Add one_d4 analysis tools to mcpserver (MCP integration)

[aaylward]

Context

Follow-up to #1028. With one_d4 deployed on the consolidated stack, mcpserver can proxy to it over the Docker network to expose chess indexing and querying to LLM agents.

Approach: HTTP Proxy (Option B)

mcpserver tools call one_d4's REST API over the Docker network (http://one_d4:8080). This keeps mcpserver lightweight with no DB dependencies, maintains a clean service boundary, and allows independent scaling.

New MCP Tools

index_chess_games

• Delegates to POST http://one_d4:8080/index
• Input: username, platform, start_month, end_month
• Returns request ID + status for polling

index_status

• Delegates to GET http://one_d4:8080/index/{id}
• Input: request_id
• Returns status, game count, error message

query_chess_games

• Delegates to POST http://one_d4:8080/query
• Input: query (ChessQL string), limit
• Rich description including ChessQL syntax reference so LLMs can construct queries
• Available motifs: pin, cross_pin, fork, skewer, discovered_attack
• Available fields: white.elo, black.elo, white.username, black.username, time.class, eco, result, num.moves

analyze_position (deferred)

• Requires new endpoint in one_d4 first (not yet implemented)

Implementation Steps

1. Create IndexerHttpClient.java in mcpserver tools — uses existing //domains/platform/libs/http_client, base URL from INDEXER_BASE_URL env var (default http://one_d4:8080)
2. Create IndexGamesTool.java, IndexStatusTool.java, QueryGamesTool.java implementing McpTool
3. Wire in McpModule.java — add IndexerHttpClient bean, register 3 new tools
4. Update BUILD.bazel — add source files and http_client dep
5. Add INDEXER_BASE_URL env var to mcpserver compose service
6. Unit tests for each tool

Example Agent Flow

User: "Index hikaru's games from March 2024 and find forks"

Agent → index_chess_games(username="hikaru", platform="chess.com", start_month="2024-03", end_month="2024-03")
  → mcpserver → POST one_d4:8080/index → {"id":"abc-123","status":"PENDING"}

Agent → index_status(request_id="abc-123")
  → mcpserver → GET one_d4:8080/index/abc-123 → {"status":"COMPLETED","gamesIndexed":147}

Agent → query_chess_games(query="white.username=\"hikaru\" AND motif(fork)", limit=10)
  → mcpserver → POST one_d4:8080/query → {"games":[...],"count":7}

References

• Design doc: domains/games/apis/one_d4/src/main/java/com/muchq/games/one_d4/docs/MCP_INTEGRATION.md
• mcpserver tool pattern: domains/games/apis/mcpserver/src/main/java/com/muchq/games/mcpserver/tools/