jarca-ledger-mcp/docs/batches/bat-014_20260703_adapter-surface-narrowing-baseline-refresh/implementation.md

BAT-014 Implementation

Plan summary

BAT-014 implements dcy-011 Phase 7 by narrowing the remaining adapter surfaces without changing public MCP tool names or dashboard behavior. The MCP server now depends on adapters/mcp/tool_contracts.py instead of a broad direct service import, and the Streamlit dashboard now calls page/domain gateways under adapters/streamlit/*_gateway.py rather than a flat broad service_gateway namespace. service_gateway.py remains as a compatibility aggregator.

Delivered changes

1. Added jarca_ledger_mcp/adapters/mcp/tool_contracts.py as the MCP adapter contract surface and repointed adapters/mcp/server.py wrappers to contracts.* callables.
2. Added page/domain Streamlit gateways:
   • overview_gateway.py
   • assets_gateway.py
   • transactions_gateway.py
   • categorization_gateway.py
   • transfers_gateway.py
   • imports_gateway.py
   • accounts_gateway.py
   • reconciliation_gateway.py
3. Reworked adapters/streamlit/service_gateway.py into a compatibility aggregator over the new gateway modules.
4. Repointed dashboard/app.py static call sites away from service.* to the owning page/domain gateway modules.
5. Preserved hot-reload fallback by changing get_service_callable() to reload the passed gateway module rather than a broad flat service namespace.
6. Refreshed docs/project-structure.md and docs/runtime-flows.md so the baseline reflects post-Phase-7 ownership and adapter seams.

Compatibility notes

• MCP tool names, argument shapes, and response contracts were intentionally preserved.
• adapters/streamlit/service_gateway.py still exists as a compatibility surface for any legacy dashboard-side imports.
• No SQL/UI business-rule ownership was moved into the dashboard; the app still goes through adapter gateways.

Files changed

• jarca_ledger_mcp/adapters/mcp/tool_contracts.py
• jarca_ledger_mcp/adapters/mcp/server.py
• jarca_ledger_mcp/adapters/streamlit/__init__.py
• jarca_ledger_mcp/adapters/streamlit/service_gateway.py
• jarca_ledger_mcp/adapters/streamlit/*_gateway.py
• dashboard/app.py
• docs/project-structure.md
• docs/runtime-flows.md

Outcome

The repository now has explicit MCP contract and Streamlit page/domain gateway seams, satisfying the final dcy-011 narrowing target while preserving all public compatibility surfaces.