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.

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Part 1 - Schema reference

An SL source is a YAML file under semantic-layer/<connectionId>/. The file's name: field is the source's identity — it mirrors the warehouse identifier verbatim (e.g. Snowflake's uppercase SIGNED_UP); the filename is only a derived label. Always address sources by name through the sl_* tools, never by file path. 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.

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)
    description: Total order revenue - filter by status or region at query time
columns:                    # computed dimensions only
  - name: is_large_order
    type: boolean
    expr: "amount > 1000"
column_overrides:           # metadata patches for inherited columns
  - name: status
    descriptions:
      user: "Order lifecycle status."
segments:
  - name: paid_non_refunded
    expr: "is_paid = true AND is_refunded = false"
joins:
  - to: customers
    on: "customer_id = customers.id"
    relationship: many_to_one