feat(editor): natural-language measurement inputs via @pascal-app/lingo

Type any unit into SliderControl / MetricControl fields — "6ft", "180cm",
"1m80", "5'11\"", "72in", "45°", "1.57rad" — and it canonicalizes to the
unit the field already stores (meters / degrees / radians / inches),
independent of the metric/imperial display toggle. A live "= 1.83 m" hint
previews the parsed value while typing.

Only the typed-text commit path changes: drag-scrub, wheel, and arrow-key
editing are untouched, and any unit the adapter doesn't recognise (%, unitless,
rad/s) falls back to Number.parseFloat, so nothing regresses. The shared
lib/measurement-parser.ts maps each field's `unit` prop to a lingo kind +
canonical unit, covering the auto-inspector and every custom panel at once.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

packages/editor/package.json

@@ -26,6 +26,7 @@
     "@dnd-kit/utilities": "^3.2.2",
     "@iconify/react": "^6.0.2",
     "@number-flow/react": "^0.6.0",
+    "@pascal-app/lingo": "^0.1.0",
     "@radix-ui/react-alert-dialog": "^1.1.15",
     "@radix-ui/react-context-menu": "^2.2.16",
     "@radix-ui/react-dialog": "^1.1.15",

packages/editor/src/components/ui/controls/metric-control.tsx

@@ -3,6 +3,11 @@
 import { useScene } from '@pascal-app/core'
 import { useViewer } from '@pascal-app/viewer'
 import { useCallback, useEffect, useRef, useState } from 'react'
+import {
+  lingoUnitSpec,
+  measurementHint,
+  parseMeasurement,
+} from '../../../lib/measurement-parser'
 import {
   getLinearUnitLabel,
   linearUnitToMeters,
@@ -229,14 +234,46 @@ export function MetricControl({
   }, [])
 
   const submitValue = useCallback(() => {
+    const spec = lingoUnitSpec(unit)
+    let stored = spec
+      ? parseMeasurement(inputValue, spec, {
+          bareUnit: isImperial ? 'ft' : spec.unitId,
+          system: isImperial ? 'us' : 'metric',
+        })
+      : null
+    if (stored === null) {
       const numValue = Number.parseFloat(inputValue)
-    if (Number.isNaN(numValue)) {
+      stored = Number.isFinite(numValue) ? toStoredValue(numValue) : null
+    }
+    if (stored === null) {
       setInputValue(toDisplayValue(value).toFixed(precision))
     } else {
-      applyCommittedValue(clamp(toStoredValue(numValue)))
+      applyCommittedValue(clamp(stored))
     }
     setIsEditing(false)
-  }, [inputValue, applyCommittedValue, clamp, toStoredValue, value, precision, toDisplayValue])
+  }, [
+    inputValue,
+    unit,
+    isImperial,
+    applyCommittedValue,
+    clamp,
+    toStoredValue,
+    value,
+    precision,
+    toDisplayValue,
+  ])
+
+  const spec = lingoUnitSpec(unit)
+  const hint =
+    isEditing && spec
+      ? measurementHint(inputValue, spec, {
+          bareUnit: isImperial ? 'ft' : spec.unitId,
+          system: isImperial ? 'us' : 'metric',
+          displayUnit: isImperial ? 'ft' : spec.unitId,
+          precision,
+          clamp,
+        })
+      : null
 
   const handleInputBlur = useCallback(() => {
     submitValue()
@@ -290,6 +327,11 @@ export function MetricControl({
       <div className="flex shrink-0 justify-end">
         {isEditing ? (
           <div className="flex items-center">
+            {hint && (
+              <span className="mr-1.5 shrink-0 whitespace-nowrap text-[11px] text-muted-foreground/50 tabular-nums">
+                {hint}
+              </span>
+            )}
             <input
               autoFocus
               className="w-full bg-transparent p-0 text-right font-mono text-foreground outline-none selection:bg-primary/30"

packages/editor/src/components/ui/controls/slider-control.tsx

@@ -2,6 +2,11 @@
 
 import { useScene } from '@pascal-app/core'
 import { useCallback, useEffect, useRef, useState } from 'react'
+import {
+  lingoUnitSpec,
+  measurementHint,
+  parseMeasurement,
+} from '../../../lib/measurement-parser'
 import { cn } from '../../../lib/utils'
 
 interface SliderControlProps {
@@ -199,16 +204,27 @@ export function SliderControl({
   }, [value, precision])
 
   const submitValue = useCallback(() => {
+    const spec = lingoUnitSpec(unit)
+    let parsed = spec ? parseMeasurement(inputValue, spec) : null
+    if (parsed === null) {
       const numValue = Number.parseFloat(inputValue)
-    if (Number.isNaN(numValue)) {
+      parsed = Number.isFinite(numValue) ? numValue : null
+    }
+    if (parsed === null) {
       setInputValue(value.toFixed(precision))
     } else {
-      const nextValue = clamp(Number.parseFloat(numValue.toFixed(precision)))
+      const nextValue = clamp(Number.parseFloat(parsed.toFixed(precision)))
       onChange(nextValue)
       onCommit?.(nextValue)
     }
     setIsEditing(false)
-  }, [inputValue, onChange, onCommit, clamp, precision, value])
+  }, [inputValue, unit, onChange, onCommit, clamp, precision, value])
+
+  const spec = lingoUnitSpec(unit)
+  const hint =
+    isEditing && spec
+      ? measurementHint(inputValue, spec, { displayUnit: spec.unitId, precision, clamp })
+      : null
 
   const handleInputKeyDown = useCallback(
     (e: React.KeyboardEvent<HTMLInputElement>) => {
@@ -279,6 +295,11 @@ export function SliderControl({
       <div className="flex items-center text-xs">
         {isEditing ? (
           <>
+            {hint && (
+              <span className="mr-1 shrink-0 whitespace-nowrap text-[10px] text-muted-foreground/50 tabular-nums">
+                {hint}
+              </span>
+            )}
             <input
               autoFocus
               className="w-14 bg-transparent p-0 text-right font-mono text-foreground outline-none selection:bg-primary/30"

packages/editor/src/lib/measurement-parser.ts

@@ -0,0 +1,116 @@
+import { type Kind, parseQuantity, quantity } from '@pascal-app/lingo'
+
+/**
+ * Natural-language measurement parsing for editor property fields, backed by
+ * `@pascal-app/lingo`. Lets a user type `6ft`, `180cm`, `1m80`, `5'11"`, `45°`
+ * or `1.57rad` into any measurement field and have it canonicalized to the
+ * unit the field stores its value in — independent of the metric/imperial
+ * display toggle.
+ *
+ * The editor stores linear values in meters and angular values in radians (a
+ * few fields store inches or degrees); lingo's `length` base is meters and its
+ * `angle` base is radians, so a field's `unit` prop already names the stored /
+ * canonical unit and doubles as the parse target.
+ */
+
+export interface LingoUnitSpec {
+  kind: Kind
+  /** Unit id the field's stored `value` is expressed in — the parse target. */
+  unitId: string
+}
+
+/**
+ * Map an editor field `unit` prop to a lingo kind + canonical unit. Returns
+ * `null` for units we deliberately do NOT natural-language-parse (plain
+ * numbers, percentages, angular rates, counts) so those keep exact
+ * `Number.parseFloat` behavior.
+ */
+export function lingoUnitSpec(unit: string | undefined): LingoUnitSpec | null {
+  switch (unit) {
+    case 'm':
+    case 'cm':
+    case 'mm':
+    case 'in':
+    case 'ft':
+      return { kind: 'length', unitId: unit }
+    case '°':
+    case 'deg':
+    case 'degrees':
+      return { kind: 'angle', unitId: 'deg' }
+    case 'rad':
+    case 'radians':
+      return { kind: 'angle', unitId: 'rad' }
+    default:
+      return null
+  }
+}
+
+export interface ParseMeasurementOptions {
+  /**
+   * Implied unit for a BARE number (e.g. `6` → `6 ft`). Defaults to the field's
+   * own `unitId`. A typed unit (`180cm`) is always honored regardless.
+   */
+  bareUnit?: string
+  /** Disambiguates gal/ton/cup families; harmless for length/angle. */
+  system?: 'metric' | 'us' | 'imperial'
+}
+
+/**
+ * Parse typed field text into the field's stored numeric unit. Returns `null`
+ * when the text can't be read as a quantity, so the caller can fall back to a
+ * plain number parse or revert to the previous value.
+ */
+export function parseMeasurement(
+  raw: string,
+  spec: LingoUnitSpec,
+  options: ParseMeasurementOptions = {},
+): number | null {
+  const result = parseQuantity(raw, {
+    kind: spec.kind,
+    unit: options.bareUnit ?? spec.unitId,
+    system: options.system,
+    strictness: 'forgiving',
+  })
+  if (!result.ok) return null
+  const value = result.quantity.to(spec.unitId).value
+  return Number.isFinite(value) ? value : null
+}
+
+export interface MeasurementHintOptions extends ParseMeasurementOptions {
+  /** Unit id the preview is rendered in (the field's displayed unit). */
+  displayUnit?: string
+  /** Max fraction digits in the preview. */
+  precision?: number
+  /**
+   * Clamp applied to the parsed stored value before previewing, so the hint
+   * reflects what a commit would actually store on a bounded field.
+   */
+  clamp?: (stored: number) => number
+}
+
+const PLAIN_NUMBER = /^[+-]?\d*\.?\d*$/
+
+/**
+ * A faint "= 1.83 m" preview of the value currently being typed, shown only
+ * when the user typed something beyond a plain decimal in the field's own unit
+ * (an explicit unit, a compound like `1m80`, or a number word) and it parses.
+ * Returns `null` when there's nothing useful to preview.
+ */
+export function measurementHint(
+  raw: string,
+  spec: LingoUnitSpec,
+  options: MeasurementHintOptions = {},
+): string | null {
+  const trimmed = raw.trim()
+  if (!trimmed || PLAIN_NUMBER.test(trimmed)) return null
+
+  const parsed = parseMeasurement(trimmed, spec, options)
+  if (parsed === null) return null
+  const stored = options.clamp ? options.clamp(parsed) : parsed
+
+  const displayUnit = options.displayUnit ?? spec.unitId
+  const precision = options.precision ?? 2
+  const q = quantity(stored, spec.unitId)
+  const shown = displayUnit === spec.unitId ? q : q.to(displayUnit)
+  return `= ${shown.format({ precision })}`
+}