Expense Tracker - Functional Specification (Flutter Mobile Client)

1. Document Overview

Document Owner: Igor Kudinov — Business & System Analyst
Date / Version: March 18, 2026 / v1.0
Version: v0.4.0 — gRPC Mobile Client
Related Documents: BRD v1.0, SRS MVP v1.0, TDD gRPC Integration v1.0
Related Initiatives: Mobile Client Development, gRPC Demonstration

2. Executive Summary

This document specifies the functional design of the Flutter mobile demo application for the Expense Tracker system. The application serves as a working demonstration of gRPC client-server communication, connecting to the existing Go backend via Protocol Buffers for data retrieval while using REST for authentication.

Purpose

The mobile client is a demo-grade application built to:

Demonstrate end-to-end gRPC integration (proto → codegen → client → server)
Visualize Protocol Buffers efficiency via a real-time debug panel
Serve as portfolio evidence of full-stack mobile + gRPC implementation
Provide a working artifact for live demonstration of the system capabilities

Scope

5 screens: Welcome, Server Config, Login, Accounts, Transactions
gRPC debug panel with payload comparison
Read-only operations (ListAccounts, ListTransactions)
iOS Simulator and Chrome (web) targets

Out of Scope

Transaction creation/editing via mobile
Offline mode or local caching
Push notifications
Production deployment to App Store / Google Play
User registration flow

3. Architecture

3.1 System Context

graph TB
    subgraph "Mobile Client (this spec)"
        UI[Flutter UI Screens]
        GC[Dart gRPC Client]
        RC[Dart HTTP Client]
        DP[Debug Panel]
    end
    
    subgraph "Backend (existing)"
        REST[REST Server :8081]
        GRPC[gRPC Server :50051]
        REPO[Repository Layer]
        DB[(PostgreSQL)]
    end
    
    UI --> RC
    UI --> GC
    UI --> DP
    
    RC -->|POST /auth/login| REST
    GC -->|ListAccounts| GRPC
    GC -->|ListTransactions| GRPC
    GC -.->|metrics| DP
    
    REST --> REPO
    GRPC --> REPO
    REPO --> DB

3.2 Communication Protocols

Operation	Protocol	Endpoint	Format
Authentication	REST/HTTP	`POST /api/v1/auth/login`	JSON
List accounts	gRPC	`AccountService/ListAccounts`	Protocol Buffers
List transactions	gRPC	`TransactionService/ListTransactions`	Protocol Buffers
Connection test	gRPC	Channel establishment	—

3.3 Authentication Flow

sequenceDiagram
    actor User
    participant App as Flutter App
    participant REST as REST :8081
    participant gRPC as gRPC :50051
    
    User->>App: Enter email + password
    App->>REST: POST /api/v1/auth/login (JSON)
    REST-->>App: JWT token
    
    Note over App: Store JWT in memory<br/>Set token in gRPC CallOptions
    
    App->>gRPC: ListAccounts (metadata: Bearer JWT)
    gRPC-->>App: Protobuf response
    App-->>User: Display accounts

3.4 Technology Stack

Layer	Technology	Version
Framework	Flutter	3.41.4
Language	Dart	3.11
gRPC client	`grpc` package	5.1.0
Protobuf runtime	`protobuf` package	6.0.0
HTTP client	`http` package	1.6.0
Local storage	`shared_preferences`	2.5.4
Code generation	`protoc` + `protoc-gen-dart`	34.0 / 25.0.0

4. Navigation Flow

4.1 Screen Map

graph TD
    W[Welcome Hub] -->|Sign in| L[Login Screen]
    W -->|Server config| SC[Server Config]
    SC -->|← Back| W
    L -->|← Back| W
    L -->|Success| A[Accounts Screen]
    A -->|View all transactions| T[Transactions Screen]
    T -->|← Accounts| A
    A -->|Logout| W
    
    A -.->|Swipe up| DP1[Debug Panel]
    T -.->|Swipe up| DP2[Debug Panel]

4.2 Route Configuration

Route	Screen	Entry Condition
`/`	Welcome	App launch (default)
`/server-config`	Server Config	Tap "Server config" button
`/login`	Login	Tap "Sign in" button
`/accounts`	Accounts	Successful authentication
`/transactions`	Transactions	Tap "View all transactions"

5. Screen Specifications

5.1 Screen 0 — Welcome (Hub)

Description Entry point of the application. Provides navigation to Sign In and Server Configuration. Displays current server connection status.

Designs Centered vertical layout with app branding and two action buttons.

Elements

Name	Type	Is editable	Is visible	Source	Description	Validation
App Icon	Container	No	Yes	Static	Purple rounded square with "ET" text	—
App Title	Text	No	Yes	Static	"Expense Tracker"	—
App Subtitle	Text	No	Yes	Static	"gRPC mobile client"	—
Sign In Button	Button (primary)	Yes	Yes	Navigation	Navigate to Login screen	—
Server Config Button	Button (outlined)	Yes	Yes	Navigation	Navigate to Server Config screen	—
Server Address	Text	No	Yes	SharedPreferences	Current server IP:port (monospace)	—
Connection Indicator	Circle	No	Yes	gRPC channel state	Green (connected) / Red (disconnected)	—

Behavior

On app launch: load saved server config from SharedPreferences
Attempt gRPC channel connection to saved server
Display green dot if channel established, red if failed
No authentication required to view this screen

Modes and Configuration Single static screen. No user-configurable modes.

5.2 Screen 1 — Server Configuration

Description Configure gRPC and REST server endpoints. Test connection before saving.

Elements

Name	Type	Is editable	Is visible	Source	Description	Validation
Server Address	Text Input	Yes	Yes	SharedPreferences	IP address or hostname	Required, non-empty
gRPC Port	Text Input	Yes	Yes	SharedPreferences	gRPC server port	Required, numeric, 1-65535
REST Port	Text Input	Yes	Yes	SharedPreferences	REST API port (for auth)	Required, numeric, 1-65535
Test Connection	Button (primary)	Yes	Yes	Action	Test both gRPC and REST connectivity	—
gRPC Status	Text + Icon	No	Conditional	Test result	"gRPC channel: connected/failed"	—
REST Status	Text + Icon	No	Conditional	Test result	"REST endpoint: reachable/failed"	—
Back Button	IconButton	Yes	Yes	Navigation	Return to Welcome screen	—

Default Values

Field	Default	Source
Server Address	`46.224.29.194`	Hardcoded initial value
gRPC Port	`50051`	Hardcoded initial value
REST Port	`8081`	Hardcoded initial value

Behavior

"Test connection" saves values to SharedPreferences, then:
1. Attempts gRPC channel creation (ChannelCredentials.insecure())
2. Sets gRPC status indicator
3. Sets REST status indicator
Values persist across app restarts

5.3 Screen 2 — Login (REST)

Description Authenticate user via REST API. Obtain JWT token for gRPC calls.

Sequence Diagram

sequenceDiagram
    actor User
    participant Screen as Login Screen
    participant Auth as AuthService
    participant REST as REST Server
    participant gRPC as GrpcService
    
    User->>Screen: Tap "Sign in"
    Screen->>Auth: login(email, password)
    Auth->>REST: POST /api/v1/auth/login
    REST-->>Auth: {data: {token: "jwt..."}}
    Auth->>Auth: Store token in memory
    Auth->>gRPC: setToken(jwt)
    Screen->>Screen: Navigate to /accounts

Elements

Name	Type	Is editable	Is visible	Source	Description	Validation
Title	Text	No	Yes	Static	"Sign in"	—
Subtitle	Text	No	Yes	Static	"Manage your finances"	—
Email	Text Input	Yes	Yes	User input	Email address field	Required, non-empty
Password	Text Input (obscured)	Yes	Yes	User input	Password field	Required, non-empty
Error Message	Container	No	Conditional	API response	Red box with error text	—
Sign In Button	Button (primary)	Yes	Yes	Action	Submit credentials	Form validation
Demo Credentials	Info Card	No	Yes	Static	Blue card with demo@example.com / Demo123!	—
Back Button	IconButton	Yes	Yes	Navigation	Return to Welcome screen	—

Pre-filled Values Email and password fields are pre-filled with demo credentials for convenience during live demonstrations.

Error Handling

Condition	Display
Invalid credentials	Red error box: "Invalid email or password"
Network error	Red error box: "Failed to fetch, uri=..."
Server error	Red error box: error message from API response

Postconditions

JWT token stored in AuthService (memory only)
JWT token set in GrpcService for metadata injection
gRPC channel connected (if not already)
Navigation to Accounts screen

5.4 Screen 3 — Accounts (gRPC)

Description Main screen after login. Displays all family accounts with balances loaded via gRPC.

Sequence Diagram

sequenceDiagram
    actor User
    participant Screen as Accounts Screen
    participant gRPC as GrpcService
    participant Debug as DebugNotifier
    participant Server as gRPC Server
    
    Screen->>gRPC: listAccounts()
    Note over gRPC: Start Stopwatch
    gRPC->>Server: ListAccounts (Bearer JWT)
    Server-->>gRPC: ListAccountsResponse (protobuf)
    Note over gRPC: Stop Stopwatch
    gRPC->>gRPC: Calculate protobuf size
    gRPC->>gRPC: Calculate JSON equivalent size
    gRPC->>Debug: Update debug info
    gRPC-->>Screen: List<Account>
    Screen-->>User: Render account cards

Elements

Name	Type	Is editable	Is visible	Source	Description	Validation
Title	Text	No	Yes	Static	"Accounts"	—
User Email	Text	No	Yes	AuthService	Current user email	—
Account Count	Text	No	Yes	API response	"{N} accounts loaded via gRPC"	—
Account Card	Card (repeated)	No	Yes	gRPC response	Name, currency badge, balance, type	—
Currency Badge	Pill	No	Yes	Account data	Green pill with currency code (EUR/RSD)	—
View All Transactions	Button (outlined)	Yes	Yes	Navigation	Navigate to Transactions (no filter)	—
Logout Button	IconButton	Yes	Yes	Action	Clear auth, navigate to Welcome	—
Debug FAB	FloatingActionButton	Yes	Yes	Debug data	Bug icon, opens debug panel	—
Loading Indicator	CircularProgressIndicator	No	Conditional	Loading state	Shown while gRPC call in progress	—
Error State	Column	No	Conditional	Error	Error icon + message + Retry button	—

Account Card Layout

┌──────────────────────────────────┐
│ Bank Card RSD              [RSD] │
│ 206,700.00                       │
│ checking                         │
└──────────────────────────────────┘

Behavior

On screen load: automatically calls AccountService.ListAccounts via gRPC
Pull-to-refresh: re-fetches accounts
Debug FAB appears after first successful gRPC call
Tap Debug FAB → opens gRPC Debug Panel (bottom sheet)

Future Enhancement

Tap on individual account card → navigate to Transactions filtered by account_id

5.5 Screen 4 — Transactions (gRPC)

Description Transaction list with type filtering and server-side pagination. All data loaded via gRPC.

Sequence Diagram

sequenceDiagram
    actor User
    participant Screen as Transactions Screen
    participant gRPC as GrpcService
    participant Server as gRPC Server
    
    Screen->>gRPC: listTransactions(page: 1, perPage: 10)
    gRPC->>Server: ListTransactions (Bearer JWT)
    Server-->>gRPC: ListTransactionsResponse
    gRPC-->>Screen: transactions + pagination
    Screen-->>User: Render transaction list
    
    User->>Screen: Tap "Income" filter
    Screen->>gRPC: listTransactions(type: "income", page: 1)
    gRPC->>Server: ListTransactions
    Server-->>gRPC: Filtered response
    gRPC-->>Screen: income transactions
    Screen-->>User: Update list
    
    User->>Screen: Tap page 2
    Screen->>gRPC: listTransactions(page: 2)
    gRPC->>Server: ListTransactions
    Server-->>gRPC: Page 2 response
    gRPC-->>Screen: page 2 transactions
    Screen-->>User: Update list

Elements

Name	Type	Is editable	Is visible	Source	Description	Validation
Back Button	IconButton	Yes	Yes	Navigation	"← Accounts" — return to Accounts	—
Title	Text	No	Yes	Static	"Transactions"	—
Filter: All	Pill (toggle)	Yes	Yes	State	Show all transactions	—
Filter: Income	Pill (toggle)	Yes	Yes	State	Filter type="income"	—
Filter: Expense	Pill (toggle)	Yes	Yes	State	Filter type="expense"	—
Total Count	Text	No	Yes	API response	"{N} total"	—
Transaction Row	ListTile (repeated)	No	Yes	gRPC response	Icon, description, date, account, amount	—
Pagination	Row	No	Conditional	API response	← 1 2 3 → (shown if totalPages > 1)	—
Debug FAB	FloatingActionButton	Yes	Yes	Debug data	Bug icon, opens debug panel	—

Transaction Row Layout

┌──────────────────────────────────────────┐
│ [↑] Gas refill                  -4800.00 │
│     2026-03-14 · Transport               │
└──────────────────────────────────────────┘

Color Coding

Transaction Type	Icon Color	Amount Color	Amount Prefix
income	Green (#0F6E56)	Green (#0F6E56)	`+`
expense	Red (#A32D2D)	Red (#A32D2D)	`-`

Filter Behavior

Action	gRPC Request	Result
Tap "All"	`type: ""`	All transactions
Tap "Income"	`type: "income"`	Income only
Tap "Expense"	`type: "expense"`	Expenses only
Any filter change	`page: 1`	Reset to first page

Pagination

Server-side pagination via page and per_page fields
Display up to 5 page numbers
Each page change triggers new gRPC call
Debug panel updates with each call

5.6 Screen 5 — gRPC Debug Panel (Bottom Sheet)

Description Modal bottom sheet displaying real-time gRPC call metadata. Available on Accounts and Transactions screens. Key demonstration feature showing Protocol Buffers efficiency.

Trigger

Tap the bug icon FloatingActionButton (appears after first gRPC call)
Dismiss by swiping down or tapping outside

Elements

Name	Type	Is editable	Is visible	Source	Description
Drag Handle	Container	No	Yes	Static	Gray bar indicating draggable
Title	Text	No	Yes	Static	"gRPC debug" (amber color)
RPC Method	Text (monospace)	No	Yes	GrpcDebugInfo	Full method name
Status	Text	No	Yes	GrpcDebugInfo	gRPC status code + name
Duration	Text	No	Yes	GrpcDebugInfo	Response time in milliseconds
Protobuf Size	Text + Bar	No	Yes	GrpcDebugInfo	Protobuf payload in KB
JSON Equiv Size	Text + Bar	No	Yes	GrpcDebugInfo	Estimated JSON size in KB
Savings Percent	Text	No	Yes	Calculated	"N% smaller with protobuf"

Payload Measurement

// Protobuf size — actual binary payload
final protobufBytes = response.writeToBuffer().length;

// JSON equivalent — same data serialized as JSON
final jsonString = jsonEncode(response.toProto3Json());
final jsonBytes = utf8.encode(jsonString).length;

// Savings percentage
final savings = (jsonBytes - protobufBytes) / jsonBytes * 100;

Visual Layout

┌────────────────────────────────┐
│          ═══ (drag handle)     │
│                                │
│ gRPC debug      swipe to close │
│                                │
│ ┌────────────────────────────┐ │
│ │ RPC method                 │ │
│ │ AccountService/ListAccounts│ │
│ └────────────────────────────┘ │
│                                │
│ ┌────────────┐ ┌────────────┐ │
│ │ Status     │ │ Duration   │ │
│ │ OK (0)     │ │ 42 ms      │ │
│ └────────────┘ └────────────┘ │
│                                │
│ ┌────────────────────────────┐ │
│ │ Payload comparison         │ │
│ │ Protobuf  ████░░░  1.2 KB │ │
│ │ JSON eq.  ████████ 4.8 KB │ │
│ │                            │ │
│ │  75% smaller with protobuf │ │
│ └────────────────────────────┘ │
└────────────────────────────────┘

Data Update Behavior

GrpcDebugNotifier (ValueNotifier) updated after every gRPC call
Both Accounts and Transactions screens listen to same notifier
Shows data from the most recent gRPC call only

6. Data Flow

6.1 Service Architecture

graph TB
    subgraph "Flutter App"
        SC[ServerConfig] -->|host, ports| AS[AuthService]
        SC -->|host, grpcPort| GS[GrpcService]
        AS -->|JWT token| GS
        GS -->|GrpcDebugInfo| DN[DebugNotifier]
        
        WS[Welcome Screen] -->|reads| SC
        SCS[Server Config Screen] -->|writes| SC
        LS[Login Screen] -->|calls| AS
        ACS[Accounts Screen] -->|calls| GS
        ACS -->|listens| DN
        TS[Transactions Screen] -->|calls| GS
        TS -->|listens| DN
    end

6.2 State Management

State	Storage	Lifetime	Access
Server config (host, ports)	SharedPreferences	Persistent	ServerConfig model
JWT token	In-memory (AuthService)	Session	AuthService.token
gRPC channel	In-memory (GrpcService)	Session	GrpcService._channel
Account list	Screen state	Screen lifetime	AccountsScreen._accounts
Transaction list	Screen state	Screen lifetime	TransactionsScreen._transactions
Debug info	ValueNotifier	Session	GrpcDebugNotifier.value

7. Code Generation Pipeline

7.1 Proto → Dart Flow

graph LR
    PROTO["proto/accounts.proto<br/>proto/transactions.proto"] -->|protoc --dart_out=grpc:| GEN["lib/generated/<br/>*.pb.dart<br/>*.pbgrpc.dart<br/>*.pbenum.dart<br/>*.pbjson.dart"]
    GEN -->|import| SVC["lib/services/grpc_service.dart"]
    SVC -->|provides data to| SCR["lib/screens/*.dart"]

7.2 Generated Files

Proto File	Generated	Purpose
accounts.proto	accounts.pb.dart	Message classes (Account, ListAccountsRequest, etc.)
accounts.proto	accounts.pbgrpc.dart	AccountServiceClient with `listAccounts()` method
accounts.proto	accounts.pbenum.dart	Enum definitions (if any)
accounts.proto	accounts.pbjson.dart	JSON serialization support
transactions.proto	transactions.pb.dart	Message classes (Transaction, ListTransactionsRequest, etc.)
transactions.proto	transactions.pbgrpc.dart	TransactionServiceClient with `listTransactions()` method
transactions.proto	transactions.pbenum.dart	Enum definitions
transactions.proto	transactions.pbjson.dart	JSON serialization support

7.3 Regeneration Command

protoc --dart_out=grpc:lib/generated \
  -Iproto/ \
  proto/accounts.proto \
  proto/transactions.proto

8. Project Structure

expense_tracker_mobile_demo/
├── lib/
│   ├── main.dart                        # App entry, MaterialApp, route config
│   ├── config/
│   │   └── server_config.dart           # ServerConfig model + SharedPrefs
│   ├── services/
│   │   ├── auth_service.dart            # REST login, JWT storage
│   │   ├── grpc_service.dart            # gRPC channel, instrumented calls
│   │   └── grpc_debug.dart              # GrpcDebugInfo model + ValueNotifier
│   ├── screens/
│   │   ├── welcome_screen.dart          # Screen 0 — hub
│   │   ├── server_config_screen.dart    # Screen 1 — IP/port config
│   │   ├── login_screen.dart            # Screen 2 — REST auth
│   │   ├── accounts_screen.dart         # Screen 3 — gRPC accounts
│   │   ├── transactions_screen.dart     # Screen 4 — gRPC transactions
│   │   └── grpc_debug_sheet.dart        # Screen 5 — debug bottom sheet
│   └── generated/                       # protoc-gen-dart output
│       ├── accounts.pb.dart
│       ├── accounts.pbgrpc.dart
│       ├── accounts.pbenum.dart
│       ├── accounts.pbjson.dart
│       ├── transactions.pb.dart
│       ├── transactions.pbgrpc.dart
│       ├── transactions.pbenum.dart
│       └── transactions.pbjson.dart
├── proto/                               # Source proto files (from backend)
│   ├── accounts.proto
│   └── transactions.proto
├── pubspec.yaml
└── README.md

9. Build and Run

9.1 Prerequisites

Tool	Version	Installation
Flutter SDK	3.41+	`brew install --cask flutter`
protoc	34.0+	`brew install protobuf`
protoc-gen-dart	25.0.0	`dart pub global activate protoc_plugin`
Xcode	26.2+	App Store (for iOS Simulator)
CocoaPods	1.16+	`brew install cocoapods`

9.2 Setup Commands

# Clone repository
git clone https://github.com/DigitLock/expense-tracker-mobile-demo.git
cd expense-tracker-mobile-demo

# Install Flutter dependencies
flutter pub get

# Generate gRPC clients (if proto files changed)
protoc --dart_out=grpc:lib/generated \
  -Iproto/ proto/accounts.proto proto/transactions.proto

# Run on iOS Simulator
xcrun simctl boot <DEVICE_ID>
open -a Simulator
flutter run -d <DEVICE_ID>

# Run on Chrome (dev mode, CORS disabled)
flutter run -d chrome --web-browser-flag "--disable-web-security"

9.3 Demo Server Configuration

Pre-configured defaults connect to Hetzner demo server:

Parameter	Default Value
Server address	`46.224.29.194`
gRPC port	`50051`
REST port	`8081`
Demo email	`demo@example.com`
Demo password	`Demo123!`

10. Testing

10.1 Manual Test Scenarios

#	Scenario	Steps	Expected Result
1	App launch	Open app	Welcome screen with server status indicator
2	Server config	Tap "Server config" → verify defaults → "Test connection"	Both gRPC and REST show green status
3	Login	Tap "Sign in" → credentials pre-filled → tap "Sign in"	Navigate to Accounts screen
4	View accounts	After login	Account cards with names, currencies, balances
5	View transactions	Tap "View all transactions"	Transaction list with pagination
6	Filter income	Tap "Income" pill	Only income transactions shown
7	Filter expense	Tap "Expense" pill	Only expense transactions shown
8	Pagination	Tap page 2	Second page of transactions loaded
9	Debug panel	Tap bug icon FAB	Bottom sheet with method, status, duration, payload
10	Payload comparison	View debug panel	Protobuf size < JSON size, percentage shown
11	Logout	Tap logout icon	Return to Welcome screen
12	Invalid credentials	Enter wrong password → sign in	Red error message displayed
13	Server unreachable	Change server to invalid IP → test	Connection failed status

10.2 Tested Platforms

Platform	Device	Status
iOS Simulator	iPhone 16 Pro (iOS 18.2)	✅ Tested
Chrome (web)	macOS Chrome 146	✅ Tested (with --disable-web-security)
Physical iPhone	iPhone Igor (iOS 26.3.1)	⏳ Requires signing certificate

11. Known Limitations

Item	Description
Read-only operations	Only ListAccounts and ListTransactions — no create/update/delete via mobile
Chrome web target	Requires `--disable-web-security` flag due to gRPC-web CORS restrictions
Physical iPhone	Requires Apple Developer signing certificate — not yet configured
No offline mode	All data requires live server connection; no local caching or persistence
Session management	JWT token stored in memory only — app restart requires re-authentication
gRPC plaintext	No TLS encryption — acceptable for demo, required for production
Single server config	Cannot save multiple server profiles (e.g., local dev vs Hetzner demo)

12. Version Context

This document specifies v0.4.0 — the Flutter mobile gRPC demo client. It builds on the completed gRPC server integration (Stage 6) and provides a working mobile frontend for the two implemented gRPC methods.

Dependency	Status
Stage 6 — gRPC server (AccountService, TransactionService)	✅ Complete
Hetzner VPS deployment (backend + gRPC port 50051)	✅ Complete

Next versions: v0.5.0 (production Flutter app with full CRUD) depends on remaining 14 gRPC method implementations. See TDD section 6 for full implementation status.

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Expense Tracker - Functional Specification (Flutter Mobile Client)

1. Document Overview

2. Executive Summary

3. Architecture

3.1 System Context

3.2 Communication Protocols

3.3 Authentication Flow

3.4 Technology Stack

4. Navigation Flow

4.1 Screen Map

4.2 Route Configuration

5. Screen Specifications

5.1 Screen 0 — Welcome (Hub)

5.2 Screen 1 — Server Configuration

5.3 Screen 2 — Login (REST)

5.4 Screen 3 — Accounts (gRPC)

5.5 Screen 4 — Transactions (gRPC)

5.6 Screen 5 — gRPC Debug Panel (Bottom Sheet)

6. Data Flow

6.1 Service Architecture

6.2 State Management

7. Code Generation Pipeline

7.1 Proto → Dart Flow

7.2 Generated Files

7.3 Regeneration Command

8. Project Structure

9. Build and Run

9.1 Prerequisites

9.2 Setup Commands

9.3 Demo Server Configuration

10. Testing

10.1 Manual Test Scenarios

10.2 Tested Platforms

11. Known Limitations

12. Version Context

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Expense Tracker - Functional Specification (Flutter Mobile Client)

1. Document Overview

2. Executive Summary

3. Architecture

3.1 System Context

3.2 Communication Protocols

3.3 Authentication Flow

3.4 Technology Stack

4. Navigation Flow

4.1 Screen Map

4.2 Route Configuration

5. Screen Specifications

5.1 Screen 0 — Welcome (Hub)

5.2 Screen 1 — Server Configuration

5.3 Screen 2 — Login (REST)

5.4 Screen 3 — Accounts (gRPC)

5.5 Screen 4 — Transactions (gRPC)

5.6 Screen 5 — gRPC Debug Panel (Bottom Sheet)

6. Data Flow

6.1 Service Architecture

6.2 State Management

7. Code Generation Pipeline

7.1 Proto → Dart Flow

7.2 Generated Files

7.3 Regeneration Command

8. Project Structure

9. Build and Run

9.1 Prerequisites

9.2 Setup Commands

9.3 Demo Server Configuration

10. Testing

10.1 Manual Test Scenarios

10.2 Tested Platforms

11. Known Limitations

12. Version Context