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Use when a chess analysis session hits a gap in chess-support-mcp (missing legal-move list, no pins, no undo, etc.) and you're tempted to plug it. Catalogues known gaps, their priority, and the constraint that keeps this workspace engine-free.
Codex 또는 Claude로 설치 이 Prompt를 복사해 Codex, Claude 또는 다른 어시스턴트에 붙여 넣으면 Skill 페이지를 검토하고 설치를 진행할 수 있습니다.
SOC 직업 분류 기준
Use when reasoning about a chess position to advise a player, after the position has been set up via chess_ MCP tools. Covers the discipline that prevents legality hallucinations (off-diagonal moves, pin blindness, miscounted material).
Use when setting up the MCP game state from a SAN PGN, before analyzing a position. Covers the SAN→UCI conversion discipline and the "one illegal move cascades" gotcha that can waste a session's worth of tokens.
| name | improving-the-fact-server |
| description | Use when a chess analysis session hits a gap in chess-support-mcp (missing legal-move list, no pins, no undo, etc.) and you're tempted to plug it. Catalogues known gaps, their priority, and the constraint that keeps this workspace engine-free. |
chess-support-mcp is the fact server. This skill is the standing list of gaps between what the research brief (/tmp/research-chess-reasoning-aids-answer.md) said we need and what the MCP actually exposes. It exists so that a future session can quickly see what's been considered, what's been decided, and what would be worth actually implementing.
We run a fork (github.com/johnnymo87/chess-support-mcp, branch enriched-status) that closes gaps 1, 2, and 4. opencode.json already points at it. Open gaps are 3 (SAN input) and 5 (undo/simulate).
No engine. No Stockfish, no Leela, no evaluation, no "best move" tool. That's the point of the whole workspace. Anything added must be a mechanical derivation from python-chess (or equivalent) — a fact, not a judgment. If a proposed improvement would give the LLM a move recommendation, reject it.
See ../../AGENTS.md and the research answer for the philosophical reasoning. It's not arbitrary.
Ranked roughly by leverage (how much each would have helped real sessions). Verify the current state of the upstream tool before acting — the toolset listed in ../../AGENTS.md is what we actually have.
list_legal_moves_detailed tool now returns [{uci, san}, ...] sorted by UCI. Shipped on the fork branch enriched-status of johnnymo87/chess-support-mcp; opencode.json points there.
Design rationale: docs/plans/2026-04-19-enriched-status-design.md §"New tool: list_legal_moves_detailed".
get_status now returns absolute_pins and checkers. New tool get_attackers_to(square) exposes the static attack map. Same fork branch.
Caveats baked into the design:
absolute_pins is absolute-only (pinned-to-king). Relative pins (through queen/rook) are out of scope; would be a separate field if ever wanted.get_attackers_to is the static attack map: pinned pieces still count as attackers, and x-ray through the king is not modeled. The tool's docstring makes this explicit; don't use it as a legality oracle.Design rationale: same design doc, §"Surface changes".
What's missing: add_move takes UCI only; a PGN or SAN move list must be hand-converted by the LLM.
Why it matters: See replaying-a-pgn — SAN→UCI conversion is tedious and error-prone, and a single mistake cascades badly. python-chess's board.parse_san("Nxe4") would eliminate this.
What we want: Either make add_move accept SAN, or add a sibling add_move_san, or a load_pgn(pgn_string) that replays the whole game server-side.
Status: Not implemented. load_pgn is probably the highest-leverage version — one tool call instead of 40. Would be the obvious next PR to the fork.
get_status now includes material (per-color piece counts, kings excluded, uncapped for promotions) and material_diff (per-piece white[k] - black[k]). Same fork branch.
What's missing: Any way to play a move and then unplay it. The only way to explore a line is add_move, then create_or_reset_game + replay everything to back out.
Why it matters: When analyzing tactical lines, the LLM wants to see "what does the board look like after Nxa5 Rxb5 Kxa2?" Right now you either reason about it in your head (risk of errors) or destroy your position to check.
What we want options:
undo_last_move — simple, adds some state complexity.peek(uci_sequence) — applies the moves, returns the resulting status, restores original state. No mutation visible to caller.Status: Not in upstream. peek is the cleanest API but requires thinking about state isolation. undo_last_move is easier and covers 80% of the use case.
board_ascii is bare — LOW LEVERAGEWhat's missing: No file/rank coordinate labels, no Unicode pieces, White's perspective only.
Why it matters: Minor readability win for humans and possibly for the LLM's spatial reasoning. The research answer is lukewarm on Unicode vs. ASCII.
What we want: Optional coords: true parameter. Optional flip: true for Black's perspective. Optional Unicode mode.
Status: Not in upstream. Cosmetic — defer.
Work on the fork: github.com/johnnymo87/chess-support-mcp, branch enriched-status. Local checkout at /home/dev/projects/chess-support-mcp. opencode.json already points there.
TDD is the expected workflow (see the existing commits on the branch for style). Each new field or tool:
tests/test_chess_support_mcp.py).src/chess_support_mcp/server.py that makes it pass.uv run pytest -q — full suite should stay green.enriched-status branch.Restart OpenCode to pick up the new server binary (or run uvx --refresh --from 'git+...@enriched-status' chess-support-mcp --help to warm the cache first).
Keep the engine constraint hard. Specifically don't add:
best_move / evaluate / get_score / anything returning a numeric evaluation.threatened_squares framed as "which squares should I be worried about" — that's evaluation, not derivation. (attackers_to_square is fine — pure geometry.)These all turn the MCP into a second intelligence in the loop, which is exactly what the research rejected.
Add entries here when the human or a session makes a decision about any of the above. Format: date, decision, reasoning.
docs/plans/2026-04-19-fact-server-gaps.md. Next session should read that plan before implementing anything.docs/plans/2026-04-19-enriched-status-design.md, 13-task plan at docs/plans/2026-04-19-enriched-status-plan.md. Fork github.com/johnnymo87/chess-support-mcp branch enriched-status; 7 commits atop upstream f75662d. End-to-end validation against the motivating PGN passed all 9 assertions (absolute pin of Nd2 by Bh6 detected correctly, material diff, legal-moves enumeration). Decided to stay on the fork indefinitely rather than PR upstream — the fork is our runtime and nothing forces the decision. Gaps 3 (SAN input / load_pgn) and 5 (undo/simulate) remain open and are the obvious next candidates.