# Architecture Audit: Design Pattern Compliance
**Date:** 2025-11-17
**Auditor:** Claude Code
**Scope:** Complete codebase review for architectural consistency
**Status:** ✅ Generally healthy with 2 minor optimization opportunities
---
## Architecture Overview
### Established Pattern
The codebase follows a clear three-layer architecture:
```
┌─────────────────────────────────────────────────────┐
│ Layer 1: MCP Server (server.py) │
│ - Thin wrappers around business logic │
│ - Formatting for human-readable output │
│ - Error handling and logging │
│ - Parameter transformation (optional) │
└─────────────────────────────────────────────────────┘
↓
┌─────────────────────────────────────────────────────┐
│ Layer 2: Business Logic (tools/*.py) │
│ - Core functionality │
│ - Returns structured data (dicts, objects) │
│ - Fully testable │
│ - No presentation concerns │
└─────────────────────────────────────────────────────┘
↓
┌─────────────────────────────────────────────────────┐
│ Layer 3: Workflow Orchestration (prompts/*.py) │
│ - Compose multiple tools │
│ - Guide users through sequential stages │
│ - Provide context and next steps │
│ - Handle auto-selection and defaults │
└─────────────────────────────────────────────────────┘
```
---
## Audit Results
### ✅ Compliant Components
**Session Management Tools (12 MCP tools)**
| MCP Tool | Business Logic | Pattern | Notes |
|----------|---------------|---------|-------|
| `create_session` | `session_tools.create_session()` | ✅ Thin wrapper | Delegates to tool, formats output |
| `load_session` | `session_tools.load_session()` | ✅ Thin wrapper | Minor formatting logic acceptable |
| `update_session_state` | `session_tools.update_session_state()` | ✅ Thin wrapper | Parameter transformation is acceptable |
| `list_example_projects` | `session_tools.list_example_projects()` | ✅ Thin wrapper | **FIXED** - Previously violated pattern |
| `delete_session` | `session_tools.delete_session()` | ✅ Thin wrapper | Perfect delegation |
**Document Processing Tools**
| MCP Tool | Business Logic | Pattern | Notes |
|----------|---------------|---------|-------|
| `discover_documents` | `document_tools.discover_documents()` | ✅ Thin wrapper | Clean delegation |
| `extract_pdf_text` | `document_tools.extract_pdf_text()` | ✅ Thin wrapper | Proper formatting layer |
| `extract_gis_metadata` | `document_tools.extract_gis_metadata()` | ✅ Thin wrapper | Clean delegation |
**Evidence Extraction Tools**
| MCP Tool | Business Logic | Pattern | Notes |
|----------|---------------|---------|-------|
| `extract_evidence` | `evidence_tools.extract_all_evidence()` | ✅ Thin wrapper | Clean delegation |
| `map_requirement` | `evidence_tools.map_requirement()` | ✅ Thin wrapper | Emoji formatting acceptable |
**Workflow Orchestration**
| MCP Tool | Business Logic | Pattern | Notes |
|----------|---------------|---------|-------|
| `start_review` | Composes `session_tools` + `document_tools` | ✅ Legitimate orchestration | Combines multiple tool calls - this is acceptable for convenience functions |
---
## ⚠️ Optimization Opportunities
### 1. `list_sessions` - Excessive Formatting Logic
**Location:** `server.py:194-263` (70 lines)
**Current Implementation:**
```python
@mcp.tool()
async def list_sessions() -> str:
sessions = await session_tools.list_sessions()
# 60+ lines of formatting logic here
session_list = []
for idx, session in enumerate(sessions, 1):
session_id = session.get('session_id', 'Unknown')
project_name = session.get('project_name', 'Unknown')
# ... extensive field extraction and formatting
```
**Analysis:**
- Business logic (`list_sessions()`) properly delegated ✅
- BUT: 60+ lines of presentation logic in the wrapper layer
- This is technically formatting, but it's quite complex
- Not tested (and shouldn't be - it's pure formatting)
**Recommendation:** **ACCEPT AS-IS**
- This is presentation logic, not business logic
- Moving it to tools layer would pollute business logic with formatting concerns
- The complexity comes from rich output formatting for user experience
- **Decision:** Keep it, but acknowledge it's at the edge of "thin wrapper"
**Alternative (if this becomes a maintenance burden):**
```python
# Could create a presentation/formatters.py module
from ..presentation import session_formatter
@mcp.tool()
async def list_sessions() -> str:
sessions = await session_tools.list_sessions()
return session_formatter.format_session_list(sessions)
```
---
### 2. `update_session_state` - Parameter Transformation Logic
**Location:** `server.py:149-191`
**Current Implementation:**
```python
@mcp.tool()
async def update_session_state(
session_id: str,
status: str | None = None,
workflow_stage: str | None = None,
workflow_status: str | None = None,
) -> str:
updates: dict = {}
if status:
updates["status"] = status
if workflow_stage and workflow_status:
updates[f"workflow_progress.{workflow_stage}"] = workflow_status
result = await session_tools.update_session_state(session_id, updates)
```
**Analysis:**
- Takes 4 parameters and transforms them into a dict
- This is parameter marshaling, which is acceptable in the wrapper layer
- The business logic properly lives in `session_tools.update_session_state()`
**Recommendation:** **ACCEPT AS-IS**
- This is idiomatic parameter transformation
- Makes the MCP API cleaner (4 optional params vs 1 complex dict)
- Very small amount of logic (just building a dict)
**Alternative (if you want absolute purity):**
Move this convenience wrapper signature to tools layer:
```python
# In session_tools.py
async def update_session_simple(
session_id: str,
status: str | None = None,
workflow_stage: str | None = None,
workflow_status: str | None = None,
) -> dict[str, Any]:
updates: dict = {}
if status:
updates["status"] = status
if workflow_stage and workflow_status:
updates[f"workflow_progress.{workflow_stage}"] = workflow_status
return await update_session_state(session_id, updates)
# In server.py
result = await session_tools.update_session_simple(
session_id, status, workflow_stage, workflow_status
)
```
But this feels like over-engineering for minimal benefit.
---
## ✅ Notable Strengths
### 1. Validation and Reporting Not Exposed as Direct Tools
**Discovery:** `validation_tools` and `report_tools` are imported in `server.py` but **not exposed as direct MCP tools**.
**Why this is excellent:**
- These are **composed by prompts** (`D_cross_validation.py`, `E_report_generation.py`)
- Follows MCP Server Primitives hierarchy: Tools → Prompts
- Prompts provide guided workflows, not just individual operations
- Users get better UX through workflow guidance
**Files checked:**
```
✓ D_cross_validation.py - Uses validation_tools internally
✓ E_report_generation.py - Uses report_tools internally
```
This demonstrates mature understanding of MCP architecture.
---
### 2. Workflow Orchestration is Intentional
**Tool:** `start_review`
**Purpose:** Quick-start convenience combining:
1. `session_tools.create_session()`
2. `document_tools.discover_documents()`
**Analysis:**
- This is **legitimate orchestration**, not a violation
- Documented as "convenience tool that combines..."
- Tested in `test_user_experience.py`
- Reduces user friction for common workflow
**Verdict:** ✅ This is the right abstraction
---
## 📊 Test Coverage Analysis
### Layer Coverage
| Layer | Test Files | Coverage Quality |
|-------|------------|------------------|
| **Business Logic** | 19 test files, 186 tests | ✅ Excellent - all core logic tested |
| **MCP Wrappers** | 1 test file (`test_user_experience.py`) | ✅ Appropriate - only UX paths tested |
| **Prompts** | Limited (workflow integration tests) | ⚠️ Could be expanded |
### Why This Distribution is Correct
**Business logic is heavily tested** ✅
- `test_infrastructure.py` - 23 tests
- `test_document_processing.py` - 6 tests
- `test_evidence_extraction.py` - 6 tests
- `test_validation.py` - 19 tests
- `test_llm_extraction.py` - 32 tests
- Plus 100+ more integration tests
**MCP wrappers are lightly tested** ✅
- Only UX flows tested (auto-selection, error messages)
- Formatting logic not tested (and shouldn't be)
- This is correct - wrappers delegate to tested business logic
**Recent fix demonstrates pattern working:**
- `list_example_projects` bug found when logic was in wrapper
- Moved to `session_tools.py` and added tests
- Now follows pattern: business logic = tested, wrapper = thin
---
## 🎯 Violations Found
### Summary
**Total Violations:** 0 (zero)
**Previous Violation (Now Fixed):**
- ✅ `list_example_projects` - Fixed on 2025-11-17
- **Before:** Business logic in `server.py` (untested, import error)
- **After:** Logic in `session_tools.py` (tested), wrapper in `server.py`
- **Tests Added:** 2 (happy path + edge case)
---
## 📋 Recommendations
### 1. Keep Current Architecture ✅
**Verdict:** No changes needed
**Reasoning:**
- Pattern is clear and consistently applied
- Test coverage matches architecture (business logic heavily tested)
- Two "heavy" wrappers (`list_sessions`, `update_session_state`) are acceptable
- Prompts properly compose tools for workflows
### 2. Optional: Document Formatting Philosophy
If the `list_sessions` 60-line formatter ever becomes contentious, document it:
```python
# In server.py or a new docs/ARCHITECTURE.md
"""
MCP Wrapper Guidelines:
1. Thin Wrapper (Preferred)
- Delegate to tool function
- Format structured data for display
- Handle errors, log operations
2. Parameter Transformation (Acceptable)
- Convert user-friendly params to internal format
- Example: update_session_state() builds dict from optional params
3. Complex Formatting (Acceptable with Limits)
- Rich output formatting for user experience
- Example: list_sessions() formats detailed session summaries
- Limit: Keep under ~100 lines, no business logic
4. Orchestration (Acceptable for Convenience)
- Combine multiple tool calls for common workflows
- Example: start_review() creates session + discovers documents
- Must be documented as convenience function
"""
```
### 3. Consider Presentation Layer (Future)
**Only if complexity grows** - not needed now:
```
src/registry_review_mcp/
├── tools/ # Business logic
├── presentation/ # Formatters (if needed)
│ ├── session_formatter.py
│ └── evidence_formatter.py
├── prompts/ # Workflows
└── server.py # MCP wrappers
```
**When to do this:**
- Multiple tools have 100+ line formatters
- Formatting logic needs to be reused
- Team wants to test formatting separately
**For now:** Not needed. Current approach is clean.
---
## 🔍 Audit Methodology
### Files Analyzed
**Core Architecture:**
- ✅ `src/registry_review_mcp/server.py` (834 lines, 12 MCP tools)
- ✅ `src/registry_review_mcp/tools/session_tools.py` (6 functions)
- ✅ `src/registry_review_mcp/tools/document_tools.py` (6 functions)
- ✅ `src/registry_review_mcp/tools/evidence_tools.py` (6 functions)
- ✅ `src/registry_review_mcp/tools/validation_tools.py` (8 functions)
- ✅ `src/registry_review_mcp/tools/report_tools.py` (5 functions)
**Workflow Layer:**
- ✅ `src/registry_review_mcp/prompts/A_initialize.py`
- ✅ `src/registry_review_mcp/prompts/B_document_discovery.py`
- ✅ `src/registry_review_mcp/prompts/C_evidence_extraction.py`
- ✅ `src/registry_review_mcp/prompts/D_cross_validation.py`
- ✅ `src/registry_review_mcp/prompts/E_report_generation.py`
- ✅ `src/registry_review_mcp/prompts/F_human_review.py`
- ✅ `src/registry_review_mcp/prompts/G_complete.py`
**Tests:**
- ✅ All 19 test files (186 tests total, 101 in infrastructure layer)
### Checks Performed
1. ✅ Each MCP tool delegates to corresponding business logic function
2. ✅ Business logic functions exist in tools/ modules
3. ✅ Business logic is tested
4. ✅ No business logic in server.py (except formatting/orchestration)
5. ✅ Prompts compose tools appropriately
6. ✅ Import structure follows layering
---
## Conclusion
### Overall Assessment: ✅ **HEALTHY**
**The codebase demonstrates:**
- Clear architectural vision
- Consistent application of patterns
- Appropriate test coverage strategy
- Mature understanding of MCP primitives (Tools → Prompts)
**The two "heavy" wrappers are:**
- Acceptable given their purpose (UX formatting and parameter convenience)
- Not violations of the pattern
- Would only need refactoring if complexity significantly increases
**The recent `list_example_projects` fix shows:**
- The pattern is understood and valued
- Violations are caught and corrected
- Test coverage is added when logic moves to tools layer
### No Action Required
Continue current practices. The architecture is sound.
---
**Audit Complete:** 2025-11-17
**Next Review:** When adding significant new functionality or if wrapper complexity grows
**Sign-off:** Pattern compliance verified ✅
