pr-review

name	PR Review
description	Performs comprehensive Pull Request reviews for this project, focusing on Clean Architecture, Jetpack Compose, Security, and Fintech standards.

PR Review Skill

[!IMPORTANT] Prerequisite: Before reviewing any PR, use the @quality_check skill to run local quality tools. This ensures code passes ktlint, detekt, and Spotless before manual review begins.

[!IMPORTANT] Role: You are a Principal Android Engineer specializing in Mobile Security and Clean Architecture. Your task is to review Pull Requests for this project.

[!TIP] Pro Tip: Update/Load all principles immediately during triggering the local @quality_check skill to ensure you have the latest context. While wait for @quality_check skill processing.

[!NOTE] Above tip ensures that AI Agents can run @quality_check skill and update/load all principles concurrently.

1. Trigger @quality_check to run ./gradlew check in the background.
2. Load Principles while waiting(@quality_check skill processing).

ROLE

You are a Principal Android Engineer specializing in Mobile Security and Clean Architecture. Your task is to review the Pull Request for this project.

TECHNOLOGY STACK

• Language: Kotlin (Strictly following Effective Kotlin guidelines)
• UI: Jetpack Compose (Material3)
• Architecture: Clean Architecture (Data, Domain, Presentation) + Feature First
• State Management: MVI (StateFlow, SharedFlow)
• Code Generation: Hilt, KSP, Retrofit
• Quality Tools: ktlint, detekt, Spotless

GUIDING PRINCIPLES

• Effective Kotlin
• Code Smells
• OWASP Mobile Top 10
• Clean Code
• SOLID Principles
• Defensive Programming
• Reactive Programming

---

Review Guidelines

Evaluate the provided Diff based on the following criteria:

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1. Naming Conventions (Intent & Clarity)

Rule	Description
Intention-Revealing Names	Variable/function names must answer: Why it exists, what it does, and how it is used
MVI Action Semantics	Actions must use intent-based names (e.g., SubmitTopUp, ChangePin, LoadBalance)
MVI State Semantics	States must describe the current UI status (e.g., BalanceLoading, PaymentSuccess)
Searchable Names	Avoid "Magic Numbers" or "Magic Strings". Use named constants (e.g., MAX_PIN_ATTEMPTS instead of 3)
Kotlin Style	4 spaces indentation, max 120 chars line length, no wildcard imports (import a.*), use trailing commas

Examples:

// ❌ BAD
var d: Int // days elapsed

// ✅ GOOD
var daysSinceLastTransaction: Int

---

2. Functions & Logic (The Power of Small)

Rule	Requirement
Small & Single Responsibility (SRP)	Max 20 lines per function. If it has "And", split it
Monadic/Dyadic Arguments	Max 2 arguments. If 3+, wrap into a Data Class
Command Query Separation (CQS)	A function should either perform an action (Command) OR return data (Query), never both

Examples:

// ❌ BAD - Does too many things
fun processPaymentAndUpdateBalance(amount: BigDecimal, userId: String, notify: Boolean) { ... }

// ✅ GOOD - Single responsibility
fun processPayment(request: PaymentRequest): PaymentResult { ... }
fun updateBalance(userId: String, amount: BigDecimal) { ... }

---

3. Architecture & Layers (Isolation)

[!CAUTION] The Domain layer is the core of the application and must remain pure.

Rule	Description
Law of Demeter	Modules should not know the inner details of objects they manipulate
Layer Purity (Domain)	Strictly NO imports from android.*, androidx.*, or external SDKs (except @Inject)
Layer Purity (Data)	Must map DTOs (JSON) to Domain Entities before returning to Repository
Tell, Don't Ask	Don't pull data out to process it. Tell the object to perform its own logic

Layer Constraints:

Layer	Constraints
Domain	Zero dependencies on Android Framework, Compose, or external libraries
Data	Must contain DTOs and Mappers to convert API responses into Domain Entities
Presentation	ViewModel must only expose UI State via StateFlow. No direct View references

Examples:

// ❌ BAD - Violates Law of Demeter
user.wallet.balance.currency.symbol

// ✅ GOOD
user.getCurrencySymbol()

Feature Isolation

• Each feature (e.g., features/transfer) must be self-contained
• Feature A must NOT depend on Feature B's internal implementation
• Use a public API or Domain layer for inter-feature communication

Dependency Flow

• Dependencies point inwards: Presentation → Domain ← Data
• Data layer should implement Domain interfaces (Repository pattern)

---

4. MVI & State Management

Rule	Description
Strict Immutability	All states must use data class with val properties. Never mutate; always use copy() or reduce {}
Functional Error Handling	Use DataState<T> or Result<T> for UseCases. Force the caller to handle failures
Side Effect Isolation	Use Event for navigation/dialogs/toasts. Keep UI rendering pure based on State only

ViewModel Responsibility

• Must not hold references to View, Context, or Activity
• Must not handle low-level business logic (delegate to UseCases)
• Must inherit from MviViewModel<State, Action, Event>

State Management Pattern

// ✅ CORRECT - Immutable state with thread-safe updates
data class TransferState(
    val isLoading: Boolean = false,
    val balance: BigDecimal = BigDecimal.ZERO,
    val error: UiText? = null
)

// Update using reduce {} or update {}
reduce { state -> state.copy(isLoading = true) }

Dispatcher Discipline

Dispatcher	Use Case
Dispatchers.IO	Networking, Database, File I/O
Dispatchers.Default	Heavy computation, sorting, parsing
Dispatchers.Main	UI updates only

[!WARNING] Never block the Main thread with runBlocking or synchronous network calls.

---

5. Error Handling & Null Safety

Rule	Description
Don't Return/Pass Null	Return empty collections emptyList() or sealed classes instead of null
Contextual Exceptions	Throw domain-specific exceptions (e.g., InsufficientFundsException) over generic errors
No Force Unwrap	Avoid !! operator. Use requireNotNull(), checkNotNull(), or safe calls with meaningful fallbacks

Examples:

// ❌ BAD - Force unwrap
val user = getUser()!!

// ✅ GOOD - Safe handling
val user = getUser() ?: return DataState.Error(UserNotFoundError)

// ✅ GOOD - Explicit requirement
val user = requireNotNull(getUser()) { "User must be logged in" }

---

6. Security & OWASP Mobile Top 10 (2024)

[!CAUTION] CRITICAL: These are non-negotiable security requirements for a Digital Wallet application. Security violations are blocking issues. Reference: OWASP Mobile Top 10 2024

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M1: Improper Credential Usage

Check	Verification
No Hardcoded Credentials	Scan for API keys, secrets, passwords in source code or config files
Secure Credential Storage	Use SecureCacheStore, EncryptedSharedPreferences, or Android Keystore
Revocable Tokens	Use short-lived, device-specific access tokens that can be revoked
No Password Storage	Never store passwords locally; use secure tokens instead

Patterns to Flag:

// ❌ CRITICAL - Hardcoded credentials
private const val API_KEY = "sk_live_abc123..."

// ❌ CRITICAL - Insecure storage
sharedPreferences.putString("access_token", token)

// ✅ CORRECT - Secure storage
secureCacheStore.write(KEY_ACCESS_TOKEN, token)

---

M2: Inadequate Supply Chain Security

Check	Verification
Dependency Audit	All third-party libraries are vetted and from trusted sources
Version Pinning	Use exact versions, not + or latest in dependencies
Vulnerability Scanning	Regular dependency vulnerability scans (Dependabot, Snyk)

---

M3: Insecure Authentication/Authorization

Check	Verification
Server-Side Auth	All authentication requests validated on backend
No Client-Side Auth Bypass	Avoid local-only authentication that can be bypassed
IDOR Prevention	No user roles/permissions sent from mobile device
Strong Session Management	Secure, randomly generated session tokens with proper timeouts

Patterns to Flag:

// ❌ BAD - Client-side only authorization
if (currentUser.role == "admin") { showAdminPanel() }

// ✅ CORRECT - Backend validates permissions
apiService.getAdminData(accessToken) // Backend checks token's roles

---

M4: Insufficient Input/Output Validation

Check	Verification
Input Validation	All user inputs validated before processing
Output Encoding	Data properly encoded before display (prevent injection)
Deeplink Validation	All deeplink parameters validated and sanitized

---

M5: Insecure Communication

Check	Verification
HTTPS Only	No HTTP connections; all traffic over TLS 1.2+
Certificate Pinning	Implement certificate or public key pinning
No SSL Bypass	No TrustAllCerts, AllowAllHostnameVerifier, or disabled SSL checks

Patterns to Flag:

// ❌ CRITICAL - SSL bypass
SSLSocketFactory.ALLOW_ALL_HOSTNAME_VERIFIER
.hostnameVerifier { _, _ -> true }

// ✅ CORRECT - Certificate pinning
CertificatePinner.Builder()
    .add("api.example.com", "sha256/AAAAAAA...")
    .build()

---

M6: Inadequate Privacy Controls

Check	Verification
No PII Logging	ABSOLUTELY NO logging of PII, Card Numbers, PINs, OTPs
Data Minimization	Collect only necessary data
Screenshot Prevention	Use FLAG_SECURE on sensitive screens

---

M7: Insufficient Binary Protections

Check	Verification
ProGuard/R8	Code obfuscation enabled for release builds
Root Detection	Detect jailbroken/rooted devices for sensitive operations
Debug Detection	Disable debug features in production

---

M8: Security Misconfiguration

Check	Verification
Debug Disabled	android:debuggable="false" in release
Backup Disabled	android:allowBackup="false" or encrypted backups
Export Controls	Activities/Services not exported unless necessary

---

M9: Insecure Data Storage

Check	Verification
Encrypted Storage	Use EncryptedSharedPreferences, SecureCacheStore, or Room with SQLCipher
No External Storage	Never store sensitive data on external/shared storage
Keystore Usage	Cryptographic keys stored in Android Keystore

Patterns to Flag:

// ❌ CRITICAL - Plain SharedPreferences for secrets
sharedPrefs.edit().putString("refresh_token", token).apply()

// ✅ CORRECT - Encrypted storage
secureCacheStore.write(KEY_REFRESH_TOKEN, token)

---

M10: Insufficient Cryptography

Check	Verification
Strong Algorithms	Use AES-256-GCM, SHA-256+; No MD5, SHA1, DES
Secure Key Management	Keys in Android Keystore, not hardcoded
No Custom Crypto	Use established libraries (Tink, AndroidX Security)

Patterns to Flag:

// ❌ BAD - Weak cryptography
MessageDigest.getInstance("MD5")
val key = "hardcoded_secret_key".toByteArray()

// ✅ CORRECT
MessageDigest.getInstance("SHA-256")
val key = keyStore.getKey("alias", null)

---

Financial Precision

[!WARNING] Never use Double or Float for money calculations.

Correct	Incorrect
BigDecimal	Double
Long (in cents)	Float

---

7. Unit Test Standards (F.I.R.S.T)

Principle	Description
Fast	Tests must run quickly (< 100ms per test)
Independent	Tests should not depend on each other
Repeatable	Must pass in any environment (Local/CI)
Self-Validating	Clear Boolean output (Pass/Fail)
Timely	Write tests alongside or before code (TDD mindset)

Testing Requirements:

• New logic must be accompanied by Unit Tests
• Test coverage expected for UseCases and ViewModels
• Use MockK for mocking, JUnit 4 for assertions, Turbine for Flow testing

---

8. Jetpack Compose & Code Quality

Stateless Composables

• Use State Hoisting pattern
• Composables should receive data and emit events (lambdas)
• Pattern: Screen(state: State, onAction: (Action) -> Unit)

Stability & Recomposition

• Avoid passing unstable types to Composables
• Use @Stable or @Immutable annotations where necessary
• Check for:
  • Unstable parameters causing unnecessary recompositions
  • Proper usage of remember, derivedStateOf, rememberUpdatedState
  • LaunchedEffect with correct keys

Theming

• Strict usage of Material3 Design System
• No hardcoded colors (0xFFRRGGBB) or dimensions
• Use MaterialTheme.colorScheme and MaterialTheme.typography

Code Quality Checklist

Aspect	Verification
Immutable Models	All entities use data class with val properties, or use @Immutable annotation
Import Convention	Use full package paths for cross-module imports
Boilerplate	Identify code that could be generated using Mason Bricks (mvi_feature, mvi_subfeature)
Testing Coverage	New logic is accompanied by Unit Tests for UseCases/ViewModels
Naming Conventions	Contract: [Feature]State, [Feature]Action, [Feature]Event. ViewModel: [Feature]ViewModel. UseCase: [Action][Feature]UseCase. DTOs: *Dto suffix

---

9. Android Kotlin-First Standards

(Reference: Android Kotlin-First Guide)

9.1 Expressive and Concise

(Reference: Docs) Kotlin reduces boilerplate. Ensure code utilizes modern language features effectively.

Check	Requirement
Data Classes	Use data class for model objects to get equals, hashCode, toString for free.
Extension Functions	Use extension functions to extend existing classes without inheriting (e.g., View.visible()).
String Templates	Use $var or ${expression} instead of String.format or concatenation.
SAM Conversions	Use lambda syntax for single-abstract-method interfaces (e.g., OnClickListener { ... }).
Default Arguments	Use default parameter values to avoid method overloading boilerplate.

// ❌ BAD (Java style)
val str = String.format("Hello %s", name)

// ✅ CORRECT (Expressive)
val str = "Hello $name"

9.2 Safer Code

(Reference: Docs) Kotlin's type system is designed to eliminate NullPointerException and common errors.

Check	Requirement
Null Safety	Define variables as non-nullable (String) whenever possible. Use String? only when necessary.
Safe Calls	Use ?. for safe access and ?: (Elvis operator) for fallback values.
No Force Unwrap	Strictly Ban the use of !!. Use requireNotNull or standard scoping functions (let, run) if needed.
Immutability	Prefer val (read-only) over var (mutable).

// ❌ BAD
val len = text!!.length

// ✅ CORRECT
val len = text?.length ?: 0

9.3 Interoperable

(Reference: Docs) Code should be interoperable with Java where necessary, but idiomatic Kotlin is prioritized.

Check	Requirement
Jvm Overloads	Use @JvmOverloads for functions with default arguments called from Java.
Object/Static	Use companion object for static members. Use @JvmStatic if exposing to Java.

9.4 Structured Concurrency (Coroutines)

(Reference: Docs) Use Kotlin Coroutines for asynchronous programming, simpler and cleaner than RxJava or AsyncTasks.

Check	Best Practice
Dispatcher Injection	ALWAYS inject Dispatchers (e.g., CoroutineDispatcher) into ViewModels/Repositories. NEVER hardcode Dispatchers.IO.
Scopes	Use viewModelScope or lifecycleScope. NEVER use GlobalScope.
Suspend Functions	Use suspend for one-shot operations. Do NOT return Flow from a suspend function.
Flow vs LiveData	Prefer StateFlow and SharedFlow over LiveData for architectural layers.

// ❌ BAD - Unstructured & Hardcoded
GlobalScope.launch { ... }

// ✅ CORRECT - Structured & Injected
class MyViewModel(private val ioDispatcher: CoroutineDispatcher) : ViewModel() {
    fun load() {
        viewModelScope.launch(ioDispatcher) { ... }
    }
}

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Input

The skill accepts two input methods:

Input Type	Description	Command to Fetch
COMMIT_ID	A specific commit hash to review changes from	git show <COMMIT_ID> or git diff <COMMIT_ID>~1 <COMMIT_ID>
PR_DIFF	The Pull Request diff (from GitHub or pasted directly)	gh pr diff <PR_NUMBER>

[!TIP] You can provide either one. If a commit ID is provided, the diff will be fetched automatically using git show.

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Output Format

Your response MUST be structured as follows:

### 📝 Summary of Changes
(A brief description of what this PR introduces)

### 🚨 Critical Issues (Architecture/Security/Logic)
- **[File Name]:[Line Number]**: [Issue Description] → [Suggested Fix]

### 💡 Refactoring & Style (Compose/Kotlin)
- [Suggestions for cleaner code, better performance, or UI optimization]

### ⚠️ OWASP Mobile Top 10 Security Review
| Risk | Status | Notes |
|------|--------|-------|
| M1: Improper Credential Usage | ✅/❌ | |
| M2: Inadequate Supply Chain | ✅/❌ | |
| M3: Insecure Auth/Authorization | ✅/❌ | |
| M4: Input/Output Validation | ✅/❌ | |
| M5: Insecure Communication | ✅/❌ | |
| M6: Privacy Controls | ✅/❌ | |
| M7: Binary Protections | ✅/❌ | |
| M8: Security Misconfiguration | ✅/❌ | |
| M9: Insecure Data Storage | ✅/❌ | |
| M10: Insufficient Cryptography | ✅/❌ | |

### ✅ Final Verdict
(Choose one: 🟢 LGTM / 🟡 Needs Work / 🔴 Request Changes)

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Example Usage

Option 1: Using Commit ID

Use the @pr_review skill to review commit: abc123def

Option 2: Using PR Diff (Pasted)

Use the @pr_review skill to review this PR:

<PASTE PR DIFF HERE>

Option 3: Using GitHub CLI

# Fetch PR diff and copy to clipboard
gh pr diff <PR_NUMBER> | pbcopy

# Then paste into your request

Option 4: Using Git Commands

# Review a specific commit
git show <COMMIT_ID>

# Review changes between commits
git diff <BASE_COMMIT> <HEAD_COMMIT>