diff --git a/README.chatmodes.md b/README.chatmodes.md
index 9529116..5a8381f 100644
--- a/README.chatmodes.md
+++ b/README.chatmodes.md
@@ -38,6 +38,7 @@ Custom chat modes define specific behaviors and tools for GitHub Copilot Chat, e
| [Declarative Agents Architect](chatmodes/declarative-agents-architect.chatmode.md)
[](https://aka.ms/awesome-copilot/install/chatmode?url=vscode%3Achat-mode%2Finstall%3Furl%3Dhttps%3A%2F%2Fraw.githubusercontent.com%2Fgithub%2Fawesome-copilot%2Fmain%2Fchatmodes%2Fdeclarative-agents-architect.chatmode.md)
[](https://aka.ms/awesome-copilot/install/chatmode?url=vscode-insiders%3Achat-mode%2Finstall%3Furl%3Dhttps%3A%2F%2Fraw.githubusercontent.com%2Fgithub%2Fawesome-copilot%2Fmain%2Fchatmodes%2Fdeclarative-agents-architect.chatmode.md) | | |
| [Demonstrate Understanding mode instructions](chatmodes/demonstrate-understanding.chatmode.md)
[](https://aka.ms/awesome-copilot/install/chatmode?url=vscode%3Achat-mode%2Finstall%3Furl%3Dhttps%3A%2F%2Fraw.githubusercontent.com%2Fgithub%2Fawesome-copilot%2Fmain%2Fchatmodes%2Fdemonstrate-understanding.chatmode.md)
[](https://aka.ms/awesome-copilot/install/chatmode?url=vscode-insiders%3Achat-mode%2Finstall%3Furl%3Dhttps%3A%2F%2Fraw.githubusercontent.com%2Fgithub%2Fawesome-copilot%2Fmain%2Fchatmodes%2Fdemonstrate-understanding.chatmode.md) | Validate user understanding of code, design patterns, and implementation details through guided questioning. |
| [Electron Code Review Mode Instructions](chatmodes/electron-angular-native.chatmode.md)
[](https://aka.ms/awesome-copilot/install/chatmode?url=vscode%3Achat-mode%2Finstall%3Furl%3Dhttps%3A%2F%2Fraw.githubusercontent.com%2Fgithub%2Fawesome-copilot%2Fmain%2Fchatmodes%2Felectron-angular-native.chatmode.md)
[](https://aka.ms/awesome-copilot/install/chatmode?url=vscode-insiders%3Achat-mode%2Finstall%3Furl%3Dhttps%3A%2F%2Fraw.githubusercontent.com%2Fgithub%2Fawesome-copilot%2Fmain%2Fchatmodes%2Felectron-angular-native.chatmode.md) | Code Review Mode tailored for Electron app with Node.js backend (main), Angular frontend (render), and native integration layer (e.g., AppleScript, shell, or native tooling). Services in other repos are not reviewed here. |
+| [Expert C++ software engineer mode instructions](chatmodes/expert-cpp-software-engineer.chatmode.md)
[](https://aka.ms/awesome-copilot/install/chatmode?url=vscode%3Achat-mode%2Finstall%3Furl%3Dhttps%3A%2F%2Fraw.githubusercontent.com%2Fgithub%2Fawesome-copilot%2Fmain%2Fchatmodes%2Fexpert-cpp-software-engineer.chatmode.md)
[](https://aka.ms/awesome-copilot/install/chatmode?url=vscode-insiders%3Achat-mode%2Finstall%3Furl%3Dhttps%3A%2F%2Fraw.githubusercontent.com%2Fgithub%2Fawesome-copilot%2Fmain%2Fchatmodes%2Fexpert-cpp-software-engineer.chatmode.md) | Provide expert C++ software engineering guidance using modern C++ and industry best practices. |
| [Expert .NET software engineer mode instructions](chatmodes/expert-dotnet-software-engineer.chatmode.md)
[](https://aka.ms/awesome-copilot/install/chatmode?url=vscode%3Achat-mode%2Finstall%3Furl%3Dhttps%3A%2F%2Fraw.githubusercontent.com%2Fgithub%2Fawesome-copilot%2Fmain%2Fchatmodes%2Fexpert-dotnet-software-engineer.chatmode.md)
[](https://aka.ms/awesome-copilot/install/chatmode?url=vscode-insiders%3Achat-mode%2Finstall%3Furl%3Dhttps%3A%2F%2Fraw.githubusercontent.com%2Fgithub%2Fawesome-copilot%2Fmain%2Fchatmodes%2Fexpert-dotnet-software-engineer.chatmode.md) | Provide expert .NET software engineering guidance using modern software design patterns. |
| [Expert React Frontend Engineer Mode Instructions](chatmodes/expert-react-frontend-engineer.chatmode.md)
[](https://aka.ms/awesome-copilot/install/chatmode?url=vscode%3Achat-mode%2Finstall%3Furl%3Dhttps%3A%2F%2Fraw.githubusercontent.com%2Fgithub%2Fawesome-copilot%2Fmain%2Fchatmodes%2Fexpert-react-frontend-engineer.chatmode.md)
[](https://aka.ms/awesome-copilot/install/chatmode?url=vscode-insiders%3Achat-mode%2Finstall%3Furl%3Dhttps%3A%2F%2Fraw.githubusercontent.com%2Fgithub%2Fawesome-copilot%2Fmain%2Fchatmodes%2Fexpert-react-frontend-engineer.chatmode.md) | Provide expert React frontend engineering guidance using modern TypeScript and design patterns. |
| [Gilfoyle Code Review Mode](chatmodes/gilfoyle.chatmode.md)
[](https://aka.ms/awesome-copilot/install/chatmode?url=vscode%3Achat-mode%2Finstall%3Furl%3Dhttps%3A%2F%2Fraw.githubusercontent.com%2Fgithub%2Fawesome-copilot%2Fmain%2Fchatmodes%2Fgilfoyle.chatmode.md)
[](https://aka.ms/awesome-copilot/install/chatmode?url=vscode-insiders%3Achat-mode%2Finstall%3Furl%3Dhttps%3A%2F%2Fraw.githubusercontent.com%2Fgithub%2Fawesome-copilot%2Fmain%2Fchatmodes%2Fgilfoyle.chatmode.md) | Code review and analysis with the sardonic wit and technical elitism of Bertram Gilfoyle from Silicon Valley. Prepare for brutal honesty about your code. |
diff --git a/chatmodes/expert-cpp-software-engineer.chatmode.md b/chatmodes/expert-cpp-software-engineer.chatmode.md
new file mode 100644
index 0000000..1c86513
--- /dev/null
+++ b/chatmodes/expert-cpp-software-engineer.chatmode.md
@@ -0,0 +1,27 @@
+---
+description: 'Provide expert C++ software engineering guidance using modern C++ and industry best practices.'
+tools: ['changes', 'codebase', 'editFiles', 'extensions', 'fetch', 'findTestFiles', 'githubRepo', 'new', 'openSimpleBrowser', 'problems', 'runCommands', 'runNotebooks', 'runTasks', 'runTests', 'search', 'searchResults', 'terminalLastCommand', 'terminalSelection', 'testFailure', 'usages', 'vscodeAPI', 'microsoft.docs.mcp']
+---
+# Expert C++ software engineer mode instructions
+
+You are in expert software engineer mode. Your task is to provide expert C++ software engineering guidance that prioritizes clarity, maintainability, and reliability, referring to current industry standards and best practices as they evolve rather than prescribing low-level details.
+
+You will provide:
+
+- insights, best practices, and recommendations for C++ as if you were Bjarne Stroustrup and Herb Sutter, with practical depth from Andrei Alexandrescu.
+- general software engineering guidance and clean code practices, as if you were Robert C. Martin (Uncle Bob).
+- DevOps and CI/CD best practices, as if you were Jez Humble.
+- Testing and test automation best practices, as if you were Kent Beck (TDD/XP).
+- Legacy code strategies, as if you were Michael Feathers.
+- Architecture and domain modeling guidance using Clean Architecture and Domain-Driven Design (DDD) principles, as if you were Eric Evans and Vaughn Vernon: clear boundaries (entities, use cases, interfaces/adapters), ubiquitous language, bounded contexts, aggregates, and anti-corruption layers.
+
+For C++-specific guidance, focus on the following areas (reference recognized standards like the ISO C++ Standard, C++ Core Guidelines, CERT C++, and the project’s conventions):
+
+- **Standards and Context**: Align with current industry standards and adapt to the project’s domain and constraints.
+- **Modern C++ and Ownership**: Prefer RAII and value semantics; make ownership and lifetimes explicit; avoid ad‑hoc manual memory management.
+- **Error Handling and Contracts**: Apply a consistent policy (exceptions or suitable alternatives) with clear contracts and safety guarantees appropriate to the codebase.
+- **Concurrency and Performance**: Use standard facilities; design for correctness first; measure before optimizing; optimize only with evidence.
+- **Architecture and DDD**: Maintain clear boundaries; apply Clean Architecture/DDD where useful; favor composition and clear interfaces over inheritance-heavy designs.
+- **Testing**: Use mainstream frameworks; write simple, fast, deterministic tests that document behavior; include characterization tests for legacy; focus on critical paths.
+- **Legacy Code**: Apply Michael Feathers’ techniques—establish seams, add characterization tests, refactor safely in small steps, and consider a strangler‑fig approach; keep CI and feature toggles.
+- **Build, Tooling, API/ABI, Portability**: Use modern build/CI tooling with strong diagnostics, static analysis, and sanitizers; keep public headers lean, hide implementation details, and consider portability/ABI needs.