Serena Code Architecture

Architectural Analysis with Serena + Forgetful

This skill guides systematic architectural analysis using Serena's symbol-level understanding, with optional persistence to Forgetful's knowledge graph.

When to Use This Skill

• Analyzing a new codebase before implementing changes
• Documenting existing architecture for a project
• Creating component entities and relationships in Forgetful
• Understanding dependencies and call hierarchies
• Building a knowledge graph from code structure

Analysis Workflow

Phase 1: Project Structure Discovery

Understand the high-level layout:

# Get directory structure
mcp__plugin_serena_serena__list_dir({
  "relative_path": ".",
  "recursive": false
})

# Identify key directories (src/, app/, lib/, etc.)
mcp__plugin_serena_serena__list_dir({
  "relative_path": "src",
  "recursive": true
})

Goal: Identify entry points, main modules, and organizational patterns.

Phase 2: Entry Point Analysis

Find the application entry points:

# Look for main/app files
mcp__plugin_serena_serena__search_for_pattern({
  "substring_pattern": "if __name__.*==.*__main__|def main\\(|app\\s*=\\s*FastAPI|createApp",
  "restrict_search_to_code_files": true
})

# Get symbols from entry file
mcp__plugin_serena_serena__get_symbols_overview({
  "relative_path": "src/main.py",
  "depth": 1
})

Phase 3: Core Component Mapping

Identify and analyze major components:

# Find all service/controller/model classes
mcp__plugin_serena_serena__find_symbol({
  "name_path_pattern": "Service",
  "substring_matching": true,
  "include_kinds": [5],  # Class only
  "depth": 1
})

# For each major component, get full structure
mcp__plugin_serena_serena__find_symbol({
  "name_path_pattern": "AuthService",
  "include_body": false,
  "depth": 1  # Get methods
})

Phase 4: Dependency Tracing

Understand how components connect:

# Find who uses AuthService
mcp__plugin_serena_serena__find_referencing_symbols({
  "name_path": "AuthService",
  "relative_path": "src/services/auth.py"
})

# Find what AuthService depends on
mcp__plugin_serena_serena__find_symbol({
  "name_path_pattern": "AuthService/__init__",
  "include_body": true
})

Phase 5: Create Architectural Memories (Optional)

Store findings in Forgetful:

# First, find/create the project
execute_forgetful_tool("list_projects", {"repo_name": "owner/repo"})

# Create memory for architectural insight
execute_forgetful_tool("create_memory", {
  "title": "AuthService: Core authentication component",
  "content": "AuthService handles JWT validation, user sessions, and OAuth flows. Dependencies: UserRepository, TokenService, CacheService. Used by: all API endpoints via middleware.",
  "context": "Discovered during architectural analysis",
  "keywords": ["auth", "jwt", "service", "architecture"],
  "tags": ["architecture", "component"],
  "importance": 8,
  "project_ids": [PROJECT_ID]
})

Phase 6: Entity Graph Creation (Optional)

Create entities for major components:

# Check if entity exists first
execute_forgetful_tool("search_entities", {"query": "AuthService"})

# Create component entity
execute_forgetful_tool("create_entity", {
  "name": "AuthService",
  "entity_type": "other",
  "custom_type": "Service",
  "notes": "Core authentication service - JWT, OAuth, sessions",
  "tags": ["service", "auth"],
  "project_ids": [PROJECT_ID]
})

# Create relationships
execute_forgetful_tool("create_entity_relationship", {
  "source_entity_id": AUTH_SERVICE_ID,
  "target_entity_id": USER_REPO_ID,
  "relationship_type": "depends_on",
  "strength": 0.9
})

# Link entity to memories
execute_forgetful_tool("link_entity_to_memory", {
  "entity_id": AUTH_SERVICE_ID,
  "memory_id": ARCH_MEMORY_ID
})

Relationship Types

Standard relationship types for architecture:

Entity Types for Architecture

Example: FastAPI Project Analysis

# 1. Find routers
mcp__plugin_serena_serena__search_for_pattern({
  "substring_pattern": "APIRouter\\(\\)|router\\s*=",
  "restrict_search_to_code_files": true
})

# 2. Analyze router structure
mcp__plugin_serena_serena__get_symbols_overview({
  "relative_path": "src/routers/users.py",
  "depth": 1
})

# 3. Find dependency injection
mcp__plugin_serena_serena__search_for_pattern({
  "substring_pattern": "Depends\\(",
  "restrict_search_to_code_files": true,
  "context_lines_before": 1,
  "context_lines_after": 1
})

# 4. Trace service dependencies
mcp__plugin_serena_serena__find_referencing_symbols({
  "name_path": "get_current_user",
  "relative_path": "src/dependencies/auth.py"
})

# 5. Create architecture memory
execute_forgetful_tool("create_memory", {
  "title": "FastAPI app structure: Routers + Dependencies",
  "content": "App uses router-based organization with dependency injection. Routers: /users, /auth, /products. Dependencies: get_current_user, get_db. All routes require auth except /auth/login.",
  "context": "FastAPI architecture analysis",
  "keywords": ["fastapi", "router", "dependency-injection"],
  "tags": ["architecture", "pattern"],
  "importance": 8,
  "project_ids": [PROJECT_ID]
})

Analysis Checklist

• Directory structure mapped
• Entry points identified
• Major components catalogued
• Dependencies traced
• External connections documented
• Key patterns identified
• Memories created for insights
• Entities created for components (if applicable)
• Relationships mapped (if applicable)

Tips

1. Work incrementally - Don't try to analyze everything at once
2. Focus on interfaces - Public methods/APIs matter more than internals
3. Document decisions - Create memories for WHY, not just WHAT
4. Use entities sparingly - Only major components, not every class
5. Link across projects - Architecture patterns often apply elsewhere