digraph when_to_use {
    "Reviewing OpenHarmony code?" [shape=diamond];
    "Is it C++ system service?" [shape=diamond];
    "Handles IPC/network data?" [shape=diamond];
    "Has shared state?" [shape=diamond];
    "Logs data?" [shape=diamond];
    "Use this skill" [shape=box];
    "Different skill needed" [shape=box];

    "Reviewing OpenHarmony code?" -> "Different skill needed" [label="no"];
    "Reviewing OpenHarmony code?" -> "Is it C++ system service?" [label="yes"];
    "Is it C++ system service?" -> "Different skill needed" [label="no"];
    "Is it C++ system service?" -> "Handles IPC/network data?" [label="yes"];
    "Handles IPC/network data?" -> "Use this skill" [label="yes"];
    "Handles IPC/network data?" -> "Has shared state?" [label="no"];
    "Has shared state?" -> "Use this skill" [label="yes"];
    "Has shared state?" -> "Logs data?" [label="no"];
    "Logs data?" -> "Use this skill" [label="yes"];
    "Logs data?" -> "Different skill needed" [label="no"];
}

// ❌ VULNERABLE: No validation
parcel.ReadInt32(val);
int32_t size = parcel.ReadInt32();

// ✅ SECURE: Always check return value
if (!parcel.ReadInt32(val)) {
    HILOG_ERROR("Failed to read value");
    return ERR_INVALID_DATA;
}
if (!parcel.ReadInt32(size)) {
    HILOG_ERROR("Failed to read size");
    return ERR_INVALID_DATA;
}

// ❌ VULNERABLE: No bounds validation
int32_t size = parcel.ReadInt32();
std::vector<char> buffer(size);  // May allocate gigabytes or overflow

// ✅ SECURE: Validate bounds immediately
int32_t size = 0;
if (!parcel.ReadInt32(size)) {
    return ERR_INVALID_DATA;
}
constexpr int32_t MAX_ALLOWED_BUFFER = 1024 * 1024;  // 1MB
if (size < 0 || size > MAX_ALLOWED_BUFFER) {
    HILOG_ERROR("Invalid size: %{public}d", size);
    return ERR_INVALID_DATA;
}
std::vector<char> buffer(size);

// ✅ SECURE: Validate before use
if (remoteObject == nullptr) {
    HILOG_ERROR("Received null RemoteObject");
    return ERR_NULL_OBJECT;
}
if (fd < 0) {
    HILOG_ERROR("Invalid file descriptor");
    return ERR_INVALID_FD;
}

// ❌ VULNERABLE: Unprotected concurrent access
std::vector<int> items_;

void AddItem(int item) {
    items_.push_back(item);  // Unsafe if called concurrently
}

void ProcessItems() {
    for (auto& item : items_) {  // Iteration
        // If AddItem called here, iterator invalidates → CRASH
    }
}

// ✅ SECURE: All access protected
std::vector<int> items_;
std::mutex itemsMutex_;

void AddItem(int item) {
    std::lock_guard<std::mutex> lock(itemsMutex_);
    items_.push_back(item);
}

void ProcessItems() {
    std::lock_guard<std::mutex> lock(itemsMutex_);
    for (auto& item : items_) {
        // Safe - lock held during iteration
    }
}

// ❌ VULNERABLE: Inconsistent protection
class Service {
    std::map<int, Data> dataMap_;
    std::mutex mutex_;

    void Update(int key, const Data& data) {
        std::lock_guard<std::mutex> lock(mutex_);
        dataMap_[key] = data;
    }

    Data Lookup(int key) {
        // ❌ NO LOCK - race condition with Update
        return dataMap_[key];
    }
};

// ✅ SECURE: Consistent protection
class Service {
    std::map<int, Data> dataMap_;
    std::mutex mutex_;

    void Update(int key, const Data& data) {
        std::lock_guard<std::mutex> lock(mutex_);
        dataMap_[key] = data;
    }

    Data Lookup(int key) {
        std::lock_guard<std::mutex> lock(mutex_);
        return dataMap_[key];
    }
};

// ❌ VULNERABLE: Deadlock risk
void Path1() {
    std::lock_guard<std::mutex> lock1(mutex1_);
    std::lock_guard<std::mutex> lock2(mutex2_);  // Order: 1 then 2
}

void Path2() {
    std::lock_guard<std::mutex> lock2(mutex2_);
    std::lock_guard<std::mutex> lock1(mutex1_);  // Order: 2 then 1 → DEADLOCK
}

// ✅ SECURE: Consistent lock order
void Path1() {
    std::lock_guard<std::mutex> lock1(mutex1_);
    std::lock_guard<std::mutex> lock2(mutex2_);  // Order: 1 then 2
}

void Path2() {
    std::lock_guard<std::mutex> lock1(mutex1_);  // Same order: 1 then 2
    std::lock_guard<std::mutex> lock2(mutex2_);
}

// ❌ VULNERABLE: TOCTOU window
if (fileExists(path)) {
    // Attacker can delete/replace file here
    file = openFile(path);  // May open different file
}

// ✅ SECURE: Atomic check-and-use
file = openFile(path);
if (file.isValid()) {
    // Use file
}

// ❌ VULNERABLE: Logs PII
HILOG_INFO("Phone: %{public}s", phoneNumber.c_str());
HILOG_ERROR("Touch at (%{public}d, %{public}d)", x, y);

// ✅ SECURE: Redact or suppress
HILOG_INFO("Phone: %{private}s", phoneNumber.c_str());  // Redacted
// Better: Don't log PII at all
HILOG_INFO("Processing phone number");

// ❌ VULNERABLE: Leaks addresses for ASLR bypass
HILOG_INFO("Object at %p", &object);
HILOG_DEBUG("Buffer address: %{public}p", buffer);

// ✅ SECURE: No address logging
HILOG_INFO("Object created");
// Use opaque IDs instead of pointers
HILOG_INFO("Object ID: %{public}d", object.id_);

// ❌ VULNERABLE: No permission check
int32_t Service::DeleteFile(const std::string& path) {
    // Any caller can delete any file!
    return unlink(path.c_str());
}

// ✅ SECURE: Validate permissions
int32_t Service::DeleteFile(const std::string& path) {
    // Verify caller has permission to access this path
    if (!HasPermission(callerToken_, path, Permission::DELETE)) {
        HILOG_ERROR("Permission denied for path: %{private}s", path.c_str());
        return ERR_PERMISSION_DENIED;
    }

    // Verify path is within allowed sandbox
    if (!IsPathInSandbox(path)) {
        HILOG_ERROR("Path outside sandbox: %{private}s", path.c_str());
        return ERR_INVALID_PATH;
    }

    return unlink(path.c_str());
}

**[HIGH SECURITY RISK] <Category>**

Location: <file_path>:<line_number>

Issue: <description>

Anti-pattern:
```cpp
<code>

<code>

undefined