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fix: consumption predictions false positives after restocking

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Root cause: baseline was 'restockQty' (only the new items added) but
actualQty = pre-existing stock + new items → always looked like 'more than expected'.

New approach: baseline = current_qty + consumed_since_restock.
This correctly reflects the true starting point regardless of pre-existing stock,
eliminating all false positives after shopping trips.
This commit is contained in:
dadaloop82
2026-05-11 17:24:44 +00:00
parent 20c16401d2
commit 5b401f8d5f
2 changed files with 14 additions and 36 deletions
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api/index.php
+12 -34
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@@ -2144,45 +2144,23 @@ function getConsumptionPredictions(PDO $db): void {
$restockDate = strtotime($restock['created_at']);
// Sum ALL 'in' transactions within 24h of the last restock (= one shopping session).
// Using only the last single transaction as restockQty causes false positives when
// the user scans multiple items separately (e.g. 3 mozzarelle one by one).
$sessionIn = $db->prepare("
SELECT SUM(quantity) as total
// Baseline = current inventory + what was consumed since the last restock.
// This avoids false positives when pre-existing stock + new restock exceeds
// what the model expected from the restock alone.
$consumedSinceRestock = $db->prepare("
SELECT COALESCE(SUM(quantity), 0)
FROM transactions
WHERE product_id = ? AND location = ? AND type = 'in' AND undone = 0
AND created_at >= datetime(?, '-24 hours')
WHERE product_id = ? AND location = ? AND type = 'out' AND undone = 0
AND created_at >= datetime(?, 'unixepoch')
");
$sessionIn->execute([$pid, $loc, $restock['created_at']]);
$restockQty = floatval($sessionIn->fetchColumn() ?: $restock['quantity']);
// If inventory was manually edited (updated_at > last restock), use the
// manual update as baseline instead — otherwise the prediction is comparing
// against a stale restock quantity that no longer reflects reality.
$lastManualUpdate = strtotime($item['updated_at']);
if ($lastManualUpdate > $restockDate) {
// Inventory was manually corrected after last restock → use current qty
// as a fresh baseline from that point; only consider OUT transactions
// that happened AFTER the manual update.
$txnsSinceUpdate = $db->prepare("
SELECT SUM(quantity) as total
FROM transactions
WHERE product_id = ? AND location = ? AND type = 'out'
AND created_at > ?
");
$txnsSinceUpdate->execute([$pid, $loc, $item['updated_at']]);
$usedSinceUpdate = floatval($txnsSinceUpdate->fetchColumn() ?: 0);
$daysSinceBaseline = max(1, (time() - $lastManualUpdate) / 86400);
// The effective "restock" qty is what inventory had at manual edit time
// which is current qty + what was consumed since then
$restockQty = floatval($item['quantity']) + $usedSinceUpdate;
$restockDate = $lastManualUpdate;
}
$consumedSinceRestock->execute([$pid, $loc, $restockDate]);
$usedSinceRestock = floatval($consumedSinceRestock->fetchColumn() ?: 0);
$baselineQty = floatval($item['quantity']) + $usedSinceRestock;
$daysSinceRestock = max(1, (time() - $restockDate) / 86400);
// Predicted remaining qty = restock qty - (daily rate * days since restock)
$expectedQty = max(0, $restockQty - ($dailyRate * $daysSinceRestock));
// Predicted remaining qty = baseline - (daily rate * days since restock)
$expectedQty = max(0, $baselineQty - ($dailyRate * $daysSinceRestock));
$actualQty = floatval($item['quantity']);
// Flag if deviation > 30% and absolute diff > meaningful threshold