Prompt:
FEN: r3k2r/p1pn2pp/1p1b4/3Ppp2/8/1BP2P1P/PBP2P2/R4RK1 w kq - 0 15
List the material inventory by side and piece type.

Answer format: return exactly two lines starting "White inventory:" and "Black inventory:".

White inventory: king=g1; queen=none; rook=a1,f1; bishop=b2,b3; knight=none; pawn=a2,c2,f2,c3,f3,h3,d5.
Black inventory: king=e8; queen=none; rook=a8,h8; bishop=d6; knight=d7; pawn=e5,f5,b6,a7,c7,g7,h7.


Prompt:
FEN: 2k1r2r/ppb2pp1/5qp1/3p4/1PQ2P2/7P/P5P1/2BR1RK1 w - - 0 24
Count each piece type for both sides.

Answer format: return exactly two lines starting "White counts:" and "Black counts:".

White counts: king=1; queen=1; rook=2; bishop=1; knight=0; pawn=5.
Black counts: king=1; queen=1; rook=2; bishop=1; knight=0; pawn=6.


Prompt:
FEN: r2q1rk1/p2nn1bp/6p1/7P/4p3/2N2Q2/PPP2PP1/R1B1K1NR w KQ - 0 15
Convert the piece counts into material value totals.

Answer format: return exactly two lines starting "White values:" and "Black values:".

White values: king=0; queen=9; rook=10; bishop=3; knight=6; pawn=6; total=34.
Black values: king=0; queen=9; rook=10; bishop=3; knight=6; pawn=4; total=32.


Prompt:
FEN: 8/8/5p2/6p1/6k1/8/4K3/8 b - - 1 55
Trace inventory, counts, values, and material balance.

Answer format: return exactly four lines starting "Inventory:", "Counts:", "Values:", and "Balance:".

Inventory: white king=e2; queen=none; rook=none; bishop=none; knight=none; pawn=none | black king=g4; queen=none; rook=none; bishop=none; knight=none; pawn=g5,f6
Counts: white king=1; queen=0; rook=0; bishop=0; knight=0; pawn=0 | black king=1; queen=0; rook=0; bishop=0; knight=0; pawn=2
Values: white total=0; black total=2
Balance: Black is up 2 point(s) of material.


Prompt:
Starting FEN: r4rk1/4qpp1/b3pn1p/p1pp4/P1P5/1P2PP2/3N2PP/R1BQ1RK1 b - - 0 17
After the moves f8c8 d2e4 d5c4, what is the resulting position?
State needed for full FEN:
Side to move: black
Castling rights: none
En passant: none
Halfmove clock: 0
Fullmove number: 17

Answer format: return exactly "Result FEN: <complete six-field FEN>".

Result FEN: r1r3k1/4qpp1/b3pn1p/p1p5/P1p1N3/1P2PP2/6PP/R1BQ1RK1 w - - 0 19


Prompt:
Position (FEN): 7Q/6p1/8/8/6PK/1k6/5q1P/8 w - - 7 56
Show me the board.


Prompt:
Here is the current board:
8 r . . q k b . Q
7 p p p n . . . .
6 . . . p p . p .
5 . . . . . . . .
4 . . . . . . . .
3 . . P . . . . .
2 P P P . . P P P
1 R . B . . R K .
  a b c d e f g h
Write the FEN for this position.
State needed for full FEN:
Side to move: white
Castling rights: q
En passant: none
Halfmove clock: 0
Fullmove number: 1

Answer format: return exactly one complete six-field FEN, with no prefix and no explanation.

r2qkb1Q/pppn4/3pp1p1/8/8/2P5/PPP2PPP/R1B2RK1 w q - 0 1


Prompt:
FEN: 2r5/8/4k3/1K6/1P1R4/8/8/8 b - -
What piece is on c8?

Answer format: for a square query, return only the piece name or empty; do not include the square. For a locate query, return only space-separated squares.


Prompt:
FEN: r1b1k2r/pp2ppbp/2n3p1/8/3P1B2/4PN2/P2qBPPP/R3K2R w KQkq -
What is the material count for both sides?

White (12 pieces): 2 bishops, 1 king, 1 knight, 6 pawns, 2 rooks. Black (13 pieces): 2 bishops, 1 king, 1 knight, 6 pawns, 1 queen, 2 rooks. Black is up 9 point(s) of material.


Prompt:
FEN: 5rk1/p6p/1pp3p1/3p4/P2P4/6PP/5R2/6K1 b - - 0 40
What is on h1?

Answer format: return exactly "<square>=<piece>" or "<square>=empty".


Prompt:
FEN: r1b3k1/pp2q2r/2p1pn1Q/3p4/2PPp3/6P1/PP2PPBP/R4RK1 w - - 1 17
What is the compressed FEN row for rank 2?

Answer format: return exactly "rank N: <compressed FEN row>".


Prompt:
FEN: 8/7p/6pk/8/8/3P1q2/5bRP/Q6K b - -
For square h5, give the FEN row-from-top and file index.

Answer format: return exactly "<square>: file=<file>; rank=<rank>; fen_row_from_top=<1-8>; file_index=<1-8>".

h5: file=h; rank=5; fen_row_from_top=4; file_index=8


Prompt:
FEN: r3kbnr/p3p2p/1pp2p2/2n3p1/2Q5/5NP1/PqPB1P1P/2R1KB1R w Kkq - 0 17
Compressed rank 5 row: 2n3p1
Expand it into file cells a through h.

Answer format: return exactly "rank N: a=<cell>; b=<cell>; ...; h=<cell>".


Prompt:
Rank 5 row before: 4p3
File g changes from 1 to r. Rewrite the compressed row.

Answer format: return exactly "rank N: <before-row> -> <after-row>".


Prompt:
Board FEN before: 8/pPk5/P7/8/1K6/8/8/8
Apply square edits: b4 K->1; b5 1->K
Return the resulting board FEN only.

Answer format: return exactly "Result board FEN: <piece-placement-field>".


Prompt:
Starting FEN: r1bqkb1r/ppp2ppp/2n1pn2/3p4/4P3/3P1NP1/PPPN1P1P/R1BQKB1R b KQkq -
Move: f6h5
List the square lookups and rank edits.

Answer format: return exactly three lines starting "Lookup:", "Squares:", and "Ranks:"; do not include Result FEN.

Lookup: f6=black knight; h5=empty.
Squares: f6 black knight->empty; h5 empty->black knight.
Ranks: rank 6 f n->1; rank 5 h 1->n.


Prompt:
Starting FEN: 5b1r/pppk2p1/1r5p/1P6/P1nPNP2/2P5/5PKP/R3R3 w - - 1 24
Move: g2f1
Use square lookups and rank edits to assemble the resulting full FEN.
State needed for full FEN:
Side to move: white
Castling rights: none
En passant: none
Halfmove clock: 1
Fullmove number: 24

Answer format: include the edit trace and exactly one final line "Result FEN: <complete six-field FEN>".

Move 1: white king g2f1.
Lookup: g2=white king; f1=empty.
Squares: g2 white king->empty; f1 empty->white king.
Ranks: rank 2 g K->1; rank 1 f 1->K.
Result FEN: 5b1r/pppk2p1/1r5p/1P6/P1nPNP2/2P5/5P1P/R3RK2 b - - 2 24


Prompt:
Starting FEN: rnbqk1nr/pp3ppp/2p5/3p4/1bPPp3/2N3P1/PP2PPBP/R1BQK1NR w KQkq - 0 1
Move: d1d3
Rewrite the affected compressed FEN rank rows and give Result FEN.
State needed for full FEN:
Side to move: white
Castling rights: KQkq
En passant: none
Halfmove clock: 0
Fullmove number: 1

Answer format: first line starts "Rows:" and final line is "Result FEN: <complete six-field FEN>".

Rows: rank 1 R1BQK1NR->R1B1K1NR; rank 3 2N3P1->2NQ2P1.
Result FEN: rnbqk1nr/pp3ppp/2p5/3p4/1bPPp3/2NQ2P1/PP2PPBP/R1B1K1NR b KQkq - 1 1


Prompt:
Starting FEN: r2qkb1r/pb1n1ppp/1p2pn2/2ppN3/3P1P2/2PBP3/PP4PP/RNBQ1RK1 b kq - 0 8
After the moves b7a6, what is the resulting position?
State needed for full FEN:
Side to move: black
Castling rights: kq
En passant: none
Halfmove clock: 0
Fullmove number: 8

Answer format: return exactly "Result FEN: <complete six-field FEN>".

Result FEN: r2qkb1r/p2n1ppp/bp2pn2/2ppN3/3P1P2/2PBP3/PP4PP/RNBQ1RK1 w kq - 1 9


Prompt:
FEN: rnbqkbnr/pp1p1ppp/8/4p3/2Pp4/3Q4/PP2PPPP/RNB1KBNR w KQkq - 0 4
List the material inventory by side and piece type.

Answer format: return exactly two lines starting "White inventory:" and "Black inventory:".

White inventory: king=e1; queen=d3; rook=a1,h1; bishop=c1,f1; knight=b1,g1; pawn=a2,b2,e2,f2,g2,h2,c4.
Black inventory: king=e8; queen=d8; rook=a8,h8; bishop=c8,f8; knight=b8,g8; pawn=d4,e5,a7,b7,d7,f7,g7,h7.


Prompt:
FEN: 8/pp6/5Nk1/6pp/8/P1B3PP/1P3PK1/8 w - - 0 33
Count each piece type for both sides.

Answer format: return exactly two lines starting "White counts:" and "Black counts:".

White counts: king=1; queen=0; rook=0; bishop=1; knight=1; pawn=5.
Black counts: king=1; queen=0; rook=0; bishop=0; knight=0; pawn=4.


Prompt:
FEN: 8/p2b4/1p6/1P1pkp2/r5P1/1R1B4/7K/8 b - - 0 44
Convert the piece counts into material value totals.

Answer format: return exactly two lines starting "White values:" and "Black values:".

White values: king=0; queen=0; rook=5; bishop=3; knight=0; pawn=2; total=10.
Black values: king=0; queen=0; rook=5; bishop=3; knight=0; pawn=4; total=12.


Prompt:
FEN: rnbqr1k1/ppp2ppp/3b1n2/3p4/4p3/1P2P1P1/PBPPNPBP/RN1Q1RK1 w - - 7 8
Trace inventory, counts, values, and material balance.

Answer format: return exactly four lines starting "Inventory:", "Counts:", "Values:", and "Balance:".

Inventory: white king=g1; queen=d1; rook=a1,f1; bishop=b2,g2; knight=b1,e2; pawn=a2,c2,d2,f2,h2,b3,e3,g3 | black king=g8; queen=d8; rook=a8,e8; bishop=d6,c8; knight=f6,b8; pawn=e4,d5,a7,b7,c7,f7,g7,h7
Counts: white king=1; queen=1; rook=2; bishop=2; knight=2; pawn=8 | black king=1; queen=1; rook=2; bishop=2; knight=2; pawn=8
Values: white total=39; black total=39
Balance: Material is equal.


Prompt:
Starting FEN: rnbqk1nr/pp3ppp/2pb4/3p4/3P4/1B3N2/PPP2PPP/RNBQK2R b KQkq - 0 1
After the moves f7f5 f3g5 a7a5, what is the resulting position?
State needed for full FEN:
Side to move: black
Castling rights: KQkq
En passant: none
Halfmove clock: 0
Fullmove number: 1

Answer format: return exactly "Result FEN: <complete six-field FEN>".

Result FEN: rnbqk1nr/1p4pp/2pb4/p2p1pN1/3P4/1B6/PPP2PPP/RNBQK2R w KQkq - 0 3


Prompt:
Position (FEN): 2kr3r/ppp1n1pp/8/4P3/1b2N3/2Pb4/PP1B2PP/2K1R2R w - - 2 18
Show me the board.


rn2kb1r/pp1B1ppp/1n6/2pqP3/8/5N2/PP4PP/RNBQK2R b KQkq - 0 11

Prompt:
Here is the current board:
8 r n . . k b . r
7 p p . B . p p p
6 . n . . . . . .
5 . . p q P . . .
4 . . . . . . . .
3 . . . . . N . .
2 P P . . . . P P
1 R N B Q K . . R
  a b c d e f g h
Write the FEN for this position.
State needed for full FEN:
Side to move: black
Castling rights: KQkq
En passant: none
Halfmove clock: 0
Fullmove number: 11

Answer format: return exactly one complete six-field FEN, with no prefix and no explanation.


Prompt:
FEN: r2q1k1r/p1p1bppp/2Qp1n2/8/8/P6P/1PPB1PP1/RN2K2R b KQ - 0 13
What piece is on a3?

Answer format: for a square query, return only the piece name or empty; do not include the square. For a locate query, return only space-separated squares.


Prompt:
FEN: r4k2/5p2/1n4pr/p5p1/1ppR4/P4P2/1PB2PK1/4R3 w - - 0 30
What is the material count for both sides?

White (8 pieces): 1 bishop, 1 king, 4 pawns, 2 rooks. Black (10 pieces): 1 king, 1 knight, 6 pawns, 2 rooks. Black is up 2 point(s) of material.


Prompt:
FEN: r1b2rk1/1pq1n1pp/p2p1p2/2p1b3/4P3/1PN1Q1P1/P1P2PBP/B1R2RK1 b - - 1 14
What is on e2?

Answer format: return exactly "<square>=<piece>" or "<square>=empty".


Prompt:
FEN: r1b2rk1/2p2ppp/ppp1n1q1/8/3P4/4B3/PPPN2PP/R2Q1R1K w - - 0 16
What is the compressed FEN row for rank 3?

Answer format: return exactly "rank N: <compressed FEN row>".


Prompt:
FEN: 5R2/2qk3p/p5p1/1p1Bp3/8/2P1B3/P1PR2PP/6K1 w - -
For square d2, give the FEN row-from-top and file index.

Answer format: return exactly "<square>: file=<file>; rank=<rank>; fen_row_from_top=<1-8>; file_index=<1-8>".

d2: file=d; rank=2; fen_row_from_top=7; file_index=4


Prompt:
FEN: 8/4k3/R6p/Pp1p4/3P4/2P4P/1P1K4/8 w - -
Compressed rank 3 row: 2P4P
Expand it into file cells a through h.

Answer format: return exactly "rank N: a=<cell>; b=<cell>; ...; h=<cell>".


Prompt:
Rank 3 row before: P1NP4
File e changes from 1 to Q. Rewrite the compressed row.

Answer format: return exactly "rank N: <before-row> -> <after-row>".


Prompt:
Board FEN before: 1k5r/pp3ppp/3r4/4p3/3n4/P4q2/5K1P/3RQ1NR
Apply square edits: g1 N->1; f3 q->N
Return the resulting board FEN only.

Answer format: return exactly "Result board FEN: <piece-placement-field>".

Result board FEN: 1k5r/pp3ppp/3r4/4p3/3n4/P4N2/5K1P/3RQ2R


Prompt:
Starting FEN: r3r1k1/5ppp/2bB4/3p4/3P3P/2P2KPN/p4P2/R7 b - - 3 30
Move: c6b5
List the square lookups and rank edits.

Answer format: return exactly three lines starting "Lookup:", "Squares:", and "Ranks:"; do not include Result FEN.

Lookup: c6=black bishop; b5=empty.
Squares: c6 black bishop->empty; b5 empty->black bishop.
Ranks: rank 6 c b->1; rank 5 b 1->b.


Prompt:
Starting FEN: r4rk1/ppp1nppp/4b3/q7/3P1PP1/1PN2N2/P1P1Q2P/2KR3R w - - 1 20
Move: e2d2
Use square lookups and rank edits to assemble the resulting full FEN.
State needed for full FEN:
Side to move: white
Castling rights: none
En passant: none
Halfmove clock: 1
Fullmove number: 20

Answer format: include the edit trace and exactly one final line "Result FEN: <complete six-field FEN>".

Move 1: white queen e2d2.
Lookup: e2=white queen; d2=empty.
Squares: e2 white queen->empty; d2 empty->white queen.
Ranks: rank 2 e Q->1; rank 2 d 1->Q.
Result FEN: r4rk1/ppp1nppp/4b3/q7/3P1PP1/1PN2N2/P1PQ3P/2KR3R b - - 2 20


Prompt:
Starting FEN: rnbqk2r/pp3ppp/3p1n2/3p4/3P4/5N2/PPP2PPP/RN1QKB1R w KQkq - 0 1
Move: f1a6
Rewrite the affected compressed FEN rank rows and give Result FEN.
State needed for full FEN:
Side to move: white
Castling rights: KQkq
En passant: none
Halfmove clock: 0
Fullmove number: 1

Answer format: first line starts "Rows:" and final line is "Result FEN: <complete six-field FEN>".

Rows: rank 1 RN1QKB1R->RN1QK2R; rank 6 3p1n2->B2p1n2.
Result FEN: rnbqk2r/pp3ppp/B2p1n2/3p4/3P4/5N2/PPP2PPP/RN1QK2R b KQkq - 1 1


Prompt:
Starting FEN: rnb1kbnr/pp3pp1/2pp1q1p/4p3/2B1P3/1QP2N2/PP1P1PPP/RNB1K2R w KQkq - 2 6
After the moves h2h4, what is the resulting position?
State needed for full FEN:
Side to move: white
Castling rights: KQkq
En passant: none
Halfmove clock: 2
Fullmove number: 6

Answer format: return exactly "Result FEN: <complete six-field FEN>".

Result FEN: rnb1kbnr/pp3pp1/2pp1q1p/4p3/2B1P2P/1QP2N2/PP1P1PP1/RNB1K2R b KQkq - 0 6


Prompt:
FEN: r4rk1/p4pbp/1p1q1np1/2pP4/1nQ2P2/P5P1/1P1PN1BP/R1B2RK1 b - - 0 18
List the material inventory by side and piece type.

Answer format: return exactly two lines starting "White inventory:" and "Black inventory:".

White inventory: king=g1; queen=c4; rook=a1,f1; bishop=c1,g2; knight=e2; pawn=b2,d2,h2,a3,g3,f4,d5.
Black inventory: king=g8; queen=d6; rook=a8,f8; bishop=g7; knight=b4,f6; pawn=c5,b6,g6,a7,f7,h7.


Prompt:
FEN: 8/8/8/8/5KPP/1k6/8/8 b - -
Count each piece type for both sides.

Answer format: return exactly two lines starting "White counts:" and "Black counts:".

White counts: king=1; queen=0; rook=0; bishop=0; knight=0; pawn=2.
Black counts: king=1; queen=0; rook=0; bishop=0; knight=0; pawn=0.


Prompt:
FEN: r1b2rk1/5ppp/p1p5/3q4/5Q2/8/PP2BPPP/R4RK1 b - -
Convert the piece counts into material value totals.

Answer format: return exactly two lines starting "White values:" and "Black values:".

White values: king=0; queen=9; rook=10; bishop=3; knight=0; pawn=5; total=27.
Black values: king=0; queen=9; rook=10; bishop=3; knight=0; pawn=5; total=27.


Prompt:
FEN: 5rk1/2p1qp2/1bnp1n1p/1p2p1p1/1P2P3/2PP1BP1/1B1N1P1P/3QR1K1 w - - 0 18
Trace inventory, counts, values, and material balance.

Answer format: return exactly four lines starting "Inventory:", "Counts:", "Values:", and "Balance:".

Inventory: white king=g1; queen=d1; rook=e1; bishop=b2,f3; knight=d2; pawn=f2,h2,c3,d3,g3,b4,e4 | black king=g8; queen=e7; rook=f8; bishop=b6; knight=c6,f6; pawn=b5,e5,g5,d6,h6,c7,f7
Counts: white king=1; queen=1; rook=1; bishop=2; knight=1; pawn=7 | black king=1; queen=1; rook=1; bishop=1; knight=2; pawn=7
Values: white total=30; black total=30
Balance: Material is equal.


Prompt:
Starting FEN: r1b2rk1/6pp/1qpp4/pp2pP2/6n1/P2PPN2/NPP1Q1PP/4RRK1 b - - 0 16
After the moves b6b8 b2b4 f8d8, what is the resulting position?
State needed for full FEN:
Side to move: black
Castling rights: none
En passant: none
Halfmove clock: 0
Fullmove number: 16

Answer format: return exactly "Result FEN: <complete six-field FEN>".

Result FEN: rqbr2k1/6pp/2pp4/pp2pP2/1P4n1/P2PPN2/N1P1Q1PP/4RRK1 w - - 1 18


Prompt:
Position (FEN): 1r4k1/2r5/1p2p1p1/p1qn1n2/P4PQ1/1P3NP1/5P1P/3RR1K1 b - -
Show me the board.


Prompt:
Here is the current board:
8 . . . . . . q .
7 . . . . . . . .
6 . . . . . Q . k
5 . . r . . . . .
4 . . . . p . . .
3 . . . . P . P P
2 . . . . . P K .
1 . . . . . . . .
  a b c d e f g h
Write the FEN for this position.
State needed for full FEN:
Side to move: black
Castling rights: none
En passant: none
Halfmove clock: 0
Fullmove number: 1

Answer format: return exactly one complete six-field FEN, with no prefix and no explanation.


Prompt:
FEN: 4r1k1/pp1b1p1p/1n4p1/2pPr1q1/4PQ2/2N2P1P/PP2B3/2K1R2R w - -
What piece is on h1?

Answer format: for a square query, return only the piece name or empty; do not include the square. For a locate query, return only space-separated squares.


Prompt:
FEN: rn2kr2/1b2b1pp/p2p1q2/1p1p4/P1p5/2NB1P2/1PP3PP/R1BQR1K1 w q - 0 16
What is the material count for both sides?

White (13 pieces): 2 bishops, 1 king, 1 knight, 6 pawns, 1 queen, 2 rooks. Black (14 pieces): 2 bishops, 1 king, 1 knight, 7 pawns, 1 queen, 2 rooks. Black is up 1 point(s) of material.


Prompt:
FEN: r5k1/2p4p/p5p1/1p3p2/1P6/P1qB1NP1/5K1P/8 w - - 0 33
What is on a4?

Answer format: return exactly "<square>=<piece>" or "<square>=empty".


Prompt:
FEN: r1bqk1nr/pp2ppbp/2np2p1/8/2P1P2Q/2N1B3/PP3PPP/R3KBNR b KQkq - 1 7
What is the compressed FEN row for rank 1?

Answer format: return exactly "rank N: <compressed FEN row>".


Prompt:
FEN: r3k1nr/pppb1ppp/8/8/2Bn3q/6N1/PP3PPP/R1BQK2R b KQkq - 1 12
For square h8, give the FEN row-from-top and file index.

Answer format: return exactly "<square>: file=<file>; rank=<rank>; fen_row_from_top=<1-8>; file_index=<1-8>".

h8: file=h; rank=8; fen_row_from_top=1; file_index=8


Prompt:
FEN: 1k1rR3/pp3p2/n1p2q1p/3p1Pp1/3P4/P1N4Q/1PP3PP/2K5 w - - 3 26
Compressed rank 3 row: P1N4Q
Expand it into file cells a through h.

Answer format: return exactly "rank N: a=<cell>; b=<cell>; ...; h=<cell>".


Prompt:
Rank 5 row before: 4Pq2
File f changes from q to 1. Rewrite the compressed row.

Answer format: return exactly "rank N: <before-row> -> <after-row>".


Prompt:
Board FEN before: 2b3rk/ppb4p/2p1p1q1/2Pn4/1P1PRp2/P4Q1P/1B3PP1/4R1K1
Apply square edits: d5 n->1; e3 1->n
Return the resulting board FEN only.

Answer format: return exactly "Result board FEN: <piece-placement-field>".

Result board FEN: 2b3rk/ppb4p/2p1p1q1/2P5/1P1PRp2/P3nQ1P/1B3PP1/4R1K1


Prompt:
Starting FEN: 1nr3k1/6p1/4R2p/3pPp2/2p2P2/B3QN1P/2q3P1/6K1 b - - 0 31
Move: c2g2
List the square lookups and rank edits.

Answer format: return exactly three lines starting "Lookup:", "Squares:", and "Ranks:"; do not include Result FEN.

Lookup: c2=black queen; g2=white pawn.
Squares: c2 black queen->empty; g2 white pawn->black queen.
Ranks: rank 2 c q->1; rank 2 g P->q.


Prompt:
Starting FEN: r1bqkbnr/pp1p1ppp/4p3/n7/2B1P3/2N2N2/PP3PPP/R1BQK2R w KQkq - 0 1
Move: a2a3
Use square lookups and rank edits to assemble the resulting full FEN.
State needed for full FEN:
Side to move: white
Castling rights: KQkq
En passant: none
Halfmove clock: 0
Fullmove number: 1

Answer format: include the edit trace and exactly one final line "Result FEN: <complete six-field FEN>".

Move 1: white pawn a2a3.
Lookup: a2=white pawn; a3=empty.
Squares: a2 white pawn->empty; a3 empty->white pawn.
Ranks: rank 2 a P->1; rank 3 a 1->P.
Result FEN: r1bqkbnr/pp1p1ppp/4p3/n7/2B1P3/P1N2N2/1P3PPP/R1BQK2R b KQkq - 0 1


Prompt:
Starting FEN: r1bqk1nr/pp1n1ppp/2p5/2b1p3/2B1P3/5N2/PPP2PPP/RNBQK2R w KQkq - 2 7
Move: c1h6
Rewrite the affected compressed FEN rank rows and give Result FEN.
State needed for full FEN:
Side to move: white
Castling rights: KQkq
En passant: none
Halfmove clock: 2
Fullmove number: 7

Answer format: first line starts "Rows:" and final line is "Result FEN: <complete six-field FEN>".

Rows: rank 1 RNBQK2R->RN1QK2R; rank 6 2p5->2p4B.
Result FEN: r1bqk1nr/pp1n1ppp/2p4B/2b1p3/2B1P3/5N2/PPP2PPP/RN1QK2R b KQkq - 3 7


Prompt:
Starting FEN: 4r1k1/pp3ppp/2p2pn1/3p4/3P2R1/2PQ1P1P/PPBqrP2/1K5R w - - 6 20
After the moves g4g1, what is the resulting position?
State needed for full FEN:
Side to move: white
Castling rights: none
En passant: none
Halfmove clock: 6
Fullmove number: 20

Answer format: return exactly "Result FEN: <complete six-field FEN>".

Result FEN: 4r1k1/pp3ppp/2p2pn1/3p4/3P4/2PQ1P1P/PPBqrP2/1K4RR b - - 7 20


Prompt:
FEN: 7k/p5rp/1p1P1Q2/5p2/q4P2/P3R2P/6PK/7r w - -
List the material inventory by side and piece type.

Answer format: return exactly two lines starting "White inventory:" and "Black inventory:".

White inventory: king=h2; queen=f6; rook=e3; bishop=none; knight=none; pawn=g2,a3,h3,f4,d6.
Black inventory: king=h8; queen=a4; rook=h1,g7; bishop=none; knight=none; pawn=f5,b6,a7,h7.


Prompt:
FEN: rnbq1rk1/ppp1bppp/3p1n2/8/8/2NB1N2/PPPP1PPP/R1BQ1RK1 w - -
Count each piece type for both sides.

Answer format: return exactly two lines starting "White counts:" and "Black counts:".

White counts: king=1; queen=1; rook=2; bishop=2; knight=2; pawn=7.
Black counts: king=1; queen=1; rook=2; bishop=2; knight=2; pawn=7.


Prompt:
FEN: 1k6/8/2Q1K3/8/4B3/8/8/8 w - -
Convert the piece counts into material value totals.

Answer format: return exactly two lines starting "White values:" and "Black values:".

White values: king=0; queen=9; rook=0; bishop=3; knight=0; pawn=0; total=12.
Black values: king=0; queen=0; rook=0; bishop=0; knight=0; pawn=0; total=0.


Prompt:
FEN: r3r1k1/pp2qpp1/8/2p5/4bB1b/1P1B3P/P1P2PPQ/3RR1K1 b - - 8 22
Trace inventory, counts, values, and material balance.

Answer format: return exactly four lines starting "Inventory:", "Counts:", "Values:", and "Balance:".

Inventory: white king=g1; queen=h2; rook=d1,e1; bishop=d3,f4; knight=none; pawn=a2,c2,f2,g2,b3,h3 | black king=g8; queen=e7; rook=a8,e8; bishop=e4,h4; knight=none; pawn=c5,a7,b7,f7,g7
Counts: white king=1; queen=1; rook=2; bishop=2; knight=0; pawn=6 | black king=1; queen=1; rook=2; bishop=2; knight=0; pawn=5
Values: white total=31; black total=30
Balance: White is up 1 point(s) of material.


Prompt:
Starting FEN: 2k5/1pp1R2p/1q6/1N1ppp2/Q3b3/1r1PNB2/1P1KP1r1/R1B5 b - - 0 1
After the moves b6a6 e3d1, what is the resulting position?
State needed for full FEN:
Side to move: black
Castling rights: none
En passant: none
Halfmove clock: 0
Fullmove number: 1

Answer format: return exactly "Result FEN: <complete six-field FEN>".


Prompt:
Position (FEN): r2qkbnr/p1pb1ppp/3p4/2p5/4P3/5N2/PPP2PPP/RNBQ1RK1 b kq - 1 8
Show me the board.


Prompt:
Here is the current board:
8 . . r q . r . .
7 . . . . b . p k
6 . p . . p . . p
5 . . p . N . . .
4 . . . P Q B P .
3 . . . . P . . .
2 P P . . . P . P
1 . . R . . R K .
  a b c d e f g h
Write the FEN for this position.
State needed for full FEN:
Side to move: black
Castling rights: none
En passant: none
Halfmove clock: 2
Fullmove number: 24

Answer format: return exactly one complete six-field FEN, with no prefix and no explanation.


Prompt:
FEN: 7Q/2k5/p7/2p2p2/8/3BK3/PPP5/8 b - - 0 39
What piece is on a2?

Answer format: for a square query, return only the piece name or empty; do not include the square. For a locate query, return only space-separated squares.


Prompt:
FEN: 3r4/3kbp1p/bp4p1/p1p5/2P1P3/1P6/3P1P2/1NBK1B1R w - - 0 27
What is the material count for both sides?

White (10 pieces): 2 bishops, 1 king, 1 knight, 5 pawns, 1 rook. Black (10 pieces): 2 bishops, 1 king, 6 pawns, 1 rook. White is up 2 point(s) of material.


Prompt:
FEN: r2qk2r/1pp2pp1/pbnp1n1p/7b/P1BPP3/4BN1P/1P1N1PP1/R2Q1RK1 w kq - 1 12
What is on b3?

Answer format: return exactly "<square>=<piece>" or "<square>=empty".


Prompt:
FEN: rnbqkbnr/pp1p1pp1/2p1p2p/7Q/2B1P3/5N2/PPPP1PPP/RNB1K2R b KQkq - 1 4
What is the compressed FEN row for rank 7?

Answer format: return exactly "rank N: <compressed FEN row>".


Prompt:
FEN: 5rk1/3bqpb1/Nr1ppnp1/np5p/8/P1NPP1P1/3BQPBP/1R3RK1 w - -
For square c3, give the FEN row-from-top and file index.

Answer format: return exactly "<square>: file=<file>; rank=<rank>; fen_row_from_top=<1-8>; file_index=<1-8>".

c3: file=c; rank=3; fen_row_from_top=6; file_index=3


Prompt:
FEN: rnbqkbnr/2p2ppp/pp2p3/2Pp4/PP1P4/8/4PPPP/RNBQKBNR b KQkq - 0 5
Compressed rank 6 row: pp2p3
Expand it into file cells a through h.

Answer format: return exactly "rank N: a=<cell>; b=<cell>; ...; h=<cell>".


Prompt:
Rank 8 row before: 3Rk2r
File d changes from R to k. Rewrite the compressed row.

Answer format: return exactly "rank N: <before-row> -> <after-row>".


Prompt:
Board FEN before: r1b2rk1/1p2b1pp/1q2pp2/3pP3/p2N4/2PQ4/PP3PPP/R1B1R1K1
Apply square edits: d3 Q->1; e4 1->Q
Return the resulting board FEN only.

Answer format: return exactly "Result board FEN: <piece-placement-field>".

Result board FEN: r1b2rk1/1p2b1pp/1q2pp2/3pP3/p2NQ3/2P5/PP3PPP/R1B1R1K1


Prompt:
Starting FEN: r1bqk2r/p4ppp/2pp1n2/2b1p3/2P1P3/2NB4/PP3PPP/R1BQ1RK1 w kq -
Move: d1e2
List the square lookups and rank edits.

Answer format: return exactly three lines starting "Lookup:", "Squares:", and "Ranks:"; do not include Result FEN.

Lookup: d1=white queen; e2=empty.
Squares: d1 white queen->empty; e2 empty->white queen.
Ranks: rank 1 d Q->1; rank 2 e 1->Q.


Prompt:
Starting FEN: 6k1/1p3pp1/p1p2q1p/2P1r3/1P1p4/P2P3P/4QPP1/R5K1 w - - 2 25
Move: a1b1
Use square lookups and rank edits to assemble the resulting full FEN.
State needed for full FEN:
Side to move: white
Castling rights: none
En passant: none
Halfmove clock: 2
Fullmove number: 25

Answer format: include the edit trace and exactly one final line "Result FEN: <complete six-field FEN>".

Move 1: white rook a1b1.
Lookup: a1=white rook; b1=empty.
Squares: a1 white rook->empty; b1 empty->white rook.
Ranks: rank 1 a R->1; rank 1 b 1->R.
Result FEN: 6k1/1p3pp1/p1p2q1p/2P1r3/1P1p4/P2P3P/4QPP1/1R4K1 b - - 3 25


Prompt:
Starting FEN: 8/8/6R1/7p/Pp5P/6Pk/1P1pKP2/2rR4 b - - 2 36
Move: h3g2
Rewrite the affected compressed FEN rank rows and give Result FEN.
State needed for full FEN:
Side to move: black
Castling rights: none
En passant: none
Halfmove clock: 2
Fullmove number: 36

Answer format: first line starts "Rows:" and final line is "Result FEN: <complete six-field FEN>".

Rows: rank 3 6Pk->6P1; rank 2 1P1pKP2->1P1pKPk1.
Result FEN: 8/8/6R1/7p/Pp5P/6P1/1P1pKPk1/2rR4 w - - 3 37


Prompt:
Starting FEN: r3kb1r/1p1b2pp/pq2pp1n/n1p5/2P1PB2/2NP1N2/PP1Q1PPP/R3K2R w KQkq - 0 12
After the moves d3d4, what is the resulting position?
State needed for full FEN:
Side to move: white
Castling rights: KQkq
En passant: none
Halfmove clock: 0
Fullmove number: 12

Answer format: return exactly "Result FEN: <complete six-field FEN>".

Result FEN: r3kb1r/1p1b2pp/pq2pp1n/n1p5/2PPPB2/2N2N2/PP1Q1PPP/R3K2R b KQkq - 0 12


Prompt:
FEN: rnbqkb1r/ppp2ppp/4p3/3n4/2PP4/5N2/PP3PPP/RNBQKB1R b KQkq - 0 5
List the material inventory by side and piece type.

Answer format: return exactly two lines starting "White inventory:" and "Black inventory:".

White inventory: king=e1; queen=d1; rook=a1,h1; bishop=c1,f1; knight=b1,f3; pawn=a2,b2,f2,g2,h2,c4,d4.
Black inventory: king=e8; queen=d8; rook=a8,h8; bishop=c8,f8; knight=d5,b8; pawn=e6,a7,b7,c7,f7,g7,h7.


Prompt:
FEN: 6r1/7k/4K3/8/8/8/8/6Q1 w - -
Count each piece type for both sides.

Answer format: return exactly two lines starting "White counts:" and "Black counts:".

White counts: king=1; queen=1; rook=0; bishop=0; knight=0; pawn=0.
Black counts: king=1; queen=0; rook=1; bishop=0; knight=0; pawn=0.


Prompt:
FEN: rn1qkb1r/pp3ppp/4bn2/2p5/2P5/2N5/PP1P1PPP/R1BQKBNR b KQkq -
Convert the piece counts into material value totals.

Answer format: return exactly two lines starting "White values:" and "Black values:".

White values: king=0; queen=9; rook=10; bishop=6; knight=6; pawn=7; total=38.
Black values: king=0; queen=9; rook=10; bishop=6; knight=6; pawn=6; total=37.


Prompt:
FEN: rnbq1rk1/pp2ppbp/3p2p1/2p3N1/2B1P3/2PP1Q2/PP3PPP/RN2K2R b KQ - 3 9
Trace inventory, counts, values, and material balance.

Answer format: return exactly four lines starting "Inventory:", "Counts:", "Values:", and "Balance:".

Inventory: white king=e1; queen=f3; rook=a1,h1; bishop=c4; knight=b1,g5; pawn=a2,b2,f2,g2,h2,c3,d3,e4 | black king=g8; queen=d8; rook=a8,f8; bishop=g7,c8; knight=b8; pawn=c5,d6,g6,a7,b7,e7,f7,h7
Counts: white king=1; queen=1; rook=2; bishop=1; knight=2; pawn=8 | black king=1; queen=1; rook=2; bishop=2; knight=1; pawn=8
Values: white total=36; black total=36
Balance: Material is equal.


Prompt:
Starting FEN: 2rq1rk1/p2bppb1/3p1np1/1p2n2p/4P2P/1BN1BP2/PPPQN1P1/2KR3R w - - 0 1
After the moves g2g4 c8c7 b3d5, what is the resulting position?
State needed for full FEN:
Side to move: white
Castling rights: none
En passant: none
Halfmove clock: 0
Fullmove number: 1

Answer format: return exactly "Result FEN: <complete six-field FEN>".

Result FEN: 3q1rk1/p1rbppb1/3p1np1/1p1Bn2p/4P1PP/2N1BP2/PPPQN3/2KR3R b - - 2 2


Prompt:
Position (FEN): r1b2rk1/pp2ppbp/2N2np1/8/4p3/2N2P2/PPPBB1PP/2KR3R b - -
Show me the board.


r1b1kbnN/p2n2p1/1p5p/2pB4/3pPq2/8/PPP2PPP/RN1QK2R w KQq - 0 10

Prompt:
Here is the current board:
8 r . b . k b n N
7 p . . n . . p .
6 . p . . . . . p
5 . . p B . . . .
4 . . . p P q . .
3 . . . . . . . .
2 P P P . . P P P
1 R N . Q K . . R
  a b c d e f g h
Write the FEN for this position.
State needed for full FEN:
Side to move: white
Castling rights: KQq
En passant: none
Halfmove clock: 0
Fullmove number: 10

Answer format: return exactly one complete six-field FEN, with no prefix and no explanation.


Prompt:
FEN: 8/1b1kq3/3rprp1/1B1pQ2p/p2P1P2/P1P3P1/1P1R3P/2K1R3 b - - 0 30
What piece is on a3?

Answer format: for a square query, return only the piece name or empty; do not include the square. For a locate query, return only space-separated squares.


Prompt:
FEN: 2k2N2/ppp5/3p1pp1/7p/3n4/1P4PK/P3r2P/R7 b - - 7 30
What is the material count for both sides?

White (7 pieces): 1 king, 1 knight, 4 pawns, 1 rook. Black (10 pieces): 1 king, 1 knight, 7 pawns, 1 rook. Black is up 3 point(s) of material.


Prompt:
FEN: 2r5/p3k1pp/1p6/3B3b/2PP4/7P/P4PP1/1R2K2R b K - 0 22
What is on b3?

Answer format: return exactly "<square>=<piece>" or "<square>=empty".


Prompt:
FEN: r1bqk2r/pp2bppp/2n2n2/2pp4/8/2NP1NP1/PP2PPBP/R1BQK2R w KQkq -
What is the compressed FEN row for rank 7?

Answer format: return exactly "rank N: <compressed FEN row>".


Prompt:
FEN: 4r1k1/r4b2/p2Q4/np3P2/4P3/1P5P/PP4P1/5RK1 b - -
For square f5, give the FEN row-from-top and file index.

Answer format: return exactly "<square>: file=<file>; rank=<rank>; fen_row_from_top=<1-8>; file_index=<1-8>".

f5: file=f; rank=5; fen_row_from_top=4; file_index=6


Prompt:
FEN: 2rqr1k1/pp2pp1p/4b1p1/3N4/3QP3/1P3P2/P5PP/R4RK1 w - -
Compressed rank 7 row: pp2pp1p
Expand it into file cells a through h.

Answer format: return exactly "rank N: a=<cell>; b=<cell>; ...; h=<cell>".


Prompt:
Rank 1 row before: 1R3RK1
File f changes from R to 1. Rewrite the compressed row.

Answer format: return exactly "rank N: <before-row> -> <after-row>".


Prompt:
Board FEN before: 7k/6p1/Q4p1p/2P5/8/1P3R1P/1r2r1P1/5R1K
Apply square edits: a6 Q->1; a1 1->Q
Return the resulting board FEN only.

Answer format: return exactly "Result board FEN: <piece-placement-field>".

Result board FEN: 7k/6p1/5p1p/2P5/8/1P3R1P/1r2r1P1/Q4R1K


Prompt:
Starting FEN: r1bq1rk1/p3ppbp/2pp1np1/2p5/4P3/2PP1N1P/PPQ2PP1/RNB2RK1 b - -
Move: c8a6
List the square lookups and rank edits.

Answer format: return exactly three lines starting "Lookup:", "Squares:", and "Ranks:"; do not include Result FEN.

Lookup: c8=black bishop; a6=empty.
Squares: c8 black bishop->empty; a6 empty->black bishop.
Ranks: rank 8 c b->1; rank 6 a 1->b.


Prompt:
Starting FEN: r2q1rk1/1pp1bppp/p1n1pn2/2Pp4/1P1P4/P3PN2/4BPPP/1RBQ1RK1 b - - 4 10
Move: b7b6
Use square lookups and rank edits to assemble the resulting full FEN.
State needed for full FEN:
Side to move: black
Castling rights: none
En passant: none
Halfmove clock: 4
Fullmove number: 10

Answer format: include the edit trace and exactly one final line "Result FEN: <complete six-field FEN>".

Move 1: black pawn b7b6.
Lookup: b7=black pawn; b6=empty.
Squares: b7 black pawn->empty; b6 empty->black pawn.
Ranks: rank 7 b p->1; rank 6 b 1->p.
Result FEN: r2q1rk1/2p1bppp/ppn1pn2/2Pp4/1P1P4/P3PN2/4BPPP/1RBQ1RK1 w - - 0 11


Prompt:
Starting FEN: r1bqk2r/pp2bppp/2n1pn2/2pp2B1/3P4/5NP1/PPP1PPBP/RN1QR1K1 b kq - 0 1
Move: d8d6
Rewrite the affected compressed FEN rank rows and give Result FEN.
State needed for full FEN:
Side to move: black
Castling rights: kq
En passant: none
Halfmove clock: 0
Fullmove number: 1

Answer format: first line starts "Rows:" and final line is "Result FEN: <complete six-field FEN>".

Rows: rank 8 r1bqk2r->r1b1k2r; rank 6 2n1pn2->2nqpn2.
Result FEN: r1b1k2r/pp2bppp/2nqpn2/2pp2B1/3P4/5NP1/PPP1PPBP/RN1QR1K1 w kq - 1 2


Prompt:
Starting FEN: 8/8/1B6/3k4/2N5/2K5/8/8 b - - 0 1
After the moves d5e6, what is the resulting position?
State needed for full FEN:
Side to move: black
Castling rights: none
En passant: none
Halfmove clock: 0
Fullmove number: 1

Answer format: return exactly "Result FEN: <complete six-field FEN>".


Prompt:
FEN: r1bq1rk1/pp3pbp/n1pp1np1/4p3/2P1P3/2NP2P1/PP2NPBP/R1BQ1RK1 w - -
List the material inventory by side and piece type.

Answer format: return exactly two lines starting "White inventory:" and "Black inventory:".

White inventory: king=g1; queen=d1; rook=a1,f1; bishop=c1,g2; knight=e2,c3; pawn=a2,b2,f2,h2,d3,g3,c4,e4.
Black inventory: king=g8; queen=d8; rook=a8,f8; bishop=g7,c8; knight=a6,f6; pawn=e5,c6,d6,g6,a7,b7,f7,h7.


Prompt:
FEN: r2r2k1/ppp2ppp/4B3/4P3/4n3/1P6/P1K2PPP/R6R w - - 1 18
Count each piece type for both sides.

Answer format: return exactly two lines starting "White counts:" and "Black counts:".

White counts: king=1; queen=0; rook=2; bishop=1; knight=0; pawn=6.
Black counts: king=1; queen=0; rook=2; bishop=0; knight=1; pawn=6.


Prompt:
FEN: 2k2b2/1ppr1np1/4p2p/p3p3/1n1pP2P/N2P1P2/PPPB1P2/2KR3R w - - 0 18
Convert the piece counts into material value totals.

Answer format: return exactly two lines starting "White values:" and "Black values:".

White values: king=0; queen=0; rook=10; bishop=3; knight=3; pawn=8; total=24.
Black values: king=0; queen=0; rook=5; bishop=3; knight=6; pawn=8; total=22.


Prompt:
FEN: r4rk1/1bqnpp1p/1p1p2p1/4n3/1RP1P3/2P1BP2/3NB1PP/3Q1RK1 w - -
Trace inventory, counts, values, and material balance.

Answer format: return exactly four lines starting "Inventory:", "Counts:", "Values:", and "Balance:".

Inventory: white king=g1; queen=d1; rook=f1,b4; bishop=e2,e3; knight=d2; pawn=g2,h2,c3,f3,c4,e4 | black king=g8; queen=c7; rook=a8,f8; bishop=b7; knight=e5,d7; pawn=b6,d6,g6,e7,f7,h7
Counts: white king=1; queen=1; rook=2; bishop=2; knight=1; pawn=6 | black king=1; queen=1; rook=2; bishop=1; knight=2; pawn=6
Values: white total=34; black total=34
Balance: Material is equal.


Prompt:
Starting FEN: r2qkbnr/ppp2ppp/2npb3/4p3/2B1PP2/5N2/PPPPQ1PP/RNB1K2R b KQkq - 3 5
After the moves a8b8 e2d3 b7b6, what is the resulting position?
State needed for full FEN:
Side to move: black
Castling rights: KQkq
En passant: none
Halfmove clock: 3
Fullmove number: 5

Answer format: return exactly "Result FEN: <complete six-field FEN>".

Result FEN: 1r1qkbnr/p1p2ppp/1pnpb3/4p3/2B1PP2/3Q1N2/PPPP2PP/RNB1K2R w KQk - 0 7


Prompt:
Position (FEN): r3q1k1/p2br1p1/2p5/3pP1Q1/5P2/P3P1bP/3B2P1/2R2RK1 w - - 1 28
Show me the board.


Prompt:
Here is the current board:
8 . . . . r k . .
7 . . . . . . . .
6 . n . R p . . p
5 . . . . R . p .
4 . . . . P . . .
3 . . . . . . N P
2 . . . . . P P K
1 . . r . . . . .
  a b c d e f g h
Write the FEN for this position.
State needed for full FEN:
Side to move: black
Castling rights: none
En passant: none
Halfmove clock: 4
Fullmove number: 36

Answer format: return exactly one complete six-field FEN, with no prefix and no explanation.


Prompt:
FEN: 6k1/p1p3pp/2p5/2P5/8/P4R1P/1N2R1PK/r6r w - - 11 32
What piece is on a7?

Answer format: for a square query, return only the piece name or empty; do not include the square. For a locate query, return only space-separated squares.


Prompt:
FEN: 8/8/3k4/3P2p1/6P1/1K6/8/8 b - -
What is the material count for both sides?

White (3 pieces): 1 king, 2 pawns. Black (2 pieces): 1 king, 1 pawn. White is up 1 point(s) of material.


Prompt:
FEN: rn2kb1r/ppp2p1p/3pBn2/4p1Np/4P3/3P4/PPP2PPP/RN2K2R b KQkq - 0 9
What is on e8?

Answer format: return exactly "<square>=<piece>" or "<square>=empty".


Prompt:
FEN: 7k/p2q1p2/1p4p1/3pr2p/1P1QBP2/P3P1P1/7P/6K1 b - -
What is the compressed FEN row for rank 4?

Answer format: return exactly "rank N: <compressed FEN row>".


Prompt:
FEN: 5k2/pb4p1/6P1/1p3NKP/5P2/P1q5/6q1/8 w - - 0 41
For square b7, give the FEN row-from-top and file index.

Answer format: return exactly "<square>: file=<file>; rank=<rank>; fen_row_from_top=<1-8>; file_index=<1-8>".

b7: file=b; rank=7; fen_row_from_top=2; file_index=2


Prompt:
FEN: 5r2/6pp/8/3k4/8/4RP2/5P1P/6K1 w - - 5 41
Compressed rank 4 row: 8
Expand it into file cells a through h.

Answer format: return exactly "rank N: a=<cell>; b=<cell>; ...; h=<cell>".


r1b1kbnr/pppp1ppp/8/2q5/8/5N2/PPP1PPPP/R1BQKB1R w KQkq - 2 7

Prompt:
Rank 3 row before: 5N2
File a changes from 1 to P. Rewrite the compressed row.

Answer format: return exactly "rank N: <before-row> -> <after-row>".


Prompt:
Board FEN before: 8/8/3p1p2/pBp1p3/P1P1r1k1/2K5/8/8
Apply square edits: c3 K->1; d3 1->K
Return the resulting board FEN only.

Answer format: return exactly "Result board FEN: <piece-placement-field>".

Result board FEN: 8/8/3p1p2/pBp1p3/P1P1r1k1/3K4/8/8


Prompt:
Starting FEN: r2qr3/p6p/2pPk3/3NBp1Q/8/8/PPP2P1P/2KR3R b - - 0 20
Move: e8f8
List the square lookups and rank edits.

Answer format: return exactly three lines starting "Lookup:", "Squares:", and "Ranks:"; do not include Result FEN.

Lookup: e8=black rook; f8=empty.
Squares: e8 black rook->empty; f8 empty->black rook.
Ranks: rank 8 e r->1; rank 8 f 1->r.


Prompt:
Starting FEN: rn1qkbnr/pp3ppp/2p5/3p4/3P1P2/3B1Q2/PPP3PP/RNB1K2R b KQkq - 0 7
Move: d8g5
Use square lookups and rank edits to assemble the resulting full FEN.
State needed for full FEN:
Side to move: black
Castling rights: KQkq
En passant: none
Halfmove clock: 0
Fullmove number: 7

Answer format: include the edit trace and exactly one final line "Result FEN: <complete six-field FEN>".

Move 1: black queen d8g5.
Lookup: d8=black queen; g5=empty.
Squares: d8 black queen->empty; g5 empty->black queen.
Ranks: rank 8 d q->1; rank 5 g 1->q.
Result FEN: rn2kbnr/pp3ppp/2p5/3p2q1/3P1P2/3B1Q2/PPP3PP/RNB1K2R w KQkq - 1 8


Prompt:
Starting FEN: 2rq1rk1/1p1b1pp1/p1nppb1p/8/3NP3/1BP3N1/PP3PPP/R2QR1K1 b - - 2 14
Move: c6d4
Rewrite the affected compressed FEN rank rows and give Result FEN.
State needed for full FEN:
Side to move: black
Castling rights: none
En passant: none
Halfmove clock: 2
Fullmove number: 14

Answer format: first line starts "Rows:" and final line is "Result FEN: <complete six-field FEN>".

Rows: rank 6 p1nppb1p->p2ppb1p; rank 4 3NP3->3nP3.
Result FEN: 2rq1rk1/1p1b1pp1/p2ppb1p/8/3nP3/1BP3N1/PP3PPP/R2QR1K1 w - - 0 15


Prompt:
Starting FEN: 3rk2r/p3bpp1/5n1p/4p3/2P4B/2N4P/PP2BPb1/R3K1R1 b Qk - 1 20
After the moves g2h1, what is the resulting position?
State needed for full FEN:
Side to move: black
Castling rights: Qk
En passant: none
Halfmove clock: 1
Fullmove number: 20

Answer format: return exactly "Result FEN: <complete six-field FEN>".

Result FEN: 3rk2r/p3bpp1/5n1p/4p3/2P4B/2N4P/PP2BP2/R3K1Rb w Qk - 2 21


Prompt:
FEN: r1b1kbnr/5p2/1q2p1p1/p1ppP3/P4P2/2PQ1NPp/1P5P/RNB2R1K b kq - 1 14
List the material inventory by side and piece type.

Answer format: return exactly two lines starting "White inventory:" and "Black inventory:".

White inventory: king=h1; queen=d3; rook=a1,f1; bishop=c1; knight=b1,f3; pawn=b2,h2,c3,g3,a4,f4,e5.
Black inventory: king=e8; queen=b6; rook=a8,h8; bishop=c8,f8; knight=g8; pawn=h3,a5,c5,d5,e6,g6,f7.


Prompt:
FEN: 1r1qrbk1/2pb1pp1/p1np1n1p/4p3/Pp2P3/2PP1N1P/1PB2PP1/R1BQRNK1 w - -
Count each piece type for both sides.

Answer format: return exactly two lines starting "White counts:" and "Black counts:".

White counts: king=1; queen=1; rook=2; bishop=2; knight=2; pawn=8.
Black counts: king=1; queen=1; rook=2; bishop=2; knight=2; pawn=8.


Prompt:
FEN: rnb4q/ppp1k1b1/3p1npp/8/3QP3/1B6/PPP2PPP/RNB1K2R w KQ - 0 11
Convert the piece counts into material value totals.

Answer format: return exactly two lines starting "White values:" and "Black values:".

White values: king=0; queen=9; rook=10; bishop=6; knight=3; pawn=7; total=35.
Black values: king=0; queen=9; rook=5; bishop=6; knight=6; pawn=6; total=32.


Prompt:
FEN: 8/6pp/4p3/k3P3/prP1N3/R1K4P/6P1/8 w - -
Trace inventory, counts, values, and material balance.

Answer format: return exactly four lines starting "Inventory:", "Counts:", "Values:", and "Balance:".

Inventory: white king=c3; queen=none; rook=a3; bishop=none; knight=e4; pawn=g2,h3,c4,e5 | black king=a5; queen=none; rook=b4; bishop=none; knight=none; pawn=a4,e6,g7,h7
Counts: white king=1; queen=0; rook=1; bishop=0; knight=1; pawn=4 | black king=1; queen=0; rook=1; bishop=0; knight=0; pawn=4
Values: white total=12; black total=9
Balance: White is up 3 point(s) of material.


Prompt:
Starting FEN: 8/2kP1n2/6pP/4p3/7P/1p1R1P2/1P2K3/7r w - - 1 37
After the moves d3d6 f7d6 d7d8q, what is the resulting position?
State needed for full FEN:
Side to move: white
Castling rights: none
En passant: none
Halfmove clock: 1
Fullmove number: 37

Answer format: return exactly "Result FEN: <complete six-field FEN>".


Prompt:
Position (FEN): 2R3k1/5p2/q3p2p/P5p1/8/1p2P1P1/5P1P/6K1 b - - 0 28
Show me the board.


Prompt:
Here is the current board:
8 . k . r . b . r
7 . p . . . p p p
6 . . . p . . . .
5 . p p R . . . .
4 . . . . P . . .
3 . . . . B P . P
2 P P . . . P . .
1 . . K . . . . R
  a b c d e f g h
Write the FEN for this position.
State needed for full FEN:
Side to move: white
Castling rights: none
En passant: none
Halfmove clock: 0
Fullmove number: 23

Answer format: return exactly one complete six-field FEN, with no prefix and no explanation.


Prompt:
FEN: r1br2k1/4ppbp/1pn3p1/p2n4/2P1P3/B4P2/PP2N1PP/R3KB1R w KQ -
What piece is on b2?

Answer format: for a square query, return only the piece name or empty; do not include the square. For a locate query, return only space-separated squares.


Prompt:
FEN: r1bq3r/2pkbQ1p/2p2p2/p2p2p1/3Pp3/BPP1P3/P2N2PP/R3NRK1 b - - 5 16
What is the material count for both sides?

White (14 pieces): 1 bishop, 1 king, 2 knights, 7 pawns, 1 queen, 2 rooks. Black (14 pieces): 2 bishops, 1 king, 8 pawns, 1 queen, 2 rooks. White is up 2 point(s) of material.


Prompt:
FEN: r4r2/pp4k1/5p2/2bp1p2/7P/2N1PN2/PPP2P2/R3K3 w Q -
What is on b4?

Answer format: return exactly "<square>=<piece>" or "<square>=empty".


Prompt:
FEN: r2qk2r/1ppb1pp1/pbn2n1p/3pp3/PP2P3/2PPBN1P/4BPP1/RN1Q1RK1 w kq - 2 11
What is the compressed FEN row for rank 1?

Answer format: return exactly "rank N: <compressed FEN row>".


Prompt:
FEN: 2r5/5k2/4R1p1/pP4rp/P7/5P2/3R1KPP/8 w - - 1 41
For square a5, give the FEN row-from-top and file index.

Answer format: return exactly "<square>: file=<file>; rank=<rank>; fen_row_from_top=<1-8>; file_index=<1-8>".

a5: file=a; rank=5; fen_row_from_top=4; file_index=1


Prompt:
FEN: 2r2k2/1b2q1pQ/p3np2/1p1p4/3P4/5N1P/PPB2PP1/1R4K1 w - - 1 27
Compressed rank 6 row: p3np2
Expand it into file cells a through h.

Answer format: return exactly "rank N: a=<cell>; b=<cell>; ...; h=<cell>".


Prompt:
Rank 3 row before: 1PP1P2P
File a changes from 1 to B. Rewrite the compressed row.

Answer format: return exactly "rank N: <before-row> -> <after-row>".


r1bq1rk1/pp6/1npb1pp1/8/3P3p/2PB4/PP1Q1PPP/R1B1R1K1 w - -

Prompt:
Board FEN before: r1bq1rk1/pp6/1npb1pp1/8/3P3p/2PB4/PP1Q1PPP/R1B1R1K1
Apply square edits: b2 P->1; b4 1->P
Return the resulting board FEN only.

Answer format: return exactly "Result board FEN: <piece-placement-field>".

Result board FEN: r1bq1rk1/pp6/1npb1pp1/8/1P1P3p/2PB4/P2Q1PPP/R1B1R1K1


Prompt:
Starting FEN: r1b1k1nr/pppp1ppp/8/2bPn3/7q/5K2/PPP3PP/RNBQ1BNR w kq - 0 10
Move: f3e2
List the square lookups and rank edits.

Answer format: return exactly three lines starting "Lookup:", "Squares:", and "Ranks:"; do not include Result FEN.

Lookup: f3=white king; e2=empty.
Squares: f3 white king->empty; e2 empty->white king.
Ranks: rank 3 f K->1; rank 2 e 1->K.


Prompt:
Starting FEN: r3kb1r/1b1n1p2/1q3np1/4p1B1/p2pP2P/1p3PNB/PPPQ4/1KNR3R w kq - 0 1
Move: d2e2
Use square lookups and rank edits to assemble the resulting full FEN.
State needed for full FEN:
Side to move: white
Castling rights: kq
En passant: none
Halfmove clock: 0
Fullmove number: 1

Answer format: include the edit trace and exactly one final line "Result FEN: <complete six-field FEN>".

Move 1: white queen d2e2.
Lookup: d2=white queen; e2=empty.
Squares: d2 white queen->empty; e2 empty->white queen.
Ranks: rank 2 d Q->1; rank 2 e 1->Q.
Result FEN: r3kb1r/1b1n1p2/1q3np1/4p1B1/p2pP2P/1p3PNB/PPP1Q3/1KNR3R b kq - 1 1


Prompt:
Starting FEN: rn1q1rk1/p4ppp/b2p1b2/1pp1p3/4P3/P1NP1N1P/BPP2PP1/R2QK2R w KQ - 0 11
Move: g2g4
Rewrite the affected compressed FEN rank rows and give Result FEN.
State needed for full FEN:
Side to move: white
Castling rights: KQ
En passant: none
Halfmove clock: 0
Fullmove number: 11

Answer format: first line starts "Rows:" and final line is "Result FEN: <complete six-field FEN>".

Rows: rank 2 BPP2PP1->BPP2P2; rank 4 4P3->4P1P1.
Result FEN: rn1q1rk1/p4ppp/b2p1b2/1pp1p3/4P1P1/P1NP1N1P/BPP2P2/R2QK2R b KQ - 0 11


Prompt:
Starting FEN: 8/8/p7/1p4kP/1K2P1p1/8/8/8 w - - 0 1
After the moves b4c3, what is the resulting position?
State needed for full FEN:
Side to move: white
Castling rights: none
En passant: none
Halfmove clock: 0
Fullmove number: 1

Answer format: return exactly "Result FEN: <complete six-field FEN>".


Prompt:
FEN: r1bqkb1r/pp3ppp/2n1p1n1/3pP3/3P3P/p1PB1N2/5PP1/RNBQK2R b KQkq -
List the material inventory by side and piece type.

Answer format: return exactly two lines starting "White inventory:" and "Black inventory:".

White inventory: king=e1; queen=d1; rook=a1,h1; bishop=c1,d3; knight=b1,f3; pawn=f2,g2,c3,d4,h4,e5.
Black inventory: king=e8; queen=d8; rook=a8,h8; bishop=c8,f8; knight=c6,g6; pawn=a3,d5,e6,a7,b7,f7,g7,h7.


Prompt:
FEN: r1b1k2r/pp3ppp/2n5/qBbp4/8/4P2P/PP3PP1/R1BQK1NR w KQkq - 1 10
Count each piece type for both sides.

Answer format: return exactly two lines starting "White counts:" and "Black counts:".

White counts: king=1; queen=1; rook=2; bishop=2; knight=1; pawn=6.
Black counts: king=1; queen=1; rook=2; bishop=2; knight=1; pawn=6.


Prompt:
FEN: 1r3rk1/1B3ppp/p3pn2/PpN5/5P2/2q4P/3P2P1/2R2R1K w - - 0 28
Convert the piece counts into material value totals.

Answer format: return exactly two lines starting "White values:" and "Black values:".

White values: king=0; queen=0; rook=10; bishop=3; knight=3; pawn=5; total=21.
Black values: king=0; queen=9; rook=10; bishop=0; knight=3; pawn=6; total=28.


Prompt:
FEN: r2q1rk1/pb2b2p/1p3p2/3p2p1/Q1pPn3/P3B1P1/1P1NPPBP/R4RK1 b - -
Trace inventory, counts, values, and material balance.

Answer format: return exactly four lines starting "Inventory:", "Counts:", "Values:", and "Balance:".

Inventory: white king=g1; queen=a4; rook=a1,f1; bishop=g2,e3; knight=d2; pawn=b2,e2,f2,h2,a3,g3,d4 | black king=g8; queen=d8; rook=a8,f8; bishop=b7,e7; knight=e4; pawn=c4,d5,g5,b6,f6,a7,h7
Counts: white king=1; queen=1; rook=2; bishop=2; knight=1; pawn=7 | black king=1; queen=1; rook=2; bishop=2; knight=1; pawn=7
Values: white total=35; black total=35
Balance: Material is equal.


Prompt:
Starting FEN: r1bqk1r1/ppp2p2/2np1n2/4p1B1/1bB1P2P/2NP4/PPP2PP1/R2QK2R w KQq - 0 1
After the moves a1b1 g8h8, what is the resulting position?
State needed for full FEN:
Side to move: white
Castling rights: KQq
En passant: none
Halfmove clock: 0
Fullmove number: 1

Answer format: return exactly "Result FEN: <complete six-field FEN>".

Result FEN: r1bqk2r/ppp2p2/2np1n2/4p1B1/1bB1P2P/2NP4/PPP2PP1/1R1QK2R w Kq - 2 2


Prompt:
Position (FEN): rnb1k1nr/pp1p1ppp/2p2q2/4p1BQ/1b2P3/2NP4/PPP2PPP/R3KBNR b KQkq - 2 5
Show me the board.

8 r n b . k . n r
7 p p . p . p p p
6 . . p . . q . .
5 . . . . p . B Q
4 . b . . P . . .
3 . . N P . . . .
2 P P P . . P P P
1 R . . . K B N R
  a b c d e f g h


1r1q1rk1/ppp1bppp/2np4/6Nn/2Q1P3/4B3/PPP2PPP/R3KB1R b KQ - 12 12

Prompt:
Here is the current board:
8 . r . q . r k .
7 p p p . b p p p
6 . . n p . . . .
5 . . . . . . N n
4 . . Q . P . . .
3 . . . . B . . .
2 P P P . . P P P
1 R . . . K B . R
  a b c d e f g h
Write the FEN for this position.
State needed for full FEN:
Side to move: black
Castling rights: KQ
En passant: none
Halfmove clock: 12
Fullmove number: 12

Answer format: return exactly one complete six-field FEN, with no prefix and no explanation.


Prompt:
FEN: r1bqr1k1/4p1bp/p4pp1/P2p4/2pP4/2P3BP/1PB1QPP1/R3R1K1 b - - 1 21
What piece is on f6?

Answer format: for a square query, return only the piece name or empty; do not include the square. For a locate query, return only space-separated squares.


Prompt:
FEN: r2q1rk1/pp3pbp/2np1np1/1N2pb2/2P5/2N1P3/PP2BPPP/R1BQR1K1 w - -
What is the material count for both sides?

White (15 pieces): 2 bishops, 1 king, 2 knights, 7 pawns, 1 queen, 2 rooks. Black (15 pieces): 2 bishops, 1 king, 2 knights, 7 pawns, 1 queen, 2 rooks. Material is equal.


Prompt:
FEN: 3r1rk1/p5p1/2p5/1p2Ppq1/8/2P1n3/PP2Q1P1/RNK4R w - -
What is on c7?

Answer format: return exactly "<square>=<piece>" or "<square>=empty".


Prompt:
FEN: 8/3k3P/P2B4/2Pp2K1/3P2P1/8/P7/8 b - - 0 55
What is the compressed FEN row for rank 4?

Answer format: return exactly "rank N: <compressed FEN row>".


Prompt:
FEN: rn1qk1nr/pbppppbp/1p4p1/3P4/2P5/2N5/PP2PPPP/R1BQKBNR w KQkq -
For square f1, give the FEN row-from-top and file index.

Answer format: return exactly "<square>: file=<file>; rank=<rank>; fen_row_from_top=<1-8>; file_index=<1-8>".

f1: file=f; rank=1; fen_row_from_top=8; file_index=6


Prompt:
FEN: r4r1k/pp3pp1/2n5/7q/1b1pBBb1/6N1/PPQ2PPP/R4RK1 b - -
Compressed rank 6 row: 2n5
Expand it into file cells a through h.

Answer format: return exactly "rank N: a=<cell>; b=<cell>; ...; h=<cell>".


Prompt:
Rank 1 row before: R5K1
File d changes from 1 to R. Rewrite the compressed row.

Answer format: return exactly "rank N: <before-row> -> <after-row>".


Prompt:
Board FEN before: 1R6/3k4/P2r2pp/2p5/4p3/6P1/4KP1P/8
Apply square edits: h2 P->1; h4 1->P
Return the resulting board FEN only.

Answer format: return exactly "Result board FEN: <piece-placement-field>".

Result board FEN: 1R6/3k4/P2r2pp/2p5/4p2P/6P1/4KP2/8


Prompt:
Starting FEN: 8/8/4B3/4N3/2K5/8/2k5/8 w - -
Move: e6d7
List the square lookups and rank edits.

Answer format: return exactly three lines starting "Lookup:", "Squares:", and "Ranks:"; do not include Result FEN.

Lookup: e6=white bishop; d7=empty.
Squares: e6 white bishop->empty; d7 empty->white bishop.
Ranks: rank 6 e B->1; rank 7 d 1->B.


Prompt:
Starting FEN: r2qk1nr/pp1n1ppp/2p1p3/2bp4/4P3/2N2QPP/PPPP1PB1/R1B1K2R w KQkq - 0 1
Move: h1f1
Use square lookups and rank edits to assemble the resulting full FEN.
State needed for full FEN:
Side to move: white
Castling rights: KQkq
En passant: none
Halfmove clock: 0
Fullmove number: 1

Answer format: include the edit trace and exactly one final line "Result FEN: <complete six-field FEN>".

Move 1: white rook h1f1.
Lookup: h1=white rook; f1=empty.
Squares: h1 white rook->empty; f1 empty->white rook.
Ranks: rank 1 h R->1; rank 1 f 1->R.
Result FEN: r2qk1nr/pp1n1ppp/2p1p3/2bp4/4P3/2N2QPP/PPPP1PB1/R1B1KR2 b Qkq - 1 1


Prompt:
Starting FEN: 3r2k1/3P3p/3P2p1/p3p3/8/3q3P/Q4BPK/8 b - - 0 1
Move: d3c4
Rewrite the affected compressed FEN rank rows and give Result FEN.
State needed for full FEN:
Side to move: black
Castling rights: none
En passant: none
Halfmove clock: 0
Fullmove number: 1

Answer format: first line starts "Rows:" and final line is "Result FEN: <complete six-field FEN>".


Prompt:
Starting FEN: 5B2/R4ppk/6bp/3B4/4P3/4R2P/5PK1/8 b - - 0 38
After the moves h6h5, what is the resulting position?
State needed for full FEN:
Side to move: black
Castling rights: none
En passant: none
Halfmove clock: 0
Fullmove number: 38

Answer format: return exactly "Result FEN: <complete six-field FEN>".


Prompt:
FEN: 6k1/3n3p/3b2p1/8/r7/4N1PB/5P1P/1R4K1 w - -
List the material inventory by side and piece type.

Answer format: return exactly two lines starting "White inventory:" and "Black inventory:".

White inventory: king=g1; queen=none; rook=b1; bishop=h3; knight=e3; pawn=f2,h2,g3.
Black inventory: king=g8; queen=none; rook=a4; bishop=d6; knight=d7; pawn=g6,h7.


Prompt:
FEN: 8/p4pkp/1p4p1/2p2bP1/3r1P1P/8/4K3/8 w - - 2 41
Count each piece type for both sides.

Answer format: return exactly two lines starting "White counts:" and "Black counts:".

White counts: king=1; queen=0; rook=0; bishop=0; knight=0; pawn=3.
Black counts: king=1; queen=0; rook=1; bishop=1; knight=0; pawn=6.


Prompt:
FEN: r4Nk1/pppn2p1/1n2pq1p/3p4/3P4/2P1P1B1/P1Q2PPP/R3R1K1 b - - 0 19
Convert the piece counts into material value totals.

Answer format: return exactly two lines starting "White values:" and "Black values:".

White values: king=0; queen=9; rook=10; bishop=3; knight=3; pawn=7; total=32.
Black values: king=0; queen=9; rook=5; bishop=0; knight=6; pawn=7; total=27.


Prompt:
FEN: 7r/1N1kr1pp/1Pp2p2/p2p4/P1bP4/Q3P3/5PPP/RR4K1 b - - 0 30
Trace inventory, counts, values, and material balance.

Answer format: return exactly four lines starting "Inventory:", "Counts:", "Values:", and "Balance:".

Inventory: white king=g1; queen=a3; rook=a1,b1; bishop=none; knight=b7; pawn=f2,g2,h2,e3,a4,d4,b6 | black king=d7; queen=none; rook=e7,h8; bishop=c4; knight=none; pawn=a5,d5,c6,f6,g7,h7
Counts: white king=1; queen=1; rook=2; bishop=0; knight=1; pawn=7 | black king=1; queen=0; rook=2; bishop=1; knight=0; pawn=6
Values: white total=29; black total=19
Balance: White is up 10 point(s) of material.


Prompt:
Starting FEN: rnbq1rk1/pp1pppbp/5np1/3P4/4P3/2N2N2/PP3PPP/R1BQKB1R b KQ - 0 7
After the moves f6d5 e1d2 g7h8, what is the resulting position?
State needed for full FEN:
Side to move: black
Castling rights: KQ
En passant: none
Halfmove clock: 0
Fullmove number: 7

Answer format: return exactly "Result FEN: <complete six-field FEN>".

Result FEN: rnbq1rkb/pp1ppp1p/6p1/3n4/4P3/2N2N2/PP1K1PPP/R1BQ1B1R w - - 2 9


Prompt:
Position (FEN): 5rk1/1b3p1p/2q1pQp1/1B1pP3/3P4/7P/5PP1/1R4K1 w - - 1 26
Show me the board.


Prompt:
Here is the current board:
8 . r . q k b . r
7 Q . . n . p p p
6 p . . P p . . .
5 . p . . B . . .
4 . . . . . . P .
3 P N N . . . . .
2 . P P . B . b P
1 . . K R . R . .
  a b c d e f g h
Write the FEN for this position.
State needed for full FEN:
Side to move: black
Castling rights: k
En passant: none
Halfmove clock: 0
Fullmove number: 1

Answer format: return exactly one complete six-field FEN, with no prefix and no explanation.

1r1qkb1r/Q2n1ppp/p2Pp3/1p2B3/6P1/PNN5/1PP1B1bP/2KR1R2 b k - 0 1


Prompt:
FEN: r3kb1r/1b3ppp/8/pPp5/P2p4/4BP1P/4B1P1/RN2K1NR b KQkq - 0 17
What piece is on g2?

Answer format: for a square query, return only the piece name or empty; do not include the square. For a locate query, return only space-separated squares.


Prompt:
FEN: 1rq1kb1r/p4ppp/b3p1n1/1P1pP3/P2p1P2/2P5/5KPP/RNBQ3R w k - 0 14
What is the material count for both sides?

White (13 pieces): 1 bishop, 1 king, 1 knight, 7 pawns, 1 queen, 2 rooks. Black (14 pieces): 2 bishops, 1 king, 1 knight, 7 pawns, 1 queen, 2 rooks. Black is up 3 point(s) of material.


Prompt:
FEN: 8/8/5k2/2K5/4Q3/8/8/8 b - -
What is on c5?

Answer format: return exactly "<square>=<piece>" or "<square>=empty".


Prompt:
FEN: 3r1rk1/1p3ppn/p1n4p/2p1p1b1/1P2P3/PBN2Q1P/2R2PP1/6K1 w - -
What is the compressed FEN row for rank 3?

Answer format: return exactly "rank N: <compressed FEN row>".


Prompt:
FEN: r1bqk2r/1p1pbpp1/p1n1p2p/2P4Q/4N3/1R2B3/2B2PPP/3R2K1 b kq -
For square d4, give the FEN row-from-top and file index.

Answer format: return exactly "<square>: file=<file>; rank=<rank>; fen_row_from_top=<1-8>; file_index=<1-8>".

d4: file=d; rank=4; fen_row_from_top=5; file_index=4


Prompt:
FEN: r2qr1k1/p1p1bpp1/8/7n/3PQ1bP/4P1P1/PP1P1P2/RNB1K2R b KQ - 2 18
Compressed rank 7 row: p1p1bpp1
Expand it into file cells a through h.

Answer format: return exactly "rank N: a=<cell>; b=<cell>; ...; h=<cell>".


r1bqk2r/pp1p1p2/2n1pn1p/2b3p1/2P1P2B/2NB1N2/PP3PPP/R2QK2R w KQkq -

Prompt:
Rank 2 row before: PP3PPP
File a changes from P to 1. Rewrite the compressed row.

Answer format: return exactly "rank N: <before-row> -> <after-row>".


Prompt:
Board FEN before: r2q1rk1/ppp2ppp/8/n2B4/5B2/2PP3b/P1P3P1/R2Q1RK1
Apply square edits: g1 K->1; f2 1->K
Return the resulting board FEN only.

Answer format: return exactly "Result board FEN: <piece-placement-field>".

Result board FEN: r2q1rk1/ppp2ppp/8/n2B4/5B2/2PP3b/P1P2KP1/R2Q1R2


Prompt:
Starting FEN: r3r1k1/7p/p2p3b/1p1P1bp1/5p2/1N2P2P/PP3PPB/R2R2K1 w - - 0 23
Move: d1d4
List the square lookups and rank edits.

Answer format: return exactly three lines starting "Lookup:", "Squares:", and "Ranks:"; do not include Result FEN.

Lookup: d1=white rook; d4=empty.
Squares: d1 white rook->empty; d4 empty->white rook.
Ranks: rank 1 d R->1; rank 4 d 1->R.


Prompt:
Starting FEN: 1k2r3/1pp2p1Q/3prp2/8/pq2P3/1P3P2/P1P3PP/1K1RR3 w - - 0 23
Move: e1g1
Use square lookups and rank edits to assemble the resulting full FEN.
State needed for full FEN:
Side to move: white
Castling rights: none
En passant: none
Halfmove clock: 0
Fullmove number: 23

Answer format: include the edit trace and exactly one final line "Result FEN: <complete six-field FEN>".

Move 1: white rook e1g1.
Lookup: e1=white rook; g1=empty.
Squares: e1 white rook->empty; g1 empty->white rook.
Ranks: rank 1 e R->1; rank 1 g 1->R.
Result FEN: 1k2r3/1pp2p1Q/3prp2/8/pq2P3/1P3P2/P1P3PP/1K1R2R1 b - - 1 23


Prompt:
Starting FEN: r4q2/1bk1n1pp/pp1pB3/2p1p1Q1/4P3/3P3P/PPP2PP1/R4RK1 w - - 0 1
Move: f1d1
Rewrite the affected compressed FEN rank rows and give Result FEN.
State needed for full FEN:
Side to move: white
Castling rights: none
En passant: none
Halfmove clock: 0
Fullmove number: 1

Answer format: first line starts "Rows:" and final line is "Result FEN: <complete six-field FEN>".

Rows: rank 1 R4RK1->R2R2K1.
Result FEN: r4q2/1bk1n1pp/pp1pB3/2p1p1Q1/4P3/3P3P/PPP2PP1/R2R2K1 b - - 1 1


Prompt:
Starting FEN: r1bqkbnr/pppp1ppp/2n5/4P3/5B2/8/PPP1PPPP/RN1QKBNR b KQkq - 0 3
After the moves d7d5, what is the resulting position?
State needed for full FEN:
Side to move: black
Castling rights: KQkq
En passant: none
Halfmove clock: 0
Fullmove number: 3

Answer format: return exactly "Result FEN: <complete six-field FEN>".

Result FEN: r1bqkbnr/ppp2ppp/2n5/3pP3/5B2/8/PPP1PPPP/RN1QKBNR w KQkq d6 0 4


Prompt:
FEN: 8/5k2/p1PKp3/4P2p/6p1/5P2/P6P/8 b - - 0 37
List the material inventory by side and piece type.

Answer format: return exactly two lines starting "White inventory:" and "Black inventory:".

White inventory: king=d6; queen=none; rook=none; bishop=none; knight=none; pawn=a2,h2,f3,e5,c6.
Black inventory: king=f7; queen=none; rook=none; bishop=none; knight=none; pawn=g4,h5,a6,e6.


Prompt:
FEN: 2br2k1/5p1p/pPN5/R1pP2p1/N1P5/5BKP/5P2/1q2r3 b - - 0 38
Count each piece type for both sides.

Answer format: return exactly two lines starting "White counts:" and "Black counts:".

White counts: king=1; queen=0; rook=1; bishop=1; knight=2; pawn=5.
Black counts: king=1; queen=1; rook=2; bishop=1; knight=0; pawn=5.


Prompt:
FEN: r1bqk2r/4bp1p/p2ppp2/1p2P3/3Q1P2/2N5/PPP3PP/2KR1B1R b kq -
Convert the piece counts into material value totals.

Answer format: return exactly two lines starting "White values:" and "Black values:".

White values: king=0; queen=9; rook=10; bishop=3; knight=3; pawn=7; total=32.
Black values: king=0; queen=9; rook=10; bishop=6; knight=0; pawn=7; total=32.


Prompt:
FEN: 2kr1b1r/ppp1pppp/2nq1n2/5b2/2BP4/2N1PN2/PP2QPPP/R1B1K2R w KQ - 7 8
Trace inventory, counts, values, and material balance.

Answer format: return exactly four lines starting "Inventory:", "Counts:", "Values:", and "Balance:".

Inventory: white king=e1; queen=e2; rook=a1,h1; bishop=c1,c4; knight=c3,f3; pawn=a2,b2,f2,g2,h2,e3,d4 | black king=c8; queen=d6; rook=d8,h8; bishop=f5,f8; knight=c6,f6; pawn=a7,b7,c7,e7,f7,g7,h7
Counts: white king=1; queen=1; rook=2; bishop=2; knight=2; pawn=7 | black king=1; queen=1; rook=2; bishop=2; knight=2; pawn=7
Values: white total=38; black total=38
Balance: Material is equal.


Prompt:
Starting FEN: r1bqk2r/1p3ppp/p1n1pn2/8/PbBP4/5N2/1P2QPPP/RNBR2K1 b kq - 0 1
After the moves b4f8 g2g4 d8d5, what is the resulting position?
State needed for full FEN:
Side to move: black
Castling rights: kq
En passant: none
Halfmove clock: 0
Fullmove number: 1

Answer format: return exactly "Result FEN: <complete six-field FEN>".

Result FEN: r1b1kb1r/1p3ppp/p1n1pn2/3q4/P1BP2P1/5N2/1P2QP1P/RNBR2K1 w kq - 1 3


Prompt:
Position (FEN): r3r1k1/ppp2ppp/2pb4/5b2/3P4/2N2P2/PPP2P1P/R1K4R b - - 0 15
Show me the board.


Prompt:
Here is the current board:
8 . . r . . . . .
7 . . . . . . p .
6 k p . . . r . p
5 p N p . . . . .
4 . . P . P . . .
3 . R . R . P P .
2 . P . . . . K P
1 . . . . . . . .
  a b c d e f g h
Write the FEN for this position.
State needed for full FEN:
Side to move: black
Castling rights: none
En passant: none
Halfmove clock: 0
Fullmove number: 34

Answer format: return exactly one complete six-field FEN, with no prefix and no explanation.


Prompt:
FEN: Nnbr1k2/pp5p/6p1/3B1pb1/2P5/1P2P1P1/Pn1N1P1P/R1K2R2 b - - 1 18
What piece is on a7?

Answer format: for a square query, return only the piece name or empty; do not include the square. For a locate query, return only space-separated squares.


Prompt:
FEN: r1b1kb1r/2ppqp1p/p1n2np1/1p1Bp3/4P3/1QPP1N2/PP3PPP/RNB1K2R b KQkq - 1 10
What is the material count for both sides?

White (16 pieces): 2 bishops, 1 king, 2 knights, 8 pawns, 1 queen, 2 rooks. Black (16 pieces): 2 bishops, 1 king, 2 knights, 8 pawns, 1 queen, 2 rooks. Material is equal.


Prompt:
FEN: r1bqk2r/ppppnpbp/2n3p1/1B2p3/3PP3/2P2N2/PP3PPP/RNBQ1RK1 b kq - 0 6
What is on h2?

Answer format: return exactly "<square>=<piece>" or "<square>=empty".


Prompt:
FEN: r1bqkb1r/pp3ppp/2n5/2ppPp2/3P4/2P2N2/PP3PPP/RNBQK2R w KQkq -
What is the compressed FEN row for rank 2?

Answer format: return exactly "rank N: <compressed FEN row>".


Prompt:
FEN: r2q1rk1/pbppbppp/np2pn2/8/3P4/1P2PN2/P1PNBPPP/R1BQ1RK1 b - - 0 8
For square b7, give the FEN row-from-top and file index.

Answer format: return exactly "<square>: file=<file>; rank=<rank>; fen_row_from_top=<1-8>; file_index=<1-8>".

b7: file=b; rank=7; fen_row_from_top=2; file_index=2


Prompt:
FEN: r1bq1bnr/pppk1Bpp/2n5/8/3P4/1Q2Pp2/PP3PPP/RNB1K2R w KQ -
Compressed rank 2 row: PP3PPP
Expand it into file cells a through h.

Answer format: return exactly "rank N: a=<cell>; b=<cell>; ...; h=<cell>".


Prompt:
Rank 7 row before: 7p
File g changes from 1 to k. Rewrite the compressed row.

Answer format: return exactly "rank N: <before-row> -> <after-row>".


r1bqk1nr/pp2ppbp/2np2p1/2p5/2B1P3/5N1P/PPPP1PP1/RNBQ1RK1 w kq - 3 6

Prompt:
Board FEN before: r1bqk1nr/pp2ppbp/2np2p1/2p5/2B1P3/5N1P/PPPP1PP1/RNBQ1RK1
Apply square edits: g1 K->1; h2 1->K
Return the resulting board FEN only.

Answer format: return exactly "Result board FEN: <piece-placement-field>".

Result board FEN: r1bqk1nr/pp2ppbp/2np2p1/2p5/2B1P3/5N1P/PPPP1PPK/RNBQ1R2


Prompt:
Starting FEN: 8/8/4bkPK/5p2/8/8/6P1/8 w - -
Move: h6h5
List the square lookups and rank edits.

Answer format: return exactly three lines starting "Lookup:", "Squares:", and "Ranks:"; do not include Result FEN.

Lookup: h6=white king; h5=empty.
Squares: h6 white king->empty; h5 empty->white king.
Ranks: rank 6 h K->1; rank 5 h 1->K.


Prompt:
Starting FEN: r3q2r/1bR2pkp/pp3b2/3Pp3/6Q1/6P1/PP3PBP/5RK1 b - - 0 1
Move: g7f8
Use square lookups and rank edits to assemble the resulting full FEN.
State needed for full FEN:
Side to move: black
Castling rights: none
En passant: none
Halfmove clock: 0
Fullmove number: 1

Answer format: include the edit trace and exactly one final line "Result FEN: <complete six-field FEN>".

Move 1: black king g7f8.
Lookup: g7=black king; f8=empty.
Squares: g7 black king->empty; f8 empty->black king.
Ranks: rank 7 g k->1; rank 8 f 1->k.
Result FEN: r3qk1r/1bR2p1p/pp3b2/3Pp3/6Q1/6P1/PP3PBP/5RK1 w - - 1 2


Prompt:
Starting FEN: r2qk2r/1pp1bppp/p1n5/3pPb2/3P4/1Qn1BN1P/PP2BPP1/R4RK1 w kq - 0 1
Move: f3h4
Rewrite the affected compressed FEN rank rows and give Result FEN.
State needed for full FEN:
Side to move: white
Castling rights: kq
En passant: none
Halfmove clock: 0
Fullmove number: 1

Answer format: first line starts "Rows:" and final line is "Result FEN: <complete six-field FEN>".

Rows: rank 3 1Qn1BN1P->1Qn1B2P; rank 4 3P4->3P3N.
Result FEN: r2qk2r/1pp1bppp/p1n5/3pPb2/3P3N/1Qn1B2P/PP2BPP1/R4RK1 b kq - 1 1


Prompt:
Starting FEN: r1bqk2r/ppp2ppp/2n1pn2/3p2B1/1bPP4/1QN5/PP2PPPP/R3KBNR w KQkq - 0 1
After the moves e1d1, what is the resulting position?
State needed for full FEN:
Side to move: white
Castling rights: KQkq
En passant: none
Halfmove clock: 0
Fullmove number: 1

Answer format: return exactly "Result FEN: <complete six-field FEN>".

Result FEN: r1bqk2r/ppp2ppp/2n1pn2/3p2B1/1bPP4/1QN5/PP2PPPP/R2K1BNR b kq - 1 1


Prompt:
FEN: r4rk1/ppqb1pp1/2nbp2p/2pnN3/3P1B2/2P3P1/PPN1QPBP/R3R1K1 w - -
List the material inventory by side and piece type.

Answer format: return exactly two lines starting "White inventory:" and "Black inventory:".

White inventory: king=g1; queen=e2; rook=a1,e1; bishop=g2,f4; knight=c2,e5; pawn=a2,b2,f2,h2,c3,g3,d4.
Black inventory: king=g8; queen=c7; rook=a8,f8; bishop=d6,d7; knight=d5,c6; pawn=c5,e6,h6,a7,b7,f7,g7.


Prompt:
FEN: 2r2n1r/p3b1p1/2p2pk1/2PP2p1/3P4/1N2P1P1/P2B3P/1R3RK1 b - - 0 24
Count each piece type for both sides.

Answer format: return exactly two lines starting "White counts:" and "Black counts:".

White counts: king=1; queen=0; rook=2; bishop=1; knight=1; pawn=7.
Black counts: king=1; queen=0; rook=2; bishop=1; knight=1; pawn=5.


Prompt:
FEN: 2k2r2/pppr2pp/8/3q2B1/1P1p1b2/P2P4/5P2/1R1QR1K1 w - - 0 22
Convert the piece counts into material value totals.

Answer format: return exactly two lines starting "White values:" and "Black values:".

White values: king=0; queen=9; rook=10; bishop=3; knight=0; pawn=4; total=26.
Black values: king=0; queen=9; rook=10; bishop=3; knight=0; pawn=6; total=28.


Prompt:
FEN: r3rnk1/pbq2p2/1p2p2Q/4P3/8/2PB4/P4PPP/2R1R1K1 b - -
Trace inventory, counts, values, and material balance.

Answer format: return exactly four lines starting "Inventory:", "Counts:", "Values:", and "Balance:".

Inventory: white king=g1; queen=h6; rook=c1,e1; bishop=d3; knight=none; pawn=a2,f2,g2,h2,c3,e5 | black king=g8; queen=c7; rook=a8,e8; bishop=b7; knight=f8; pawn=b6,e6,a7,f7
Counts: white king=1; queen=1; rook=2; bishop=1; knight=0; pawn=6 | black king=1; queen=1; rook=2; bishop=1; knight=1; pawn=4
Values: white total=28; black total=29
Balance: Black is up 1 point(s) of material.


Prompt:
Starting FEN: 8/4R3/1k6/1p5p/1p6/8/PP6/K7 w - - 1 46
After the moves e7g7 b6a5 g7g1, what is the resulting position?
State needed for full FEN:
Side to move: white
Castling rights: none
En passant: none
Halfmove clock: 1
Fullmove number: 46

Answer format: return exactly "Result FEN: <complete six-field FEN>".


Prompt:
Position (FEN): 7k/5p1p/1p6/p7/P1P3r1/R7/KP1qp3/8 w - - 0 41
Show me the board.


Prompt:
Here is the current board:
8 r . . . k . n r
7 p . p . . p . .
6 . p . p . . . p
5 . . . P p q . .
4 . . . . n . . .
3 P . . . B P . .
2 . . Q . . . P .
1 . . . . K B . R
  a b c d e f g h
Write the FEN for this position.
State needed for full FEN:
Side to move: white
Castling rights: kq
En passant: none
Halfmove clock: 0
Fullmove number: 24

Answer format: return exactly one complete six-field FEN, with no prefix and no explanation.


Prompt:
FEN: 5n1b/8/8/8/2N5/1kpK4/8/1N6 b - - 16 67
What piece is on f8?

Answer format: for a square query, return only the piece name or empty; do not include the square. For a locate query, return only space-separated squares.


Prompt:
FEN: 6Q1/8/2N5/8/1P4k1/3K3p/8/8 b - - 2 48
What is the material count for both sides?

White (4 pieces): 1 king, 1 knight, 1 pawn, 1 queen. Black (2 pieces): 1 king, 1 pawn. White is up 12 point(s) of material.


Prompt:
FEN: 8/8/8/1Q6/8/4K3/3n4/4k3 w - -
What is on b7?

Answer format: return exactly "<square>=<piece>" or "<square>=empty".


Prompt:
FEN: r1b1q1k1/1p2rpp1/p3pP1p/3p3Q/3P4/2PBN2P/PP4P1/R5K1 b - -
What is the compressed FEN row for rank 7?

Answer format: return exactly "rank N: <compressed FEN row>".


Prompt:
FEN: r6r/pp2bRpp/4k3/3p4/8/2N5/PP4PP/R1B1K3 w Q -
For square c3, give the FEN row-from-top and file index.

Answer format: return exactly "<square>: file=<file>; rank=<rank>; fen_row_from_top=<1-8>; file_index=<1-8>".

c3: file=c; rank=3; fen_row_from_top=6; file_index=3


Prompt:
FEN: r3r1k1/pp3pp1/7p/8/8/1PN5/1P4PP/4R2K w - -
Compressed rank 3 row: 1PN5
Expand it into file cells a through h.

Answer format: return exactly "rank N: a=<cell>; b=<cell>; ...; h=<cell>".


Prompt:
Rank 7 row before: p1p3pp
File h changes from p to 1. Rewrite the compressed row.

Answer format: return exactly "rank N: <before-row> -> <after-row>".


Prompt:
Board FEN before: 2r1rR1k/1b5p/p5p1/8/3q4/PB1Q4/5PPP/6K1
Apply square edits: h8 k->1; g7 1->k
Return the resulting board FEN only.

Answer format: return exactly "Result board FEN: <piece-placement-field>".

Result board FEN: 2r1rR2/1b4kp/p5p1/8/3q4/PB1Q4/5PPP/6K1


Prompt:
Starting FEN: 8/p4k1p/5p2/2R5/8/3p3P/4r1P1/3K4 w - - 1 48
Move: c5c1
List the square lookups and rank edits.

Answer format: return exactly three lines starting "Lookup:", "Squares:", and "Ranks:"; do not include Result FEN.

Lookup: c5=white rook; c1=empty.
Squares: c5 white rook->empty; c1 empty->white rook.
Ranks: rank 5 c R->1; rank 1 c 1->R.


Prompt:
Starting FEN: K7/8/8/8/8/6Q1/6p1/5k2 w - - 0 1
Move: g3g6
Use square lookups and rank edits to assemble the resulting full FEN.
State needed for full FEN:
Side to move: white
Castling rights: none
En passant: none
Halfmove clock: 0
Fullmove number: 1

Answer format: include the edit trace and exactly one final line "Result FEN: <complete six-field FEN>".

Move 1: white queen g3g6.
Lookup: g3=white queen; g6=empty.
Squares: g3 white queen->empty; g6 empty->white queen.
Ranks: rank 3 g Q->1; rank 6 g 1->Q.
Result FEN: K7/8/6Q1/8/8/8/6p1/5k2 b - - 1 1


Prompt:
Starting FEN: r1q2b1r/p1pbkBpp/8/1p3pN1/3nnB2/2N5/PPP3PP/R2QR1K1 w - - 0 14
Move: g5h3
Rewrite the affected compressed FEN rank rows and give Result FEN.
State needed for full FEN:
Side to move: white
Castling rights: none
En passant: none
Halfmove clock: 0
Fullmove number: 14

Answer format: first line starts "Rows:" and final line is "Result FEN: <complete six-field FEN>".

Rows: rank 5 1p3pN1->1p3p2; rank 3 2N5->2N4N.
Result FEN: r1q2b1r/p1pbkBpp/8/1p3p2/3nnB2/2N4N/PPP3PP/R2QR1K1 b - - 1 14


Prompt:
Starting FEN: 8/8/8/5K2/3k4/8/3p4/1Q6 b - - 0 1
After the moves d4d5, what is the resulting position?
State needed for full FEN:
Side to move: black
Castling rights: none
En passant: none
Halfmove clock: 0
Fullmove number: 1

Answer format: return exactly "Result FEN: <complete six-field FEN>".


Prompt:
FEN: rnb1k1nr/pppq1ppp/3b4/8/3P4/5N2/PPP1BPPP/RNBQ1RK1 b kq - 3 7
List the material inventory by side and piece type.

Answer format: return exactly two lines starting "White inventory:" and "Black inventory:".

White inventory: king=g1; queen=d1; rook=a1,f1; bishop=c1,e2; knight=b1,f3; pawn=a2,b2,c2,f2,g2,h2,d4.
Black inventory: king=e8; queen=d7; rook=a8,h8; bishop=d6,c8; knight=b8,g8; pawn=a7,b7,c7,f7,g7,h7.


Prompt:
FEN: 8/6pk/3R2pp/r7/3P2P1/7P/1r3P2/5RK1 w - -
Count each piece type for both sides.

Answer format: return exactly two lines starting "White counts:" and "Black counts:".

White counts: king=1; queen=0; rook=2; bishop=0; knight=0; pawn=4.
Black counts: king=1; queen=0; rook=2; bishop=0; knight=0; pawn=3.


Prompt:
FEN: 1r1q1rk1/5p1p/p1n1bbp1/4p3/2p1P3/2P2Q1N/P2N1PPP/2RB1RK1 w - - 0 19
Convert the piece counts into material value totals.

Answer format: return exactly two lines starting "White values:" and "Black values:".

White values: king=0; queen=9; rook=10; bishop=3; knight=6; pawn=6; total=34.
Black values: king=0; queen=9; rook=10; bishop=6; knight=3; pawn=6; total=34.


Prompt:
FEN: r1bqk2r/pp3ppp/2p1pn2/6B1/2QPP3/2N2N2/PP3PPP/R3K2R b KQkq - 2 10
Trace inventory, counts, values, and material balance.

Answer format: return exactly four lines starting "Inventory:", "Counts:", "Values:", and "Balance:".

Inventory: white king=e1; queen=c4; rook=a1,h1; bishop=g5; knight=c3,f3; pawn=a2,b2,f2,g2,h2,d4,e4 | black king=e8; queen=d8; rook=a8,h8; bishop=c8; knight=f6; pawn=c6,e6,a7,b7,f7,g7,h7
Counts: white king=1; queen=1; rook=2; bishop=1; knight=2; pawn=7 | black king=1; queen=1; rook=2; bishop=1; knight=1; pawn=7
Values: white total=35; black total=32
Balance: White is up 3 point(s) of material.


Prompt:
Starting FEN: rnbq1rk1/ppp1ppbp/3p2p1/6Bn/3P4/4PN2/PPPNBPPP/R2QK2R b KQ - 0 1
After the moves c8g4 g2g3, what is the resulting position?
State needed for full FEN:
Side to move: black
Castling rights: KQ
En passant: none
Halfmove clock: 0
Fullmove number: 1

Answer format: return exactly "Result FEN: <complete six-field FEN>".

Result FEN: rn1q1rk1/ppp1ppbp/3p2p1/6Bn/3P2b1/4PNP1/PPPNBP1P/R2QK2R b KQ - 0 2


Prompt:
Position (FEN): rr4k1/3p2bp/2pNp1p1/2P1Pp2/qP3P1P/pR2B1P1/P3Q3/7K w - - 4 27
Show me the board.


rn1qkb1r/p2b1ppp/1p1p1n2/2pNp3/2P1P3/1Q6/PP1P1PPP/R1B1KBNR w KQkq - 0 7

Prompt:
Here is the current board:
8 r n . q k b . r
7 p . . b . p p p
6 . p . p . n . .
5 . . p N p . . .
4 . . P . P . . .
3 . Q . . . . . .
2 P P . P . P P P
1 R . B . K B N R
  a b c d e f g h
Write the FEN for this position.
State needed for full FEN:
Side to move: white
Castling rights: KQkq
En passant: none
Halfmove clock: 0
Fullmove number: 7

Answer format: return exactly one complete six-field FEN, with no prefix and no explanation.


Prompt:
FEN: 2r1k2r/pp3pp1/4bn2/n2pN3/7P/B1PP4/P3PPBP/2R2RK1 b k -
What piece is on e2?

Answer format: for a square query, return only the piece name or empty; do not include the square. For a locate query, return only space-separated squares.


Prompt:
FEN: r3k3/p1b1qp2/2p4r/2Pp2pp/P2Pp1b1/2B1P3/3NNQ2/R3K1R1 b q -
What is the material count for both sides?

White (11 pieces): 1 bishop, 1 king, 2 knights, 4 pawns, 1 queen, 2 rooks. Black (13 pieces): 2 bishops, 1 king, 7 pawns, 1 queen, 2 rooks. Material is equal.


Prompt:
FEN: r2q1r1k/2p4p/p1n3p1/1p2p3/6N1/1BpQ1P2/PP5P/R1B3K1 w - -
What is on b7?

Answer format: return exactly "<square>=<piece>" or "<square>=empty".


Prompt:
FEN: Rr3r2/1P4pk/6pp/5n2/8/2B1P1P1/1Pq2PBP/R5K1 w - - 5 29
What is the compressed FEN row for rank 6?

Answer format: return exactly "rank N: <compressed FEN row>".


Prompt:
FEN: rnbqkbnr/3p1ppp/p3p3/1pp5/2B1P3/5N2/PPPP1PPP/RNBQK2R w KQkq - 0 5
For square a7, give the FEN row-from-top and file index.

Answer format: return exactly "<square>: file=<file>; rank=<rank>; fen_row_from_top=<1-8>; file_index=<1-8>".

a7: file=a; rank=7; fen_row_from_top=2; file_index=1


Prompt:
FEN: 6k1/p4p1p/2Q1p1p1/2P5/P2r2P1/4RB1n/1r1q1P2/5RK1 w - -
Compressed rank 7 row: p4p1p
Expand it into file cells a through h.

Answer format: return exactly "rank N: a=<cell>; b=<cell>; ...; h=<cell>".


Prompt:
Rank 2 row before: r7
File b changes from 1 to r. Rewrite the compressed row.

Answer format: return exactly "rank N: <before-row> -> <after-row>".


Prompt:
Board FEN before: 2r2rk1/1p2bpp1/3pq2p/2p4P/3QP1P1/1P1P1B2/P1P2P2/R3K2R
Apply square edits: d4 Q->1; c3 1->Q
Return the resulting board FEN only.

Answer format: return exactly "Result board FEN: <piece-placement-field>".

Result board FEN: 2r2rk1/1p2bpp1/3pq2p/2p4P/4P1P1/1PQP1B2/P1P2P2/R3K2R


Prompt:
Starting FEN: r1b2rk1/1p3ppp/p1n1pq2/2bp4/4P3/1PP5/PB1QBPPP/RN3RK1 w - -
Move: h2h3
List the square lookups and rank edits.

Answer format: return exactly three lines starting "Lookup:", "Squares:", and "Ranks:"; do not include Result FEN.

Lookup: h2=white pawn; h3=empty.
Squares: h2 white pawn->empty; h3 empty->white pawn.
Ranks: rank 2 h P->1; rank 3 h 1->P.


Prompt:
Starting FEN: r4rk1/1p1b1ppp/pn2p3/2bpP3/3N1P2/2P2N2/PP4PP/R1B2R1K w - - 2 16
Move: f1g1
Use square lookups and rank edits to assemble the resulting full FEN.
State needed for full FEN:
Side to move: white
Castling rights: none
En passant: none
Halfmove clock: 2
Fullmove number: 16

Answer format: include the edit trace and exactly one final line "Result FEN: <complete six-field FEN>".

Move 1: white rook f1g1.
Lookup: f1=white rook; g1=empty.
Squares: f1 white rook->empty; g1 empty->white rook.
Ranks: rank 1 f R->1; rank 1 g 1->R.
Result FEN: r4rk1/1p1b1ppp/pn2p3/2bpP3/3N1P2/2P2N2/PP4PP/R1B3RK b - - 3 16


Prompt:
Starting FEN: r1bk1b1r/pp4pp/2p2n2/3pq3/2B1p3/2N1B3/PPP2PPP/R2Q1RK1 w - - 0 1
Move: c3b5
Rewrite the affected compressed FEN rank rows and give Result FEN.
State needed for full FEN:
Side to move: white
Castling rights: none
En passant: none
Halfmove clock: 0
Fullmove number: 1

Answer format: first line starts "Rows:" and final line is "Result FEN: <complete six-field FEN>".

Rows: rank 3 2N1B3->4B3; rank 5 3pq3->1N1pq3.
Result FEN: r1bk1b1r/pp4pp/2p2n2/1N1pq3/2B1p3/4B3/PPP2PPP/R2Q1RK1 b - - 1 1


Prompt:
Starting FEN: 6k1/p1p3p1/2p5/8/3p4/1q6/3KR3/8 b - - 0 1
After the moves b3e3, what is the resulting position?
State needed for full FEN:
Side to move: black
Castling rights: none
En passant: none
Halfmove clock: 0
Fullmove number: 1

Answer format: return exactly "Result FEN: <complete six-field FEN>".


Prompt:
FEN: 6r1/k1pbbp2/Pn1p1n2/B2PpP2/2P1P1pr/6N1/3N1KBP/R6R w - - 1 29
List the material inventory by side and piece type.

Answer format: return exactly two lines starting "White inventory:" and "Black inventory:".

White inventory: king=f2; queen=none; rook=a1,h1; bishop=g2,a5; knight=d2,g3; pawn=h2,c4,e4,d5,f5,a6.
Black inventory: king=a7; queen=none; rook=h4,g8; bishop=d7,e7; knight=b6,f6; pawn=g4,e5,d6,c7,f7.


Prompt:
FEN: rnbqk2r/ppp1ppb1/3p1npp/8/2PP1B2/2N1P3/PP3PPP/R2QKBNR w KQkq -
Count each piece type for both sides.

Answer format: return exactly two lines starting "White counts:" and "Black counts:".

White counts: king=1; queen=1; rook=2; bishop=2; knight=2; pawn=8.
Black counts: king=1; queen=1; rook=2; bishop=2; knight=2; pawn=8.


Prompt:
FEN: 2r2rk1/ppq2ppp/3bp3/5b2/2BPnN1Q/1P2R2P/P4PP1/R1B3K1 b - - 7 21
Convert the piece counts into material value totals.

Answer format: return exactly two lines starting "White values:" and "Black values:".

White values: king=0; queen=9; rook=10; bishop=6; knight=3; pawn=6; total=34.
Black values: king=0; queen=9; rook=10; bishop=6; knight=3; pawn=6; total=34.


Prompt:
FEN: r2q1rk1/pb1n2bp/3pp1p1/1pp5/8/1PP2NP1/PB1Q1PBP/RN3RK1 b - -
Trace inventory, counts, values, and material balance.

Answer format: return exactly four lines starting "Inventory:", "Counts:", "Values:", and "Balance:".

Inventory: white king=g1; queen=d2; rook=a1,f1; bishop=b2,g2; knight=b1,f3; pawn=a2,f2,h2,b3,c3,g3 | black king=g8; queen=d8; rook=a8,f8; bishop=b7,g7; knight=d7; pawn=b5,c5,d6,e6,g6,a7,h7
Counts: white king=1; queen=1; rook=2; bishop=2; knight=2; pawn=6 | black king=1; queen=1; rook=2; bishop=2; knight=1; pawn=7
Values: white total=37; black total=35
Balance: White is up 2 point(s) of material.


Prompt:
Starting FEN: 6k1/2p1rpp1/N6p/2BR4/8/1P6/P4PPb/5K2 w - - 0 25
After the moves c5e3 e7e4 d5d1, what is the resulting position?
State needed for full FEN:
Side to move: white
Castling rights: none
En passant: none
Halfmove clock: 0
Fullmove number: 25

Answer format: return exactly "Result FEN: <complete six-field FEN>".


Prompt:
Position (FEN): 4Rnk1/p4ppp/1qpp4/8/8/1P3PP1/P1P1R2P/7K b - - 2 26
Show me the board.


Prompt:
Here is the current board:
8 . . . . . . . .
7 . . . . . . . .
6 . . k . . . . .
5 . . . . . R . .
4 . . . . . . . .
3 . . . . K . . .
2 . . . . . . . .
1 . . . . . . . .
  a b c d e f g h
Write the FEN for this position.
State needed for full FEN:
Side to move: white
Castling rights: none
En passant: none
Halfmove clock: 0
Fullmove number: 1

Answer format: return exactly one complete six-field FEN, with no prefix and no explanation.


Prompt:
FEN: r2b1r1k/6pp/p1n2p2/3N4/2p5/2N1P1P1/PP3P1P/R1B1R1K1 b - -
What piece is on c6?

Answer format: for a square query, return only the piece name or empty; do not include the square. For a locate query, return only space-separated squares.


Prompt:
FEN: 4K3/3Q4/8/2kr4/8/8/8/8 w - -
What is the material count for both sides?

White (2 pieces): 1 king, 1 queen. Black (2 pieces): 1 king, 1 rook. White is up 4 point(s) of material.


Prompt:
FEN: rnbqkb1r/p2ppppp/5n2/1ppP4/P7/5N2/1PP1PPPP/RNBQKB1R b KQkq -
What is on f6?

Answer format: return exactly "<square>=<piece>" or "<square>=empty".


Prompt:
FEN: rnb1k2r/ppq1nppp/2pb4/3p4/3P4/2NB3P/PPP1NPP1/R1BQ1RK1 b kq -
What is the compressed FEN row for rank 4?

Answer format: return exactly "rank N: <compressed FEN row>".


Prompt:
FEN: rnbq1rk1/ppp2ppp/3bpn2/3p4/8/3PPN2/PPP1BPPP/RNBQ1RK1 w - -
For square a7, give the FEN row-from-top and file index.

Answer format: return exactly "<square>: file=<file>; rank=<rank>; fen_row_from_top=<1-8>; file_index=<1-8>".

a7: file=a; rank=7; fen_row_from_top=2; file_index=1


Prompt:
FEN: 8/4kp2/7K/4Q3/8/3p4/8/8 b - - 0 59
Compressed rank 2 row: 8
Expand it into file cells a through h.

Answer format: return exactly "rank N: a=<cell>; b=<cell>; ...; h=<cell>".


Prompt:
Rank 2 row before: PPR2KP1
File f changes from K to 1. Rewrite the compressed row.

Answer format: return exactly "rank N: <before-row> -> <after-row>".


r1bqkbnr/pp1p1ppp/2n1p3/8/3P1P2/5N2/PP2P1PP/RNBQKB1R b KQkq - 2 5

Prompt:
Board FEN before: r1bqkbnr/pp1p1ppp/2n1p3/8/3P1P2/5N2/PP2P1PP/RNBQKB1R
Apply square edits: d8 q->1; a5 1->q
Return the resulting board FEN only.

Answer format: return exactly "Result board FEN: <piece-placement-field>".

Result board FEN: r1b1kbnr/pp1p1ppp/2n1p3/q7/3P1P2/5N2/PP2P1PP/RNBQKB1R


Prompt:
Starting FEN: 6k1/6pp/2R5/8/1Pp5/2K4P/7r/8 w - -
Move: c6d6
List the square lookups and rank edits.

Answer format: return exactly three lines starting "Lookup:", "Squares:", and "Ranks:"; do not include Result FEN.

Lookup: c6=white rook; d6=empty.
Squares: c6 white rook->empty; d6 empty->white rook.
Ranks: rank 6 c R->1; rank 6 d 1->R.


Prompt:
Starting FEN: 8/1r3p1k/4p3/R2pP1P1/1PpN3p/1bP4P/6P1/7K w - - 0 1
Move: g2g3
Use square lookups and rank edits to assemble the resulting full FEN.
State needed for full FEN:
Side to move: white
Castling rights: none
En passant: none
Halfmove clock: 0
Fullmove number: 1

Answer format: include the edit trace and exactly one final line "Result FEN: <complete six-field FEN>".

Move 1: white pawn g2g3.
Lookup: g2=white pawn; g3=empty.
Squares: g2 white pawn->empty; g3 empty->white pawn.
Ranks: rank 2 g P->1; rank 3 g 1->P.
Result FEN: 8/1r3p1k/4p3/R2pP1P1/1PpN3p/1bP3PP/8/7K b - - 0 1


Prompt:
Starting FEN: rnbqk2r/pp2bppp/4pn2/2pp4/3PP3/2P2N2/PP1N1PPP/R1BQKB1R w KQkq - 0 1
Move: d2c4
Rewrite the affected compressed FEN rank rows and give Result FEN.
State needed for full FEN:
Side to move: white
Castling rights: KQkq
En passant: none
Halfmove clock: 0
Fullmove number: 1

Answer format: first line starts "Rows:" and final line is "Result FEN: <complete six-field FEN>".

Rows: rank 2 PP1N1PPP->PP3PPP; rank 4 3PP3->2NPP3.
Result FEN: rnbqk2r/pp2bppp/4pn2/2pp4/2NPP3/2P2N2/PP3PPP/R1BQKB1R b KQkq - 1 1


Prompt:
Starting FEN: r1bq1rk1/ppp2pp1/2np1n1p/2b5/2B1P2B/2NP1N2/PPP3PP/R2QK2R b KQ - 0 1
After the moves d8e7, what is the resulting position?
State needed for full FEN:
Side to move: black
Castling rights: KQ
En passant: none
Halfmove clock: 0
Fullmove number: 1

Answer format: return exactly "Result FEN: <complete six-field FEN>".

Result FEN: r1b2rk1/ppp1qpp1/2np1n1p/2b5/2B1P2B/2NP1N2/PPP3PP/R2QK2R w KQ - 1 2


Prompt:
FEN: 2r2rk1/1b3ppp/p2bpn2/1p1n4/2P5/1N2BN2/PP2BPPP/3RR1K1 b - -
List the material inventory by side and piece type.

Answer format: return exactly two lines starting "White inventory:" and "Black inventory:".

White inventory: king=g1; queen=none; rook=d1,e1; bishop=e2,e3; knight=b3,f3; pawn=a2,b2,f2,g2,h2,c4.
Black inventory: king=g8; queen=none; rook=c8,f8; bishop=d6,b7; knight=d5,f6; pawn=b5,a6,e6,f7,g7,h7.


Prompt:
FEN: r3r1k1/pppq1ppp/1b6/3P4/2B2PP1/2P4P/PP1B3Q/2KR4 w - - 1 21
Count each piece type for both sides.

Answer format: return exactly two lines starting "White counts:" and "Black counts:".

White counts: king=1; queen=1; rook=1; bishop=2; knight=0; pawn=7.
Black counts: king=1; queen=1; rook=2; bishop=1; knight=0; pawn=6.


Prompt:
FEN: r1b1r1k1/1p2Bppp/p3p3/3pP1Q1/n1p2P2/2q1PB2/P1P3PP/R4RK1 b - -
Convert the piece counts into material value totals.

Answer format: return exactly two lines starting "White values:" and "Black values:".

White values: king=0; queen=9; rook=10; bishop=6; knight=0; pawn=7; total=32.
Black values: king=0; queen=9; rook=10; bishop=3; knight=3; pawn=8; total=33.


Prompt:
FEN: r4b1N/pp2p1pq/n6p/k2B1b2/P2Q4/2P1P1B1/5PP1/2R2RK1 w - - 1 25
Trace inventory, counts, values, and material balance.

Answer format: return exactly four lines starting "Inventory:", "Counts:", "Values:", and "Balance:".

Inventory: white king=g1; queen=d4; rook=c1,f1; bishop=g3,d5; knight=h8; pawn=f2,g2,c3,e3,a4 | black king=a5; queen=h7; rook=a8; bishop=f5,f8; knight=a6; pawn=h6,a7,b7,e7,g7
Counts: white king=1; queen=1; rook=2; bishop=2; knight=1; pawn=5 | black king=1; queen=1; rook=1; bishop=2; knight=1; pawn=5
Values: white total=33; black total=28
Balance: White is up 5 point(s) of material.


Prompt:
Starting FEN: 4r2k/2qnbb1p/2p2pp1/1pPp4/1P1P4/R1N2N1P/5PP1/Q4BK1 b - - 0 1
After the moves c7e5 g1h1 g6g5, what is the resulting position?
State needed for full FEN:
Side to move: black
Castling rights: none
En passant: none
Halfmove clock: 0
Fullmove number: 1

Answer format: return exactly "Result FEN: <complete six-field FEN>".

Result FEN: 4r2k/3nbb1p/2p2p2/1pPpq1p1/1P1P4/R1N2N1P/5PP1/Q4B1K w - - 0 3


Prompt:
Position (FEN): r4rk1/p5pp/1p6/3PpNQ1/4b3/P5P1/2q1nP1P/R3RK2 b - - 1 28
Show me the board.


Prompt:
Here is the current board:
8 r . . . q r . k
7 p p p . . . p p
6 . . . . b n . .
5 . . . . . . . .
4 . . . . . B . .
3 . . . Q . . . P
2 P P P . . . P .
1 R N . . . R K .
  a b c d e f g h
Write the FEN for this position.
State needed for full FEN:
Side to move: black
Castling rights: none
En passant: none
Halfmove clock: 1
Fullmove number: 19

Answer format: return exactly one complete six-field FEN, with no prefix and no explanation.


Prompt:
FEN: r3kb1r/pp1n1ppp/1n6/2pqP3/8/5N2/PP4PP/RNBQK2R w KQkq - 0 12
What piece is on b6?

Answer format: for a square query, return only the piece name or empty; do not include the square. For a locate query, return only space-separated squares.


Prompt:
FEN: r2q1rk1/pp2ppbp/4bnp1/3n2B1/3P4/1BN2N2/PP3PPP/R2QR1K1 w - -
What is the material count for both sides?

White (14 pieces): 2 bishops, 1 king, 2 knights, 6 pawns, 1 queen, 2 rooks. Black (14 pieces): 2 bishops, 1 king, 2 knights, 6 pawns, 1 queen, 2 rooks. Material is equal.


Prompt:
FEN: r2nk2r/3qb1p1/4p3/p1ppPppn/1P6/P1PB1PP1/3N1B1P/R2QK2R w KQkq -
What is on h2?

Answer format: return exactly "<square>=<piece>" or "<square>=empty".


Prompt:
FEN: 2r1k2r/pp1qnpp1/4p2p/3pP2P/1b1P1B2/5N2/PP2QPP1/R2R2K1 b k -
What is the compressed FEN row for rank 7?

Answer format: return exactly "rank N: <compressed FEN row>".


Prompt:
FEN: 5rk1/5ppp/4p3/3n2P1/8/1b6/6P1/5RK1 w - - 0 31
For square h7, give the FEN row-from-top and file index.

Answer format: return exactly "<square>: file=<file>; rank=<rank>; fen_row_from_top=<1-8>; file_index=<1-8>".

h7: file=h; rank=7; fen_row_from_top=2; file_index=8


Prompt:
FEN: r1bqkb1r/pp1p1ppp/2n1pn2/8/4P3/2P1Q3/PP1P1PPP/RNB1KBNR b KQkq -
Compressed rank 1 row: RNB1KBNR
Expand it into file cells a through h.

Answer format: return exactly "rank N: a=<cell>; b=<cell>; ...; h=<cell>".

rank 1: a=R; b=N; c=B; d=1; e=K; f=B; g=N; h=R


Prompt:
Rank 4 row before: P3P3
File c changes from 1 to p. Rewrite the compressed row.

Answer format: return exactly "rank N: <before-row> -> <after-row>".


r2q1rn1/1pp2p1k/1n1p2pp/pB1Pp1b1/P3P1P1/4B2P/1PPQNPK1/R4R2 w - -

Prompt:
Board FEN before: r2q1rn1/1pp2p1k/1n1p2pp/pB1Pp1b1/P3P1P1/4B2P/1PPQNPK1/R4R2
Apply square edits: f1 R->1; h1 1->R
Return the resulting board FEN only.

Answer format: return exactly "Result board FEN: <piece-placement-field>".

Result board FEN: r2q1rn1/1pp2p1k/1n1p2pp/pB1Pp1b1/P3P1P1/4B2P/1PPQNPK1/R6R


Prompt:
Starting FEN: r3r1k1/p3qp1p/2p2p2/5b2/8/8/PPPQBPPP/R3K2R w KQ -
Move: d2d8
List the square lookups and rank edits.

Answer format: return exactly three lines starting "Lookup:", "Squares:", and "Ranks:"; do not include Result FEN.

Lookup: d2=white queen; d8=empty.
Squares: d2 white queen->empty; d8 empty->white queen.
Ranks: rank 2 d Q->1; rank 8 d 1->Q.


Prompt:
Starting FEN: r1b2rk1/pp2ppbp/2np1np1/3N2B1/2P1P3/5P2/PP1qB1PP/R3K1NR w KQ - 0 1
Move: e1f1
Use square lookups and rank edits to assemble the resulting full FEN.
State needed for full FEN:
Side to move: white
Castling rights: KQ
En passant: none
Halfmove clock: 0
Fullmove number: 1

Answer format: include the edit trace and exactly one final line "Result FEN: <complete six-field FEN>".

Move 1: white king e1f1.
Lookup: e1=white king; f1=empty.
Squares: e1 white king->empty; f1 empty->white king.
Ranks: rank 1 e K->1; rank 1 f 1->K.
Result FEN: r1b2rk1/pp2ppbp/2np1np1/3N2B1/2P1P3/5P2/PP1qB1PP/R4KNR b - - 1 1


Prompt:
Starting FEN: 4r2k/p1p1nRbp/1q4p1/8/Q2PPB2/2PB4/Pr4PP/5RK1 w - - 2 26
Move: a4b5
Rewrite the affected compressed FEN rank rows and give Result FEN.
State needed for full FEN:
Side to move: white
Castling rights: none
En passant: none
Halfmove clock: 2
Fullmove number: 26

Answer format: first line starts "Rows:" and final line is "Result FEN: <complete six-field FEN>".

Rows: rank 4 Q2PPB2->3PPB2; rank 5 8->1Q6.
Result FEN: 4r2k/p1p1nRbp/1q4p1/1Q6/3PPB2/2PB4/Pr4PP/5RK1 b - - 3 26


Prompt:
Starting FEN: k7/p1p2pbp/P7/6B1/1P1rr3/8/5PPP/R4RK1 w - - 0 1
After the moves g2g4, what is the resulting position?
State needed for full FEN:
Side to move: white
Castling rights: none
En passant: none
Halfmove clock: 0
Fullmove number: 1

Answer format: return exactly "Result FEN: <complete six-field FEN>".

Result FEN: k7/p1p2pbp/P7/6B1/1P1rr1P1/8/5P1P/R4RK1 b - - 0 1


Prompt:
FEN: r3k3/pppnn2p/3bQ3/3P4/8/1P1N2P1/P6P/1KB2r2 w q - 5 27
List the material inventory by side and piece type.

Answer format: return exactly two lines starting "White inventory:" and "Black inventory:".

White inventory: king=b1; queen=e6; rook=none; bishop=c1; knight=d3; pawn=a2,h2,b3,g3,d5.
Black inventory: king=e8; queen=none; rook=f1,a8; bishop=d6; knight=d7,e7; pawn=a7,b7,c7,h7.


Prompt:
FEN: r1b1k2r/pp2ppbp/2n2np1/2p5/4PP2/2PB1N2/PP1N2PP/R1BK3R b kq -
Count each piece type for both sides.

Answer format: return exactly two lines starting "White counts:" and "Black counts:".

White counts: king=1; queen=0; rook=2; bishop=2; knight=2; pawn=7.
Black counts: king=1; queen=0; rook=2; bishop=2; knight=2; pawn=7.


Prompt:
FEN: 3r1rk1/p4p1p/3P2p1/1p2p2n/3PP3/P1P2qP1/1B1Q1P1P/4R1K1 b - - 1 22
Convert the piece counts into material value totals.

Answer format: return exactly two lines starting "White values:" and "Black values:".

White values: king=0; queen=9; rook=5; bishop=3; knight=0; pawn=8; total=25.
Black values: king=0; queen=9; rook=10; bishop=0; knight=3; pawn=6; total=28.


Prompt:
FEN: r4rk1/pbp3pp/1b6/4N3/4p3/1P5P/1P3PP1/R1B2RK1 b - -
Trace inventory, counts, values, and material balance.

Answer format: return exactly four lines starting "Inventory:", "Counts:", "Values:", and "Balance:".

Inventory: white king=g1; queen=none; rook=a1,f1; bishop=c1; knight=e5; pawn=b2,f2,g2,b3,h3 | black king=g8; queen=none; rook=a8,f8; bishop=b6,b7; knight=none; pawn=e4,a7,c7,g7,h7
Counts: white king=1; queen=0; rook=2; bishop=1; knight=1; pawn=5 | black king=1; queen=0; rook=2; bishop=2; knight=0; pawn=5
Values: white total=21; black total=21
Balance: Material is equal.


Prompt:
Starting FEN: 6Q1/8/3k4/3r4/5K2/8/8/8 w - - 0 1
After the moves g8g1 d5f5 f4g3, what is the resulting position?
State needed for full FEN:
Side to move: white
Castling rights: none
En passant: none
Halfmove clock: 0
Fullmove number: 1

Answer format: return exactly "Result FEN: <complete six-field FEN>".


Prompt:
Position (FEN): r1bq1rk1/ppp1b1pp/4p3/4n3/3P4/2P2N2/PP1N2PP/R1Q2RK1 w - - 0 15
Show me the board.


Prompt:
Here is the current board:
8 r n b q k b . r
7 . p . . . p . .
6 p . . p . n p p
5 . . . . p N . .
4 . . . . P . . .
3 . . N . B Q . .
2 P P P . . P P P
1 R . . . K B . R
  a b c d e f g h
Write the FEN for this position.
State needed for full FEN:
Side to move: white
Castling rights: KQkq
En passant: none
Halfmove clock: 0
Fullmove number: 1

Answer format: return exactly one complete six-field FEN, with no prefix and no explanation.

rnbqkb1r/1p3p2/p2p1npp/4pN2/4P3/2N1BQ2/PPP2PPP/R3KB1R w KQkq - 0 1


Prompt:
FEN: r1b1kb1r/2q2ppp/p1p1p3/3pP3/6Q1/8/PPP2PPP/RNB1R1K1 b kq -
What piece is on c2?

Answer format: for a square query, return only the piece name or empty; do not include the square. For a locate query, return only space-separated squares.


Prompt:
FEN: 7k/8/4K2P/6P1/6Q1/8/8/8 w - - 1 60
What is the material count for both sides?

White (4 pieces): 1 king, 2 pawns, 1 queen. Black (1 pieces): 1 king. White is up 11 point(s) of material.


Prompt:
FEN: rnb1k2r/ppp2pp1/1b5p/4P3/2B1n3/4BN2/PP3PPP/RN1R2K1 b kq - 2 11
What is on h6?

Answer format: return exactly "<square>=<piece>" or "<square>=empty".


Prompt:
FEN: r4rk1/1p3ppp/p2qb3/3p4/3P2n1/2NB2R1/PP3PPP/R2Q2K1 b - - 4 15
What is the compressed FEN row for rank 1?

Answer format: return exactly "rank N: <compressed FEN row>".


Prompt:
FEN: 4r1k1/1b1q1pp1/p2p3p/2pP4/5Q2/1P3N1P/P4PP1/3R2K1 b - - 1 27
For square d6, give the FEN row-from-top and file index.

Answer format: return exactly "<square>: file=<file>; rank=<rank>; fen_row_from_top=<1-8>; file_index=<1-8>".

d6: file=d; rank=6; fen_row_from_top=3; file_index=4


Prompt:
FEN: 6k1/1q1nbppp/1p1np3/1P1p4/3P3P/1P1QP1P1/1B3PBK/8 b - - 7 28
Compressed rank 3 row: 1P1QP1P1
Expand it into file cells a through h.

Answer format: return exactly "rank N: a=<cell>; b=<cell>; ...; h=<cell>".


rnb1kbnr/1p3ppp/2p5/1B6/8/1N6/PPP2PPP/R1B1K2R w KQkq - 0 12

Prompt:
Rank 2 row before: PPP2PPP
File h changes from P to 1. Rewrite the compressed row.

Answer format: return exactly "rank N: <before-row> -> <after-row>".


r2qr1k1/pp1n1pbp/3p1np1/2pP2B1/2P3b1/2N2N2/PP1QBPPP/R4RK1 w - -

Prompt:
Board FEN before: r2qr1k1/pp1n1pbp/3p1np1/2pP2B1/2P3b1/2N2N2/PP1QBPPP/R4RK1
Apply square edits: a2 P->1; a4 1->P
Return the resulting board FEN only.

Answer format: return exactly "Result board FEN: <piece-placement-field>".

Result board FEN: r2qr1k1/pp1n1pbp/3p1np1/2pP2B1/P1P3b1/2N2N2/1P1QBPPP/R4RK1


Prompt:
Starting FEN: rnbqkb1r/ppp2ppp/4pn2/3P4/2p1P3/2N2N2/PP3PPP/R1BQKB1R w KQkq -
Move: b2b3
List the square lookups and rank edits.

Answer format: return exactly three lines starting "Lookup:", "Squares:", and "Ranks:"; do not include Result FEN.

Lookup: b2=white pawn; b3=empty.
Squares: b2 white pawn->empty; b3 empty->white pawn.
Ranks: rank 2 b P->1; rank 3 b 1->P.


Prompt:
Starting FEN: r2q1rk1/ppp2ppp/2np1n2/4p3/1bB1PPb1/2NP1N2/PPP3PP/R1BQ1RK1 w - - 0 1
Move: c4e6
Use square lookups and rank edits to assemble the resulting full FEN.
State needed for full FEN:
Side to move: white
Castling rights: none
En passant: none
Halfmove clock: 0
Fullmove number: 1

Answer format: include the edit trace and exactly one final line "Result FEN: <complete six-field FEN>".

Move 1: white bishop c4e6.
Lookup: c4=white bishop; e6=empty.
Squares: c4 white bishop->empty; e6 empty->white bishop.
Ranks: rank 4 c B->1; rank 6 e 1->B.
Result FEN: r2q1rk1/ppp2ppp/2npBn2/4p3/1b2PPb1/2NP1N2/PPP3PP/R1BQ1RK1 b - - 1 1


Prompt:
Starting FEN: 8/1pp1k3/p6p/b7/8/1K5P/5rP1/8 w - - 0 43
Move: h3h4
Rewrite the affected compressed FEN rank rows and give Result FEN.
State needed for full FEN:
Side to move: white
Castling rights: none
En passant: none
Halfmove clock: 0
Fullmove number: 43

Answer format: first line starts "Rows:" and final line is "Result FEN: <complete six-field FEN>".


Prompt:
Starting FEN: r1bqk2r/2ppbppp/p1n2n2/1p2p1B1/4P3/P1PP1Q2/BP3PPP/RN2K1NR w KQkq - 2 9
After the moves g5d2, what is the resulting position?
State needed for full FEN:
Side to move: white
Castling rights: KQkq
En passant: none
Halfmove clock: 2
Fullmove number: 9

Answer format: return exactly "Result FEN: <complete six-field FEN>".

Result FEN: r1bqk2r/2ppbppp/p1n2n2/1p2p3/4P3/P1PP1Q2/BP1B1PPP/RN2K1NR b KQkq - 3 9


Prompt:
FEN: 4kr2/1p5Q/p2p2R1/2p2qp1/3p4/P2P1P2/1PP3PP/6K1 w - - 5 37
List the material inventory by side and piece type.

Answer format: return exactly two lines starting "White inventory:" and "Black inventory:".

White inventory: king=g1; queen=h7; rook=g6; bishop=none; knight=none; pawn=b2,c2,g2,h2,a3,d3,f3.
Black inventory: king=e8; queen=f5; rook=f8; bishop=none; knight=none; pawn=d4,c5,g5,a6,d6,b7.


Prompt:
FEN: rnb4r/1p1k1ppp/8/pq1p1N2/3p2P1/4PP2/3B1K1P/7R b - - 1 22
Count each piece type for both sides.

Answer format: return exactly two lines starting "White counts:" and "Black counts:".

White counts: king=1; queen=0; rook=1; bishop=1; knight=1; pawn=4.
Black counts: king=1; queen=1; rook=2; bishop=1; knight=1; pawn=7.


Prompt:
FEN: r4rk1/pp1qnppp/2n1p3/1B6/1B1P4/8/P4PPP/1R1Q1RK1 w - -
Convert the piece counts into material value totals.

Answer format: return exactly two lines starting "White values:" and "Black values:".

White values: king=0; queen=9; rook=10; bishop=6; knight=0; pawn=5; total=30.
Black values: king=0; queen=9; rook=10; bishop=0; knight=6; pawn=6; total=31.


Prompt:
FEN: 2q3k1/4Q3/r4p2/3bpN2/3p2p1/3P2P1/8/1R4K1 b - -
Trace inventory, counts, values, and material balance.

Answer format: return exactly four lines starting "Inventory:", "Counts:", "Values:", and "Balance:".

Inventory: white king=g1; queen=e7; rook=b1; bishop=none; knight=f5; pawn=d3,g3 | black king=g8; queen=c8; rook=a6; bishop=d5; knight=none; pawn=d4,g4,e5,f6
Counts: white king=1; queen=1; rook=1; bishop=0; knight=1; pawn=2 | black king=1; queen=1; rook=1; bishop=1; knight=0; pawn=4
Values: white total=19; black total=21
Balance: Black is up 2 point(s) of material.


Prompt:
Starting FEN: 4k3/p1p3p1/1p3p2/2r4p/3n1N1P/2N2P2/PP4P1/7K w - - 2 29
After the moves f4h3 g7g5 f3f4, what is the resulting position?
State needed for full FEN:
Side to move: white
Castling rights: none
En passant: none
Halfmove clock: 2
Fullmove number: 29

Answer format: return exactly "Result FEN: <complete six-field FEN>".


Prompt:
Position (FEN): 2kr1b2/pppq4/2b1pP2/3pPn1p/2PP4/N4N2/PP5P/R1B3QK b - - 0 19
Show me the board.


Prompt:
Here is the current board:
8 . . r . . . . r
7 p p . . k p . .
6 . . . p . n . p
5 . . . . . . p P
4 . . . . P p . .
3 . . . . . P . .
2 P P P . . . . .
1 . . K R . . . R
  a b c d e f g h
Write the FEN for this position.
State needed for full FEN:
Side to move: white
Castling rights: none
En passant: none
Halfmove clock: 0
Fullmove number: 1

Answer format: return exactly one complete six-field FEN, with no prefix and no explanation.


Prompt:
FEN: r3k2r/pppb1ppp/8/8/4Q3/4B3/P2NKPPP/7q b kq - 1 16
What piece is on g2?

Answer format: for a square query, return only the piece name or empty; do not include the square. For a locate query, return only space-separated squares.


Prompt:
FEN: 4r3/p2n1kp1/1p1R3p/1b6/1B2n3/P7/1P3PPP/2R3K1 w - - 8 25
What is the material count for both sides?

White (9 pieces): 1 bishop, 1 king, 5 pawns, 2 rooks. Black (9 pieces): 1 bishop, 1 king, 2 knights, 4 pawns, 1 rook. Material is equal.


Prompt:
FEN: rn1qk2r/pppbbppp/6n1/3P4/7P/2N5/PP2QPP1/R1B1KBNR b KQkq -
What is on h4?

Answer format: return exactly "<square>=<piece>" or "<square>=empty".


Prompt:
FEN: rnbqk1nr/pp3Bpp/2pp4/4p3/4P3/2P2N2/PPP2PPP/R1BQK2R b KQkq -
What is the compressed FEN row for rank 6?

Answer format: return exactly "rank N: <compressed FEN row>".


Prompt:
FEN: 3r2k1/5ppp/8/8/8/5QP1/5P1P/2q3K1 w - -
For square g3, give the FEN row-from-top and file index.

Answer format: return exactly "<square>: file=<file>; rank=<rank>; fen_row_from_top=<1-8>; file_index=<1-8>".

g3: file=g; rank=3; fen_row_from_top=6; file_index=7