The candidates of a nice loop form a coloring cluster. This review puzzle from the Lucky Panda Sudoku review illustrates a decisive nice loop coloring. Two hidden UR 2 show up as well.
After a productive bypass and box marking,
a naked triple is confirmed on the last line marked row.
Then in the bv scan, a hidden unique rectangle. If r1c7 is 4, r1c8 is 1, and r8c8 is 4. The 1-slink then forces 1 in r8c7 for at least a double solution.
In the bv map, XY chains house two almost nice loops, one leaving a hidden single in r9. The railway also includes an XY nice loop having no direct victims. But Nice loops generate coloring clusters. This cluster is extended by slinks. The 5r8c6 elimination turns 5r8c4 blue and traps 5r2c4.
After a follow up of E3, N24 and N15,
a second hidden unique rectangle. This time the forcing slink is a 2-slink.
Then, an ANL recycling part of the nice loop to remove 5r1c9 to create an aligned triple boxline.
As E48 expands the cluster, a skyscraper 1-chain wraps green
The blue collapse is immediate. You can trace the skyscraper back to the first coloring, to see if it is decisive, without the later removals..
Next post skims through the next three Lucky Panda review puzzles: 288, 336, and 384. If you are trying Lucky Panda review puzzles ahead, you probably already have your copy. Otherwise, you can pull the givens out of the grids of the next post.