sl

# Semantic Layer KTX's semantic layer (SL) is a structured catalog. Each **source** represents a table, a SQL view, or an overlay that enriches a manifest-backed table with measures, computed columns, joins, and named segments. The catalog is the single source of truth for reusable business metrics. This skill covers two parts: - **Part 1** - Schema reference (what an SL source looks like). - **Part 2** - Querying via `sl_query`. Capture (when and how to add new patterns to the SL) is a separate concern handled by the memory-agent - see the `sl_capture` skill if you are running in capture mode. The research agent **reads** and **queries** the SL via the tools described here; it does not write to it. For capture-time identifier verification, load `sl_capture`. Synthesis writer skills must verify warehouse identifiers with `discover_data`, `entity_details`, and `sql_execution` before emitting table or column names. --- ## Part 1 - Schema reference An SL source is a YAML file at `semantic-layer/<connectionId>/<source_name>.yaml`. There are three flavors: ### Overlay sources Enrich a manifest-backed table with measures, computed columns, joins, and segments. No `table` or `sql` field. The base table's columns and grain are inherited from the manifest. ```yaml name: fct_orders # must match an existing manifest table descriptions: user: "Overlay adding business measures to the orders fact table." measures: - name: total_revenue expr: sum(amount) desc...