Add pedagogical metadata to expert README files

Author: lucasbellesi

CONTRIBUTING.md

@@ -70,6 +70,7 @@ The public PowerShell and Bash scripts are thin wrappers over the shared Python
 
 - New concept modules should follow the existing folder layout.
 - Every concept README in implemented levels should include:
+  - recommended `## Learning Metadata` before `## Quick Run` with difficulty, estimated time, prerequisites, and cross-language guidance
   - `## Quick Run`
   - `## Topics Covered`
   - `## Common Pitfalls`
@@ -80,6 +81,7 @@ The public PowerShell and Bash scripts are thin wrappers over the shared Python
   - `README.md`
   - runnable entrypoint (`main.cs` + `.csproj`, `main.go`, or `main.py`)
   - the same learner goal, input/output shape, and acceptance expectations as the corresponding C++ checkpoint
+  - recommended `## Learning Metadata` with difficulty, estimated time, prerequisites, and checkpoint focus
 - Checkpoint README structure should mirror the matching C++ checkpoint style, not the module README contract.
 - Every `example/main.*` file should include intent-first comments for:
   - program flow,

README.md

@@ -86,6 +86,13 @@ All concept module README files under `languages/<language>/<level>/<module>/REA
 
 Reference: [Module README Style](languages/cpp/MODULE_README_STYLE.md)
 
+A standardized `## Learning Metadata` block is also recommended before `## Quick Run` for modules and major checkpoints. Use it to record:
+
+- difficulty
+- estimated time
+- prerequisites
+- cross-language comparison guidance
+
 Checkpoint artifacts under `languages/<language>/projects/*` and `languages/<language>/assessments/*` should mirror the corresponding C++ checkpoint style:
 
 - `README.md`

languages/cpp/04-expert/README.md

@@ -2,6 +2,12 @@
 
 This level focuses on ownership, concurrency, performance thinking, and multi-file structure.
 
+## Learning Metadata
+
+- Difficulty: Expert Level.
+- Estimated Time: 4-6 hours across all modules, project, and assessment.
+- Prerequisites: completion of `03-advanced` plus its project or assessment checkpoint.
+- Study Strategy: finish the modules in order, then the `projects/04-expert` capstone, then the `assessments/04-expert` checkpoint.
 ## Module Order
 
 1. [memory-management-and-raii](./memory-management-and-raii/README.md)

languages/cpp/04-expert/concurrency-basics/README.md

@@ -2,6 +2,12 @@
 
 This module introduces real multithreaded programming with `std::thread`.
 
+## Learning Metadata
+
+- Difficulty: Expert.
+- Estimated Time: 45-60 minutes.
+- Prerequisites: `01-foundations/control-flow`, `03-advanced/structs-and-classes`.
+- Cross-Language Lens: Compare `std::thread`, `Task` plus `lock`, goroutines, and Python threads as different concurrency models.
 ## Quick Run
 
 ```bash

languages/cpp/04-expert/memory-management-and-raii/README.md

@@ -2,6 +2,12 @@
 
 This module introduces ownership and deterministic cleanup in C++.
 
+## Learning Metadata
+
+- Difficulty: Expert.
+- Estimated Time: 35-50 minutes.
+- Prerequisites: `03-advanced/constructors-and-invariants`, `03-advanced/copy-and-move-semantics`.
+- Cross-Language Lens: Compare deterministic cleanup in C++ with `IDisposable`, `defer`, and context managers in the other tracks.
 ## Quick Run
 
 ```bash

languages/cpp/04-expert/modularization-and-build-structure/README.md

@@ -2,6 +2,12 @@
 
 This module introduces basic multi-file organization principles.
 
+## Learning Metadata
+
+- Difficulty: Expert.
+- Estimated Time: 30-45 minutes.
+- Prerequisites: `02-core/file-io-basics`, `03-advanced/structs-and-classes`.
+- Cross-Language Lens: Compare headers and source files, project references, packages, and Python modules as ways to separate responsibilities.
 ## Quick Run
 
 ```bash

languages/cpp/04-expert/performance-and-profiling-basics/README.md

@@ -2,6 +2,12 @@
 
 This module introduces simple measurement and optimization patterns.
 
+## Learning Metadata
+
+- Difficulty: Expert.
+- Estimated Time: 35-50 minutes.
+- Prerequisites: `02-core/algorithms-basics`, `01-foundations/arrays-and-vectors`.
+- Cross-Language Lens: Compare timing APIs, allocation behavior, and why micro-benchmarks can mislead in different runtimes.
 ## Quick Run
 
 ```bash

languages/cpp/04-expert/smart-pointers-in-depth/README.md

@@ -2,6 +2,12 @@
 
 This module expands ownership modeling with `unique_ptr`, `shared_ptr`, and `weak_ptr`.
 
+## Learning Metadata
+
+- Difficulty: Expert.
+- Estimated Time: 40-55 minutes.
+- Prerequisites: `04-expert/memory-management-and-raii`, `03-advanced/copy-and-move-semantics`.
+- Cross-Language Lens: Compare explicit ownership in C++ with managed references, pointers, and weak observers in the other tracks.
 ## Quick Run
 
 ```bash

languages/cpp/MODULE_README_STYLE.md

@@ -20,6 +20,7 @@ This structure is required for all implemented concept modules.
 
 ## Section Rules
 
+- `Learning Metadata` (recommended): include difficulty, estimated time, prerequisites, and a short cross-language lens before `Quick Run`.
 - `Quick Run`: include one runnable command for `example/main.*` (or equivalent entry project).
 - `Topics Covered`: concise bullets of concepts practiced in the module.
 - `Common Pitfalls`: practical mistakes beginners frequently make.

languages/cpp/assessments/04-expert/README.md

@@ -17,6 +17,12 @@ Write a program that:
 - maximum value
 5. Prints per-thread partial sums and final summary.
 
+## Learning Metadata
+
+- Difficulty: Expert Assessment.
+- Estimated Time: 45-60 minutes.
+- Prerequisites: `04-expert/concurrency-basics`, `04-expert/memory-management-and-raii`, `04-expert/smart-pointers-in-depth`.
+- Learning Focus: prove you can coordinate concurrent workers, protect shared aggregation, and reason about ownership boundaries without step-by-step scaffolding.
 ## Quick Run
 
 ```bash