Smoke-sweep fixes: exact saves, local dates, safer remove, readable markers

- Garden and plant dialogs keep centimeters as the source of truth
  (LengthField in lib/units.ts): a no-change Save no longer rewrites
  900 cm as 899.922 or a 45 cm spacing as 44.958, bumping versions and
  writing bogus history entries on the way.
- The UI stamps every date with the browser's local day (lib/dates.ts).
  Journal notes already did; plop placement, fill and removal now do too,
  so a 9 pm placement isn't "planted tomorrow". The fill endpoint gained an
  optional plantedAt; API and agent callers still default to UTC today.
- Removing an object that holds plants asks first and says how many go
  with it. An empty one still goes straight away (one Undo restores it).
- The expanded plant card's action row wraps instead of clipping "Delete".
- Monogram lettering switches to a dark ink on pale marker colors (garlic,
  cabbage, marigold) instead of near-white on near-white.
- Copy-as-plan proposes the next free year and warns when the typed name
  already exists, so two gardens can't both read as "the 2027 plan".
- Plan cards show the base name with a "2027 plan" tag, so the year — the
  point of the name — survives truncation.
- A rejected model spec now says which model and why: a wrapped
  ErrInvalidInput's reason reaches the client as the 400's message, and the
  Settings field shows it inline instead of toasting "invalid input".

Also defuses a clock bomb in TestRemainingReturnsWhenAPlantingIsRemoved,
which only passed while the real date was before 2026-08-01.

Co-Authored-By: Claude Fable 5 <[email protected]>

web/src/components/gardens/GardenDialog.tsx

@@ -9,13 +9,15 @@ import { errorMessage } from '@/lib/api'
 import { conflictGarden, useCreateGarden, useUpdateGarden, type Garden } from '@/lib/gardens'
 import {
   cmFromFtIn,
+  convertDimensionField,
+  dimensionField,
   dimensionInputMode,
   dimensionUnitLabel,
+  editDimensionField,
   formatCm,
-  formatDimensionInput,
   isValidDimensionCm,
   MIN_GARDEN_GRID_CM,
-  parseDimension,
+  type LengthField,
   type UnitPref,
 } from '@/lib/units'
 
@@ -36,8 +38,11 @@ function entryHint(unit: UnitPref): string {
 
 /**
  * "A new garden" (no garden) or edit (garden given). Dimensions are typed in the
- * chosen unit and stored as centimeters; switching units converts what's typed so
- * the physical size holds. A 409 rebases the form onto the server's fresh row.
+ * chosen unit and stored as centimeters: each field is a LengthField, so
+ * switching units re-shows the same centimeters and a Save sends exactly what
+ * was loaded unless the person typed over it (re-parsing the display string is
+ * how 900 cm once became 899.922). A 409 rebases the form onto the server's
+ * fresh row.
  */
 export function GardenDialog({ garden, onClose }: { garden?: Garden; onClose: () => void }) {
   const isEdit = !!garden
@@ -48,14 +53,10 @@ export function GardenDialog({ garden, onClose }: { garden?: Garden; onClose: ()
   const initialUnit: UnitPref = garden?.unitPref ?? 'imperial'
   const [name, setName] = useState(garden?.name ?? '')
   const [unit, setUnit] = useState<UnitPref>(initialUnit)
-  const [width, setWidth] = useState(() =>
-    garden ? formatDimensionInput(garden.widthCm, initialUnit) : formatDimensionInput(cmFromFtIn(DEFAULT_W_FT), 'imperial'),
-  )
-  const [height, setHeight] = useState(() =>
-    garden ? formatDimensionInput(garden.heightCm, initialUnit) : formatDimensionInput(cmFromFtIn(DEFAULT_H_FT), 'imperial'),
-  )
-  const [gridSize, setGridSize] = useState(() =>
-    formatDimensionInput(garden?.gridSizeCm ?? (initialUnit === 'imperial' ? cmFromFtIn(1) : DEFAULT_GRID_CM), initialUnit),
+  const [width, setWidth] = useState<LengthField>(() => dimensionField(garden?.widthCm ?? cmFromFtIn(DEFAULT_W_FT), initialUnit))
+  const [height, setHeight] = useState<LengthField>(() => dimensionField(garden?.heightCm ?? cmFromFtIn(DEFAULT_H_FT), initialUnit))
+  const [gridSize, setGridSize] = useState<LengthField>(() =>
+    dimensionField(garden?.gridSizeCm ?? (initialUnit === 'imperial' ? cmFromFtIn(1) : DEFAULT_GRID_CM), initialUnit),
   )
   const [snapToGrid, setSnapToGrid] = useState(garden?.snapToGrid ?? false)
   const [notes, setNotes] = useState(garden?.notes ?? '')
@@ -65,17 +66,13 @@ export function GardenDialog({ garden, onClose }: { garden?: Garden; onClose: ()
   const [formError, setFormError] = useState<string | null>(null)
 
   function changeUnit(next: UnitPref) {
-    const convert = (s: string) => {
-      const cm = parseDimension(s, unit)
-      return cm === null ? s : formatDimensionInput(cm, next)
-    }
-    setWidth(convert(width))
-    setHeight(convert(height))
-    setGridSize(convert(gridSize))
+    setWidth((f) => convertDimensionField(f, next))
+    setHeight((f) => convertDimensionField(f, next))
+    setGridSize((f) => convertDimensionField(f, next))
     setUnit(next)
   }
 
-  const gridSizeCm = parseDimension(gridSize, unit)
+  const gridSizeCm = gridSize.cm
   const gridTooFine = gridSizeCm !== null && gridSizeCm > 0 && gridSizeCm < MIN_GARDEN_GRID_CM
 
   async function onSubmit(e: FormEvent) {
@@ -86,8 +83,8 @@ export function GardenDialog({ garden, onClose }: { garden?: Garden; onClose: ()
       setFormError('Give the garden a name.')
       return
     }
-    const widthCm = parseDimension(width, unit)
-    const heightCm = parseDimension(height, unit)
+    const widthCm = width.cm
+    const heightCm = height.cm
     if (widthCm === null || heightCm === null) {
       setFormError(entryHint(unit))
       return
@@ -111,9 +108,9 @@ export function GardenDialog({ garden, onClose }: { garden?: Garden; onClose: ()
         setVersion(current.version)
         setName(current.name)
         setUnit(current.unitPref)
-        setWidth(formatDimensionInput(current.widthCm, current.unitPref))
-        setHeight(formatDimensionInput(current.heightCm, current.unitPref))
-        setGridSize(formatDimensionInput(current.gridSizeCm, current.unitPref))
+        setWidth(dimensionField(current.widthCm, current.unitPref))
+        setHeight(dimensionField(current.heightCm, current.unitPref))
+        setGridSize(dimensionField(current.gridSizeCm, current.unitPref))
         setSnapToGrid(current.snapToGrid)
         setNotes(current.notes)
         setConflict('This garden changed elsewhere. The latest values are shown — look them over and save again.')
@@ -138,8 +135,8 @@ export function GardenDialog({ garden, onClose }: { garden?: Garden; onClose: ()
             type="text"
             inputMode={inputMode}
             required
-            value={width}
-            onChange={(e) => setWidth(e.target.value)}
+            value={width.text}
+            onChange={(e) => setWidth(editDimensionField(e.target.value, unit))}
             wrapperClassName="flex-1"
           />
           <TextField
@@ -148,8 +145,8 @@ export function GardenDialog({ garden, onClose }: { garden?: Garden; onClose: ()
             type="text"
             inputMode={inputMode}
             required
-            value={height}
-            onChange={(e) => setHeight(e.target.value)}
+            value={height.text}
+            onChange={(e) => setHeight(editDimensionField(e.target.value, unit))}
             wrapperClassName="flex-1"
           />
           <div className="field">
@@ -171,8 +168,8 @@ export function GardenDialog({ garden, onClose }: { garden?: Garden; onClose: ()
                 name="gridSize"
                 type="text"
                 inputMode={inputMode}
-                value={gridSize}
-                onChange={(e) => setGridSize(e.target.value)}
+                value={gridSize.text}
+                onChange={(e) => setGridSize(editDimensionField(e.target.value, unit))}
                 wrapperClassName="flex-1"
                 hint={
                   gridTooFine && gridSizeCm !== null