Replace xmax upsert trick with RETURNING full row

Upsert methods now RETURNING all struct columns and scan the result
back into the pointer receiver, keeping the caller in sync with the
actual DB state (id, created_at, etc. from the existing row on
conflict). Insert detection compares the saved original ID with the
returned ID instead of relying on the PostgreSQL-internal xmax column.

Signed-off-by: Émile Ré <emile@probo.com>

pkg/coredata/common_tracker_pattern.go

@@ -189,10 +189,10 @@ INSERT INTO common_tracker_patterns (
 	return nil
 }
 
-func (p CommonTrackerPattern) Upsert(
+func (p *CommonTrackerPattern) Upsert(
 	ctx context.Context,
 	conn pg.Tx,
-) (actualID gid.GID, inserted bool, err error) {
+) (inserted bool, err error) {
 	q := `
 INSERT INTO common_tracker_patterns (
     id,
@@ -224,9 +224,21 @@ SET
     description           = EXCLUDED.description,
     confidence            = EXCLUDED.confidence,
     updated_at            = EXCLUDED.updated_at
-RETURNING id, (xmax = 0) AS inserted
+RETURNING
+    id,
+    common_third_party_id,
+    tracker_type,
+    pattern,
+    match_type,
+    description,
+    max_age_seconds,
+    confidence,
+    created_at,
+    updated_at
 `
 
+	originalID := p.ID
+
 	args := pgx.StrictNamedArgs{
 		"id":                    p.ID,
 		"common_third_party_id": p.CommonThirdPartyID,
@@ -242,27 +254,18 @@ RETURNING id, (xmax = 0) AS inserted
 
 	rows, err := conn.Query(ctx, q, args)
 	if err != nil {
-		return gid.GID{}, false, fmt.Errorf("cannot upsert common tracker pattern: %w", err)
+		return false, fmt.Errorf("cannot upsert common tracker pattern: %w", err)
 	}
 	defer rows.Close()
 
-	type upsertResult struct {
-		ID       gid.GID
-		Inserted bool
-	}
-
-	res, err := pgx.CollectExactlyOneRow(
-		rows,
-		func(row pgx.CollectableRow) (upsertResult, error) {
-			var r upsertResult
-			return r, row.Scan(&r.ID, &r.Inserted)
-		},
-	)
+	row, err := pgx.CollectExactlyOneRow(rows, pgx.RowToStructByName[CommonTrackerPattern])
 	if err != nil {
-		return gid.GID{}, false, fmt.Errorf("cannot collect upsert result: %w", err)
+		return false, fmt.Errorf("cannot collect upsert result: %w", err)
 	}
 
-	return res.ID, res.Inserted, nil
+	*p = row
+
+	return originalID == p.ID, nil
 }
 
 func (p CommonTrackerPattern) Delete(