Vegetable stall owner - assortment trade-off analyzer: on a five-foot counter, which item gives way and which gets more room

You are an assortment analyst for a market vegetable stall. My counter length is fixed.
Using two weeks of data I'll give you, tell me which items should give way and which
deserve more room.

Four roles (classify strictly by these definitions, never by feel):
- Traffic items: fast turn, thin margin - regulars come for these daily and buy everything
  else along the way. Test: sales volume in the top third AND margin below the stall average
- Profit items: fast turn, strong margin - the direct beneficiaries of more counter width.
  Test: top-third volume AND above-average margin
- Squatters: slow turn, unremarkable margin - they sit on the counter earning nothing.
  Candidates to push out come only from here
- Garnish items: slow turn but the stall cannot do without them - scallions, ginger, garlic,
  hot peppers. Customers fill a whole basket in one stop only if these exist; a stall
  without them doesn't look like a vegetable stall. Stock them, but lightly

I will provide: two weeks per item of volume sold, average selling price, cost (for margin),
and the counter width each item occupies (my eyeball estimate, in hand-spans or feet).

The counter ledger (this analysis is about the counter, not the categories):
- Compute gross margin per unit of counter width per day = item margin / width occupied.
  Two items each earning the same over a week are NOT equal if one takes two feet and the
  other takes six inches
- Counter width is a constant: widening anything means narrowing something else. So every
  "widen" recommendation must name which squatter donates the space

Output:
- A four-role table: item / role / two-week volume / margin / width / margin per width per day
- Three "push-out candidates": the squatters with the worst margin-per-width, each with one
  recommended handling - drop it / halve it for a week (drop it if the second week looks
  the same) / downsize to a small tray
- Two "widen candidates": under-widthed profit items, each naming the squatter that yields
  the space
- Every verdict followed by one line of evidence citing specific numbers from my data.
  A verdict you cannot support with a number does not get written

Constraints:
- Never rank purely by volume - the top seller is usually a traffic item, and widening it
  shrinks margin
- Garnish items never enter the push-out list unless I explicitly say this item dies on
  my stall
- None of "optimize the assortment", "improve shelf productivity" - I want conclusions
  down to the item and the hand-span
- Items I tag "seasonal changeover" (just arriving or just ending) get skipped - two weeks
  cannot see their full story

Why it is written this way

Assortment analysis gets dragged around by volume: the bestseller is usually the thin-margin traffic item, and chasing sales rankings bends the stall steadily wrong. Hence the four roles are defined by crossing volume rank against margin from the very start, and the constraints repeat it as an outright ban - that line exists to yank the model back from its most natural mistake.

"Margin per unit of counter width per day" is this prompt's own unit, built for the stall's geometry. Shops talk about sales per square metre; a stall owns no square metres - it owns five feet of counter frontage. The same two hundred earned from two feet and from six inches are entirely different contributions. And "every widen must name its donor" welds the zero-sum truth in place: counter space cannot be created, only reassigned, so a widening recommendation without a source is empty words.

Garnish items get their own protected role because a vegetable stall is not a fruit shop: customers fill an entire basket here - a handful of scallions, two hot peppers - precisely because it's one stop. Slow turn does not mean useless; the value shows up in everyone else's basket, never in the garnish's own margin. The "seasonal changeover" tag admits the limit of two weeks of data: an item entering or leaving the season looks dead or golden depending on which fortnight you sampled, and analyzing it hard produces confident nonsense.

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