
Governor	A component that records events and builds a bounded prompt for each model call.
Library runtime	The process-owned services for one database. These services include workers, caches, and reading desks.
Protected event	An event that remains eligible for prompt assembly until a caller releases it. A token budget still limits the prompt.
Reading desk	The bounded set of retrieved books for one thread and subject. The model sees the desk context, not the full catalog.
Recent ring	An ordered in-memory list of recent thread events. Count and token limits bound this list.
Semantic paging	Selection of protected, recent, and relevant context for one bounded prompt. The complete source stays in durable storage.
Session ID	A stable identifier that an application gives to one chat thread.
Thread	One ordered chat or agent work stream.
Thread key	The pair ThreadKey(collection, session_id). This pair identifies one thread inside one collection.
Working set	The context that is ready for immediate use. A reading desk is a retrieval working set.

Storage and retrieval terms

Term	Meaning in this project
Approximate nearest-neighbor search (ANN)	A vector search method that reduces work by returning likely matches. It can omit a relevant match.
Cache	Disposable storage that gives faster access to data that another source can restore.
Chunk	One part of a larger document. The Library indexes chunks as separate records.
Embedding	A list of numbers that represents the meaning of text for vector search.
Embedder	A component that changes text into an embedding.
Full-text search (FTS)	Search that finds records from the words in their text. SQLite FTS5 supplies this function.
Hybrid retrieval	Search that combines full-text scores and vector scores.
Index	Data that helps a search find records without reading all source text in sequence.
Least-frequently-used policy (LFU)	A cache rule that removes items with the lowest use count.
Least-recently-used policy (LRU)	A cache rule that removes items that have not been used for the longest time.
Metadata	Structured descriptive data about an event or record. Metadata is not the record text.
Redis	An optional in-memory data service. The Library uses Redis only as a disposable local cache.
Retrieval	The process that finds stored records for a subject or query.
Retrieval-augmented generation (RAG)	A design that gives retrieved source text to a model before the model produces an answer.
SQLite	The embedded database that stores the authoritative Library data in one file.
Vector search	Search that compares embeddings to find text with a related meaning.
Write-ahead log (WAL)	A SQLite file that records database changes before SQLite adds them to the main database file.

Runtime and recovery terms

Term	Meaning in this project
Atomic operation	An operation that completes all of its durable changes or completes none of them.
Broker	A service that stores or routes messages between producers and consumers. Redis cache is not the Library broker.
Daemon	A long-running local process that owns one Library database and serves local clients.
Durable	Able to remain after a process stops or a cache loses its data.
Idempotent operation	An operation that has the same durable result when a caller repeats it with the same identity and content.
Lease	A time-limited claim that gives one runtime owner the right to process an outbox event.
Outbox	A SQLite table of durable indexing work. An event and its outbox item enter SQLite in one atomic operation.
Quarantine	A terminal state for work that failed too many times. An operator can inspect and retry the work.
Ring buffer	A bounded in-memory queue or ordered list. SQLite remains the recovery source when the work ring is full.
Watermark	A sequence number that shows the last event that reached a processing stage.
Worker	A runtime task that processes queued work. The Library uses a fixed number of indexing workers.

Interface and security terms

Term	Meaning in this project
Application programming interface (API)	A defined set of operations that software can call.
Authentication	A check that verifies the identity or credential of a caller.
Authorization	A decision that permits or refuses an operation for an identified caller.
Command-line interface (CLI)	A program interface that accepts commands in a terminal.
Hypertext Transfer Protocol (HTTP)	The request and response protocol that the local daemon uses.
Model Context Protocol (MCP)	A protocol that lets an agent host call external tools and read their results.
Scope	A record visibility rule. The Library has thread, project, and trusted team scopes.
Standard input and output (STDIO)	Process streams that an MCP host uses to communicate with a local tool server.
Transport	The method that moves requests and responses between a client and a service.
Transport Layer Security (TLS)	A protocol that encrypts and authenticates network connections. The loopback daemon does not supply TLS.

Measurement terms

Term	Meaning in this project
Non-functional requirement (NFR)	A measurable quality requirement, such as latency, capacity, or recovery time.
Recovery point objective (RPO)	The maximum amount of committed data that a failure is permitted to lose.
Recovery time objective (RTO)	The maximum time that recovery is permitted to take.
Resident set size (RSS)	The amount of physical memory that an operating system assigns to a process.
Service-level objective (SLO)	A measurable target for service behavior during a stated workload and time period.