Prompt:
Starting FEN: 2k1r3/3r2pp/2pBp3/R3P3/2b5/2P5/2P3PP/4K2R w K - 0 25
Move: d6b8
Use square lookups and rank edits to assemble the resulting full FEN.
State needed for full FEN:
Side to move: white
Castling rights: K
En passant: none
Halfmove clock: 0
Fullmove number: 25

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

Move 1: white bishop d6b8.
Lookup: d6=white bishop; b8=empty.
Squares: d6 white bishop->empty; b8 empty->white bishop.
Ranks: rank 6 d B->1; rank 8 b 1->B.
Result FEN: 1Bk1r3/3r2pp/2p1p3/R3P3/2b5/2P5/2P3PP/4K2R b K - 1 25


Prompt:
Starting FEN: r4r2/5pkp/p2p2p1/1p2q3/1P1nP3/8/P1B2PPP/R2QR1K1 b - - 5 25
Move: e5f5
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: 5
Fullmove number: 25

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

Rows: rank 5 1p2q3->1p3q2.
Result FEN: r4r2/5pkp/p2p2p1/1p3q2/1P1nP3/8/P1B2PPP/R2QR1K1 w - - 6 26


Prompt:
Starting FEN: 1r2r1k1/R4R2/3Bpb2/8/1P3P2/8/4N2P/5K2 b - - 3 35
After the moves e8e7, what is the resulting position?
State needed for full FEN:
Side to move: black
Castling rights: none
En passant: none
Halfmove clock: 3
Fullmove number: 35

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


Prompt:
FEN: r2qkb1r/1pp1pppp/p1n2n2/3p1b2/3P1B2/4PN1P/PPP2PP1/RN1QKB1R w 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=f1,f4; knight=b1,f3; pawn=a2,b2,c2,f2,g2,e3,h3,d4.
Black inventory: king=e8; queen=d8; rook=a8,h8; bishop=f5,f8; knight=c6,f6; pawn=d5,a6,b7,c7,e7,f7,g7,h7.


Prompt:
FEN: 8/1pp3k1/p2p2p1/P2Pp3/1P2P3/4Bq2/2PK3r/R1Q5 w - - 2 42
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=1; knight=0; pawn=5.
Black counts: king=1; queen=1; rook=1; bishop=0; knight=0; pawn=6.


Prompt:
FEN: 3k3r/1p3R2/p1p3pp/8/PPr5/2N3P1/8/3R2K1 b - - 3 31
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=0; knight=3; pawn=3; total=16.
Black values: king=0; queen=0; rook=10; bishop=0; knight=0; pawn=5; total=15.


Prompt:
FEN: rn2k1r1/1p1bq2p/1pp1p1pB/8/P3P3/2P5/3QB1nP/RN2K1NR w KQq - 0 17
Trace inventory, counts, values, and material balance.

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

Inventory: white king=e1; queen=d2; rook=a1,h1; bishop=e2,h6; knight=b1,g1; pawn=h2,c3,a4,e4 | black king=e8; queen=e7; rook=a8,g8; bishop=d7; knight=g2,b8; pawn=b6,c6,e6,g6,b7,h7
Counts: white king=1; queen=1; rook=2; bishop=2; knight=2; pawn=4 | black king=1; queen=1; rook=2; bishop=1; knight=2; pawn=6
Values: white total=35; black total=34
Balance: White is up 1 point(s) of material.


Prompt:
Starting FEN: r1b1Q1k1/ppqp2p1/2n1n2p/3B4/8/2P5/PPP3PP/5RK1 b - - 0 1
After the moves g8h7 a2a3, 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: r1b1Q3/ppqp2pk/2n1n2p/3B4/8/P1P5/1PP3PP/5RK1 b - - 0 2


Prompt:
Position (FEN): 8/pp4pp/3pk3/8/QKr1q1bP/3r4/PP6/R3R3 w - - 0 28
Show me the board.


r1bqkb1r/p1pppppp/1pn2n2/8/3P4/5N1P/PPP1PPP1/RNBQKB1R w KQkq - 0 4

Prompt:
Here is the current board:
8 r . b q k b . r
7 p . p p p p p p
6 . p n . . n . .
5 . . . . . . . .
4 . . . P . . . .
3 . . . . . N . P
2 P P P . P P P .
1 R N B Q 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: 4

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


Prompt:
FEN: 2kr3r/2q1npp1/p1p1N2p/1pp1p3/4P3/2NP4/PPP2PPP/R2Q1RK1 b - - 0 13
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: r3k2r/pp3ppp/3p4/2P1p3/4P2P/3b1PP1/1P1BNnB1/qNKR3R w kq - 3 20
What is the material count for both sides?

White (13 pieces): 2 bishops, 1 king, 2 knights, 6 pawns, 2 rooks. Black (13 pieces): 1 bishop, 1 king, 1 knight, 7 pawns, 1 queen, 2 rooks. Black is up 4 point(s) of material.


Prompt:
FEN: 5QB1/8/8/6k1/8/4K3/8/8 w - -
What is on g7?

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


Prompt:
FEN: 5rk1/2pq1pp1/2n1p2p/8/1Q1PP3/5N2/5PPP/R5K1 w - - 1 22
What is the compressed FEN row for rank 4?

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


Prompt:
FEN: q4rk1/1Qp2p1p/4p1p1/p3P3/P2P4/2P5/6PP/1R4K1 b - - 9 32
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: rnbqk1nr/ppp2ppp/3bp3/8/2BP4/5Q2/PPP2PPP/RNB1K1NR w KQkq - 1 6
Compressed rank 1 row: RNB1K1NR
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: 2BN4
File c changes from B to 1. Rewrite the compressed row.

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


Prompt:
Board FEN before: r1b4r/4kp2/2p1pNp1/1p1Bq3/7p/2P5/P4PPP/R1B1R1K1
Apply square edits: d5 B->1; c6 p->B
Return the resulting board FEN only.

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

Result board FEN: r1b4r/4kp2/2B1pNp1/1p2q3/7p/2P5/P4PPP/R1B1R1K1


Prompt:
Starting FEN: r2R2k1/pp3ppp/4b3/8/8/q4NP1/P3QP1P/R5K1 b - - 0 18
Move: a3f8
List the square lookups and rank edits.

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

Lookup: a3=black queen; f8=empty.
Squares: a3 black queen->empty; f8 empty->black queen.
Ranks: rank 3 a q->1; rank 8 f 1->q.


Prompt:
Starting FEN: r3r1k1/1p2b1p1/pq1p1pnp/3P4/3NPp2/P1N4P/1P1QBP2/1R3RK1 w - - 1 23
Move: e2a6
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: 23

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

Move 1: white bishop e2a6. Captures black pawn on a6.
Lookup: e2=white bishop; a6=black pawn.
Squares: e2 white bishop->empty; a6 black pawn->white bishop.
Ranks: rank 2 e B->1; rank 6 a p->B.
Result FEN: r3r1k1/1p2b1p1/Bq1p1pnp/3P4/3NPp2/P1N4P/1P1Q1P2/1R3RK1 b - - 0 23


Prompt:
Starting FEN: 4k3/1r6/8/3Bp2p/1BP1Pb2/3P3P/4KP2/8 w - - 0 45
Move: d5e6
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: 45

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


Prompt:
Starting FEN: 5rk1/p1b2p1p/1pp1r1p1/P7/1P1R2P1/2P1P3/1K1B3P/5R2 w - - 0 29
After the moves d2e1, 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: 29

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


Prompt:
FEN: r4rk1/pppn1p1p/3p1qp1/3P4/3N4/4P3/PP3PPP/R2QKB1R b KQ - 2 12
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=f1; knight=d4; pawn=a2,b2,f2,g2,h2,e3,d5.
Black inventory: king=g8; queen=f6; rook=a8,f8; bishop=none; knight=d7; pawn=d6,g6,a7,b7,c7,f7,h7.


Prompt:
FEN: 8/8/6Pk/p4P2/P5K1/8/8/2b5 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=0; bishop=0; knight=0; pawn=3.
Black counts: king=1; queen=0; rook=0; bishop=1; knight=0; pawn=1.


Prompt:
FEN: r1b1k2r/ppp2p1p/2n2p2/3qp3/3P4/P1P1P3/5PPP/R2QKBNR 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=3; knight=3; pawn=7; total=32.
Black values: king=0; queen=9; rook=10; bishop=3; knight=3; pawn=7; total=32.


Prompt:
FEN: Qn3rk1/p1p3pp/8/3Pp2q/5Pbb/3PPN1n/PP2K2P/RNB4R w - - 1 18
Trace inventory, counts, values, and material balance.

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

Inventory: white king=e2; queen=a8; rook=a1,h1; bishop=c1; knight=b1,f3; pawn=a2,b2,h2,d3,e3,f4,d5 | black king=g8; queen=h5; rook=f8; bishop=g4,h4; knight=h3,b8; pawn=e5,a7,c7,g7,h7
Counts: white king=1; queen=1; rook=2; bishop=1; knight=2; pawn=7 | black king=1; queen=1; rook=1; bishop=2; knight=2; pawn=5
Values: white total=35; black total=31
Balance: White is up 4 point(s) of material.


Prompt:
Starting FEN: 5rk1/Qbq3pp/1p1r1p2/3pp3/8/1P4P1/P1P1PP1P/R3K1NR w KQ - 0 20
After the moves e1f1 c7c5, what is the resulting position?
State needed for full FEN:
Side to move: white
Castling rights: KQ
En passant: none
Halfmove clock: 0
Fullmove number: 20

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

Result FEN: 5rk1/Qb4pp/1p1r1p2/2qpp3/8/1P4P1/P1P1PP1P/R4KNR w - - 2 21


Prompt:
Position (FEN): r2qk2r/pp1nppb1/3p2pp/2p5/3nP3/2NPB3/PPPQ1PPP/R3NRK1 b kq -
Show me the board.


Prompt:
Here is the current board:
8 r . . . n . k .
7 p . q . . p b p
6 . p b . p . p .
5 . . p . . . . .
4 . . P . P . . .
3 . . N . B P . .
2 P P . R B . P P
1 . . . Q . . 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: 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: r1bqk1nr/pppp2pp/5p2/2b1p3/2QPP3/2P2N2/P4PPP/RNB1K2R b KQkq -
What piece is on b7?

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: 6k1/R7/6p1/7p/8/5KPP/1r3P2/8 b - -
What is the material count for both sides?

White (5 pieces): 1 king, 3 pawns, 1 rook. Black (4 pieces): 1 king, 2 pawns, 1 rook. White is up 1 point(s) of material.


Prompt:
FEN: r6r/1Q4k1/1p1NR1pp/5n2/2Pb4/8/PP3PPP/1R4K1 b - - 2 26
What is on g2?

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


Prompt:
FEN: rnbqk2r/ppp1bppp/3ppn2/8/3PPP2/4BNP1/PPP4P/RN1QKB1R w KQkq - 3 7
What is the compressed FEN row for rank 5?

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


Prompt:
FEN: 3r1r2/pp4pk/2p1pn1p/4N3/4nP2/4B2P/PPP3P1/R4RK1 w - - 1 23
For square e6, 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>".

e6: file=e; rank=6; fen_row_from_top=3; file_index=5


Prompt:
FEN: rnbqkb1r/pppp4/5n1p/5ppN/2PPp3/6P1/PP2PP1P/RNBQKB1R w KQkq -
Compressed rank 2 row: PP2PP1P
Expand it into file cells a through h.

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


r1b1nr1k/1q2bpp1/p3p2p/3pB3/3R4/2N3Q1/PPP1BPPP/2K4R w - -

Prompt:
Rank 1 row before: 2K4R
File c changes from K to 1. Rewrite the compressed row.

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


Prompt:
Board FEN before: rn3rk1/p4p2/3p3p/1bpP2p1/2NqP3/1Q1B4/P4PPP/R4RK1
Apply square edits: h6 p->1; h5 1->p
Return the resulting board FEN only.

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

Result board FEN: rn3rk1/p4p2/3p4/1bpP2pp/2NqP3/1Q1B4/P4PPP/R4RK1


Prompt:
Starting FEN: 2kr1b1r/p1p1pppp/2p2n2/q4b2/3P4/2N5/PPPB1PPP/R2QK1NR w KQ - 0 9
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: 4n3/1Q1k4/8/4K3/8/8/8/8 b - - 0 1
Move: e8c7
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 knight e8c7.
Lookup: e8=black knight; c7=empty.
Squares: e8 black knight->empty; c7 empty->black knight.
Ranks: rank 8 e n->1; rank 7 c 1->n.
Result FEN: 8/1Qnk4/8/4K3/8/8/8/8 w - - 1 2


Prompt:
Starting FEN: r3kb1r/pp2nppp/1q2p3/1b1pP3/3P1P2/PB1n1N2/1P1K2PP/RNBQ3R b kq - 2 12
Move: e8c8
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: 2
Fullmove number: 12

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

Rows: rank 8 r3kb1r->2kr1b1r.
Result FEN: 2kr1b1r/pp2nppp/1q2p3/1b1pP3/3P1P2/PB1n1N2/1P1K2PP/RNBQ3R w - - 3 13


Prompt:
Starting FEN: 8/8/8/8/3p2r1/3K4/5Pk1/7R b - - 0 65
After the moves g4g3, 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: 65

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


Prompt:
FEN: rnbqk2r/pp2bpp1/4p2p/3p4/3NN1PP/4B3/PPP2P2/R2QKBR1 b Qkq -
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,g1; bishop=f1,e3; knight=d4,e4; pawn=a2,b2,c2,f2,g4,h4.
Black inventory: king=e8; queen=d8; rook=a8,h8; bishop=e7,c8; knight=b8; pawn=d5,e6,h6,a7,b7,f7,g7.


Prompt:
FEN: 3r3k/p1p3p1/1p4pp/8/1P2PP2/P5P1/7P/5RK1 w - - 0 28
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=0; knight=0; pawn=6.
Black counts: king=1; queen=0; rook=1; bishop=0; knight=0; pawn=6.


Prompt:
FEN: 8/p1p2b2/2p2P2/k1P5/3PK1B1/6P1/8/8 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=0; rook=0; bishop=3; knight=0; pawn=4; total=7.
Black values: king=0; queen=0; rook=0; bishop=3; knight=0; pawn=3; total=6.


Prompt:
FEN: rnbqkbnr/p4ppp/2p1p3/2Np4/3P4/8/PP2PPPP/R1BQKBNR b KQkq - 0 6
Trace inventory, counts, values, and material balance.

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

Inventory: white king=e1; queen=d1; rook=a1,h1; bishop=c1,f1; knight=g1,c5; pawn=a2,b2,e2,f2,g2,h2,d4 | black king=e8; queen=d8; rook=a8,h8; bishop=c8,f8; knight=b8,g8; pawn=d5,c6,e6,a7,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: 8/8/1k6/4K3/Q7/8/8/8 w - - 0 1
After the moves a4e4 b6c7, 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): 2kr4/ppb3p1/5n1p/nq6/3P4/1B2P3/PP3PPP/R1BK3R w - - 2 16
Show me the board.


Prompt:
Here is the current board:
8 . . . . . b k .
7 . . . . . . . p
6 . p . . p . p P
5 . . p . P p . .
4 . p P . . P . .
3 q P . r . P . .
2 P . . . . Q . R
1 . 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: none
En passant: none
Halfmove clock: 0
Fullmove number: 28

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


Prompt:
FEN: rnbqk1nr/p4pp1/1pppp3/6N1/3PP2P/P7/1PP2P2/RN1QKB1R b KQkq - 0 9
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: 8/p4pkp/4n1p1/r7/2n5/P2NPP1P/5KP1/R7 b - - 2 31
What is the material count for both sides?

White (8 pieces): 1 king, 1 knight, 5 pawns, 1 rook. Black (8 pieces): 1 king, 2 knights, 4 pawns, 1 rook. Black is up 2 point(s) of material.


Prompt:
FEN: r1b1k2r/ppq2pp1/2p2n1p/4b3/8/P1N2N2/1PP1B1PP/R2QK2R w KQkq - 0 16
What is on e7?

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


Prompt:
FEN: r3k2r/pp2bpp1/2p1p3/4P3/4P1pP/3P4/PP4P1/2KR1B1R w kq -
What is the compressed FEN row for rank 5?

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


Prompt:
FEN: 3b1rk1/5pp1/2qnb2p/3p1N2/2pP2P1/R1P2QB1/P1B2PP1/6K1 b - -
For square g1, 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>".

g1: file=g; rank=1; fen_row_from_top=8; file_index=7


Prompt:
FEN: r1bqkb1r/1p2pppp/p1n2n2/3p2B1/3P4/2N2N2/PP2PPPP/R2QKB1R w KQkq -
Compressed rank 1 row: R2QKB1R
Expand it into file cells a through h.

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


1kr2bnr/pb2nppp/1p2p3/8/3p4/PPN3P1/2QPPPBP/R3K1NR w KQ - 0 14

Prompt:
Rank 1 row before: R3K1NR
File c changes from 1 to R. Rewrite the compressed row.

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


Prompt:
Board FEN before: 4k3/8/3P2P1/3K4/4P2r/8/8/8
Apply square edits: g6 P->1; g7 1->P
Return the resulting board FEN only.

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


Prompt:
Starting FEN: r1b2rk1/2pp1ppp/p1n5/1pb1n3/3NP3/1BP4P/PP3P2/RNB1RK2 b - - 0 14
Move: c6d8
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 knight; d8=empty.
Squares: c6 black knight->empty; d8 empty->black knight.
Ranks: rank 6 c n->1; rank 8 d 1->n.


Prompt:
Starting FEN: 1r3rk1/p1pn1ppb/4pn1p/7P/q2P2P1/1NP4R/P1P1QPB1/R1B1K3 w Q - 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: Q
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: 1r3rk1/p1pn1ppb/4pn1p/7P/q2P2P1/1NP4R/P1P1QPB1/R1B2K2 b - - 1 1


Prompt:
Starting FEN: 2r1r1k1/pp1bppb1/2np1np1/q6p/4PN2/1PN2PP1/PBPQB2P/1K1R3R b - - 0 1
Move: h5h4
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>".

Rows: rank 5 q6p->q7; rank 4 4PN2->4PN1p.
Result FEN: 2r1r1k1/pp1bppb1/2np1np1/q7/4PN1p/1PN2PP1/PBPQB2P/1K1R3R w - - 0 2


Prompt:
Starting FEN: 8/8/5k2/4pp2/5Kp1/6Bp/5Pb1/8 w - - 0 55
After the moves f4e3, 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: 55

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


Prompt:
FEN: r5k1/2R2pp1/p3p1np/1p1pP3/1P3PP1/P7/4NK1P/8 b - - 4 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=c7; bishop=none; knight=e2; pawn=h2,a3,b4,f4,g4,e5.
Black inventory: king=g8; queen=none; rook=a8; bishop=none; knight=g6; pawn=b5,d5,a6,e6,h6,f7,g7.


Prompt:
FEN: 8/5K2/8/5k1p/6p1/6P1/7P/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=2.


Prompt:
FEN: r1bqrnk1/pp3pp1/2pb1p1p/8/2PP4/3BB3/PPQ1NPPP/2KR3R 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=3; pawn=7; total=35.
Black values: king=0; queen=9; rook=10; bishop=6; knight=3; pawn=7; total=35.


Prompt:
FEN: r2b1rk1/1p1q1ppb/3p3p/pPpP4/P1P1PN2/1Q4P1/6BP/R4RK1 w - - 1 21
Trace inventory, counts, values, and material balance.

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

Inventory: white king=g1; queen=b3; rook=a1,f1; bishop=g2; knight=f4; pawn=h2,g3,a4,c4,e4,b5,d5 | black king=g8; queen=d7; rook=a8,f8; bishop=h7,d8; knight=none; pawn=a5,c5,d6,h6,b7,f7,g7
Counts: white king=1; queen=1; rook=2; bishop=1; knight=1; pawn=7 | black king=1; queen=1; rook=2; bishop=2; knight=0; pawn=7
Values: white total=32; black total=32
Balance: Material is equal.


Prompt:
Starting FEN: 1k1r1r2/1p6/p1n1q3/3p2Rp/Q2P1Pb1/P3P3/1P6/1K2R3 b - - 4 34
After the moves e6d7 e1g1, what is the resulting position?
State needed for full FEN:
Side to move: black
Castling rights: none
En passant: none
Halfmove clock: 4
Fullmove number: 34

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


Prompt:
Position (FEN): 3Rk3/2p2ppp/b1p5/p1b4P/4PN2/2P2P2/P5P1/1rB1K2R b K - 0 19
Show me the board.


Prompt:
Here is the current board:
8 . . . K . . . .
7 . . . . . . . .
6 . Q . . . P B .
5 . . p . . . . .
4 p . P . . . . .
3 . . . . . . . .
2 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: 41

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


Prompt:
FEN: r1bqkbnr/3p1ppp/p1n1p3/1pp5/2B1P3/2P2N2/PP1P1PPP/RNBQ1RK1 w kq - 0 6
What piece is on f2?

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: 1R6/P4K2/3k4/8/8/8/8/5r2 w - -
What is the material count for both sides?

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


Prompt:
FEN: 2kr3r/pbppb1q1/1p2p3/2n1P1p1/6B1/N1P1B2P/PPQ2P2/2KR4 b - - 6 19
What is on e3?

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


Prompt:
FEN: q4r1k/p5pp/1n2Q3/8/2p1n3/1PP1P1P1/P4P1P/R1B2RK1 w - - 1 19
What is the compressed FEN row for rank 6?

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


Prompt:
FEN: r2qkb1r/pp1n1ppp/2n1p3/3pP3/3P4/2NBB3/PP3PPP/R2QK2R b KQkq -
For square d7, 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>".

d7: file=d; rank=7; fen_row_from_top=2; file_index=4


Prompt:
FEN: r1b1kb1r/pp3ppp/2n1pn2/3q4/1p1P4/P4N2/2P1BPPP/RNBQK2R w KQkq -
Compressed rank 5 row: 3q4
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: R7
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: 4rrk1/2p2ppp/p2p1bq1/3P3n/2P5/3P1PP1/PP4QP/2BRR1K1
Apply square edits: g2 Q->1; f1 1->Q
Return the resulting board FEN only.

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

Result board FEN: 4rrk1/2p2ppp/p2p1bq1/3P3n/2P5/3P1PP1/PP5P/2BRRQK1


Prompt:
Starting FEN: r2q1rk1/pp3ppp/n2b4/1N1Ppb2/2B5/4B3/PP3PPP/R2Q1RK1 b - -
Move: d8c7
List the square lookups and rank edits.

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

Lookup: d8=black queen; c7=empty.
Squares: d8 black queen->empty; c7 empty->black queen.
Ranks: rank 8 d q->1; rank 7 c 1->q.


Prompt:
Starting FEN: 2r3q1/2kp1p2/b3p3/1p1pPPNQ/p2P4/P6P/1PP2P2/2KR2R1 w - - 1 29
Move: g5f3
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: 29

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

Move 1: white knight g5f3.
Lookup: g5=white knight; f3=empty.
Squares: g5 white knight->empty; f3 empty->white knight.
Ranks: rank 5 g N->1; rank 3 f 1->N.
Result FEN: 2r3q1/2kp1p2/b3p3/1p1pPP1Q/p2P4/P4N1P/1PP2P2/2KR2R1 b - - 2 29


Prompt:
Starting FEN: rn1qkb1r/pb1p1ppp/1p2pn2/8/3P4/P3PN1P/1P3PP1/RNBQKB1R b KQkq - 0 7
Move: e6e5
Rewrite the affected compressed FEN rank rows and give Result FEN.
State needed for full FEN:
Side to move: black
Castling rights: KQkq
En passant: none
Halfmove clock: 0
Fullmove number: 7

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

Rows: rank 6 1p2pn2->1p3n2; rank 5 8->4p3.
Result FEN: rn1qkb1r/pb1p1ppp/1p3n2/4p3/3P4/P3PN1P/1P3PP1/RNBQKB1R w KQkq - 0 8


Prompt:
Starting FEN: r3kbnr/p1p3pp/2p1bq2/5p2/3P4/5Q2/PPP2PPP/RNB1R1K1 w kq - 0 12
After the moves f3e2, what is the resulting position?
State needed for full FEN:
Side to move: white
Castling rights: kq
En passant: none
Halfmove clock: 0
Fullmove number: 12

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

Result FEN: r3kbnr/p1p3pp/2p1bq2/5p2/3P4/8/PPP1QPPP/RNB1R1K1 b kq - 1 12


Prompt:
FEN: 8/3k4/6P1/3P3K/8/5p2/8/6r1 b - - 0 60
List the material inventory by side and piece type.

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

White inventory: king=h5; queen=none; rook=none; bishop=none; knight=none; pawn=d5,g6.
Black inventory: king=d7; queen=none; rook=g1; bishop=none; knight=none; pawn=f3.


Prompt:
FEN: 1n4k1/p5b1/1p1N2pp/2p1p3/2P4P/PP2B1P1/5PK1/8 b - - 0 28
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=6.
Black counts: king=1; queen=0; rook=0; bishop=1; knight=1; pawn=6.


Prompt:
FEN: 8/8/8/3P2K1/1pB1k3/1P5P/8/8 b - - 2 57
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=0; bishop=3; knight=0; pawn=3; total=6.
Black values: king=0; queen=0; rook=0; bishop=0; knight=0; pawn=1; total=1.


Prompt:
FEN: 4k2r/n1p1qppp/4b3/8/4n1P1/4PN1P/P2PK1B1/1R6 w k - 0 23
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=b1; bishop=g2; knight=f3; pawn=a2,d2,e3,h3,g4 | black king=e8; queen=e7; rook=h8; bishop=e6; knight=e4,a7; pawn=c7,f7,g7,h7
Counts: white king=1; queen=0; rook=1; bishop=1; knight=1; pawn=5 | black king=1; queen=1; rook=1; bishop=1; knight=2; pawn=4
Values: white total=16; black total=27
Balance: Black is up 11 point(s) of material.


Prompt:
Starting FEN: rn2k1nr/pp1q2p1/2p3p1/4P1p1/2P3P1/8/PP2Q2P/RN1KR3 w kq - 1 20
After the moves e2d3 b7b6 d1c1, what is the resulting position?
State needed for full FEN:
Side to move: white
Castling rights: kq
En passant: none
Halfmove clock: 1
Fullmove number: 20

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

Result FEN: rn2k1nr/p2q2p1/1pp3p1/4P1p1/2P3P1/3Q4/PP5P/RNK1R3 b kq - 1 21


Prompt:
Position (FEN): rnbqk2r/pp1p1ppp/4p3/2p5/2PPn3/P1P5/5PPP/R1BQKBNR w KQkq -
Show me the board.


Prompt:
Here is the current board:
8 . . . . . . . .
7 . . . r . . . .
6 . . p . . . k p
5 . . B n . R p .
4 p . . . . . P .
3 P . P . . . K P
2 . P . . . 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: 4
Fullmove number: 33

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


Prompt:
FEN: r1bqk2r/p1pp1ppp/1pn2n2/2b1P1Q1/8/2N5/PPP2PPP/R1B1KBNR b KQkq - 0 7
What piece is on c3?

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: 8/8/3r4/2k2K1P/8/5PP1/4R3/8 b - - 0 51
What is the material count for both sides?

White (5 pieces): 1 king, 3 pawns, 1 rook. Black (2 pieces): 1 king, 1 rook. White is up 3 point(s) of material.


Prompt:
FEN: r3k2r/pp1b2pp/3Ppp2/4Nn2/8/2B5/PP3PPP/R4RK1 w kq - 0 19
What is on a2?

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


Prompt:
FEN: 8/pK6/P3kn2/7p/7P/8/4B1P1/8 b - -
What is the compressed FEN row for rank 6?

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


Prompt:
FEN: 4rk2/3q1pb1/1p1p1npp/pPpP4/1nP2B2/1P3N1P/5PP1/1B1QR1K1 b - -
For square d7, 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>".

d7: file=d; rank=7; fen_row_from_top=2; file_index=4


Prompt:
FEN: rnbqkbnr/5ppp/p3p3/1pp5/3pP3/P7/BPPPNPPP/R1BQK1NR b KQkq -
Compressed rank 5 row: 1pp5
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: 2KR1B1R
File d changes from R to 1. Rewrite the compressed row.

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


Prompt:
Board FEN before: 3Q1k2/7p/4pp2/1rq4r/5P2/7R/1R4PK/8
Apply square edits: f8 k->1; f7 1->k
Return the resulting board FEN only.

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

Result board FEN: 3Q4/5k1p/4pp2/1rq4r/5P2/7R/1R4PK/8


Prompt:
Starting FEN: rnbqk2r/pp3pbp/2p2pp1/8/2BP4/2P5/PP2QPPP/R1B1K1NR b KQkq -
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 king; f8=empty.
Squares: e8 black king->empty; f8 empty->black king.
Ranks: rank 8 e k->1; rank 8 f 1->k.


Prompt:
Starting FEN: rnb1k1nr/bp1p2pp/5p2/q1PPp3/8/5N2/P2NBPPP/R1BQR1K1 w kq - 0 15
Move: f3h4
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: 15

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

Move 1: white knight f3h4.
Lookup: f3=white knight; h4=empty.
Squares: f3 white knight->empty; h4 empty->white knight.
Ranks: rank 3 f N->1; rank 4 h 1->N.
Result FEN: rnb1k1nr/bp1p2pp/5p2/q1PPp3/7N/8/P2NBPPP/R1BQR1K1 b kq - 1 15


Prompt:
Starting FEN: rnbqk2r/pp3pbp/2p1pnp1/8/2pP4/2N2NP1/PP2PPBP/R1BQR1K1 b kq - 1 8
Move: d8e7
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: 1
Fullmove number: 8

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

Rows: rank 8 rnbqk2r->rnb1k2r; rank 7 pp3pbp->pp2qpbp.
Result FEN: rnb1k2r/pp2qpbp/2p1pnp1/8/2pP4/2N2NP1/PP2PPBP/R1BQR1K1 w kq - 2 9


Prompt:
Starting FEN: r1bqk2r/ppp2ppp/2n1pn2/2b5/2Pp4/3PPNP1/PP3PBP/RNBQ1RK1 b kq - 0 1
After the moves c5a3, 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: r1bqk2r/ppp2ppp/2n1pn2/8/2Pp4/b2PPNP1/PP3PBP/RNBQ1RK1 w kq - 1 2


Prompt:
FEN: r3k2r/1ppbnppp/p1pq4/8/4P3/2N5/PPP1NPPP/R2Q1RK1 b kq -
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=none; knight=e2,c3; pawn=a2,b2,c2,f2,g2,h2,e4.
Black inventory: king=e8; queen=d6; rook=a8,h8; bishop=d7; knight=e7; pawn=a6,c6,b7,c7,f7,g7,h7.


Prompt:
FEN: 3k4/4P3/8/3K1N2/8/8/8/8 b - - 0 70
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=1; pawn=1.
Black counts: king=1; queen=0; rook=0; bishop=0; knight=0; pawn=0.


Prompt:
FEN: 5rk1/1p3ppp/1p1p4/pP1Pp1q1/P3B3/2r5/2P2PP1/R2QK2R w KQ - 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=9; rook=10; bishop=3; knight=0; pawn=6; total=28.
Black values: king=0; queen=9; rook=10; bishop=0; knight=0; pawn=8; total=27.


Prompt:
FEN: 3r4/1pQ5/6k1/6pp/4P3/P2PKP2/6R1/8 b - - 3 46
Trace inventory, counts, values, and material balance.

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

Inventory: white king=e3; queen=c7; rook=g2; bishop=none; knight=none; pawn=a3,d3,f3,e4 | black king=g6; queen=none; rook=d8; bishop=none; knight=none; pawn=g5,h5,b7
Counts: white king=1; queen=1; rook=1; bishop=0; knight=0; pawn=4 | black king=1; queen=0; rook=1; bishop=0; knight=0; pawn=3
Values: white total=18; black total=8
Balance: White is up 10 point(s) of material.


Prompt:
Starting FEN: r2q1rk1/pp1nb1p1/4p2p/2p2p1P/3PN1n1/5N2/PPPBQP2/1K1R3R w - - 0 1
After the moves a2a4 g4e5, 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: r2q1rk1/pp1nb1p1/4p2p/2p1np1P/P2PN3/5N2/1PPBQP2/1K1R3R w - - 1 2


Prompt:
Position (FEN): 8/3Q4/8/8/2B1K3/8/8/2k5 w - -
Show me the board.


Prompt:
Here is the current board:
8 . . k r . . . r
7 p p q . . . . .
6 . . p b . n . p
5 . . . p . p . .
4 P . . P . p . .
3 . . . N . . . P
2 . P P N . P P .
1 R . . Q . 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: 0
Fullmove number: 1

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


Prompt:
FEN: rnbqk2r/ppbp1ppp/2p2n2/8/5N2/2N1P3/PPP2PPP/R1BQKB1R w KQkq - 4 7
What piece is on b8?

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: r1b2rk1/pp1n1pbp/3p4/7Q/P2P1p2/1PP3qP/8/RNB2KNR b - - 0 15
What is the material count for both sides?

White (12 pieces): 1 bishop, 1 king, 2 knights, 5 pawns, 1 queen, 2 rooks. Black (13 pieces): 2 bishops, 1 king, 1 knight, 6 pawns, 1 queen, 2 rooks. Black is up 1 point(s) of material.


Prompt:
FEN: r1b2rk1/ppqnbppp/2p1pn2/3p2B1/2PP4/2NBPN2/PP3PPP/R2Q1RK1 w - -
What is on g1?

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


Prompt:
FEN: 2r1r1k1/7p/2p3p1/P2p4/4B2P/2P2R2/6P1/5R1K b - -
What is the compressed FEN row for rank 6?

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


Prompt:
FEN: r4rk1/pp2ppbp/1nn3p1/5b2/1qP5/1QN2N2/PP1B1PPP/R3KB1R w KQ -
For square e6, 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>".

e6: file=e; rank=6; fen_row_from_top=3; file_index=5


Prompt:
FEN: rnb1k1nr/pp3pp1/4p2p/3pP2P/q7/P4N2/2PB1PP1/R2QKB1R w KQkq -
Compressed rank 6 row: 4p2p
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: R4RK1
File a changes from R to 1. Rewrite the compressed row.

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


Prompt:
Board FEN before: 2k4r/3R4/3K4/8/8/1R5P/1P6/8
Apply square edits: d6 K->1; e6 1->K
Return the resulting board FEN only.

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

Result board FEN: 2k4r/3R4/4K3/8/8/1R5P/1P6/8


Prompt:
Starting FEN: r2qr1k1/pb1n1pbp/1p3np1/1Npp2B1/3P2N1/4PQ2/PP3PPP/1BR1R1K1 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: r1bqkb1r/pppnpp1p/3p1np1/8/3P1P2/4PN2/PPP3PP/RNBQKB1R w KQkq - 0 5
Move: b1a3
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: 5

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

Move 1: white knight b1a3.
Lookup: b1=white knight; a3=empty.
Squares: b1 white knight->empty; a3 empty->white knight.
Ranks: rank 1 b N->1; rank 3 a 1->N.
Result FEN: r1bqkb1r/pppnpp1p/3p1np1/8/3P1P2/N3PN2/PPP3PP/R1BQKB1R b KQkq - 1 5


Prompt:
Starting FEN: 8/r2k1ppp/5n2/1R1p4/p2P4/B1R1PP1P/4r1PK/8 b - - 2 29
Move: f6g4
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: 29

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

Rows: rank 6 5n2->8; rank 4 p2P4->p2P2n1.
Result FEN: 8/r2k1ppp/8/1R1p4/p2P2n1/B1R1PP1P/4r1PK/8 w - - 3 30


Prompt:
Starting FEN: r1b1k1nr/pp1p1ppp/2n1p3/q1b5/4P3/2P1QN2/PP3PPP/RNB1KB1R w KQkq - 0 1
After the moves g2g4, 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: r1b1k1nr/pp1p1ppp/2n1p3/q1b5/4P1P1/2P1QN2/PP3P1P/RNB1KB1R b KQkq - 0 1


Prompt:
FEN: rnb1k2r/pp1p1ppp/2qb1n2/8/3P4/P1B5/2PN1PPP/R2QKBNR w KQkq - 3 10
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=f1,c3; knight=g1,d2; pawn=c2,f2,g2,h2,a3,d4.
Black inventory: king=e8; queen=c6; rook=a8,h8; bishop=d6,c8; knight=f6,b8; pawn=a7,b7,d7,f7,g7,h7.


Prompt:
FEN: r2qkr2/pppn1pQp/4p3/7b/4N3/3PPN1P/P1P1B1P1/5K1R w q - 1 15
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=1; knight=2; pawn=6.
Black counts: king=1; queen=1; rook=2; bishop=1; knight=1; pawn=6.


Prompt:
FEN: 2kr3r/1p3ppp/p1npb3/2p5/8/3P1N2/PPP2PPP/R1B1RK2 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=0; rook=10; bishop=3; knight=3; pawn=7; total=23.
Black values: king=0; queen=0; rook=10; bishop=3; knight=3; pawn=7; total=23.


Prompt:
FEN: 4r3/3kbRR1/pp1p4/2p5/P1P1P2p/3P3K/8/8 b - - 5 39
Trace inventory, counts, values, and material balance.

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

Inventory: white king=h3; queen=none; rook=f7,g7; bishop=none; knight=none; pawn=d3,a4,c4,e4 | black king=d7; queen=none; rook=e8; bishop=e7; knight=none; pawn=h4,c5,a6,b6,d6
Counts: white king=1; queen=0; rook=2; bishop=0; knight=0; pawn=4 | black king=1; queen=0; rook=1; bishop=1; knight=0; pawn=5
Values: white total=14; black total=13
Balance: White is up 1 point(s) of material.


Prompt:
Starting FEN: 2r2k1r/p4ppp/q1pb1n2/4R3/P2p4/1P4P1/2QP1PBP/R1B3K1 w - - 1 18
After the moves e5a5 a6d3, 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: 18

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

Result FEN: 2r2k1r/p4ppp/2pb1n2/R7/P2p4/1P1q2P1/2QP1PBP/R1B3K1 w - - 3 19


Prompt:
Position (FEN): 1k3br1/1p3p2/2p2q2/p1n2N2/P1n3Pp/2N4B/1P1QPP2/3R3K w - -
Show me the board.


rn1qkb1r/p4ppp/1pp1pn2/3p1P2/3P4/3BPQ2/PPP3PP/RNB2RK1 b kq - 0 8

Prompt:
Here is the current board:
8 r n . q k b . r
7 p . . . . p p p
6 . p p . p n . .
5 . . . p . P . .
4 . . . P . . . .
3 . . . B P Q . .
2 P P P . . . P P
1 R N 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: black
Castling rights: kq
En passant: none
Halfmove clock: 0
Fullmove number: 8

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


Prompt:
FEN: rn3k2/2p2p1r/1p1pB3/p2Pp3/Q1P3PR/1KP5/P2q4/5R2 b - - 0 25
What piece is on g4?

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: r1r5/pp1bkp1R/8/3p4/1P4Q1/P3P3/1b2KP2/8 b - - 1 27
What is the material count for both sides?

White (7 pieces): 1 king, 4 pawns, 1 queen, 1 rook. Black (9 pieces): 2 bishops, 1 king, 4 pawns, 2 rooks. Black is up 2 point(s) of material.


Prompt:
FEN: r1bq1rk1/ppp2pb1/3p1npn/3Np1N1/2B1P3/3P4/PPP2PP1/R1BQK2R b KQ - 1 10
What is on f5?

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


Prompt:
FEN: r4rk1/pp1qbpp1/2np1n1p/4p1B1/4P3/2N2N2/PPPQ1PPP/R3R1K1 w - -
What is the compressed FEN row for rank 6?

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


Prompt:
FEN: r2qk1nr/pp3ppp/2n1p3/3p4/1bPP2b1/1QN2N2/PP2BPPP/R1B1K2R b KQkq - 5 8
For square g2, 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>".

g2: file=g; rank=2; fen_row_from_top=7; file_index=7


Prompt:
FEN: 3r1rk1/pppq1pp1/1bnpbn1p/4p3/4P3/1BNPBN1P/PPPQ1PP1/R3R1K1 w - -
Compressed rank 4 row: 4P3
Expand it into file cells a through h.

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


Prompt:
Rank 4 row before: 8
File a changes from 1 to P. Rewrite the compressed row.

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


r2qk2r/pp3pp1/2n1pn1p/2b4b/4N3/2PB1N1P/PP3PP1/R1BQ1RK1 b kq - 0 11

Prompt:
Board FEN before: r2qk2r/pp3pp1/2n1pn1p/2b4b/4N3/2PB1N1P/PP3PP1/R1BQ1RK1
Apply square edits: c5 b->1; e7 1->b
Return the resulting board FEN only.

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

Result board FEN: r2qk2r/pp2bpp1/2n1pn1p/7b/4N3/2PB1N1P/PP3PP1/R1BQ1RK1


Prompt:
Starting FEN: 6k1/5ppp/p1p5/2Bp4/2n5/P4PKP/1r4P1/2R5 b - - 2 30
Move: a6a5
List the square lookups and rank edits.

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

Lookup: a6=black pawn; a5=empty.
Squares: a6 black pawn->empty; a5 empty->black pawn.
Ranks: rank 6 a p->1; rank 5 a 1->p.


Prompt:
Starting FEN: 6k1/6p1/4R2p/3p4/3N1q2/3p3K/1r4P1/8 b - - 4 31
Move: h6h5
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: 31

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

Move 1: black pawn h6h5.
Lookup: h6=black pawn; h5=empty.
Squares: h6 black pawn->empty; h5 empty->black pawn.
Ranks: rank 6 h p->1; rank 5 h 1->p.
Result FEN: 6k1/6p1/4R3/3p3p/3N1q2/3p3K/1r4P1/8 w - - 0 32


Prompt:
Starting FEN: r3k2r/1p2q1bp/n1Pp1pp1/p3p3/Q1P3PP/P4N2/1P1B1P2/1K1R1B1R b kq - 0 20
Move: h8f8
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: 20

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

Rows: rank 8 r3k2r->r3kr2.
Result FEN: r3kr2/1p2q1bp/n1Pp1pp1/p3p3/Q1P3PP/P4N2/1P1B1P2/1K1R1B1R w q - 1 21


Prompt:
Starting FEN: 8/5k2/8/8/1Q2K1B1/8/8/8 w - - 0 1
After the moves g4d7, 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: 3r3k/ppp5/6p1/1n1PR3/8/nP1K4/P4PPP/2R5 b - - 7 26
List the material inventory by side and piece type.

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

White inventory: king=d3; queen=none; rook=c1,e5; bishop=none; knight=none; pawn=a2,f2,g2,h2,b3,d5.
Black inventory: king=h8; queen=none; rook=d8; bishop=none; knight=a3,b5; pawn=g6,a7,b7,c7.


Prompt:
FEN: r3kb1r/ppp1pppp/2n2n2/8/3P4/2N2P2/PPP2P1P/R1BQK2R b KQkq - 0 9
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=1; pawn=7.
Black counts: king=1; queen=0; rook=2; bishop=1; knight=2; pawn=7.


Prompt:
FEN: r5k1/pp3ppp/1N2q2n/4r3/5Q2/2P5/P4PPP/3R1bK1 w - - 0 23
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=0; knight=3; pawn=5; total=22.
Black values: king=0; queen=9; rook=10; bishop=3; knight=3; pawn=5; total=30.


Prompt:
FEN: r2qr3/pp2b2p/2n2kpB/2P5/3p4/1Q4P1/PPP1P1BP/5RK1 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=b3; rook=f1; bishop=g2,h6; knight=none; pawn=a2,b2,c2,e2,h2,g3,c5 | black king=f6; queen=d8; rook=a8,e8; bishop=e7; knight=c6; pawn=d4,g6,a7,b7,h7
Counts: white king=1; queen=1; rook=1; bishop=2; knight=0; pawn=7 | black king=1; queen=1; rook=2; bishop=1; knight=1; pawn=5
Values: white total=27; black total=30
Balance: Black is up 3 point(s) of material.


Prompt:
Starting FEN: 3R4/8/4K3/2k5/8/8/8/8 w - - 26 81
After the moves d8d6 c5b4, what is the resulting position?
State needed for full FEN:
Side to move: white
Castling rights: none
En passant: none
Halfmove clock: 26
Fullmove number: 81

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


Prompt:
Position (FEN): r2q1rk1/pp1bbppp/4p3/nPPpP3/8/2QB1N2/P1P2PPP/RN2K2R w KQ -
Show me the board.


Prompt:
Here is the current board:
8 r . b q . r k .
7 p p p n p p b p
6 . . . p . n p .
5 . . . . . . N .
4 . . B P . . . .
3 . Q P . P . . .
2 P P . . . P P P
1 R N B . 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: KQ
En passant: none
Halfmove clock: 0
Fullmove number: 1

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

r1bq1rk1/pppnppbp/3p1np1/6N1/2BP4/1QP1P3/PP3PPP/RNB1K2R b KQ - 0 1


Prompt:
FEN: 8/pp2q1kp/2p2pp1/3rp3/8/5Q1P/PP4P1/2R4K b - - 3 37
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: 8/7p/5kbP/1p1p1p2/1P1P1P1K/8/8/8 w - -
What is the material count for both sides?

White (5 pieces): 1 king, 4 pawns. Black (6 pieces): 1 bishop, 1 king, 4 pawns. Black is up 3 point(s) of material.


Prompt:
FEN: 5r2/8/pP6/P6R/2k1p2P/4K3/6P1/8 b - - 0 48
What is on a4?

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


Prompt:
FEN: 4r2k/p1p3pp/4r3/7b/4N3/2P1KPP1/PP6/4R3 b - - 0 26
What is the compressed FEN row for rank 1?

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


Prompt:
FEN: r2r2k1/5pp1/pn5p/1p6/3N4/2P5/1P1R1PPP/4RK2 b - - 8 26
For square f2, 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>".

f2: file=f; rank=2; fen_row_from_top=7; file_index=6


Prompt:
FEN: 1rbqk2r/5ppp/p1np4/1p1Np1b1/4P3/2P5/PPN2PPP/R2QKB1R w KQk -
Compressed rank 7 row: 5ppp
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: N1P1B3
File e changes from B to 1. Rewrite the compressed row.

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


Prompt:
Board FEN before: 6k1/ppp3pp/3p4/8/P1P1N3/1P6/2P2KPP/8
Apply square edits: c7 p->1; c5 1->p
Return the resulting board FEN only.

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

Result board FEN: 6k1/pp4pp/3p4/2p5/P1P1N3/1P6/2P2KPP/8


Prompt:
Starting FEN: 7k/1R4p1/r3p2p/4P2P/8/8/4K1P1/8 b - -
Move: a6a2
List the square lookups and rank edits.

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

Lookup: a6=black rook; a2=empty.
Squares: a6 black rook->empty; a2 empty->black rook.
Ranks: rank 6 a r->1; rank 2 a 1->r.


Prompt:
Starting FEN: 2rq1kr1/1Q3p2/1p2p3/1B1p3p/P2n1Pp1/8/n4RPP/1N4K1 w - - 0 30
Move: b7b8
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: 30

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

Move 1: white queen b7b8.
Lookup: b7=white queen; b8=empty.
Squares: b7 white queen->empty; b8 empty->white queen.
Ranks: rank 7 b Q->1; rank 8 b 1->Q.
Result FEN: 1Qrq1kr1/5p2/1p2p3/1B1p3p/P2n1Pp1/8/n4RPP/1N4K1 b - - 1 30


Prompt:
Starting FEN: Qn2kr2/p5pp/2pb4/8/2BP2P1/7K/PPP2q1P/R6R b - - 0 1
Move: f8f4
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>".

Rows: rank 8 Qn2kr2->Qn2k3; rank 4 2BP2P1->2BP1rP1.
Result FEN: Qn2k3/p5pp/2pb4/8/2BP1rP1/7K/PPP2q1P/R6R w - - 1 2


Prompt:
Starting FEN: rn3rk1/1bp1qppp/p3p3/8/2BPn3/2N1PN2/PP3PPP/R2Q1RK1 w - - 0 12
After the moves d1d2, 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: 12

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

Result FEN: rn3rk1/1bp1qppp/p3p3/8/2BPn3/2N1PN2/PP1Q1PPP/R4RK1 b - - 1 12


Prompt:
FEN: rn1qkbnr/pbpppppp/1p6/6B1/2PP4/8/PP2PPPP/RN1QKBNR b KQkq - 2 3
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=f1,g5; knight=b1,g1; pawn=a2,b2,e2,f2,g2,h2,c4,d4.
Black inventory: king=e8; queen=d8; rook=a8,h8; bishop=b7,f8; knight=b8,g8; pawn=b6,a7,c7,d7,e7,f7,g7,h7.


Prompt:
FEN: 2q1k2r/R2p1p1p/6p1/1Pp2nB1/8/1P1Q1P2/1b3P1P/6K1 b k - 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=1; knight=0; pawn=5.
Black counts: king=1; queen=1; rook=1; bishop=1; knight=1; pawn=5.


Prompt:
FEN: rn1qk2r/pp2npb1/2p5/3pP1B1/3P2b1/1BNQ4/PPP4p/R4R1K b kq - 0 14
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=5; total=33.
Black values: king=0; queen=9; rook=10; bishop=6; knight=6; pawn=6; total=37.


Prompt:
FEN: 2k5/p4R1p/1p2r3/8/8/3pBb1P/PP1K1P2/8 b - - 6 30
Trace inventory, counts, values, and material balance.

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

Inventory: white king=d2; queen=none; rook=f7; bishop=e3; knight=none; pawn=a2,b2,f2,h3 | black king=c8; queen=none; rook=e6; bishop=f3; knight=none; pawn=d3,b6,a7,h7
Counts: white king=1; queen=0; rook=1; bishop=1; knight=0; pawn=4 | black king=1; queen=0; rook=1; bishop=1; knight=0; pawn=4
Values: white total=12; black total=12
Balance: Material is equal.


Prompt:
Starting FEN: 5rk1/1pp2pp1/n1b1p2p/4P3/2P5/2B2BP1/5K1P/3R4 b - - 0 29
After the moves a6b8 d1d8 b8a6, 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: 29

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


Prompt:
Position (FEN): 5Q2/7p/6p1/6k1/3N1b1P/1P2p3/P4PP1/3R2K1 b - - 0 39
Show me the board.


Prompt:
Here is the current board:
8 r n b q . r k .
7 p p . . n p p p
6 . . . . p . . B
5 . . . p P . . .
4 . . p P . . Q .
3 P . P B . . . .
2 . . P . . P P P
1 R . . . K . N 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: 0
Fullmove number: 1

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

rnbq1rk1/pp2nppp/4p2B/3pP3/2pP2Q1/P1PB4/2P2PPP/R3K1NR b KQ - 0 1


Prompt:
FEN: rnbqk2r/3pppbp/p4np1/1PpP2B1/8/2N5/PP2PPPP/R2QKBNR w KQkq -
What piece is on h2?

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: 8/5B2/b1p3p1/4k3/5p1p/5Pb1/3K4/6B1 b - - 1 44
What is the material count for both sides?

White (4 pieces): 2 bishops, 1 king, 1 pawn. Black (7 pieces): 2 bishops, 1 king, 4 pawns. Black is up 3 point(s) of material.


Prompt:
FEN: 4Q3/6k1/4K3/8/8/3B4/8/8 w - -
What is on g7?

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


Prompt:
FEN: r1bq1rk1/4bppp/p1np1n2/1p2p3/4P3/2N1N1P1/PPP2P1P/R1BQKB1R w KQ -
What is the compressed FEN row for rank 2?

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


Prompt:
FEN: 2r3k1/p3Q1pp/8/3P3q/b4P2/8/PP6/1K2RR2 w - - 2 41
For square g2, 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>".

g2: file=g; rank=2; fen_row_from_top=7; file_index=7


Prompt:
FEN: 4Q3/5pkp/6p1/5p2/p2q4/Pn3N1P/3r1PP1/5RK1 b - - 5 32
Compressed rank 3 row: Pn3N1P
Expand it into file cells a through h.

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


Prompt:
Rank 6 row before: pQ1p4
File b changes from Q to 1. Rewrite the compressed row.

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


Prompt:
Board FEN before: 4r3/8/6pk/8/8/8/3K4/1R6
Apply square edits: e8 r->1; e6 1->r
Return the resulting board FEN only.

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

Result board FEN: 8/8/4r1pk/8/8/8/3K4/1R6


Prompt:
Starting FEN: r1bqkbnr/pp3ppp/2n5/1B1p4/8/5N2/PP1PQPPP/RNB1K2R b KQkq -
Move: d8e7
List the square lookups and rank edits.

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

Lookup: d8=black queen; e7=empty.
Squares: d8 black queen->empty; e7 empty->black queen.
Ranks: rank 8 d q->1; rank 7 e 1->q.


Prompt:
Starting FEN: rn2r1k1/1b3ppp/p4q2/1p1pp3/8/PB1PQP2/1PP3PP/2K2RNR b - - 1 15
Move: a6a5
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: 1
Fullmove number: 15

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

Move 1: black pawn a6a5.
Lookup: a6=black pawn; a5=empty.
Squares: a6 black pawn->empty; a5 empty->black pawn.
Ranks: rank 6 a p->1; rank 5 a 1->p.
Result FEN: rn2r1k1/1b3ppp/5q2/pp1pp3/8/PB1PQP2/1PP3PP/2K2RNR w - - 0 16


Prompt:
Starting FEN: 8/8/8/4k3/2K5/4R3/8/3r4 b - - 1 52
Move: e5f4
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: 1
Fullmove number: 52

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


Prompt:
Starting FEN: r1bqkbnr/1pp2pp1/p1n1p2p/3p4/3P1B2/P1P2N1P/1P2PPP1/RN1QKB1R b KQkq - 1 6
After the moves g7g6, what is the resulting position?
State needed for full FEN:
Side to move: black
Castling rights: KQkq
En passant: none
Halfmove clock: 1
Fullmove number: 6

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

Result FEN: r1bqkbnr/1pp2p2/p1n1p1pp/3p4/3P1B2/P1P2N1P/1P2PPP1/RN1QKB1R w KQkq - 0 7


Prompt:
FEN: 7R/2K5/2Q4P/5kP1/8/8/8/2r5 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=c7; queen=c6; rook=h8; bishop=none; knight=none; pawn=g5,h6.
Black inventory: king=f5; queen=none; rook=c1; bishop=none; knight=none; pawn=none.


Prompt:
FEN: r4rk1/ppqbppb1/2np1npB/7p/2B1P2P/1NN2P2/PPPQ2P1/2KR3R b - - 3 13
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: 5k2/p4p1p/1np2pp1/1p6/1PPP4/1P1K2PP/4rP2/R7 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=0; rook=5; bishop=0; knight=0; pawn=7; total=12.
Black values: king=0; queen=0; rook=5; bishop=0; knight=3; pawn=7; total=15.


Prompt:
FEN: 2K5/2P1k3/2n5/3B1ppp/8/p5P1/4PP1P/8 w - -
Trace inventory, counts, values, and material balance.

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

Inventory: white king=c8; queen=none; rook=none; bishop=d5; knight=none; pawn=e2,f2,h2,g3,c7 | black king=e7; queen=none; rook=none; bishop=none; knight=c6; pawn=a3,f5,g5,h5
Counts: white king=1; queen=0; rook=0; bishop=1; knight=0; pawn=5 | black king=1; queen=0; rook=0; bishop=0; knight=1; pawn=4
Values: white total=8; black total=7
Balance: White is up 1 point(s) of material.


Prompt:
Starting FEN: rnbqkbnr/ppppp1pp/8/5p2/2P2P2/8/PP1PP1PP/RNBQKBNR b KQkq - 0 1
After the moves g7g6 g2g4 f8h6, 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/ppppp2p/6pb/5p2/2P2PP1/8/PP1PP2P/RNBQKBNR w KQkq - 1 3


Prompt:
Position (FEN): r1bb1rk1/3n1ppp/pp1P1n2/2p5/P1N5/2N5/1P2BPPP/R1B2RK1 w - -
Show me the board.


Prompt:
Here is the current board:
8 . . . . . . . .
7 . . . . . . . .
6 . . . . . . . .
5 . . . . . K . .
4 . . . . Q . . .
3 . . k . . . . .
2 . b . . . . . .
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: rnbqkb1r/pp1ppppp/5n2/2p5/4P3/2P2N2/PP1P1PPP/RNBQKB1R b KQkq -
What piece is on f7?

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: r2qk2r/p1p2pp1/2p2n1p/4p3/2p1P3/3P1Q1P/PPP2PP1/R1B1K2R w KQkq -
What is the material count for both sides?

White (13 pieces): 1 bishop, 1 king, 8 pawns, 1 queen, 2 rooks. Black (13 pieces): 1 king, 1 knight, 8 pawns, 1 queen, 2 rooks. Material is equal.


Prompt:
FEN: 3bR1k1/p2P4/5p1p/2p2BpP/1P6/2P5/P5P1/7K b - -
What is on f6?

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


Prompt:
FEN: r3r1k1/2R1pp1p/p2p2pb/3P4/p3b1P1/5N1P/PB3P2/R5K1 w - - 0 32
What is the compressed FEN row for rank 8?

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


Prompt:
FEN: 3rk2r/ppp2ppp/2n1n3/4p3/1b6/2N2N2/PPP2PPP/R1B1R1K1 w k -
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: 3r2k1/3Q1p1p/R2B1qp1/1Pp5/2b5/4P2P/5PP1/6K1 w - -
Compressed rank 1 row: 6K1
Expand it into file cells a through h.

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


r4rk1/4bppp/p2pbn2/2q5/4P3/2NQB3/PPP2PPP/R2R2K1 b - -

Prompt:
Rank 5 row before: 2q5
File d changes from 1 to n. Rewrite the compressed row.

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


Prompt:
Board FEN before: 8/6kp/p4qp1/6n1/2P2R2/6P1/P2P2QP/4R1K1
Apply square edits: f6 q->1; a1 1->q
Return the resulting board FEN only.

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

Result board FEN: 8/6kp/p5p1/6n1/2P2R2/6P1/P2P2QP/q3R1K1


Prompt:
Starting FEN: 8/8/7R/Q3K3/8/8/1k6/8 w - -
Move: h6f6
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 rook; f6=empty.
Squares: h6 white rook->empty; f6 empty->white rook.
Ranks: rank 6 h R->1; rank 6 f 1->R.


Prompt:
Starting FEN: rn1qk2r/ppp1nbpp/8/4Q3/4pP2/8/PPPP1KPP/RNB2B1R w kq - 0 1
Move: e5g7
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 e5g7. Captures black pawn on g7.
Lookup: e5=white queen; g7=black pawn.
Squares: e5 white queen->empty; g7 black pawn->white queen.
Ranks: rank 5 e Q->1; rank 7 g p->Q.
Result FEN: rn1qk2r/ppp1nbQp/8/8/4pP2/8/PPPP1KPP/RNB2B1R b kq - 0 1


Prompt:
Starting FEN: 6k1/pp1n4/7p/2Pp1ppb/2P5/P3rP2/6PP/R4RK1 w - - 0 27
Move: f1b1
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: 27

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

Rows: rank 1 R4RK1->RR4K1.
Result FEN: 6k1/pp1n4/7p/2Pp1ppb/2P5/P3rP2/6PP/RR4K1 b - - 1 27


Prompt:
Starting FEN: 2r1r2k/1pp1npqn/p2pb1p1/3N4/3PPB2/PB1Q4/1P3PP1/3RR1K1 w - - 10 26
After the moves f4h2, what is the resulting position?
State needed for full FEN:
Side to move: white
Castling rights: none
En passant: none
Halfmove clock: 10
Fullmove number: 26

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

Result FEN: 2r1r2k/1pp1npqn/p2pb1p1/3N4/3PP3/PB1Q4/1P3PPB/3RR1K1 b - - 11 26


Prompt:
FEN: r4rk1/p1qnn3/1pbN2pp/2p1Np2/2P5/6P1/PQ1RPPBP/5RK1 b - - 6 20
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=b2; rook=f1,d2; bishop=g2; knight=e5,d6; pawn=a2,e2,f2,h2,g3,c4.
Black inventory: king=g8; queen=c7; rook=a8,f8; bishop=c6; knight=d7,e7; pawn=c5,f5,b6,g6,h6,a7.


Prompt:
FEN: r3k2r/1p3pp1/p1pp3p/4Pb2/2Bp1P2/3P4/PPP3PP/R4RK1 w kq - 0 17
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=8.
Black counts: king=1; queen=0; rook=2; bishop=1; knight=0; pawn=8.


Prompt:
FEN: 2r3k1/p5p1/1p2p2p/3p4/3P4/1P6/P1r2PKP/4RR2 w - - 0 25
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=0; knight=0; pawn=5; total=15.
Black values: king=0; queen=0; rook=10; bishop=0; knight=0; pawn=6; total=16.


Prompt:
FEN: 2qr1k2/1p3p2/7p/1P5Q/4N3/p3P1P1/P5KP/8 b - - 2 32
Trace inventory, counts, values, and material balance.

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

Inventory: white king=g2; queen=h5; rook=none; bishop=none; knight=e4; pawn=a2,h2,e3,g3,b5 | black king=f8; queen=c8; rook=d8; bishop=none; knight=none; pawn=a3,h6,b7,f7
Counts: white king=1; queen=1; rook=0; bishop=0; knight=1; pawn=5 | black king=1; queen=1; rook=1; bishop=0; knight=0; pawn=4
Values: white total=17; black total=18
Balance: Black is up 1 point(s) of material.


Prompt:
Starting FEN: 8/6K1/4k3/5q2/8/8/8/8 b - - 10 80
After the moves f5c2 g7f8, what is the resulting position?
State needed for full FEN:
Side to move: black
Castling rights: none
En passant: none
Halfmove clock: 10
Fullmove number: 80

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


Prompt:
Position (FEN): 8/p2rR1pk/5rq1/6np/5p2/1Q3P2/PPP3PP/4R2K b - - 6 30
Show me the board.


Prompt:
Here is the current board:
8 k . . . . . . .
7 . . . . Q . . .
6 . . K . . . . .
5 . . . . . . . .
4 . . B . . . . .
3 . . . . . . . .
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: r5k1/pp1bp1bp/1q1p1np1/6B1/2r1P1P1/1NN2P2/PPPQ3R/2KR4 b - - 1 17
What piece is on f3?

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: 8/3k4/7p/3P3P/3K4/8/8/8 w - -
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: rn1qkbnr/pp3ppp/4b3/2pp4/5B2/1N2P3/PPP2PPP/RN1QKB1R w KQkq -
What is on a1?

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


Prompt:
FEN: rn1qk1nr/pp1b1ppp/8/1Bb5/4p3/2N5/PP3PPP/R1BQK1NR w KQkq -
What is the compressed FEN row for rank 8?

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


Prompt:
FEN: 1R6/6kp/p1N2p2/1pb3p1/n7/6B1/PPP2PPP/4R1K1 w - - 1 27
For square d3, 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>".

d3: file=d; rank=3; fen_row_from_top=6; file_index=4


Prompt:
FEN: 1r6/1p3n1k/p2p2pp/2p5/P1B1P3/1P1P2b1/1BP3Kq/R1QN4 w - -
Compressed rank 3 row: 1P1P2b1
Expand it into file cells a through h.

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


Prompt:
Rank 6 row before: 1kQ5
File b changes from k to 1. Rewrite the compressed row.

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


r1b1kb1r/1pqn1pp1/p2p1n1p/4pN2/4PPPP/2NB4/PPP1Q3/R1B1K2R b KQkq -

Prompt:
Board FEN before: r1b1kb1r/1pqn1pp1/p2p1n1p/4pN2/4PPPP/2NB4/PPP1Q3/R1B1K2R
Apply square edits: c7 q->1; c3 N->q
Return the resulting board FEN only.

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

Result board FEN: r1b1kb1r/1p1n1pp1/p2p1n1p/4pN2/4PPPP/2qB4/PPP1Q3/R1B1K2R


Prompt:
Starting FEN: r4r2/pp2ppk1/2np2p1/2p5/2P1PP2/3P3R/q1N3P1/2RK1B2 b - - 0 19
Move: e7e5
List the square lookups and rank edits.

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

Lookup: e7=black pawn; e5=empty.
Squares: e7 black pawn->empty; e5 empty->black pawn.
Ranks: rank 7 e p->1; rank 5 e 1->p.


Prompt:
Starting FEN: 5rk1/6p1/p7/3Q1b2/2pP4/q7/P2N1PPP/2R2RK1 b - - 1 30
Move: f8f7
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: 1
Fullmove number: 30

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

Move 1: black rook f8f7.
Lookup: f8=black rook; f7=empty.
Squares: f8 black rook->empty; f7 empty->black rook.
Ranks: rank 8 f r->1; rank 7 f 1->r.
Result FEN: 6k1/5rp1/p7/3Q1b2/2pP4/q7/P2N1PPP/2R2RK1 w - - 2 31


Prompt:
Starting FEN: 8/1R5p/1P4k1/8/5pp1/1r6/6KP/8 b - - 1 44
Move: g6h5
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: 1
Fullmove number: 44

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


Prompt:
Starting FEN: rnbqkb1r/pp3ppp/2p5/3pP3/8/5Q2/PPP2PPP/RNB1K1NR w KQkq - 0 8
After the moves f3h5, 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: 8

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

Result FEN: rnbqkb1r/pp3ppp/2p5/3pP2Q/8/8/PPP2PPP/RNB1K1NR b KQkq - 1 8


Prompt:
FEN: r2qkbnr/1pp1p1pp/p1n2p2/1B1pPb2/3P1B2/8/PPP2PPP/RN1QK1NR w KQkq - 0 6
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=f4,b5; knight=b1,g1; pawn=a2,b2,c2,f2,g2,h2,d4,e5.
Black inventory: king=e8; queen=d8; rook=a8,h8; bishop=f5,f8; knight=c6,g8; pawn=d5,a6,f6,b7,c7,e7,g7,h7.


Prompt:
FEN: k7/7R/p7/3b4/1R6/6P1/3r1K1P/8 w - - 5 42
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=2.
Black counts: king=1; queen=0; rook=1; bishop=1; knight=0; pawn=1.


Prompt:
FEN: 2rq1rk1/p3Pppp/1p2p3/2p5/2P5/2N1P1P1/PB1P3P/R2Q1bK1 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=5; bishop=3; knight=3; pawn=7; total=27.
Black values: king=0; queen=9; rook=10; bishop=3; knight=0; pawn=7; total=29.


Prompt:
FEN: 8/3P4/2k1K3/8/8/8/8/3r4 w - -
Trace inventory, counts, values, and material balance.

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

Inventory: white king=e6; queen=none; rook=none; bishop=none; knight=none; pawn=d7 | black king=c6; queen=none; rook=d1; bishop=none; knight=none; pawn=none
Counts: white king=1; queen=0; rook=0; bishop=0; knight=0; pawn=1 | black king=1; queen=0; rook=1; bishop=0; knight=0; pawn=0
Values: white total=1; black total=5
Balance: Black is up 4 point(s) of material.


Prompt:
Starting FEN: 8/pp3pk1/2p3p1/3P2P1/2B1PpR1/2P2P1q/P4K2/7r w - - 0 1
After the moves g4h4 h1g1 h4h6, 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): 1R6/p4p1k/1p4p1/3pQ2p/1P2nP2/P5P1/5qKP/5B2 w - -
Show me the board.


rn1qkb1r/pp2pppp/2pp1n2/8/3P2b1/4PN2/PPPB1PPP/RN1QKB1R w KQkq - 3 5

Prompt:
Here is the current board:
8 r n . q k b . r
7 p p . . p p p p
6 . . p p . n . .
5 . . . . . . . .
4 . . . P . . b .
3 . . . . P N . .
2 P P P B . P P P
1 R N . Q 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: 3
Fullmove number: 5

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


Prompt:
FEN: r2q1rk1/1pp1n1pp/p2pbp2/8/2nP4/4BNP1/P1Q1PPBP/R4RK1 w - - 0 15
What piece is on f3?

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: 5kr1/pp5Q/5Pn1/8/2P5/P3P3/1P4PP/5RK1 w - - 1 32
What is the material count for both sides?

White (10 pieces): 1 king, 7 pawns, 1 queen, 1 rook. Black (5 pieces): 1 king, 1 knight, 2 pawns, 1 rook. White is up 11 point(s) of material.


Prompt:
FEN: rnbqk2r/ppp1bppp/4pn2/8/3P4/2N2N1P/PPP2PP1/R1BQKB1R w KQkq -
What is on a6?

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


Prompt:
FEN: rnbqkbnr/pp1p1ppp/4p3/2p5/4P3/3P4/PPP1QPPP/RNB1KBNR b KQkq - 1 3
What is the compressed FEN row for rank 7?

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


Prompt:
FEN: 8/1p5p/2p4k/p2p1p2/5P1r/8/8/1K6 b - - 0 41
For square c6, 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>".

c6: file=c; rank=6; fen_row_from_top=3; file_index=3


Prompt:
FEN: 8/1k6/4R2p/5N1P/1r2p1P1/3pK3/8/8 w - -
Compressed rank 1 row: 8
Expand it into file cells a through h.

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


rnbqk2r/ppp2pbp/3p1np1/4p3/2PPP3/2N2P2/PP2N1PP/R1BQKB1R b KQkq -

Prompt:
Rank 6 row before: 3p1np1
File f changes from n to 1. Rewrite the compressed row.

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


r1bq1rk1/pp2ppbp/n2p1np1/2pP4/2P5/2NBP3/PP2NPPP/R1BQ1RK1 b - - 0 8

Prompt:
Board FEN before: r1bq1rk1/pp2ppbp/n2p1np1/2pP4/2P5/2NBP3/PP2NPPP/R1BQ1RK1
Apply square edits: e7 p->1; e6 1->p
Return the resulting board FEN only.

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

Result board FEN: r1bq1rk1/pp3pbp/n2ppnp1/2pP4/2P5/2NBP3/PP2NPPP/R1BQ1RK1


Prompt:
Starting FEN: 6nk/p5pp/8/1Pq5/P1P5/1Kq5/8/8 w - - 0 50
Move: b3a2
List the square lookups and rank edits.

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

Lookup: b3=white king; a2=empty.
Squares: b3 white king->empty; a2 empty->white king.
Ranks: rank 3 b K->1; rank 2 a 1->K.


Prompt:
Starting FEN: rn2kbnr/pbppq3/1p2pp2/6pp/3P4/2PBP3/PP1N1PPP/R1BQNRK1 b kq - 1 8
Move: b7g2
Use square lookups and rank edits to assemble the resulting full FEN.
State needed for full FEN:
Side to move: black
Castling rights: kq
En passant: none
Halfmove clock: 1
Fullmove number: 8

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

Move 1: black bishop b7g2. Captures white pawn on g2.
Lookup: b7=black bishop; g2=white pawn.
Squares: b7 black bishop->empty; g2 white pawn->black bishop.
Ranks: rank 7 b b->1; rank 2 g P->b.
Result FEN: rn2kbnr/p1ppq3/1p2pp2/6pp/3P4/2PBP3/PP1N1PbP/R1BQNRK1 w kq - 0 9


Prompt:
Starting FEN: r2q1rk1/pp3ppp/2ppbn2/2n1p3/1bP1P3/2NPBPP1/PP2N1BP/R2Q1RK1 w - - 1 11
Move: e3f2
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: 1
Fullmove number: 11

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

Rows: rank 3 2NPBPP1->2NP1PP1; rank 2 PP2N1BP->PP2NBBP.
Result FEN: r2q1rk1/pp3ppp/2ppbn2/2n1p3/1bP1P3/2NP1PP1/PP2NBBP/R2Q1RK1 b - - 2 11


Prompt:
Starting FEN: 4k2r/2pn1ppp/2n1p3/8/1P6/P1P2P2/2P2P1P/R2R2K1 b k - 0 17
After the moves e8d8, what is the resulting position?
State needed for full FEN:
Side to move: black
Castling rights: k
En passant: none
Halfmove clock: 0
Fullmove number: 17

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


Prompt:
FEN: 8/B4k1p/4p3/2P3b1/3P4/P2K4/1r6/8 b - - 0 42
List the material inventory by side and piece type.

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

White inventory: king=d3; queen=none; rook=none; bishop=a7; knight=none; pawn=a3,d4,c5.
Black inventory: king=f7; queen=none; rook=b2; bishop=g5; knight=none; pawn=e6,h7.


Prompt:
FEN: 2r4r/1p2k3/p2pbp2/4n1p1/7p/2P1B2P/PP2BPP1/1K1R3R 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=2; bishop=2; knight=0; pawn=6.
Black counts: king=1; queen=0; rook=2; bishop=1; knight=1; pawn=6.


Prompt:
FEN: r4rk1/pp1nppbp/1qp2np1/3p4/1P1P1B2/2N1PB1P/P1P2PP1/1R1Q1RK1 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=3; pawn=8; total=36.
Black values: king=0; queen=9; rook=10; bishop=3; knight=6; pawn=8; total=36.


Prompt:
FEN: r4rk1/pbp3pp/1bN5/8/4p3/1P2B2P/1P3PP1/R4RK1 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=none; rook=a1,f1; bishop=e3; knight=c6; 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: 5rk1/1bq2ppp/p7/1p6/1P1Q4/P4P2/6PP/R4RK1 w - - 1 26
After the moves f1c1 b7a8, 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: 26

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


Prompt:
Position (FEN): 2r1r1k1/2q1bppp/p2p4/4pP2/1NP5/1P2BQ2/P5PP/3n1RK1 w - -
Show me the board.


Prompt:
Here is the current board:
8 r . . q k b . r
7 . . . . . . . p
6 p . . p . p . p
5 n . . . p . . .
4 . P . P P . . .
3 . . P . . N . P
2 P . . . . P P .
1 R N . . . Q 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: kq
En passant: none
Halfmove clock: 0
Fullmove number: 17

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


Prompt:
FEN: rnbqkb1r/pp3ppp/4pn2/2P3B1/2p1P3/2N5/PP3PPP/R2QKBNR b KQkq -
What piece is on e6?

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: 2r5/7k/p1qbp1pp/2p5/2P3Q1/1PBR4/P4PP1/6K1 b - -
What is the material count for both sides?

White (9 pieces): 1 bishop, 1 king, 5 pawns, 1 queen, 1 rook. Black (9 pieces): 1 bishop, 1 king, 5 pawns, 1 queen, 1 rook. Material is equal.


Prompt:
FEN: r1b2rk1/1ppn2pp/pbn1B3/6B1/8/2N2N2/PP3PPP/3R1RK1 b - - 0 14
What is on f3?

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


Prompt:
FEN: r1r5/3bppk1/3p1np1/8/4P1PP/1B6/1PP5/2KN2RR b - - 0 25
What is the compressed FEN row for rank 6?

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


Prompt:
FEN: 3rqr2/pkp4p/1p2p1p1/3pP3/4N3/P6P/1PPQ1PP1/2KR3R b - - 0 20
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: r1b1kb1r/ppNnq1pp/2p2n2/8/8/8/PPP2PPP/RNBQ1RK1 b kq -
Compressed rank 2 row: PPP2PPP
Expand it into file cells a through h.

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


rn1q1rk1/pp2ppbp/2p1bNp1/4p1N1/2B4P/8/PPPP1PP1/R1BQK2R b KQ - 0 9

Prompt:
Rank 7 row before: pp2ppbp
File e changes from p to 1. Rewrite the compressed row.

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


r2q1rk1/pp2bppp/3pbn2/4p3/3pP3/P2P3P/BPP1NPP1/R1BQ1RK1 b - - 3 11

Prompt:
Board FEN before: r2q1rk1/pp2bppp/3pbn2/4p3/3pP3/P2P3P/BPP1NPP1/R1BQ1RK1
Apply square edits: b7 p->1; b5 1->p
Return the resulting board FEN only.

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

Result board FEN: r2q1rk1/p3bppp/3pbn2/1p2p3/3pP3/P2P3P/BPP1NPP1/R1BQ1RK1


Prompt:
Starting FEN: 3qk1B1/2p1b3/3p2pB/7p/r3P3/P2P1Q1P/2P2P2/2KR4 b - - 0 29
Move: a4b4
List the square lookups and rank edits.

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

Lookup: a4=black rook; b4=empty.
Squares: a4 black rook->empty; b4 empty->black rook.
Ranks: rank 4 a r->1; rank 4 b 1->r.


Prompt:
Starting FEN: 8/2R2p1p/2N3pk/8/6P1/5P2/3q2KP/r7 w - - 1 39
Move: g2h3
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: 39

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

Move 1: white king g2h3.
Lookup: g2=white king; h3=empty.
Squares: g2 white king->empty; h3 empty->white king.
Ranks: rank 2 g K->1; rank 3 h 1->K.
Result FEN: 8/2R2p1p/2N3pk/8/6P1/5P1K/3q3P/r7 b - - 2 39


Prompt:
Starting FEN: 5k2/p7/1p3P2/1P1PK3/P3n3/8/8/8 b - - 0 74
Move: a7a5
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: 74

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


Prompt:
Starting FEN: 1r2r3/ppQ5/3Pkp1p/3Np3/3nP1qP/6P1/PP3PK1/8 b - - 0 26
After the moves g4d1, 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: 26

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

Result FEN: 1r2r3/ppQ5/3Pkp1p/3Np3/3nP2P/6P1/PP3PK1/3q4 w - - 1 27


Prompt:
FEN: rn1qkb1r/pb2p1pp/1pp5/3nPp2/2BP4/2N2P2/PP4PP/R1BQK1NR b KQkq - 1 9
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,c4; knight=g1,c3; pawn=a2,b2,g2,h2,f3,d4,e5.
Black inventory: king=e8; queen=d8; rook=a8,h8; bishop=b7,f8; knight=d5,b8; pawn=f5,b6,c6,a7,e7,g7,h7.


Prompt:
FEN: 2kr1r2/p1pp4/1p2pp1n/3Pn3/2P1N3/1P2PPN1/q5P1/1R3RK1 w - - 2 27
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=2; pawn=6.
Black counts: king=1; queen=1; rook=2; bishop=0; knight=2; pawn=6.


Prompt:
FEN: 8/2pk2p1/pp1p3p/1P1P1p1P/P1P2P2/2K5/6P1/8 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=0; rook=0; bishop=0; knight=0; pawn=7; total=7.
Black values: king=0; queen=0; rook=0; bishop=0; knight=0; pawn=7; total=7.


Prompt:
FEN: 8/1p6/p7/P1ppkPp1/6P1/2P1K3/1P6/8 w - - 0 33
Trace inventory, counts, values, and material balance.

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

Inventory: white king=e3; queen=none; rook=none; bishop=none; knight=none; pawn=b2,c3,g4,a5,f5 | black king=e5; queen=none; rook=none; bishop=none; knight=none; pawn=c5,d5,g5,a6,b7
Counts: white king=1; queen=0; rook=0; bishop=0; knight=0; pawn=5 | black king=1; queen=0; rook=0; bishop=0; knight=0; pawn=5
Values: white total=5; black total=5
Balance: Material is equal.


Prompt:
Starting FEN: r1bq1rk1/ppp1bppp/2n1pn2/3p4/5P2/2PPB1P1/PP1NP2P/R2QKBNR w KQ - 4 7
After the moves d1a4 d8d7, what is the resulting position?
State needed for full FEN:
Side to move: white
Castling rights: KQ
En passant: none
Halfmove clock: 4
Fullmove number: 7

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

Result FEN: r1b2rk1/pppqbppp/2n1pn2/3p4/Q4P2/2PPB1P1/PP1NP2P/R3KBNR w KQ - 6 8


Prompt:
Position (FEN): rnb2rk1/pp3ppp/1q1bpn2/2pp4/3P4/4PNB1/PPPN1PPP/1R1QKB1R w K -
Show me the board.

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


Prompt:
Here is the current board:
8 . . . . R . . .
7 . . N . . p p k
6 . . p . . . b p
5 . p . . p . . .
4 . P . . . r . .
3 . . . . . . K P
2 . . . . . 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: 5
Fullmove number: 35

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


Prompt:
FEN: r1bqknnr/pp2bpp1/2ppp3/7p/1P1PP3/2PB1N2/P2N1PPP/R1BQ1RK1 b kq - 2 8
What piece is on h2?

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/ppppnpp1/2nb2p1/6B1/3P2B1/2P2R2/PP1NQP1P/R3K3 b Qkq - 5 14
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, 2 knights, 7 pawns, 2 rooks. White is up 5 point(s) of material.


Prompt:
FEN: 7k/6pp/8/4p3/K7/5P1P/5r2/8 w - - 1 45
What is on h3?

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


Prompt:
FEN: r1bq1rk1/pp2ppbp/2n2np1/2p5/4PP2/2NBBN2/PPP3PP/R2Q1RK1 b - - 3 9
What is the compressed FEN row for rank 3?

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


Prompt:
FEN: 7Q/8/4k3/1p6/1P6/P3P3/5PP1/R5K1 w - - 1 59
For square c7, 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>".

c7: file=c; rank=7; fen_row_from_top=2; file_index=3


Prompt:
FEN: rn2kbnr/pbppq3/1p2p2p/4P1pQ/3P4/3BB1PN/PPP4P/RN3RK1 b kq - 1 13
Compressed rank 2 row: PPP4P
Expand it into file cells a through h.

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


r1b2rk1/3n1ppp/1q2p3/p2pP3/1ppP1P2/5N2/P1Q1B1PP/R2NK2R w KQ -

Prompt:
Rank 4 row before: 1ppP1P2
File c changes from p to Q. Rewrite the compressed row.

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


Prompt:
Board FEN before: 2Q5/1kp5/p1Nb4/3P4/1P5p/p6P/K3R1P1/5q2
Apply square edits: b7 k->1; b6 1->k
Return the resulting board FEN only.

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

Result board FEN: 2Q5/2p5/pkNb4/3P4/1P5p/p6P/K3R1P1/5q2


Prompt:
Starting FEN: r2q1rk1/pp2ppb1/1np2n1p/6p1/3P4/2NbPNBP/PP3PP1/R2Q1RK1 w - - 0 14
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: r2qk2r/ppp3pp/2nbbn2/1B1pp3/7B/P3P3/1PP2PPP/RN1QK1NR w KQkq - 6 9
Move: c2c4
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: 6
Fullmove number: 9

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

Move 1: white pawn c2c4.
Lookup: c2=white pawn; c4=empty.
Squares: c2 white pawn->empty; c4 empty->white pawn.
Ranks: rank 2 c P->1; rank 4 c 1->P.
Result FEN: r2qk2r/ppp3pp/2nbbn2/1B1pp3/2P4B/P3P3/1P3PPP/RN1QK1NR b KQkq - 0 9


Prompt:
Starting FEN: 4rknr/pp4pp/2p5/4Bb2/2B5/8/PPP2PPP/2KRR3 b - - 5 16
Move: f5e6
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: 5
Fullmove number: 16

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

Rows: rank 5 4Bb2->4B3; rank 6 2p5->2p1b3.
Result FEN: 4rknr/pp4pp/2p1b3/4B3/2B5/8/PPP2PPP/2KRR3 w - - 6 17


Prompt:
Starting FEN: 1r4k1/3R4/2R1P1Bp/3n4/8/1p5P/5PPK/4r3 b - - 0 1
After the moves e1e5, 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: rnbqk2r/ppp1bpp1/5n1p/3p4/3P4/5PPN/PPP3BP/RNBQ1RK1 w kq -
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=b1,h3; pawn=a2,b2,c2,h2,f3,g3,d4.
Black inventory: king=e8; queen=d8; rook=a8,h8; bishop=e7,c8; knight=f6,b8; pawn=d5,h6,a7,b7,c7,f7,g7.


Prompt:
FEN: r1b1k2r/ppp1n1p1/3p4/3Pp2q/2P1P1pp/2N1B3/PPQ2PP1/1K1R3R b kq - 2 17
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=1; pawn=7.
Black counts: king=1; queen=1; rook=2; bishop=1; knight=1; pawn=8.


Prompt:
FEN: 2r3k1/1pp3p1/1p1p2p1/3Pp1p1/r1P1P3/6PP/PP3P2/R1R3K1 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=0; rook=10; bishop=0; knight=0; pawn=8; total=18.
Black values: king=0; queen=0; rook=10; bishop=0; knight=0; pawn=8; total=18.


Prompt:
FEN: 3R4/5kp1/4pp1p/p1r5/Ppp5/4K3/1PP2PPP/8 w - - 4 32
Trace inventory, counts, values, and material balance.

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

Inventory: white king=e3; queen=none; rook=d8; bishop=none; knight=none; pawn=b2,c2,f2,g2,h2,a4 | black king=f7; queen=none; rook=c5; bishop=none; knight=none; pawn=b4,c4,a5,e6,f6,h6,g7
Counts: white king=1; queen=0; rook=1; bishop=0; knight=0; pawn=6 | black king=1; queen=0; rook=1; bishop=0; knight=0; pawn=7
Values: white total=11; black total=12
Balance: Black is up 1 point(s) of material.


Prompt:
Starting FEN: r3r1k1/1b3ppp/pq1b1n2/4n3/3p1N2/6N1/PP1B1PPP/1BRQ1RK1 w - - 0 1
After the moves c1c7 e8c8, 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: r1r3k1/1bR2ppp/pq1b1n2/4n3/3p1N2/6N1/PP1B1PPP/1B1Q1RK1 w - - 2 2


Prompt:
Position (FEN): 3r1rk1/pp2q2p/5p2/2pPp1pP/3n4/2N1Q3/PPP2PP1/2KRR3 w - -
Show me the board.


Prompt:
Here is the current board:
8 . . . . r . . k
7 . . . r . . . p
6 . . . p b . . .
5 p N . . p p . .
4 . p P . . P q P
3 . P . . Q . P .
2 P . . R . R . 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: r1bq1rk1/1p3pp1/1b1p1n1p/pPpPn3/2P5/P1N3P1/4NPBP/R1BQK2R w KQ - 1 13
What piece is on c5?

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: rn1qk2r/p3npp1/1p2p2p/3pP2P/b1pP4/P1PB1N2/2P2PP1/R1BQK2R w KQkq -
What is the material count for both sides?

White (15 pieces): 2 bishops, 1 king, 1 knight, 8 pawns, 1 queen, 2 rooks. Black (15 pieces): 1 bishop, 1 king, 2 knights, 8 pawns, 1 queen, 2 rooks. Material is equal.


Prompt:
FEN: 8/6Bp/1p2k1p1/PKn5/5P2/8/7P/8 b - -
What is on c5?

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


Prompt:
FEN: 8/1K4q1/8/P7/7n/2N2k1b/8/8 w - - 1 57
What is the compressed FEN row for rank 5?

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


Prompt:
FEN: 6k1/2p2p1p/1p1p2p1/pR1P4/r1P5/2P3P1/5P1P/6K1 w - - 0 24
For square f4, 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>".

f4: file=f; rank=4; fen_row_from_top=5; file_index=6


Prompt:
FEN: rn1qkb1r/pp3ppp/4pn2/3p4/3P1Pb1/5N1P/PPP1B1P1/RNBQK2R b KQkq -
Compressed rank 2 row: PPP1B1P1
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: 1P3N2
File e changes from 1 to n. Rewrite the compressed row.

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


2r2rk1/3nq1pp/bppbp3/p2p1p2/P1PP4/1P1NPPP1/1B1n2BP/2RQR1K1 w - -

Prompt:
Board FEN before: 2r2rk1/3nq1pp/bppbp3/p2p1p2/P1PP4/1P1NPPP1/1B1n2BP/2RQR1K1
Apply square edits: e1 R->1; f1 1->R
Return the resulting board FEN only.

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

Result board FEN: 2r2rk1/3nq1pp/bppbp3/p2p1p2/P1PP4/1P1NPPP1/1B1n2BP/2RQ1RK1


Prompt:
Starting FEN: rn2kbnr/pb2qppp/1pp5/3p4/3PPP2/2N2N2/PP4PP/R1BQKB1R w KQkq - 0 8
Move: f3h4
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 knight; h4=empty.
Squares: f3 white knight->empty; h4 empty->white knight.
Ranks: rank 3 f N->1; rank 4 h 1->N.


Prompt:
Starting FEN: 8/p1R3p1/7k/6r1/3P2pp/2KBP3/r6P/6R1 w - - 0 40
Move: c7e7
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: 40

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

Move 1: white rook c7e7.
Lookup: c7=white rook; e7=empty.
Squares: c7 white rook->empty; e7 empty->white rook.
Ranks: rank 7 c R->1; rank 7 e 1->R.
Result FEN: 8/p3R1p1/7k/6r1/3P2pp/2KBP3/r6P/6R1 b - - 1 40


Prompt:
Starting FEN: r1b2rk1/1p1nq1pp/2pbpn2/3pNp2/p1PP4/1P4P1/PBQNPPBP/R4RK1 w - - 0 1
Move: b2a3
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 2 PBQNPPBP->P1QNPPBP; rank 3 1P4P1->BP4P1.
Result FEN: r1b2rk1/1p1nq1pp/2pbpn2/3pNp2/p1PP4/BP4P1/P1QNPPBP/R4RK1 b - - 1 1


Prompt:
Starting FEN: rnbqk2r/ppp1bppp/4pn2/3p4/3P1B2/2P2N1P/PP2PPP1/RN1QKB1R w KQkq - 0 1
After the moves f4e5, 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: rnbqk2r/ppp1bppp/4pn2/3pB3/3P4/2P2N1P/PP2PPP1/RN1QKB1R b KQkq - 1 1


Prompt:
FEN: 3r3r/ppk1b3/1qp3pp/4P3/3p1P2/1P1R3P/P2Q2P1/2R3K1 b - - 0 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=g1; queen=d2; rook=c1,d3; bishop=none; knight=none; pawn=a2,g2,b3,h3,f4,e5.
Black inventory: king=c7; queen=b6; rook=d8,h8; bishop=e7; knight=none; pawn=d4,c6,g6,h6,a7,b7.


Prompt:
FEN: r1b1rk2/pp4bp/2p2np1/2n3B1/8/1Q6/PPP3PP/3R1RK1 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=1; knight=0; pawn=5.
Black counts: king=1; queen=0; rook=2; bishop=2; knight=2; pawn=5.


Prompt:
FEN: r3r2k/pppq2pp/3b4/3Bpp2/2NB4/1P1P2P1/P1P2P1P/4QRK1 b - - 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=9; rook=5; bishop=6; knight=3; pawn=7; total=30.
Black values: king=0; queen=9; rook=10; bishop=3; knight=0; pawn=7; total=29.


Prompt:
FEN: 2k5/3n3R/8/2P2pP1/1p6/P3P1P1/6K1/3N4 w - -
Trace inventory, counts, values, and material balance.

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

Inventory: white king=g2; queen=none; rook=h7; bishop=none; knight=d1; pawn=a3,e3,g3,c5,g5 | black king=c8; queen=none; rook=none; bishop=none; knight=d7; pawn=b4,f5
Counts: white king=1; queen=0; rook=1; bishop=0; knight=1; pawn=5 | black king=1; queen=0; rook=0; bishop=0; knight=1; pawn=2
Values: white total=13; black total=5
Balance: White is up 8 point(s) of material.


Prompt:
Starting FEN: rnbqkb1r/pp3ppp/4p3/3n4/3Q4/4PN2/PP3PPP/RNB1KB1R w KQkq - 0 7
After the moves b2b3 b7b5, 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: 7

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

Result FEN: rnbqkb1r/p4ppp/4p3/1p1n4/3Q4/1P2PN2/P4PPP/RNB1KB1R w KQkq - 0 8


Prompt:
Position (FEN): 8/5pk1/6p1/6Pp/4RprP/7K/8/8 w - -
Show me the board.


Prompt:
Here is the current board:
8 . . k r . b . r
7 p p q . p . p p
6 . . . p b . . .
5 . . p . . . . .
4 . . . . P R B .
3 . . P P . . Q .
2 P P . . . . P P
1 R N . . . . 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: 14

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


Prompt:
FEN: 5bk1/1p3ppp/8/p1P5/1P6/P2R2P1/2r2PKP/1r1NR3 b - -
What piece is on h7?

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: 2q2rk1/pb2bppp/np1Npn2/3p4/1P1P1B2/P4NP1/4PPBP/2Q2RK1 b - - 1 16
What is the material count for both sides?

White (14 pieces): 2 bishops, 1 king, 2 knights, 7 pawns, 1 queen, 1 rook. Black (14 pieces): 2 bishops, 1 king, 2 knights, 7 pawns, 1 queen, 1 rook. Material is equal.


Prompt:
FEN: 8/8/R2R4/1k6/8/4K3/8/8 b - -
What is on e3?

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


Prompt:
FEN: 1n6/2Q2ppk/2p5/p1Pp4/3P4/5NPn/PP2q2P/R1B4K b - -
What is the compressed FEN row for rank 8?

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