[iamgp]

Why the change

The scan proposed one table spanning a plate map and the sample metadata columns beside it, stretched through rows of N/A filler, and a field saved over a suggested range left its suggestion card in the sidebar.

Special things to note

• A plate grid is now proposed as a transposed table: the records are the plate columns (1..12) and the row letters (A..H) name the values. One row per well would need a different field shape.
• Table suggestions stay open-ended, so the tighter block end only changes ranking and the preview bounds, not the saved range.
• A card is retired only when the saved field covers the whole suggestion; mapping part of a suggested range keeps it.

Change outline

The scan builds candidates per sheet, then dedupes, suppresses overlaps and ranks them. Three new guards sit inside that pipeline, and one sits where a field is saved.

 findTableSuggestions
+  if (!hasInformativeHeaders(headers)) continue      # a header row of placeholders names nothing
   assessHeaderRow
   measureTableBlock
+    a row of placeholders counts as a spacer row     # N/A filler no longer extends the block
 findTransposedTableSuggestions
-  isRecordName(value)   # strings only, so 1..12 was rejected and the grid was lost
+  isRecordName(value)   # numbers count, so the plate reads as one matrix table
 coalesceHeaderRuns
   shouldMergeHeaderRuns
+    runsAreSeparateBlocks                           # grid columns repeat / numbered axis beside labels

The two shape rules, as pseudocode:

runsAreSeparateBlocks(leftRun, rightRun)
  if three or more columns repeat the column before them
    return true          # a grid copies whole columns, a record table does not
  if the left run is a numbered axis (1, 2, 3, ..) and the right run is labels
    return true          # 1..12 belongs to the grid, not to the table beside it
  return false

measureTableBlock(rowsBelowHeader)
  if a row is sparse, or holds only placeholders (N/A, -, none)
    treat it as a spacer row    # it pads a block without describing it

Saving a field now prunes the list, so drawing a selection and pressing Accept end in the same state:

 handleSaveField(field)
   schema.addField(field) / replaceField
+  setSuggestions(current =>
+    dropSuggestionsCoveredBy(current, [...fields, field], defaultSheet))
   if pendingSuggestionId
     drop that card

 editor/src/
 ├── App.tsx                     # retires suggestions a saved field covers
 └── lib/
     ├── suggestions.ts          # grid, placeholder and axis guards, plus dropSuggestionsCoveredBy
     └── suggestions.test.ts     # 9 new cases, including the reported plate-layout workbook