Fix best move arrow not shown when engine lines set to zero#3100
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veloce merged 1 commit intoMay 4, 2026
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Fix: Best move arrow not shown when engine lines is set to 0
When the "Show best move arrow" option was enabled but the number of engine lines was set to 0, the best move arrow was not displayed on the board.
Root cause
In analysis_board.dart, the best moves were filtered using .take(enginePrefs.numEvalLines). When numEvalLines is 0, .take(0) returns an empty list, so no arrow was drawn. This was inconsistent with the UCI protocol layer in uci_protocol.dart, which already uses math.max(1, multiPv) to ensure Stockfish always evaluates at least one line.
Fix
Changed .take(enginePrefs.numEvalLines) to .take(math.max(1, enginePrefs.numEvalLines)) in analysis_board.dart, so that at least the best move is always passed to computeBestMoveShapes() when the engine is running, regardless of the number of displayed lines.
Test
A new test was added to the Engine best move arrow group in analysis_screen_test.dart, verifying that the best move arrow is displayed even when the number of engine lines is set to 0.
Fixes: #2871