Semantic-model annotations

Annotations are native TMDL declarations. Weaver recognizes the following seven names in its reserved namespace. Unknown names in Weaver are errors; annotations in an undefined project namespace remain native. Names are dispatched exactly, not repaired or normalized. Built-ins run on the final composed model, with located file/line diagnostics.

Annotation	Scope	Value	Phase/effect
Weaver.Source	table	canonical managed relation	schema; lineage, and source generation when no partition is authored
Weaver.BaseSemanticModels	model	one local model name per non-blank line	composition directive, not a handler
Weaver.MeasureTable	table	exactly true	schema; calculated measure selector table
Weaver.Switch	measure	one measure reference per non-blank line	post-schema; generated value and dynamic format expressions
Weaver.AutoHideColumns	model or table	one case-sensitive glob per non-blank line	post-schema; sets matching columns' isHidden
Weaver.AutoHideForeignKeys	model	exactly true or false	post-schema; hides relationship many-side columns when true
Weaver.Exclude	table or column	exactly true or false	post-schema; removes the addressed object when true

Omission means the transformation is not requested. Boolean false is a no-op for ForeignKeys and Exclude, not an instruction to reverse an earlier native edit. A local false can replace shared policy before execution. These annotations are not a general security policy or a runtime service dependency; executing them again requires Weaver.

Weaver.Source

table Deliveries
    annotation 'Weaver.Source' = Warehouse/Operations/Parcel.Deliveries

The value must be Warehouse/<item>/<schema>.<object> or Lakehouse/<item>/Tables/<schema>.<object>. Lakehouse Files and bare or workspace-qualified relation names are unsupported. The annotation declares the source relation and managed lineage; it does not itself load that relation.

For a table with authored partitions, Weaver retains the native partition, mode and authored column types. The declaration provides lineage and available descriptions; it does not broadly replace M or generate every source column. Known lineage can be declared without a catalogue for a known source item, but managed-source metadata generation is a separate boundary.

For a table without an authored partition, Build needs resolved source endpoint and column metadata. Build the managed source first, then the model with catalogue integration. Source columns are generated and refined by authored columns, matched by sourceColumn or name. An unmatched authored column must be calculated. Unsupported source types fail; source housekeeping audit/signature columns are omitted unless explicitly authored. Existing table/column descriptions win; otherwise available source descriptions/notes fill them. There is no Weaver.IncludeDescriptions annotation.

Generated partitions use M navigation in a model with defaultMode: import; otherwise the generation path supplies Direct Lake entity partitions. Their shared SQL expression is reused for tables reading the same item. Direct Lake still needs its service/capacity/source prerequisites. A source annotation is not a grant of credentials. See source mapping.

Weaver.BaseSemanticModels

model Model
    annotation 'Weaver.BaseSemanticModels' =
        Foundation
        Measures

Non-blank lines name local definitions in the same Power BI group, optionally double quoted. Raw bases merge in listed recursive order before the final policy and overlay. Missing/non-local bases, self-reference, cycles and repeated ancestors fail. This does not select a physical base for deployment or inherit base validations. See composition precedence.

Weaver.MeasureTable

table 'Measure selector'
    annotation 'Weaver.MeasureTable' = true

Use a bare table. This creates an Import calculated partition from INFO.VIEW.MEASURES() with string columns Measure name, Expression, Format string definition, Description, Display folder, Table and Data category. It retains separately authored visibility. Ordinary DataType and FormatString projections are not generated. false is rejected.

An authored partition cannot be replaced. The only permitted existing partition is the exact generated same-name calculated partition with the generated expression. Native DAX/function availability and refresh remain service requirements.

Weaver.Switch

ref table Metrics
    measure 'Selected measure' = 0
        annotation 'Weaver.Switch' =
            Metrics[Delivery count]
            Metrics[Late count]

Exactly one table in the completed model must carry Weaver.MeasureTable. Each reference is Table[Measure] (native quoted table names allowed) or a unique unqualified measure name, optionally bracketed. Lookup ignores case. At least one reference is required.

The generated value expression switches on SELECTEDVALUE('<selector>'[Measure name]). The dynamic format expression switches by the same measure-name labels, taking a referenced measure's usable dynamic format or its static formatString. Missing/ambiguous references, duplicate selector labels, references to another Switch measure and measure-context-dependent formats (SELECTEDMEASURE, SELECTEDMEASURENAME, SELECTEDMEASUREFORMATSTRING, ISSELECTEDMEASURE) fail. Qualified references do not permit two identical selector labels from different tables.

This generates a measure, not a calculation group. Shared native calculation groups can be authored in TMDL; no built-in calculation-group annotation is supplied.

Weaver.AutoHideColumns

model Model
    annotation 'Weaver.AutoHideColumns' =
        *Key
        Internal*

At model scope all tables are inspected; at table scope only that table. Values are newline-separated non-empty, case-sensitive native glob patterns (*, ?, bracket classes), not regular expressions. Matches receive isHidden = true; non-matches are not unhidden. It runs after source generation so inferred columns can match too.

Weaver.AutoHideForeignKeys

model Model
    annotation 'Weaver.AutoHideForeignKeys' = true

When true, native relationship cardinality selects each many-side column. Omitted cardinalities default to from=many, to=one. Both many sides of a many-to-many relation may be hidden. An unaddressable many-side endpoint fails with the relationship name. A model without relationships has no column to change. This is visibility, not RLS/OLS.

Weaver.Exclude

ref table Deliveries
    ref column InternalKey
        annotation 'Weaver.Exclude' = true

When true, deletes the table or column and its native references. Exclusion is checked as absence on deployed readback; source inference does not reintroduce an excluded generated column. Removing an object can leave unrelated authored DAX references invalid; verify the final model. false retains the object but does not recreate something absent from the composed source. Exclusion is not a substitute for permissions or security validation.

See Python extension API for custom namespaces, trusted-code boundaries and schema/post_schema ordering.