01
Write the larger grid before removing the labels
The first output row is A, B, A, A, B, A. The second is B, A, B, B, A, B. Rows three and four repeat rows one and two respectively. A source cell therefore appears once in each of the four tile copies. For example, the source tile’s top-left A appears at output positions (1,1), (1,4), (3,1) and (3,4), using row-first coordinates starting at one. Keeping these positions visible helps detect an accidental flip or shift. The complete grid is a more reliable reference than an unlabeled impression of how the pattern ought to continue.
02
Inspect the seam instead of assuming alternation
The original tile alternates letters within each row, but it is three columns wide. When two copies meet, the last A of the first row touches the first A of the next copy. The second row similarly has B beside B at that boundary. The repeated image is therefore not a continuous checkerboard. This is the correct result of the specified translation rule. If continuous horizontal alternation were the design goal, the tile or placement rule would need to change. Preserve that as a separate version rather than silently correcting the supplied pattern.
03
Check counts and preserve the repeat specification
Each source tile contains three A cells and three B cells. Four copies contain twelve of each, for twenty-four cells total. These totals are useful checks, but they cannot prove that every cell is in the right position: a scrambled grid can have the same counts. Save the source rows, copy counts, placement operation, output dimensions and labeled output together. Add a note identifying the equal-letter seams. This gives a reviewer both a numerical check and a positional reference, while leaving palette, scale and any later production decisions as explicit additional choices.