# Development Session Summary - November 7, 2025

## Session Overview

This session focused on implementing user confirmation for destructive operations in the
MCP server using native MCP elicitation support, followed by extensive testing via MCP
Inspector which uncovered and fixed several critical bugs.

## Major Changes

### 1. User Confirmation Implementation (PR #81)

**Feature**: Implemented native MCP elicitation for user confirmation on destructive
operations

**Files Changed**:

- `stocktrim_mcp_server/src/stocktrim_mcp_server/tools/foundation/purchase_orders.py`
- `stocktrim_mcp_server/tests/test_tools/test_foundation/test_purchase_orders.py`

**Details**:

- Added `@elicit_user_confirmation` decorator to wrap destructive tool operations
- Implemented for `purchase_orders_delete` and `purchase_orders_upsert_from_forecast`
  tools
- Uses MCP Protocol 2025-06-18 native elicitation support
- User can Accept (`{}`), Decline (`{"declined": "reason"}`), or Cancel
  (`{"cancelled": "reason"}`)
- Comprehensive test coverage for all three response types

**Testing Notes**:

- MCP Inspector requires manually typing `{}` for yes/no approvals
- The UI shows placeholder text but doesn't pre-fill the response field
- Elicitation works correctly when user types the response

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### 2. Test Infrastructure Improvements

**Issue**: Tests were using `MagicMock()` which accepts any attribute without
validation, allowing tests to pass even when calling non-existent methods.

**Files Changed**:

- `stocktrim_mcp_server/tests/conftest.py` - Implemented autospec for all service mocks
- `stocktrim_mcp_server/tests/test_resources/test_foundation.py` - Removed fixture
  override
- `stocktrim_mcp_server/tests/test_resources/test_reports.py` - Fixed method names

**Details**:

- Used `unittest.mock.create_autospec()` to enforce interface compliance
- Autospec'd services: Products, Customers, Suppliers, Locations, Inventory,
  PurchaseOrders, SalesOrders
- Removed `mock_foundation_context` fixture that was overriding autospec with plain
  AsyncMock
- All 276 tests pass with interface enforcement

**Impact**: Future interface mismatches will be caught during testing, not at runtime

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### 3. Bug Fixes Discovered via MCP Inspector Testing

#### Bug #1: Supplier Directory Resource - Wrong Method Name

**Error**: `'SupplierService' object has no attribute 'list_suppliers'`

**Root Cause**: Resource calling `list_suppliers()` instead of `list_all()`

**Files Fixed**:

- `stocktrim_mcp_server/src/stocktrim_mcp_server/resources/reports.py:215`
- `stocktrim_mcp_server/tests/test_resources/test_reports.py` (4 occurrences)

**Why Tests Didn't Catch It**: Tests were mocking the wrong method name, and
`MagicMock()` accepted it

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#### Bug #2: Nullable Enum Validation Error

**Error**: `"None is not a valid CurrentStatusEnum"`

**Root Cause**: API returns `null` for `currentStatus` in `OrderPlanFilterCriteria` but
OpenAPI spec didn't mark it nullable

**Files Changed**:

- `scripts/regenerate_client.py` - Added `add_nullable_to_enum_fields()` function
- `stocktrim_public_api_client/generated/models/order_plan_filter_criteria.py` -
  Regenerated with nullable enum

**Details**:

- Added Step 2.6 to regeneration script to handle nullable enum fields
- Uses `allOf` + `nullable: true` pattern for enum references
- Only marked `OrderPlanFilterCriteria.currentStatus` as nullable (confirmed by real API
  behavior)
- Created Issue #83 to track OpenAPI spec fix

**Why Tests Didn't Catch It**: Runtime data validation error, not interface mismatch

______________________________________________________________________

#### Bug #3: Product Catalog - Invalid Parameter

**Error**: `ProductService.list_all() got an unexpected keyword argument 'limit'`

**Root Cause**: Resource calling `products.list_all(limit=50)` but service doesn't
accept `limit` parameter

**Files Fixed**:

- `stocktrim_mcp_server/src/stocktrim_mcp_server/resources/foundation.py:78` - Removed
  limit param, use slicing
- `stocktrim_mcp_server/tests/test_resources/test_foundation.py` - Removed mock
  override, fixed assertions

**Why Tests Didn't Catch It**: `test_foundation.py` had `mock_foundation_context`
fixture overriding autospec'd services

______________________________________________________________________

#### Bug #4: Supplier Directory - 404 Error

**Error**: `"No parsed response data for status 404"` when accessing real API

**Root Cause**: Using `/api/Suppliers` endpoint without code parameter (returns 404).
StockTrim API has inconsistent design:

- Customers/Products: `/api/Customers` and `/api/Products` return arrays
- Suppliers: `/api/Suppliers?code=X` returns single supplier, `/api/SuppliersBulk`
  returns all suppliers

**Files Fixed**:

- `stocktrim_public_api_client/helpers/suppliers.py` - Use conditional endpoint
  selection

**Details**:

```python
if isinstance(code, Unset):
    # Use bulk endpoint to get all suppliers
    response = await get_api_suppliers_bulk.asyncio_detailed(client=self._client)
else:
    # Use single supplier endpoint with code filter
    response = await get_api_suppliers.asyncio_detailed(client=self._client, code=code)
```

**Testing**: All 73 client tests pass, including all 18 supplier service tests

______________________________________________________________________

## Issues Created

- **Issue #82**: Improve test infrastructure to catch interface mismatches (Completed -
  autospec implemented)
- **Issue #83**: Fix OpenAPI spec to mark nullable enum fields (Workaround in
  regeneration script)

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## Test Results

- **Before**: 276 tests passing (but with hidden bugs)
- **After**: 276 tests passing (with autospec enforcement + 4 bugs fixed)
- **Client Tests**: 73 tests passing

______________________________________________________________________

## Key Learnings

### 1. MCP Elicitation

- MCP Protocol 2025-06-18 has native support for user confirmations
- Response types: `AcceptedElicitation` (`{}`), `DeclinedElicitation`,
  `CancelledElicitation`
- MCP Inspector requires manual typing of response JSON

### 2. Testing Patterns

- **AutoSpec is Critical**: Always use `create_autospec()` for service mocks to catch
  interface mismatches
- **Avoid Override Fixtures**: Don't create fixtures that replace autospec'd mocks with
  plain mocks
- **Test What You Ship**: Mock behavior should match production code exactly

### 3. API Inconsistencies

- StockTrim API has inconsistent endpoint design for suppliers vs other resources
- Some endpoints return single objects, others return arrays
- Some endpoints have dedicated bulk variants

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## Documentation Updates

- Created this session summary document
- CHANGELOGs will be updated with the release
- Architecture Decision Record 001 documents the user confirmation pattern

______________________________________________________________________

## Commits

1. `d5ee08d` - feat(mcp): add user confirmation via native MCP elicitation
1. `d87b49c` - fix: supplier directory resource method name (list_suppliers → list_all)
1. `934d7bb` - test: implement autospec for service mocks to catch interface bugs
1. `9b2cdd1` - fix: add nullable support for enum fields in OpenAPI spec
1. `1e5a546` - fix: remove limit parameter from ProductService.list_all() calls
1. `44e4d26` - fix: use bulk endpoint for listing all suppliers

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## Follow-up Items

1. Monitor Issue #83 for upstream OpenAPI spec fix
1. Consider adding integration tests that run against real API endpoints
1. Review other helper methods for similar endpoint inconsistencies
1. Document the elicitation pattern for future tool implementations

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## Session Statistics

- **Duration**: ~4 hours
- **Files Modified**: 15
- **Tests Added/Fixed**: 10+
- **Bugs Found**: 4
- **Bugs Fixed**: 4
- **Issues Created**: 2
