Architecture

This chapter describes how ELS Compass is built and how a request travels through it, from an uploaded file to a cited answer.

The material comes from the backend engineering documentation and tracks the implementation as it stands. Where a page and the running code disagree, the code wins and the page needs updating.

Page	What it covers
Overview	Layered structure, composition root, storage split, startup behaviour, request flow diagram.
Request routing	How an incoming question is classified and routed.
Document ingestion	The ingestion pipeline stage by stage, the durable job runner, and the catalog and retrieval-pyramid projections.
Chunking	Chunk layers, section ordinal metadata, extractive and abstractive summaries.
Answering	Conversation orchestration, Creative and Grounded evidence regimes, workload planning, retrieval, reranking, answer publication.
Model coordination	Shared model placement, leases and residency state across processes and nodes.
Document lifecycle	Document states, allowed transitions, reprocessing rules.
Workspace and conversation governance	Workspace lifecycle, conversation boundary, archive and delete rules.
Design decisions	Implementation choices that matter today, plus deliberate deferrals.