Add reminders to update ARCHITECTURE.md when making changes

Add prominent reminders in both CLAUDE.md and AGENTS.md to update
the shared ARCHITECTURE.md file when making architectural changes.
This helps ensure the documentation stays current and both AI tools
have accurate context.

Changes include:
- Added step in development workflow to update docs
- Added "Important: Keep Documentation Updated" section
- Listed specific types of changes that require doc updates
- Emphasized that this keeps both tools in sync

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

AGENTS.md

@@ -85,7 +85,20 @@ When analyzing code, refer to [ARCHITECTURE.md](./ARCHITECTURE.md) for:
 2. **Use** existing service patterns and interfaces
 3. **Follow** Single Responsibility Principle
 4. **Test** with mockable interfaces
-5. **Update** documentation when adding major features
+5. **Update [ARCHITECTURE.md](./ARCHITECTURE.md) when making architectural changes**
+
+## Important: Keep Documentation Updated
+
+**When making architectural changes, always update [ARCHITECTURE.md](./ARCHITECTURE.md):**
+- Adding/removing domain models (Account, Transaction, Receipt, etc.)
+- Adding/removing services or changing their responsibilities
+- Modifying database schema, relationships, or constraints
+- Adding new workflows or processes
+- Changing design patterns or conventions
+- Adding new pages or major features
+- Modifying security or performance considerations
+
+This shared documentation ensures both Claude Code and Codex CLI have accurate context for future work.
 
 ## Reference Links
 

CLAUDE.md

@@ -95,7 +95,20 @@ dotnet ef database update
 2. Make changes to models, services, or pages
 3. Test locally
 4. Create database migration if schema changed
-5. Commit with descriptive message
+5. **Update [ARCHITECTURE.md](./ARCHITECTURE.md) if architecture changes** (new models, services, workflows, etc.)
+6. Commit with descriptive message
+
+## Important: Keep Documentation Updated
+
+**When making architectural changes, always update [ARCHITECTURE.md](./ARCHITECTURE.md):**
+- Adding/removing domain models
+- Adding/removing services or changing their responsibilities
+- Modifying database schema or relationships
+- Adding new workflows or processes
+- Changing design patterns or conventions
+- Adding new pages or major features
+
+This ensures both Claude Code and Codex CLI have accurate, up-to-date context.
 
 ## Configuration