Eng-council sweep: export hygiene, dead code, helper dedup, declare vega-expression

src/core/chart-builder.ts

@@ -34,8 +34,7 @@ export const MARK_TYPES = ['bar', 'line', 'point', 'area', 'circle'] as const;
 export type MarkType = (typeof MARK_TYPES)[number];
 
 /** The four Vega-Lite field types a channel may carry, in override-menu order. */
-export const FIELD_TYPES = ['quantitative', 'nominal', 'ordinal', 'temporal'] as const;
-export type FieldType = (typeof FIELD_TYPES)[number];
+export type FieldType = 'quantitative' | 'nominal' | 'ordinal' | 'temporal';
 
 /** The four encoding channels the builder offers, in display order (spec §06). */
 export const CHANNELS = ['x', 'y', 'color', 'size'] as const;
@@ -49,8 +48,7 @@ export type ChannelName = (typeof CHANNELS)[number];
  * reduce a quantitative field; min/max also order a temporal or ordinal one. See
  * `validAggregateOps` for the per-type menu.
  */
-export const AGGREGATE_OPS = ['count', 'distinct', 'sum', 'mean', 'median', 'min', 'max'] as const;
-export type AggregateOp = (typeof AGGREGATE_OPS)[number];
+export type AggregateOp = 'count' | 'distinct' | 'sum' | 'mean' | 'median' | 'min' | 'max';
 
 /**
  * Temporal granularities (Vega-Lite `timeUnit`), coarse → fine, with the combined
@@ -71,12 +69,10 @@ export const TIME_UNITS = [
 export type TimeUnit = (typeof TIME_UNITS)[number];
 
 /** Sort the categorical axis by its measure (spec §06 → Ranking). */
-export const SORT_ORDERS = ['ascending', 'descending'] as const;
-export type SortOrder = (typeof SORT_ORDERS)[number];
+export type SortOrder = 'ascending' | 'descending';
 
 /** Part-to-whole stacking for bar/area + a colour series: absolute vs 100%. */
-export const STACK_MODES = ['zero', 'normalize'] as const;
-export type StackMode = (typeof STACK_MODES)[number];
+export type StackMode = 'zero' | 'normalize';
 
 /**
  * Comparison operators a guarded filter predicate offers (Vega-Lite field
@@ -85,17 +81,7 @@ export type StackMode = (typeof STACK_MODES)[number];
  * `range`; a category offers membership (`oneOf`). `notEqual` is expressed as a
  * `{ not: { …equal } }` logical wrapper (Vega-Lite has no bare `!=` predicate).
  */
-export const FILTER_OPS = [
-  'equal',
-  'notEqual',
-  'lt',
-  'lte',
-  'gt',
-  'gte',
-  'range',
-  'oneOf',
-] as const;
-export type FilterOp = (typeof FILTER_OPS)[number];
+export type FilterOp = 'equal' | 'notEqual' | 'lt' | 'lte' | 'gt' | 'gte' | 'range' | 'oneOf';
 
 /** How a filter expresses its predicate: a guarded shelf, or a raw expression. */
 export type FilterMode = 'predicate' | 'expression';