chore: import MusifyBackend into monorepo (preserving history)

git-subtree-dir: MusifyBackend
git-subtree-mainline: 6829e769ed
git-subtree-split: ed7b00c2cc

MusifyBackend/.agents/skills/csharp-async/SKILL.md

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+---
+name: csharp-async
+description: 'Get best practices for C# async programming'
+---
+
+# C# Async Programming Best Practices
+
+Your goal is to help me follow best practices for asynchronous programming in C#.
+
+## Naming Conventions
+
+- Use the 'Async' suffix for all async methods
+- Match method names with their synchronous counterparts when applicable (e.g., `GetDataAsync()` for `GetData()`)
+
+## Return Types
+
+- Return `Task<T>` when the method returns a value
+- Return `Task` when the method doesn't return a value
+- Consider `ValueTask<T>` for high-performance scenarios to reduce allocations
+- Avoid returning `void` for async methods except for event handlers
+
+## Exception Handling
+
+- Use try/catch blocks around await expressions
+- Avoid swallowing exceptions in async methods
+- Use `ConfigureAwait(false)` when appropriate to prevent deadlocks in library code
+- Propagate exceptions with `Task.FromException()` instead of throwing in async Task returning methods
+
+## Performance
+
+- Use `Task.WhenAll()` for parallel execution of multiple tasks
+- Use `Task.WhenAny()` for implementing timeouts or taking the first completed task
+- Avoid unnecessary async/await when simply passing through task results
+- Consider cancellation tokens for long-running operations
+
+## Common Pitfalls
+
+- Never use `.Wait()`, `.Result`, or `.GetAwaiter().GetResult()` in async code
+- Avoid mixing blocking and async code
+- Don't create async void methods (except for event handlers)
+- Always await Task-returning methods
+
+## Implementation Patterns
+
+- Implement the async command pattern for long-running operations
+- Use async streams (IAsyncEnumerable<T>) for processing sequences asynchronously
+- Consider the task-based asynchronous pattern (TAP) for public APIs
+
+When reviewing my C# code, identify these issues and suggest improvements that follow these best practices.

MusifyBackend/.agents/skills/csharp-docs/SKILL.md

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+---
+name: csharp-docs
+description: 'Ensure that C# types are documented with XML comments and follow best practices for documentation.'
+---
+
+# C# Documentation Best Practices
+
+- Public members should be documented with XML comments.
+- It is encouraged to document internal members as well, especially if they are complex or not self-explanatory.
+
+## Guidance for all APIs
+
+- Use `<summary>` to provide a brief, one sentence, description of what the type or member does. Start the summary with a present-tense, third-person verb.
+- Use `<remarks>` for additional information, which can include implementation details, usage notes, or any other relevant context.
+- Use `<see langword>` for language-specific keywords like `null`, `true`, `false`, `int`, `bool`, etc.
+- Use `<c>` for inline code snippets.
+- Use `<example>` for usage examples on how to use the member.
+  - Use `<code>` for code blocks. `<code>` tags should be placed within an `<example>` tag. Add the language of the code example using the `language` attribute, for example, `<code language="csharp">`.
+- Use `<see cref>` to reference other types or members inline (in a sentence).
+- Use `<seealso>` for standalone (not in a sentence) references to other types or members in the "See also" section of the online docs.
+- Use `<inheritdoc/>` to inherit documentation from base classes or interfaces.
+  - Unless there is major behavior change, in which case you should document the differences.
+
+## Methods
+
+- Use `<param>` to describe method parameters.
+  - The description should be a noun phrase that doesn't specify the data type.
+  - Begin with an introductory article.
+  - If the parameter is a flag enum, start the description with "A bitwise combination of the enumeration values that specifies...".
+  - If the parameter is a non-flag enum, start the description with "One of the enumeration values that specifies...".
+  - If the parameter is a Boolean, the wording should be of the form "`<see langword="true" />` to ...; otherwise, `<see langword="false" />`.".
+  - If the parameter is an "out" parameter, the wording should be of the form "When this method returns, contains .... This parameter is treated as uninitialized.".
+- Use `<paramref>` to reference parameter names in documentation.
+- Use `<typeparam>` to describe type parameters in generic types or methods.
+- Use `<typeparamref>` to reference type parameters in documentation.
+- Use `<returns>` to describe what the method returns.
+  - The description should be a noun phrase that doesn't specify the data type.
+  - Begin with an introductory article.
+  - If the return type is Boolean, the wording should be of the form "`<see langword="true" />` if ...; otherwise, `<see langword="false" />`.".
+
+## Constructors
+
+- The summary wording should be "Initializes a new instance of the <Class> class [or struct].".
+
+## Properties
+
+- The `<summary>` should start with:
+  - "Gets or sets..." for a read-write property.
+  - "Gets..." for a read-only property.
+  - "Gets [or sets] a value that indicates whether..." for properties that return a Boolean value.
+- Use `<value>` to describe the value of the property.
+  - The description should be a noun phrase that doesn't specify the data type.
+  - If the property has a default value, add it in a separate sentence, for example, "The default is `<see langword="false" />`".
+  - If the value type is Boolean, the wording should be of the form "`<see langword="true" />` if ...; otherwise, `<see langword="false" />`. The default is ...".
+
+## Exceptions
+
+- Use `<exception cref>` to document exceptions thrown by constructors, properties, indexers, methods, operators, and events.
+- Document all exceptions thrown directly by the member.
+- For exceptions thrown by nested members, document only the exceptions users are most likely to encounter.
+- The description of the exception describes the condition under which it's thrown.
+  - Omit "Thrown if ..." or "If ..." at the beginning of the sentence. Just state the condition directly, for example "An error occurred when accessing a Message Queuing API."

MusifyBackend/.agents/skills/csharp-mstest/SKILL.md

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+---
+name: csharp-mstest
+description: 'Get best practices for MSTest 3.x/4.x unit testing, including modern assertion APIs and data-driven tests'
+---
+
+# MSTest Best Practices (MSTest 3.x/4.x)
+
+Your goal is to help me write effective unit tests with modern MSTest, using current APIs and best practices.
+
+## Project Setup
+
+- Use a separate test project with naming convention `[ProjectName].Tests`
+- Reference MSTest 3.x+ NuGet packages (includes analyzers)
+- Consider using MSTest.Sdk for simplified project setup
+- Run tests with `dotnet test`
+
+## Test Class Structure
+
+- Use `[TestClass]` attribute for test classes
+- **Seal test classes by default** for performance and design clarity
+- Use `[TestMethod]` for test methods (prefer over `[DataTestMethod]`)
+- Follow Arrange-Act-Assert (AAA) pattern
+- Name tests using pattern `MethodName_Scenario_ExpectedBehavior`
+
+```csharp
+[TestClass]
+public sealed class CalculatorTests
+{
+    [TestMethod]
+    public void Add_TwoPositiveNumbers_ReturnsSum()
+    {
+        // Arrange
+        var calculator = new Calculator();
+
+        // Act
+        var result = calculator.Add(2, 3);
+
+        // Assert
+        Assert.AreEqual(5, result);
+    }
+}
+```
+
+## Test Lifecycle
+
+- **Prefer constructors over `[TestInitialize]`** - enables `readonly` fields and follows standard C# patterns
+- Use `[TestCleanup]` for cleanup that must run even if test fails
+- Combine constructor with async `[TestInitialize]` when async setup is needed
+
+```csharp
+[TestClass]
+public sealed class ServiceTests
+{
+    private readonly MyService _service;  // readonly enabled by constructor
+
+    public ServiceTests()
+    {
+        _service = new MyService();
+    }
+
+    [TestInitialize]
+    public async Task InitAsync()
+    {
+        // Use for async initialization only
+        await _service.WarmupAsync();
+    }
+
+    [TestCleanup]
+    public void Cleanup() => _service.Reset();
+}
+```
+
+### Execution Order
+
+1. **Assembly Initialization** - `[AssemblyInitialize]` (once per test assembly)
+2. **Class Initialization** - `[ClassInitialize]` (once per test class)
+3. **Test Initialization** (for every test method):
+   1. Constructor
+   2. Set `TestContext` property
+   3. `[TestInitialize]`
+4. **Test Execution** - test method runs
+5. **Test Cleanup** (for every test method):
+   1. `[TestCleanup]`
+   2. `DisposeAsync` (if implemented)
+   3. `Dispose` (if implemented)
+6. **Class Cleanup** - `[ClassCleanup]` (once per test class)
+7. **Assembly Cleanup** - `[AssemblyCleanup]` (once per test assembly)
+
+## Modern Assertion APIs
+
+MSTest provides three assertion classes: `Assert`, `StringAssert`, and `CollectionAssert`.
+
+### Assert Class - Core Assertions
+
+```csharp
+// Equality
+Assert.AreEqual(expected, actual);
+Assert.AreNotEqual(notExpected, actual);
+Assert.AreSame(expectedObject, actualObject);      // Reference equality
+Assert.AreNotSame(notExpectedObject, actualObject);
+
+// Null checks
+Assert.IsNull(value);
+Assert.IsNotNull(value);
+
+// Boolean
+Assert.IsTrue(condition);
+Assert.IsFalse(condition);
+
+// Fail/Inconclusive
+Assert.Fail("Test failed due to...");
+Assert.Inconclusive("Test cannot be completed because...");
+```
+
+### Exception Testing (Prefer over `[ExpectedException]`)
+
+```csharp
+// Assert.Throws - matches TException or derived types
+var ex = Assert.Throws<ArgumentException>(() => Method(null));
+Assert.AreEqual("Value cannot be null.", ex.Message);
+
+// Assert.ThrowsExactly - matches exact type only
+var ex = Assert.ThrowsExactly<InvalidOperationException>(() => Method());
+
+// Async versions
+var ex = await Assert.ThrowsAsync<HttpRequestException>(async () => await client.GetAsync(url));
+var ex = await Assert.ThrowsExactlyAsync<InvalidOperationException>(async () => await Method());
+```
+
+### Collection Assertions (Assert class)
+
+```csharp
+Assert.Contains(expectedItem, collection);
+Assert.DoesNotContain(unexpectedItem, collection);
+Assert.ContainsSingle(collection);  // exactly one element
+Assert.HasCount(5, collection);
+Assert.IsEmpty(collection);
+Assert.IsNotEmpty(collection);
+```
+
+### String Assertions (Assert class)
+
+```csharp
+Assert.Contains("expected", actualString);
+Assert.StartsWith("prefix", actualString);
+Assert.EndsWith("suffix", actualString);
+Assert.DoesNotStartWith("prefix", actualString);
+Assert.DoesNotEndWith("suffix", actualString);
+Assert.MatchesRegex(@"\d{3}-\d{4}", phoneNumber);
+Assert.DoesNotMatchRegex(@"\d+", textOnly);
+```
+
+### Comparison Assertions
+
+```csharp
+Assert.IsGreaterThan(lowerBound, actual);
+Assert.IsGreaterThanOrEqualTo(lowerBound, actual);
+Assert.IsLessThan(upperBound, actual);
+Assert.IsLessThanOrEqualTo(upperBound, actual);
+Assert.IsInRange(actual, low, high);
+Assert.IsPositive(number);
+Assert.IsNegative(number);
+```
+
+### Type Assertions
+
+```csharp
+// MSTest 3.x - uses out parameter
+Assert.IsInstanceOfType<MyClass>(obj, out var typed);
+typed.DoSomething();
+
+// MSTest 4.x - returns typed result directly
+var typed = Assert.IsInstanceOfType<MyClass>(obj);
+typed.DoSomething();
+
+Assert.IsNotInstanceOfType<WrongType>(obj);
+```
+
+### Assert.That (MSTest 4.0+)
+
+```csharp
+Assert.That(result.Count > 0);  // Auto-captures expression in failure message
+```
+
+### StringAssert Class
+
+> **Note:** Prefer `Assert` class equivalents when available (e.g., `Assert.Contains("expected", actual)` over `StringAssert.Contains(actual, "expected")`).
+
+```csharp
+StringAssert.Contains(actualString, "expected");
+StringAssert.StartsWith(actualString, "prefix");
+StringAssert.EndsWith(actualString, "suffix");
+StringAssert.Matches(actualString, new Regex(@"\d{3}-\d{4}"));
+StringAssert.DoesNotMatch(actualString, new Regex(@"\d+"));
+```
+
+### CollectionAssert Class
+
+> **Note:** Prefer `Assert` class equivalents when available (e.g., `Assert.Contains`).
+
+```csharp
+// Containment
+CollectionAssert.Contains(collection, expectedItem);
+CollectionAssert.DoesNotContain(collection, unexpectedItem);
+
+// Equality (same elements, same order)
+CollectionAssert.AreEqual(expectedCollection, actualCollection);
+CollectionAssert.AreNotEqual(unexpectedCollection, actualCollection);
+
+// Equivalence (same elements, any order)
+CollectionAssert.AreEquivalent(expectedCollection, actualCollection);
+CollectionAssert.AreNotEquivalent(unexpectedCollection, actualCollection);
+
+// Subset checks
+CollectionAssert.IsSubsetOf(subset, superset);
+CollectionAssert.IsNotSubsetOf(notSubset, collection);
+
+// Element validation
+CollectionAssert.AllItemsAreInstancesOfType(collection, typeof(MyClass));
+CollectionAssert.AllItemsAreNotNull(collection);
+CollectionAssert.AllItemsAreUnique(collection);
+```
+
+## Data-Driven Tests
+
+### DataRow
+
+```csharp
+[TestMethod]
+[DataRow(1, 2, 3)]
+[DataRow(0, 0, 0, DisplayName = "Zeros")]
+[DataRow(-1, 1, 0, IgnoreMessage = "Known issue #123")]  // MSTest 3.8+
+public void Add_ReturnsSum(int a, int b, int expected)
+{
+    Assert.AreEqual(expected, Calculator.Add(a, b));
+}
+```
+
+### DynamicData
+
+The data source can return any of the following types:
+
+- `IEnumerable<(T1, T2, ...)>` (ValueTuple) - **preferred**, provides type safety (MSTest 3.7+)
+- `IEnumerable<Tuple<T1, T2, ...>>` - provides type safety
+- `IEnumerable<TestDataRow>` - provides type safety plus control over test metadata (display name, categories)
+- `IEnumerable<object[]>` - **least preferred**, no type safety
+
+> **Note:** When creating new test data methods, prefer `ValueTuple` or `TestDataRow` over `IEnumerable<object[]>`. The `object[]` approach provides no compile-time type checking and can lead to runtime errors from type mismatches.
+
+```csharp
+[TestMethod]
+[DynamicData(nameof(TestData))]
+public void DynamicTest(int a, int b, int expected)
+{
+    Assert.AreEqual(expected, Calculator.Add(a, b));
+}
+
+// ValueTuple - preferred (MSTest 3.7+)
+public static IEnumerable<(int a, int b, int expected)> TestData =>
+[
+    (1, 2, 3),
+    (0, 0, 0),
+];
+
+// TestDataRow - when you need custom display names or metadata
+public static IEnumerable<TestDataRow<(int a, int b, int expected)>> TestDataWithMetadata =>
+[
+    new((1, 2, 3)) { DisplayName = "Positive numbers" },
+    new((0, 0, 0)) { DisplayName = "Zeros" },
+    new((-1, 1, 0)) { DisplayName = "Mixed signs", IgnoreMessage = "Known issue #123" },
+];
+
+// IEnumerable<object[]> - avoid for new code (no type safety)
+public static IEnumerable<object[]> LegacyTestData =>
+[
+    [1, 2, 3],
+    [0, 0, 0],
+];
+```
+
+## TestContext
+
+The `TestContext` class provides test run information, cancellation support, and output methods.
+See [TestContext documentation](https://learn.microsoft.com/dotnet/core/testing/unit-testing-mstest-writing-tests-testcontext) for complete reference.
+
+### Accessing TestContext
+
+```csharp
+// Property (MSTest suppresses CS8618 - don't use nullable or = null!)
+public TestContext TestContext { get; set; }
+
+// Constructor injection (MSTest 3.6+) - preferred for immutability
+[TestClass]
+public sealed class MyTests
+{
+    private readonly TestContext _testContext;
+
+    public MyTests(TestContext testContext)
+    {
+        _testContext = testContext;
+    }
+}
+
+// Static methods receive it as parameter
+[ClassInitialize]
+public static void ClassInit(TestContext context) { }
+
+// Optional for cleanup methods (MSTest 3.6+)
+[ClassCleanup]
+public static void ClassCleanup(TestContext context) { }
+
+[AssemblyCleanup]
+public static void AssemblyCleanup(TestContext context) { }
+```
+
+### Cancellation Token
+
+Always use `TestContext.CancellationToken` for cooperative cancellation with `[Timeout]`:
+
+```csharp
+[TestMethod]
+[Timeout(5000)]
+public async Task LongRunningTest()
+{
+    await _httpClient.GetAsync(url, TestContext.CancellationToken);
+}
+```
+
+### Test Run Properties
+
+```csharp
+TestContext.TestName              // Current test method name
+TestContext.TestDisplayName       // Display name (3.7+)
+TestContext.CurrentTestOutcome    // Pass/Fail/InProgress
+TestContext.TestData              // Parameterized test data (3.7+, in TestInitialize/Cleanup)
+TestContext.TestException         // Exception if test failed (3.7+, in TestCleanup)
+TestContext.DeploymentDirectory   // Directory with deployment items
+```
+
+### Output and Result Files
+
+```csharp
+// Write to test output (useful for debugging)
+TestContext.WriteLine("Processing item {0}", itemId);
+
+// Attach files to test results (logs, screenshots)
+TestContext.AddResultFile(screenshotPath);
+
+// Store/retrieve data across test methods
+TestContext.Properties["SharedKey"] = computedValue;
+```
+
+## Advanced Features
+
+### Retry for Flaky Tests (MSTest 3.9+)
+
+```csharp
+[TestMethod]
+[Retry(3)]
+public void FlakyTest() { }
+```
+
+### Conditional Execution (MSTest 3.10+)
+
+Skip or run tests based on OS or CI environment:
+
+```csharp
+// OS-specific tests
+[TestMethod]
+[OSCondition(OperatingSystems.Windows)]
+public void WindowsOnlyTest() { }
+
+[TestMethod]
+[OSCondition(OperatingSystems.Linux | OperatingSystems.MacOS)]
+public void UnixOnlyTest() { }
+
+[TestMethod]
+[OSCondition(ConditionMode.Exclude, OperatingSystems.Windows)]
+public void SkipOnWindowsTest() { }
+
+// CI environment tests
+[TestMethod]
+[CICondition]  // Runs only in CI (default: ConditionMode.Include)
+public void CIOnlyTest() { }
+
+[TestMethod]
+[CICondition(ConditionMode.Exclude)]  // Skips in CI, runs locally
+public void LocalOnlyTest() { }
+```
+
+### Parallelization
+
+```csharp
+// Assembly level
+[assembly: Parallelize(Workers = 4, Scope = ExecutionScope.MethodLevel)]
+
+// Disable for specific class
+[TestClass]
+[DoNotParallelize]
+public sealed class SequentialTests { }
+```
+
+### Work Item Traceability (MSTest 3.8+)
+
+Link tests to work items for traceability in test reports:
+
+```csharp
+// Azure DevOps work items
+[TestMethod]
+[WorkItem(12345)]  // Links to work item #12345
+public void Feature_Scenario_ExpectedBehavior() { }
+
+// Multiple work items
+[TestMethod]
+[WorkItem(12345)]
+[WorkItem(67890)]
+public void Feature_CoversMultipleRequirements() { }
+
+// GitHub issues (MSTest 3.8+)
+[TestMethod]
+[GitHubWorkItem("https://github.com/owner/repo/issues/42")]
+public void BugFix_Issue42_IsResolved() { }
+```
+
+Work item associations appear in test results and can be used for:
+- Tracing test coverage to requirements
+- Linking bug fixes to regression tests
+- Generating traceability reports in CI/CD pipelines
+
+## Common Mistakes to Avoid
+
+```csharp
+// ❌ Wrong argument order
+Assert.AreEqual(actual, expected);
+// ✅ Correct
+Assert.AreEqual(expected, actual);
+
+// ❌ Using ExpectedException (obsolete)
+[ExpectedException(typeof(ArgumentException))]
+// ✅ Use Assert.Throws
+Assert.Throws<ArgumentException>(() => Method());
+
+// ❌ Using LINQ Single() - unclear exception
+var item = items.Single();
+// ✅ Use ContainsSingle - better failure message
+var item = Assert.ContainsSingle(items);
+
+// ❌ Hard cast - unclear exception
+var handler = (MyHandler)result;
+// ✅ Type assertion - shows actual type on failure
+var handler = Assert.IsInstanceOfType<MyHandler>(result);
+
+// ❌ Ignoring cancellation token
+await client.GetAsync(url, CancellationToken.None);
+// ✅ Flow test cancellation
+await client.GetAsync(url, TestContext.CancellationToken);
+
+// ❌ Making TestContext nullable - leads to unnecessary null checks
+public TestContext? TestContext { get; set; }
+// ❌ Using null! - MSTest already suppresses CS8618 for this property
+public TestContext TestContext { get; set; } = null!;
+// ✅ Declare without nullable or initializer - MSTest handles the warning
+public TestContext TestContext { get; set; }
+```
+
+## Test Organization
+
+- Group tests by feature or component
+- Use `[TestCategory("Category")]` for filtering
+- Use `[TestProperty("Name", "Value")]` for custom metadata (e.g., `[TestProperty("Bug", "12345")]`)
+- Use `[Priority(1)]` for critical tests
+- Enable relevant MSTest analyzers (MSTEST0020 for constructor preference)
+
+## Mocking and Isolation
+
+- Use Moq or NSubstitute for mocking dependencies
+- Use interfaces to facilitate mocking
+- Mock dependencies to isolate units under test

MusifyBackend/.agents/skills/csharp-nunit/SKILL.md

@@ -0,0 +1,71 @@
+---
+name: csharp-nunit
+description: 'Get best practices for NUnit unit testing, including data-driven tests'
+---
+
+# NUnit Best Practices
+
+Your goal is to help me write effective unit tests with NUnit, covering both standard and data-driven testing approaches.
+
+## Project Setup
+
+- Use a separate test project with naming convention `[ProjectName].Tests`
+- Reference Microsoft.NET.Test.Sdk, NUnit, and NUnit3TestAdapter packages
+- Create test classes that match the classes being tested (e.g., `CalculatorTests` for `Calculator`)
+- Use .NET SDK test commands: `dotnet test` for running tests
+
+## Test Structure
+
+- Apply `[TestFixture]` attribute to test classes
+- Use `[Test]` attribute for test methods
+- Follow the Arrange-Act-Assert (AAA) pattern
+- Name tests using the pattern `MethodName_Scenario_ExpectedBehavior`
+- Use `[SetUp]` and `[TearDown]` for per-test setup and teardown
+- Use `[OneTimeSetUp]` and `[OneTimeTearDown]` for per-class setup and teardown
+- Use `[SetUpFixture]` for assembly-level setup and teardown
+
+## Standard Tests
+
+- Keep tests focused on a single behavior
+- Avoid testing multiple behaviors in one test method
+- Use clear assertions that express intent
+- Include only the assertions needed to verify the test case
+- Make tests independent and idempotent (can run in any order)
+- Avoid test interdependencies
+
+## Data-Driven Tests
+
+- Use `[TestCase]` for inline test data
+- Use `[TestCaseSource]` for programmatically generated test data
+- Use `[Values]` for simple parameter combinations
+- Use `[ValueSource]` for property or method-based data sources
+- Use `[Random]` for random numeric test values
+- Use `[Range]` for sequential numeric test values
+- Use `[Combinatorial]` or `[Pairwise]` for combining multiple parameters
+
+## Assertions
+
+- Use `Assert.That` with constraint model (preferred NUnit style)
+- Use constraints like `Is.EqualTo`, `Is.SameAs`, `Contains.Item`
+- Use `Assert.AreEqual` for simple value equality (classic style)
+- Use `CollectionAssert` for collection comparisons
+- Use `StringAssert` for string-specific assertions
+- Use `Assert.Throws<T>` or `Assert.ThrowsAsync<T>` to test exceptions
+- Use descriptive messages in assertions for clarity on failure
+
+## Mocking and Isolation
+
+- Consider using Moq or NSubstitute alongside NUnit
+- Mock dependencies to isolate units under test
+- Use interfaces to facilitate mocking
+- Consider using a DI container for complex test setups
+
+## Test Organization
+
+- Group tests by feature or component
+- Use categories with `[Category("CategoryName")]`
+- Use `[Order]` to control test execution order when necessary
+- Use `[Author("DeveloperName")]` to indicate ownership
+- Use `[Description]` to provide additional test information
+- Consider `[Explicit]` for tests that shouldn't run automatically
+- Use `[Ignore("Reason")]` to temporarily skip tests

MusifyBackend/.agents/skills/csharp-tunit/SKILL.md

@@ -0,0 +1,100 @@
+---
+name: csharp-tunit
+description: 'Get best practices for TUnit unit testing, including data-driven tests'
+---
+
+# TUnit Best Practices
+
+Your goal is to help me write effective unit tests with TUnit, covering both standard and data-driven testing approaches.
+
+## Project Setup
+
+- Use a separate test project with naming convention `[ProjectName].Tests`
+- Reference TUnit package and TUnit.Assertions for fluent assertions
+- Create test classes that match the classes being tested (e.g., `CalculatorTests` for `Calculator`)
+- Use .NET SDK test commands: `dotnet test` for running tests
+- TUnit requires .NET 8.0 or higher
+
+## Test Structure
+
+- No test class attributes required (like xUnit/NUnit)
+- Use `[Test]` attribute for test methods (not `[Fact]` like xUnit)
+- Follow the Arrange-Act-Assert (AAA) pattern
+- Name tests using the pattern `MethodName_Scenario_ExpectedBehavior`
+- Use lifecycle hooks: `[Before(Test)]` for setup and `[After(Test)]` for teardown
+- Use `[Before(Class)]` and `[After(Class)]` for shared context between tests in a class
+- Use `[Before(Assembly)]` and `[After(Assembly)]` for shared context across test classes
+- TUnit supports advanced lifecycle hooks like `[Before(TestSession)]` and `[After(TestSession)]`
+
+## Standard Tests
+
+- Keep tests focused on a single behavior
+- Avoid testing multiple behaviors in one test method
+- Use TUnit's fluent assertion syntax with `await Assert.That()`
+- Include only the assertions needed to verify the test case
+- Make tests independent and idempotent (can run in any order)
+- Avoid test interdependencies (use `[DependsOn]` attribute if needed)
+
+## Data-Driven Tests
+
+- Use `[Arguments]` attribute for inline test data (equivalent to xUnit's `[InlineData]`)
+- Use `[MethodData]` for method-based test data (equivalent to xUnit's `[MemberData]`)
+- Use `[ClassData]` for class-based test data
+- Create custom data sources by implementing `ITestDataSource`
+- Use meaningful parameter names in data-driven tests
+- Multiple `[Arguments]` attributes can be applied to the same test method
+
+## Assertions
+
+- Use `await Assert.That(value).IsEqualTo(expected)` for value equality
+- Use `await Assert.That(value).IsSameReferenceAs(expected)` for reference equality
+- Use `await Assert.That(value).IsTrue()` or `await Assert.That(value).IsFalse()` for boolean conditions
+- Use `await Assert.That(collection).Contains(item)` or `await Assert.That(collection).DoesNotContain(item)` for collections
+- Use `await Assert.That(value).Matches(pattern)` for regex pattern matching
+- Use `await Assert.That(action).Throws<TException>()` or `await Assert.That(asyncAction).ThrowsAsync<TException>()` to test exceptions
+- Chain assertions with `.And` operator: `await Assert.That(value).IsNotNull().And.IsEqualTo(expected)`
+- Use `.Or` operator for alternative conditions: `await Assert.That(value).IsEqualTo(1).Or.IsEqualTo(2)`
+- Use `.Within(tolerance)` for DateTime and numeric comparisons with tolerance
+- All assertions are asynchronous and must be awaited
+
+## Advanced Features
+
+- Use `[Repeat(n)]` to repeat tests multiple times
+- Use `[Retry(n)]` for automatic retry on failure
+- Use `[ParallelLimit<T>]` to control parallel execution limits
+- Use `[Skip("reason")]` to skip tests conditionally
+- Use `[DependsOn(nameof(OtherTest))]` to create test dependencies
+- Use `[Timeout(milliseconds)]` to set test timeouts
+- Create custom attributes by extending TUnit's base attributes
+
+## Test Organization
+
+- Group tests by feature or component
+- Use `[Category("CategoryName")]` for test categorization
+- Use `[DisplayName("Custom Test Name")]` for custom test names
+- Consider using `TestContext` for test diagnostics and information
+- Use conditional attributes like custom `[WindowsOnly]` for platform-specific tests
+
+## Performance and Parallel Execution
+
+- TUnit runs tests in parallel by default (unlike xUnit which requires explicit configuration)
+- Use `[NotInParallel]` to disable parallel execution for specific tests
+- Use `[ParallelLimit<T>]` with custom limit classes to control concurrency
+- Tests within the same class run sequentially by default
+- Use `[Repeat(n)]` with `[ParallelLimit<T>]` for load testing scenarios
+
+## Migration from xUnit
+
+- Replace `[Fact]` with `[Test]`
+- Replace `[Theory]` with `[Test]` and use `[Arguments]` for data
+- Replace `[InlineData]` with `[Arguments]`
+- Replace `[MemberData]` with `[MethodData]`
+- Replace `Assert.Equal` with `await Assert.That(actual).IsEqualTo(expected)`
+- Replace `Assert.True` with `await Assert.That(condition).IsTrue()`
+- Replace `Assert.Throws<T>` with `await Assert.That(action).Throws<T>()`
+- Replace constructor/IDisposable with `[Before(Test)]`/`[After(Test)]`
+- Replace `IClassFixture<T>` with `[Before(Class)]`/`[After(Class)]`
+
+**Why TUnit over xUnit?**
+
+TUnit offers a modern, fast, and flexible testing experience with advanced features not present in xUnit, such as asynchronous assertions, more refined lifecycle hooks, and improved data-driven testing capabilities. TUnit's fluent assertions provide clearer and more expressive test validation, making it especially suitable for complex .NET projects.

MusifyBackend/.agents/skills/csharp-xunit/SKILL.md

@@ -0,0 +1,68 @@
+---
+name: csharp-xunit
+description: 'Get best practices for XUnit unit testing, including data-driven tests'
+---
+
+# XUnit Best Practices
+
+Your goal is to help me write effective unit tests with XUnit, covering both standard and data-driven testing approaches.
+
+## Project Setup
+
+- Use a separate test project with naming convention `[ProjectName].Tests`
+- Reference Microsoft.NET.Test.Sdk, xunit, and xunit.runner.visualstudio packages
+- Create test classes that match the classes being tested (e.g., `CalculatorTests` for `Calculator`)
+- Use .NET SDK test commands: `dotnet test` for running tests
+
+## Test Structure
+
+- No test class attributes required (unlike MSTest/NUnit)
+- Use fact-based tests with `[Fact]` attribute for simple tests
+- Follow the Arrange-Act-Assert (AAA) pattern
+- Name tests using the pattern `MethodName_Scenario_ExpectedBehavior`
+- Use constructor for setup and `IDisposable.Dispose()` for teardown
+- Use `IClassFixture<T>` for shared context between tests in a class
+- Use `ICollectionFixture<T>` for shared context between multiple test classes
+
+## Standard Tests
+
+- Keep tests focused on a single behavior
+- Avoid testing multiple behaviors in one test method
+- Use clear assertions that express intent
+- Include only the assertions needed to verify the test case
+- Make tests independent and idempotent (can run in any order)
+- Avoid test interdependencies
+
+## Data-Driven Tests
+
+- Use `[Theory]` combined with data source attributes
+- Use `[InlineData]` for inline test data
+- Use `[MemberData]` for method-based test data
+- Use `[ClassData]` for class-based test data
+- Create custom data attributes by implementing `DataAttribute`
+- Use meaningful parameter names in data-driven tests
+
+## Assertions
+
+- Use `Assert.Equal` for value equality
+- Use `Assert.Same` for reference equality
+- Use `Assert.True`/`Assert.False` for boolean conditions
+- Use `Assert.Contains`/`Assert.DoesNotContain` for collections
+- Use `Assert.Matches`/`Assert.DoesNotMatch` for regex pattern matching
+- Use `Assert.Throws<T>` or `await Assert.ThrowsAsync<T>` to test exceptions
+- Use fluent assertions library for more readable assertions
+
+## Mocking and Isolation
+
+- Consider using Moq or NSubstitute alongside XUnit
+- Mock dependencies to isolate units under test
+- Use interfaces to facilitate mocking
+- Consider using a DI container for complex test setups
+
+## Test Organization
+
+- Group tests by feature or component
+- Use `[Trait("Category", "CategoryName")]` for categorization
+- Use collection fixtures to group tests with shared dependencies
+- Consider output helpers (`ITestOutputHelper`) for test diagnostics
+- Skip tests conditionally with `Skip = "reason"` in fact/theory attributes

MusifyBackend/.agents/skills/dotnet-best-practices/SKILL.md

@@ -0,0 +1,85 @@
+---
+name: dotnet-best-practices
+description: 'Ensure .NET/C# code meets best practices for the solution/project.'
+---
+
+# .NET/C# Best Practices
+
+Your task is to ensure .NET/C# code in ${selection} meets the best practices specific to this solution/project. This includes:
+
+## Documentation & Structure
+
+- Create comprehensive XML documentation comments for all public classes, interfaces, methods, and properties
+- Include parameter descriptions and return value descriptions in XML comments
+- Follow the established namespace structure: {Core|Console|App|Service}.{Feature}
+
+## Design Patterns & Architecture
+
+- Use primary constructor syntax for dependency injection (e.g., `public class MyClass(IDependency dependency)`)
+- Implement the Command Handler pattern with generic base classes (e.g., `CommandHandler<TOptions>`)
+- Use interface segregation with clear naming conventions (prefix interfaces with 'I')
+- Follow the Factory pattern for complex object creation.
+
+## Dependency Injection & Services
+
+- Use constructor dependency injection with null checks via ArgumentNullException
+- Register services with appropriate lifetimes (Singleton, Scoped, Transient)
+- Use Microsoft.Extensions.DependencyInjection patterns
+- Implement service interfaces for testability
+
+## Resource Management & Localization
+
+- Use ResourceManager for localized messages and error strings
+- Separate LogMessages and ErrorMessages resource files
+- Access resources via `_resourceManager.GetString("MessageKey")`
+
+## Async/Await Patterns
+
+- Use async/await for all I/O operations and long-running tasks
+- Return Task or Task<T> from async methods
+- Use ConfigureAwait(false) where appropriate
+- Handle async exceptions properly
+
+## Testing Standards
+
+- Use MSTest framework with FluentAssertions for assertions
+- Follow AAA pattern (Arrange, Act, Assert)
+- Use Moq for mocking dependencies
+- Test both success and failure scenarios
+- Include null parameter validation tests
+
+## Configuration & Settings
+
+- Use strongly-typed configuration classes with data annotations
+- Implement validation attributes (Required, NotEmptyOrWhitespace)
+- Use IConfiguration binding for settings
+- Support appsettings.json configuration files
+
+## Semantic Kernel & AI Integration
+
+- Use Microsoft.SemanticKernel for AI operations
+- Implement proper kernel configuration and service registration
+- Handle AI model settings (ChatCompletion, Embedding, etc.)
+- Use structured output patterns for reliable AI responses
+
+## Error Handling & Logging
+
+- Use structured logging with Microsoft.Extensions.Logging
+- Include scoped logging with meaningful context
+- Throw specific exceptions with descriptive messages
+- Use try-catch blocks for expected failure scenarios
+
+## Performance & Security
+
+- Use C# 12+ features and .NET 8 optimizations where applicable
+- Implement proper input validation and sanitization
+- Use parameterized queries for database operations
+- Follow secure coding practices for AI/ML operations
+
+## Code Quality
+
+- Ensure SOLID principles compliance
+- Avoid code duplication through base classes and utilities
+- Use meaningful names that reflect domain concepts
+- Keep methods focused and cohesive
+- Implement proper disposal patterns for resources

MusifyBackend/.agents/skills/dotnet-design-pattern-review/SKILL.md

@@ -0,0 +1,42 @@
+---
+name: dotnet-design-pattern-review
+description: 'Review the C#/.NET code for design pattern implementation and suggest improvements.'
+---
+
+# .NET/C# Design Pattern Review
+
+Review the C#/.NET code in ${selection} for design pattern implementation and suggest improvements for the solution/project. Do not make any changes to the code, just provide a review.
+
+## Required Design Patterns
+
+- **Command Pattern**: Generic base classes (`CommandHandler<TOptions>`), `ICommandHandler<TOptions>` interface, `CommandHandlerOptions` inheritance, static `SetupCommand(IHost host)` methods
+- **Factory Pattern**: Complex object creation service provider integration
+- **Dependency Injection**: Primary constructor syntax, `ArgumentNullException` null checks, interface abstractions, proper service lifetimes
+- **Repository Pattern**: Async data access interfaces provider abstractions for connections
+- **Provider Pattern**: External service abstractions (database, AI), clear contracts, configuration handling
+- **Resource Pattern**: ResourceManager for localized messages, separate .resx files (LogMessages, ErrorMessages)
+
+## Review Checklist
+
+- **Design Patterns**: Identify patterns used. Are Command Handler, Factory, Provider, and Repository patterns correctly implemented? Missing beneficial patterns?
+- **Architecture**: Follow namespace conventions (`{Core|Console|App|Service}.{Feature}`)? Proper separation between Core/Console projects? Modular and readable?
+- **.NET Best Practices**: Primary constructors, async/await with Task returns, ResourceManager usage, structured logging, strongly-typed configuration?
+- **GoF Patterns**: Command, Factory, Template Method, Strategy patterns correctly implemented?
+- **SOLID Principles**: Single Responsibility, Open/Closed, Liskov Substitution, Interface Segregation, Dependency Inversion violations?
+- **Performance**: Proper async/await, resource disposal, ConfigureAwait(false), parallel processing opportunities?
+- **Maintainability**: Clear separation of concerns, consistent error handling, proper configuration usage?
+- **Testability**: Dependencies abstracted via interfaces, mockable components, async testability, AAA pattern compatibility?
+- **Security**: Input validation, secure credential handling, parameterized queries, safe exception handling?
+- **Documentation**: XML docs for public APIs, parameter/return descriptions, resource file organization?
+- **Code Clarity**: Meaningful names reflecting domain concepts, clear intent through patterns, self-explanatory structure?
+- **Clean Code**: Consistent style, appropriate method/class size, minimal complexity, eliminated duplication?
+
+## Improvement Focus Areas
+
+- **Command Handlers**: Validation in base class, consistent error handling, proper resource management
+- **Factories**: Dependency configuration, service provider integration, disposal patterns
+- **Providers**: Connection management, async patterns, exception handling and logging
+- **Configuration**: Data annotations, validation attributes, secure sensitive value handling
+- **AI/ML Integration**: Semantic Kernel patterns, structured output handling, model configuration
+
+Provide specific, actionable recommendations for improvements aligned with the project's architecture and .NET best practices.

MusifyBackend/.agents/skills/dotnet-upgrade/SKILL.md

@@ -0,0 +1,116 @@
+---
+name: dotnet-upgrade
+description: 'Ready-to-use prompts for comprehensive .NET framework upgrade analysis and execution'
+---
+
+# Project Discovery & Assessment
+  - name: "Project Classification Analysis"
+    prompt: "Identify all projects in the solution and classify them by type (`.NET Framework`, `.NET Core`, `.NET Standard`). Analyze each `.csproj` for its current `TargetFramework` and SDK usage."
+
+  - name: "Dependency Compatibility Review"
+    prompt: "Review external and internal dependencies for framework compatibility. Determine the upgrade complexity based on dependency graph depth."
+
+  - name: "Legacy Package Detection"
+    prompt: "Identify legacy `packages.config` projects needing migration to `PackageReference` format."
+
+  # Upgrade Strategy & Sequencing
+  - name: "Project Upgrade Ordering"
+    prompt: "Recommend a project upgrade order from least to most dependent components. Suggest how to isolate class library upgrades before API or Azure Function migrations."
+
+  - name: "Incremental Strategy Planning"
+    prompt: "Propose an incremental upgrade strategy with rollback checkpoints. Evaluate the use of **Upgrade Assistant** or **manual upgrades** based on project structure."
+
+  - name: "Progress Tracking Setup"
+    prompt: "Generate an upgrade checklist for tracking build, test, and deployment readiness across all projects."
+
+  # Framework Targeting & Code Adjustments
+  - name: "Target Framework Selection"
+    prompt: "Suggest the correct `TargetFramework` for each project (e.g., `net8.0`). Review and update deprecated SDK or build configurations."
+
+  - name: "Code Modernization Analysis"
+    prompt: "Identify code patterns needing modernization (e.g., `WebHostBuilder` → `HostBuilder`). Suggest replacements for deprecated .NET APIs and third-party libraries."
+
+  - name: "Async Pattern Conversion"
+    prompt: "Recommend conversion of synchronous calls to async where appropriate for improved performance and scalability."
+
+  # NuGet & Dependency Management
+  - name: "Package Compatibility Analysis"
+    prompt: "Analyze outdated or incompatible NuGet packages and suggest compatible versions. Identify third-party libraries that lack .NET 8 support and provide migration paths."
+
+  - name: "Shared Dependency Strategy"
+    prompt: "Recommend strategies for handling shared dependency upgrades across projects. Evaluate usage of legacy packages and suggest alternatives in Microsoft-supported namespaces."
+
+  - name: "Transitive Dependency Review"
+    prompt: "Review transitive dependencies and potential version conflicts after upgrade. Suggest resolution strategies for dependency conflicts."
+
+  # CI/CD & Build Pipeline Updates
+  - name: "Pipeline Configuration Analysis"
+    prompt: "Analyze YAML build definitions for SDK version pinning and recommend updates. Suggest modifications for `UseDotNet@2` and `NuGetToolInstaller` tasks."
+
+  - name: "Build Pipeline Modernization"
+    prompt: "Generate updated build pipeline snippets for .NET 8 migration. Recommend validation builds on feature branches before merging to main."
+
+  - name: "CI Automation Enhancement"
+    prompt: "Identify opportunities to automate test and build verification in CI pipelines. Suggest strategies for continuous integration validation."
+
+  # Testing & Validation
+  - name: "Build Validation Strategy"
+    prompt: "Propose validation checks to ensure the upgraded solution builds and runs successfully. Recommend automated test execution for unit and integration suites post-upgrade."
+
+  - name: "Service Integration Verification"
+    prompt: "Generate validation steps to verify logging, telemetry, and service connectivity. Suggest strategies for verifying backward compatibility and runtime behavior."
+
+  - name: "Deployment Readiness Check"
+    prompt: "Recommend UAT deployment verification steps before production rollout. Create comprehensive testing scenarios for upgraded components."
+
+  # Breaking Change Analysis
+  - name: "API Deprecation Detection"
+    prompt: "Identify deprecated APIs or removed namespaces between target versions. Suggest automated scanning using `.NET Upgrade Assistant` and API Analyzer."
+
+  - name: "API Replacement Strategy"
+    prompt: "Recommend replacement APIs or libraries for known breaking areas. Review configuration changes such as `Startup.cs` → `Program.cs` refactoring."
+
+  - name: "Regression Testing Focus"
+    prompt: "Suggest regression testing scenarios focused on upgraded API endpoints or services. Create test plans for critical functionality validation."
+
+  # Version Control & Commit Strategy
+  - name: "Branching Strategy Planning"
+    prompt: "Recommend branching strategy for safe upgrade with rollback capability. Generate commit templates for partial and complete project upgrades."
+
+  - name: "PR Structure Optimization"
+    prompt: "Suggest best practices for creating structured PRs (`Upgrade to .NET [Version]`). Identify tagging strategies for PRs involving breaking changes."
+
+  - name: "Code Review Guidelines"
+    prompt: "Recommend peer review focus areas (build, test, and dependency validation). Create checklists for effective upgrade reviews."
+
+  # Documentation & Communication
+  - name: "Upgrade Documentation Strategy"
+    prompt: "Suggest how to document each project's framework change in the PR. Propose automated release note generation summarizing upgrades and test results."
+
+  - name: "Stakeholder Communication"
+    prompt: "Recommend communicating version upgrades and migration timelines to consumers. Generate documentation templates for dependency updates and validation results."
+
+  - name: "Progress Tracking Systems"
+    prompt: "Suggest maintaining an upgrade summary dashboard or markdown checklist. Create templates for tracking upgrade progress across multiple projects."
+
+  # Tools & Automation
+  - name: "Upgrade Tool Selection"
+    prompt: "Recommend when and how to use: `.NET Upgrade Assistant`, `dotnet list package --outdated`, `dotnet migrate`, and `graph.json` dependency visualization."
+
+  - name: "Analysis Script Generation"
+    prompt: "Generate scripts or prompts for analyzing dependency graphs before upgrading. Propose AI-assisted prompts for Copilot to identify upgrade issues automatically."
+
+  - name: "Multi-Repository Validation"
+    prompt: "Suggest how to validate automation output across multiple repositories. Create standardized validation workflows for enterprise-scale upgrades."
+
+  # Final Validation & Delivery
+  - name: "Final Solution Validation"
+    prompt: "Generate validation steps to confirm the final upgraded solution passes all validation checks. Suggest production deployment verification steps post-upgrade."
+
+  - name: "Deployment Readiness Confirmation"
+    prompt: "Recommend generating final test results and build artifacts. Create a checklist summarizing completion across projects (builds/tests/deployment)."
+
+  - name: "Release Documentation"
+    prompt: "Generate a release note summarizing framework changes and CI/CD updates. Create comprehensive upgrade summary documentation."
+
+---

MusifyBackend/.github/copilot-instructions.md

@@ -0,0 +1,4 @@
+# Copilot Instructions
+
+## Project Guidelines
+- No crear pruebas/tests si el usuario no lo solicita explícitamente; evitar cambios no pedidos.

MusifyBackend/.gitignore

@@ -0,0 +1,428 @@
+## Ignore Visual Studio temporary files, build results, and
+## files generated by popular Visual Studio add-ons.
+##
+## Get latest from https://github.com/github/gitignore/blob/main/VisualStudio.gitignore
+
+# User-specific files
+*.rsuser
+*.suo
+*.user
+*.userosscache
+*.sln.docstates
+*.env
+
+# User-specific files (MonoDevelop/Xamarin Studio)
+*.userprefs
+
+# Mono auto generated files
+mono_crash.*
+
+# Build results
+[Dd]ebug/
+[Dd]ebugPublic/
+[Rr]elease/
+[Rr]eleases/
+
+[Dd]ebug/x64/
+[Dd]ebugPublic/x64/
+[Rr]elease/x64/
+[Rr]eleases/x64/
+bin/x64/
+obj/x64/
+
+[Dd]ebug/x86/
+[Dd]ebugPublic/x86/
+[Rr]elease/x86/
+[Rr]eleases/x86/
+bin/x86/
+obj/x86/
+
+[Ww][Ii][Nn]32/
+[Aa][Rr][Mm]/
+[Aa][Rr][Mm]64/
+[Aa][Rr][Mm]64[Ee][Cc]/
+bld/
+[Oo]bj/
+[Oo]ut/
+[Ll]og/
+[Ll]ogs/
+
+# Build results on 'Bin' directories
+**/[Bb]in/*
+# Uncomment if you have tasks that rely on *.refresh files to move binaries
+# (https://github.com/github/gitignore/pull/3736)
+#!**/[Bb]in/*.refresh
+
+# Visual Studio 2015/2017 cache/options directory
+.vs/
+# Uncomment if you have tasks that create the project's static files in wwwroot
+#wwwroot/
+
+# Visual Studio 2017 auto generated files
+Generated\ Files/
+
+# MSTest test Results
+[Tt]est[Rr]esult*/
+[Bb]uild[Ll]og.*
+*.trx
+
+# NUnit
+*.VisualState.xml
+TestResult.xml
+nunit-*.xml
+
+# Approval Tests result files
+*.received.*
+
+# Build Results of an ATL Project
+[Dd]ebugPS/
+[Rr]eleasePS/
+dlldata.c
+
+# Benchmark Results
+BenchmarkDotNet.Artifacts/
+
+# .NET Core
+project.lock.json
+project.fragment.lock.json
+artifacts/
+
+# ASP.NET Scaffolding
+ScaffoldingReadMe.txt
+
+# StyleCop
+StyleCopReport.xml
+
+# Files built by Visual Studio
+*_i.c
+*_p.c
+*_h.h
+*.ilk
+*.meta
+*.obj
+*.idb
+*.iobj
+*.pch
+*.pdb
+*.ipdb
+*.pgc
+*.pgd
+*.rsp
+# but not Directory.Build.rsp, as it configures directory-level build defaults
+!Directory.Build.rsp
+*.sbr
+*.tlb
+*.tli
+*.tlh
+*.tmp
+*.tmp_proj
+*_wpftmp.csproj
+*.log
+*.tlog
+*.vspscc
+*.vssscc
+.builds
+*.pidb
+*.svclog
+*.scc
+
+# Chutzpah Test files
+_Chutzpah*
+
+# Visual C++ cache files
+ipch/
+*.aps
+*.ncb
+*.opendb
+*.opensdf
+*.sdf
+*.cachefile
+*.VC.db
+*.VC.VC.opendb
+
+# Visual Studio profiler
+*.psess
+*.vsp
+*.vspx
+*.sap
+
+# Visual Studio Trace Files
+*.e2e
+
+# TFS 2012 Local Workspace
+$tf/
+
+# Guidance Automation Toolkit
+*.gpState
+
+# ReSharper is a .NET coding add-in
+_ReSharper*/
+*.[Rr]e[Ss]harper
+*.DotSettings.user
+
+# TeamCity is a build add-in
+_TeamCity*
+
+# DotCover is a Code Coverage Tool
+*.dotCover
+
+# AxoCover is a Code Coverage Tool
+.axoCover/*
+!.axoCover/settings.json
+
+# Coverlet is a free, cross platform Code Coverage Tool
+coverage*.json
+coverage*.xml
+coverage*.info
+
+# Visual Studio code coverage results
+*.coverage
+*.coveragexml
+
+# NCrunch
+_NCrunch_*
+.NCrunch_*
+.*crunch*.local.xml
+nCrunchTemp_*
+
+# MightyMoose
+*.mm.*
+AutoTest.Net/
+
+# Web workbench (sass)
+.sass-cache/
+
+# Installshield output folder
+[Ee]xpress/
+
+# DocProject is a documentation generator add-in
+DocProject/buildhelp/
+DocProject/Help/*.HxT
+DocProject/Help/*.HxC
+DocProject/Help/*.hhc
+DocProject/Help/*.hhk
+DocProject/Help/*.hhp
+DocProject/Help/Html2
+DocProject/Help/html
+
+# Click-Once directory
+publish/
+
+# Publish Web Output
+*.[Pp]ublish.xml
+*.azurePubxml
+# Note: Comment the next line if you want to checkin your web deploy settings,
+# but database connection strings (with potential passwords) will be unencrypted
+*.pubxml
+*.publishproj
+
+# Microsoft Azure Web App publish settings. Comment the next line if you want to
+# checkin your Azure Web App publish settings, but sensitive information contained
+# in these scripts will be unencrypted
+PublishScripts/
+
+# NuGet Packages
+*.nupkg
+# NuGet Symbol Packages
+*.snupkg
+# The packages folder can be ignored because of Package Restore
+**/[Pp]ackages/*
+# except build/, which is used as an MSBuild target.
+!**/[Pp]ackages/build/
+# Uncomment if necessary however generally it will be regenerated when needed
+#!**/[Pp]ackages/repositories.config
+# NuGet v3's project.json files produces more ignorable files
+*.nuget.props
+*.nuget.targets
+
+# Microsoft Azure Build Output
+csx/
+*.build.csdef
+
+# Microsoft Azure Emulator
+ecf/
+rcf/
+
+# Windows Store app package directories and files
+AppPackages/
+BundleArtifacts/
+Package.StoreAssociation.xml
+_pkginfo.txt
+*.appx
+*.appxbundle
+*.appxupload
+
+# Visual Studio cache files
+# files ending in .cache can be ignored
+*.[Cc]ache
+# but keep track of directories ending in .cache
+!?*.[Cc]ache/
+
+# Others
+ClientBin/
+~$*
+*~
+*.dbmdl
+*.dbproj.schemaview
+*.jfm
+*.pfx
+*.publishsettings
+orleans.codegen.cs
+
+# Including strong name files can present a security risk
+# (https://github.com/github/gitignore/pull/2483#issue-259490424)
+#*.snk
+
+# Since there are multiple workflows, uncomment next line to ignore bower_components
+# (https://github.com/github/gitignore/pull/1529#issuecomment-104372622)
+#bower_components/
+
+# RIA/Silverlight projects
+Generated_Code/
+
+# Backup & report files from converting an old project file
+# to a newer Visual Studio version. Backup files are not needed,
+# because we have git ;-)
+_UpgradeReport_Files/
+Backup*/
+UpgradeLog*.XML
+UpgradeLog*.htm
+ServiceFabricBackup/
+*.rptproj.bak
+
+# SQL Server files
+*.mdf
+*.ldf
+*.ndf
+
+# Business Intelligence projects
+*.rdl.data
+*.bim.layout
+*.bim_*.settings
+*.rptproj.rsuser
+*- [Bb]ackup.rdl
+*- [Bb]ackup ([0-9]).rdl
+*- [Bb]ackup ([0-9][0-9]).rdl
+
+# Microsoft Fakes
+FakesAssemblies/
+
+# GhostDoc plugin setting file
+*.GhostDoc.xml
+
+# Node.js Tools for Visual Studio
+.ntvs_analysis.dat
+node_modules/
+
+# Visual Studio 6 build log
+*.plg
+
+# Visual Studio 6 workspace options file
+*.opt
+
+# Visual Studio 6 auto-generated workspace file (contains which files were open etc.)
+*.vbw
+
+# Visual Studio 6 workspace and project file (working project files containing files to include in project)
+*.dsw
+*.dsp
+
+# Visual Studio 6 technical files
+*.ncb
+*.aps
+
+# Visual Studio LightSwitch build output
+**/*.HTMLClient/GeneratedArtifacts
+**/*.DesktopClient/GeneratedArtifacts
+**/*.DesktopClient/ModelManifest.xml
+**/*.Server/GeneratedArtifacts
+**/*.Server/ModelManifest.xml
+_Pvt_Extensions
+
+# Paket dependency manager
+**/.paket/paket.exe
+paket-files/
+
+# FAKE - F# Make
+**/.fake/
+
+# CodeRush personal settings
+**/.cr/personal
+
+# Python Tools for Visual Studio (PTVS)
+**/__pycache__/
+*.pyc
+
+# Cake - Uncomment if you are using it
+#tools/**
+#!tools/packages.config
+
+# Tabs Studio
+*.tss
+
+# Telerik's JustMock configuration file
+*.jmconfig
+
+# BizTalk build output
+*.btp.cs
+*.btm.cs
+*.odx.cs
+*.xsd.cs
+
+# OpenCover UI analysis results
+OpenCover/
+
+# Azure Stream Analytics local run output
+ASALocalRun/
+
+# MSBuild Binary and Structured Log
+*.binlog
+MSBuild_Logs/
+
+# AWS SAM Build and Temporary Artifacts folder
+.aws-sam
+
+# NVidia Nsight GPU debugger configuration file
+*.nvuser
+
+# MFractors (Xamarin productivity tool) working folder
+**/.mfractor/
+
+# Local History for Visual Studio
+**/.localhistory/
+
+# Visual Studio History (VSHistory) files
+.vshistory/
+
+# BeatPulse healthcheck temp database
+healthchecksdb
+
+# Backup folder for Package Reference Convert tool in Visual Studio 2017
+MigrationBackup/
+
+# Ionide (cross platform F# VS Code tools) working folder
+**/.ionide/
+
+# Fody - auto-generated XML schema
+FodyWeavers.xsd
+
+# VS Code files for those working on multiple tools
+.vscode/*
+!.vscode/settings.json
+!.vscode/tasks.json
+!.vscode/launch.json
+!.vscode/extensions.json
+!.vscode/*.code-snippets
+
+# Local History for Visual Studio Code
+.history/
+
+# Built Visual Studio Code Extensions
+*.vsix
+
+# Windows Installer files from build outputs
+*.cab
+*.msi
+*.msix
+*.msm
+*.msp

MusifyBackend/Application/Application.csproj

@@ -0,0 +1,35 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net10.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+	<RootNamespace>Musify.Application</RootNamespace>
+	<PackageId>Musify.Application</PackageId>
+    <Version>0.1.2</Version>
+    <Authors>NotS1mp</Authors>
+    <RepositoryUrl>https://github.com/XShine555/MusifyBackend</RepositoryUrl>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Ardalis.Result" Version="10.1.0" />
+    <PackageReference Include="MassTransit" Version="8.5.9" />
+    <PackageReference Include="Mediator.Abstractions" Version="3.0.2" />
+    <PackageReference Include="Mediator.SourceGenerator" Version="3.0.2">
+      <PrivateAssets>all</PrivateAssets>
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+    </PackageReference>
+    <PackageReference Include="Microsoft.EntityFrameworkCore" Version="10.0.8" />
+    <PackageReference Include="Microsoft.Extensions.Configuration" Version="10.0.8" />
+    <PackageReference Include="Microsoft.Extensions.Configuration.Binder" Version="10.0.8" />
+    <PackageReference Include="Microsoft.Extensions.Options.ConfigurationExtensions" Version="10.0.8" />
+    <PackageReference Include="Microsoft.Extensions.Options.DataAnnotations" Version="10.0.8" />
+    <PackageReference Include="X.PagedList" Version="10.5.9" />
+    <PackageReference Include="X.PagedList.EF" Version="10.5.9" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\Domain\Domain.csproj" />
+  </ItemGroup>
+
+</Project>

MusifyBackend/Application/Configuration/ApplicationStorageConfiguration.cs

@@ -0,0 +1,13 @@
+using System.ComponentModel.DataAnnotations;
+
+namespace Musify.Application.Configuration
+{
+    public class ApplicationStorageConfiguration
+    {
+        public const string SectionName = "ApplicationStorage";
+
+        [Required]
+        [StringLength(128, MinimumLength = 1)]
+        public required string Bucket { get; set; }
+    }
+}

MusifyBackend/Application/Configuration/ConfigurationDependencyInjection.cs

@@ -0,0 +1,57 @@
+using Microsoft.Extensions.Configuration;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Options;
+
+namespace Musify.Application.Configuration
+{
+    public static class ConfigurationDependencyInjection
+    {
+        public static IServiceCollection AddApplicationStorageConfiguration(this IServiceCollection serviceDescriptors, IConfiguration configuration)
+        {
+            serviceDescriptors
+                .AddOptionsWithValidateOnStart<ApplicationStorageConfiguration>()
+                .Bind(configuration.GetRequiredSection(ApplicationStorageConfiguration.SectionName))
+                .ValidateDataAnnotations();
+            serviceDescriptors.AddSingleton(serviceProvider =>
+                serviceProvider.GetRequiredService<IOptions<ApplicationStorageConfiguration>>().Value);
+
+            return serviceDescriptors;
+        }
+
+        public static IServiceCollection AddPlayListConfiguration(this IServiceCollection serviceDescriptors, IConfiguration configuration)
+        {
+            serviceDescriptors
+                .AddOptionsWithValidateOnStart<PlayListConfiguration>()
+                .Bind(configuration.GetRequiredSection(PlayListConfiguration.SectionName))
+                .ValidateDataAnnotations();
+            serviceDescriptors.AddSingleton(serviceProvider =>
+                serviceProvider.GetRequiredService<IOptions<PlayListConfiguration>>().Value);
+
+            return serviceDescriptors;
+        }
+
+        public static IServiceCollection AddTrackConfiguration(this IServiceCollection serviceDescriptors, IConfiguration configuration)
+        {
+            serviceDescriptors
+                .AddOptionsWithValidateOnStart<TrackConfiguration>()
+                .Bind(configuration.GetRequiredSection(TrackConfiguration.SectionName))
+                .ValidateDataAnnotations();
+            serviceDescriptors.AddSingleton(serviceProvider =>
+                serviceProvider.GetRequiredService<IOptions<TrackConfiguration>>().Value);
+
+            return serviceDescriptors;
+        }
+
+        public static IServiceCollection AddStreamGatewayConfiguration(this IServiceCollection serviceDescriptors, IConfiguration configuration)
+        {
+            serviceDescriptors
+                .AddOptionsWithValidateOnStart<StreamGatewayConfiguration>()
+                .Bind(configuration.GetRequiredSection(StreamGatewayConfiguration.SectionName))
+                .ValidateDataAnnotations();
+            serviceDescriptors.AddSingleton(serviceProvider =>
+                serviceProvider.GetRequiredService<IOptions<StreamGatewayConfiguration>>().Value);
+
+            return serviceDescriptors;
+        }
+    }
+}

MusifyBackend/Application/Configuration/PlayListConfiguration.cs

@@ -0,0 +1,97 @@
+using System.ComponentModel.DataAnnotations;
+using Musify.Application.Shared;
+
+namespace Musify.Application.Configuration
+{
+    public class PlayListConfiguration
+    {
+        public const string SectionName = "PlayList";
+
+        [Required]
+        public PlayListRoutes Routes { get; set; } = new PlayListRoutes();
+
+        [Required]
+        public PlayListPicturesSizes PicturesSizes { get; set; } = new PlayListPicturesSizes();
+    }
+
+    public class PlayListRoutes
+    {
+        [Required]
+        public string UploadsFolder { get; set; } = "uploads";
+
+        [Required]
+        public string ParentFolders { get; set; } = "PlayLists";
+
+        [Required]
+        public string OriginalPicturesFolder { get; set; } = "OriginalPictures";
+
+        [Required]
+        public string SmallPicturesFolder { get; set; } = "SmallPictures";
+
+        [Required]
+        public string MediumPicturesFolder { get; set; } = "MediumPictures";
+
+        [Required]
+        public string LargePicturesFolder { get; set; } = "LargePictures";
+
+        [Required]
+        public string PresetOriginalPicture { get; set; } = "PresetOriginalPicture.webp";
+
+        [Required]
+        public string PresetSmallPicture { get; set; } = "PresetSmallPicture.webp";
+
+        [Required]
+        public string PresetMediumPicture { get; set; } = "PresetMediumPicture.webp";
+
+        [Required]
+        public string PresetLargePicture { get; set; } = "PresetLargePicture.webp";
+
+        public string SmallPicturesPath => StorageKey.Combine(ParentFolders, SmallPicturesFolder);
+
+        public string MediumPicturesPath => StorageKey.Combine(ParentFolders, MediumPicturesFolder);
+
+        public string LargePicturesPath => StorageKey.Combine(ParentFolders, LargePicturesFolder);
+
+        public string PresetSmallPicturePath => StorageKey.Combine(ParentFolders, PresetSmallPicture);
+
+        public string PresetMediumPicturePath => StorageKey.Combine(ParentFolders, PresetMediumPicture);
+
+        public string PresetLargePicturePath => StorageKey.Combine(ParentFolders, PresetLargePicture);
+
+        public string OriginalPicturesPath => StorageKey.Combine(ParentFolders, OriginalPicturesFolder);
+
+        public string BuildOriginalPicturePath(string pictureName) => StorageKey.Combine(ParentFolders, OriginalPicturesFolder, pictureName);
+
+        public string BuildOriginalPicturePath(long userId, string pictureName) => StorageKey.Combine(UploadsFolder, userId.ToString(), ParentFolders, OriginalPicturesFolder, pictureName);
+
+        public string BuildSmallPicturePath(string pictureName) => StorageKey.Combine(ParentFolders, SmallPicturesFolder, pictureName);
+
+        public string BuildMediumPicturePath(string pictureName) => StorageKey.Combine(ParentFolders, MediumPicturesFolder, pictureName);
+
+        public string BuildLargePicturePath(string pictureName) => StorageKey.Combine(ParentFolders, LargePicturesFolder, pictureName);
+
+        public string BuildTempPicturePath(string tempRootPrefix, long userId, string objectName) =>
+            StorageKey.Combine(tempRootPrefix, userId.ToString(), ParentFolders, objectName);
+    }
+
+    public class PlayListPicturesSizes
+    {
+        [Range(1, 1024)]
+        public int SmallPictureWidth { get; set; } = 128;
+
+        [Range(1, 1024)]
+        public int SmallPictureHeight { get; set; } = 128;
+
+        [Range(1, 1024)]
+        public int MediumPictureWidth { get; set; } = 256;
+
+        [Range(1, 1024)]
+        public int MediumPictureHeight { get; set; } = 256;
+
+        [Range(1, 1024)]
+        public int LargePictureWidth { get; set; } = 512;
+
+        [Range(1, 1024)]
+        public int LargePictureHeight { get; set; } = 512;
+    }
+}

MusifyBackend/Application/Configuration/StreamGatewayConfiguration.cs

@@ -0,0 +1,16 @@
+using System.ComponentModel.DataAnnotations;
+
+namespace Musify.Application.Configuration
+{
+    public class StreamGatewayConfiguration
+    {
+        public const string SectionName = "StreamGateway";
+
+        [Url]
+        [Required]
+        public required string PublicBaseUrl { get; set; }
+
+        [Required]
+        public string AudioFileName { get; set; } = "audio.m4a";
+    }
+}

MusifyBackend/Application/Configuration/TrackConfiguration.cs

@@ -0,0 +1,116 @@
+using System.ComponentModel.DataAnnotations;
+using Musify.Application.Shared;
+
+namespace Musify.Application.Configuration
+{
+    public class TrackConfiguration
+    {
+        public const string SectionName = "Track";
+
+        [Required]
+        public TrackRoutes Routes { get; set; } = new TrackRoutes();
+
+        [Required]
+        public TrackPicturesSizes PicturesSizes { get; set; } = new TrackPicturesSizes();
+    }
+
+    public class TrackRoutes
+    {
+        [Required]
+        public string UploadsFolder { get; set; } = "uploads";
+
+        [Required]
+        public string ParentFolder { get; set; } = "Tracks";
+
+        [Required]
+        public string OriginalPicturesFolder { get; set; } = "OriginalPictures";
+
+        [Required]
+        public string SmallPicturesFolder { get; set; } = "SmallPictures";
+
+        [Required]
+        public string MediumPicturesFolder { get; set; } = "MediumPictures";
+
+        [Required]
+        public string LargePicturesFolder { get; set; } = "LargePictures";
+
+        [Required]
+        public string PresetOriginalPicture { get; set; } = "PresetOriginalPicture.webp";
+
+        [Required]
+        public string PresetSmallPicture { get; set; } = "PresetSmallPicture.webp";
+
+        [Required]
+        public string PresetMediumPicture { get; set; } = "PresetMediumPicture.webp";
+
+        [Required]
+        public string PresetLargePicture { get; set; } = "PresetLargePicture.webp";
+
+        [Required]
+        public string OriginalAudiosFolder { get; set; } = "OriginalAudios";
+
+        [Required]
+        public string ProcessedAudioFolder { get; set; } = "ProcessedAudios";
+
+        public string SmallPicturesPath => StorageKey.Combine(ParentFolder, SmallPicturesFolder);
+
+        public string MediumPicturesPath => StorageKey.Combine(ParentFolder, MediumPicturesFolder);
+
+        public string LargePicturesPath => StorageKey.Combine(ParentFolder, LargePicturesFolder);
+
+        public string PresetSmallPicturePath => StorageKey.Combine(ParentFolder, PresetSmallPicture);
+
+        public string PresetMediumPicturePath => StorageKey.Combine(ParentFolder, PresetMediumPicture);
+
+        public string PresetLargePicturePath => StorageKey.Combine(ParentFolder, PresetLargePicture);
+
+        public string OriginalPicturesPath => StorageKey.Combine(ParentFolder, OriginalPicturesFolder);
+
+        public string OriginalAudiosPath => StorageKey.Combine(ParentFolder, OriginalAudiosFolder);
+
+        public string ProcessedAudiosPath => StorageKey.Combine(ParentFolder, ProcessedAudioFolder);
+
+        public string BuildOriginalPicturePath(string pictureName) => StorageKey.Combine(OriginalPicturesPath, pictureName);
+
+        public string BuildOriginalPicturePath(long userId, string pictureName) => StorageKey.Combine(UploadsFolder, userId.ToString(), OriginalPicturesPath, pictureName);
+
+        public string BuildSmallPicturePath(string pictureName) => StorageKey.Combine(SmallPicturesPath, pictureName);
+
+        public string BuildMediumPicturePath(string pictureName) => StorageKey.Combine(MediumPicturesPath, pictureName);
+
+        public string BuildLargePicturePath(string pictureName) => StorageKey.Combine(LargePicturesPath, pictureName);
+
+        public string BuildOriginalAudioPath(string audioName) => StorageKey.Combine(OriginalAudiosPath, audioName);
+
+        public string BuildOriginalAudioPath(long userId, string audioName) => StorageKey.Combine(UploadsFolder, userId.ToString(), OriginalAudiosPath, audioName);
+
+        public string BuildProcessedAudioPath(string audioName) => StorageKey.Combine(ProcessedAudiosPath, audioName);
+
+        public string BuildTempPicturePath(string tempRootPrefix, long userId, string objectName) =>
+            StorageKey.Combine(tempRootPrefix, userId.ToString(), ParentFolder, objectName);
+
+        public string BuildTempAudioPath(string tempRootPrefix, long userId, string objectName) =>
+            StorageKey.Combine(tempRootPrefix, userId.ToString(), ParentFolder, objectName);
+    }
+
+    public class TrackPicturesSizes
+    {
+        [Range(1, 1024)]
+        public int SmallPictureWidth { get; set; } = 128;
+
+        [Range(1, 1024)]
+        public int SmallPictureHeight { get; set; } = 128;
+
+        [Range(1, 1024)]
+        public int MediumPictureWidth { get; set; } = 256;
+
+        [Range(1, 1024)]
+        public int MediumPictureHeight { get; set; } = 256;
+
+        [Range(1, 1024)]
+        public int LargePictureWidth { get; set; } = 512;
+
+        [Range(1, 1024)]
+        public int LargePictureHeight { get; set; } = 512;
+    }
+}

MusifyBackend/Application/Configuration/UploadIntentConfiguration.cs

@@ -0,0 +1,42 @@
+using System.ComponentModel.DataAnnotations;
+
+namespace Musify.Application.Configuration
+{
+    public class UploadIntentConfiguration
+    {
+        public const string SectionName = "UploadIntent";
+
+        [Range(10, 3600)]
+        public int UploadUrlExpiresInSeconds { get; set; } = 120;
+
+        [Range(1, 100)]
+        public int MaxActiveUploadIntentsPerUser { get; set; } = 5;
+
+        [Range(1, long.MaxValue)]
+        public long MaxActiveUploadBytesPerUser { get; set; } = 200L * 1024 * 1024;
+
+        [Range(1, long.MaxValue)]
+        public long MaxUploadBytes { get; set; } = 100L * 1024 * 1024;
+
+        [Range(1, long.MaxValue)]
+        public long DefaultExpectedPictureSizeBytes { get; set; } = 10L * 1024 * 1024;
+
+        [Range(1, long.MaxValue)]
+        public long DefaultExpectedAudioSizeBytes { get; set; } = 100L * 1024 * 1024;
+
+        [Range(30, 86400)]
+        public int ExpirationJobIntervalSeconds { get; set; } = 300;
+
+        [Range(0, 365)]
+        public int ExpiredIntentsRetentionDays { get; set; } = 7;
+
+        [Required, MinLength(1)]
+        public string TemporalRootPrefix { get; set; } = "temporal";
+
+        [Range(1, 30)]
+        public int TemporalUploadsRetentionDays { get; set; } = 3;
+
+        [Range(60, 86400)]
+        public int TemporalCleanUpJobIntervalSeconds { get; set; } = 3600;
+    }
+}

MusifyBackend/Application/Contracts/IAudioTranscoderService.cs

@@ -0,0 +1,9 @@
+namespace Musify.Application.Contracts
+{
+    public interface IAudioTranscoderService
+    {
+        Task<int> TranscodeToAudioFileAsync(Stream audioStream, string destinationPath, CancellationToken cancellationToken);
+
+        Task<bool> IsValidAudioFileAsync(string filePath, CancellationToken cancellationToken);
+    }
+}

MusifyBackend/Application/Contracts/IDatabase.cs

@@ -0,0 +1,26 @@
+using Microsoft.EntityFrameworkCore;
+using Musify.Domain.Entities;
+
+namespace Musify.Application.Contracts
+{
+    public interface IDatabase
+    {
+        DbSet<User> Users { get; }
+
+        DbSet<PlayList> PlayLists { get; }
+
+        DbSet<Track> Tracks { get; }
+
+        DbSet<UserHasTrack> UserHasTracks { get; }
+
+        DbSet<PlayListHasTrack> PlayListHasTracks { get; }
+
+        DbSet<Upload> Uploads { get; }
+
+        DbSet<UploadIntent> UploadIntents { get; }
+
+        Task<IDatabaseTransaction> BeginTransactionAsync(System.Data.IsolationLevel isolationLevel, CancellationToken cancellationToken);
+
+        Task<int> SaveChangesAsync(CancellationToken cancellationToken);
+    }
+}

MusifyBackend/Application/Contracts/IDatabaseTransaction.cs

@@ -0,0 +1,7 @@
+namespace Musify.Application.Contracts
+{
+    public interface IDatabaseTransaction : IAsyncDisposable
+    {
+        Task CommitAsync(CancellationToken cancellationToken = default);
+    }
+}

MusifyBackend/Application/Contracts/IEventBus.cs

@@ -0,0 +1,7 @@
+namespace Musify.Application.Contracts
+{
+    public interface IEventBus
+    {
+        Task PublishAsync<T>(T message, CancellationToken cancellationToken) where T : class;
+    }
+}

MusifyBackend/Application/Contracts/IPictureService.cs

@@ -0,0 +1,7 @@
+namespace Musify.Application.Contracts
+{
+    public interface IPictureService
+    {
+        Task<Stream> ResizePictureAsWebpAsync(Stream pictureStream, int width, int height, CancellationToken cancellationToken);
+    }
+}

MusifyBackend/Application/Contracts/IStorageService.cs

@@ -0,0 +1,28 @@
+namespace Musify.Application.Contracts
+{
+    public interface IStorageService
+    {
+        Task<Stream> GetFileAsync(string bucket, string key, CancellationToken cancellationToken);
+
+        Task<ObjectMetaData?> HeadObjectAsync(string bucket, string key, CancellationToken cancellationToken);
+
+        Task<string> GetUrlAsync(string bucket, string key, TimeSpan ExpirationTime, CancellationToken cancellationToken);
+
+        Task<string> GetUploadUrlAsync(string bucket, string key, string contentType, TimeSpan expirationTime, CancellationToken cancellationToken, bool preventOverwrite = true);
+
+        Task UploadFileAsync(string filePath, string bucket, string key, CancellationToken cancellationToken);
+
+        Task UploadFileAsync(Stream sourceStream, string contentType, string bucket, string key, CancellationToken cancellationToken);
+
+        Task TransferFilesAsync(string sourceDirectory, string bucket, string route, CancellationToken cancellationToken);
+
+        Task RemoveFileAsync(string bucket, string key, CancellationToken cancellationToken);
+
+        Task CopyFileAsync(string sourceBucket, string sourceKey, string destinationBucket, string destinationKey,
+            CancellationToken cancellationToken);
+
+        Task RemoveFolderAsync(string bucket, string folderKey, CancellationToken cancellationToken);
+        
+        IAsyncEnumerable<StorageObject> ListObjectsAsync(string bucket, string prefix, CancellationToken cancellationToken);
+    }
+}

MusifyBackend/Application/Contracts/IStreamTicketService.cs

@@ -0,0 +1,9 @@
+namespace Musify.Application.Contracts
+{
+    public interface IStreamTicketService
+    {
+        StreamTicket IssueTicket(long userId, string keyPrefix);
+    }
+
+    public record StreamTicket(string Token, int ExpiresInSeconds);
+}

MusifyBackend/Application/Contracts/ObjectMetaData.cs

@@ -0,0 +1,4 @@
+namespace Musify.Application.Contracts
+{
+    public record ObjectMetaData(string ContentType, long ContentLength);
+}

MusifyBackend/Application/Contracts/StorageObject.cs

@@ -0,0 +1,4 @@
+namespace Musify.Application.Contracts
+{
+    public record StorageObject(string Key, DateTime LastModifiedUtc);
+}

MusifyBackend/Application/Events/CreatePlayListResourcesEvent.cs

@@ -0,0 +1,14 @@
+using Musify.Application.Shared;
+
+namespace Musify.Application.Events
+{
+    public record CreatePlayListResourcesEvent(
+        Guid PlayListId,
+        Guid PictureIntentId,
+        string Bucket,
+        string PictureSourceKey,
+        string PictureDestinationKey,
+        ImageSize Small,
+        ImageSize Medium,
+        ImageSize Large);
+}

MusifyBackend/Application/Events/CreateTrackResourcesEvent.cs

@@ -0,0 +1,18 @@
+using Musify.Application.Shared;
+
+namespace Musify.Application.Events
+{
+    public record CreateTrackResourcesEvent(
+        Guid TrackId,
+        Guid PictureIntentId,
+        Guid AudioIntentId,
+        string Bucket,
+        string PictureSourceKey,
+        string PictureDestinationKey,
+        string AudioSourceKey,
+        string AudioDestinationKey,
+        string AudioProcessedFolderKey,
+        ImageSize Small,
+        ImageSize Medium,
+        ImageSize Large);
+}

MusifyBackend/Application/Events/DeletePlayListEvent.cs

@@ -0,0 +1,6 @@
+namespace Musify.Application.Events
+{
+    public record DeletePlayListEvent(
+        Guid PlayListId,
+        long UserId);
+}

MusifyBackend/Application/Events/DeleteTrackEvent.cs

@@ -0,0 +1,6 @@
+namespace Musify.Application.Events
+{
+    public record DeleteTrackEvent(
+        Guid TrackId,
+        long UserId);
+}

MusifyBackend/Application/Events/UpdatePlayListPictureEvent.cs

@@ -0,0 +1,12 @@
+using Musify.Application.Shared;
+
+namespace Musify.Application.Events
+{
+    public record UpdatePlayListPictureEvent(
+        Guid PlayListId,
+        string Bucket,
+        string SourceKey,
+        ImageSize Small,
+        ImageSize Medium,
+        ImageSize Large);
+}

MusifyBackend/Application/Events/UpdatePlayListPictureSourceEvent.cs

@@ -0,0 +1,14 @@
+using Musify.Application.Shared;
+
+namespace Musify.Application.Events
+{
+    public record UpdatePlayListPictureSourceEvent(
+        Guid PlayListId,
+        Guid PictureIntentId,
+        string Bucket,
+        string PictureSourceKey,
+        string PictureDestinationKey,
+        ImageSize Small,
+        ImageSize Medium,
+        ImageSize Large);
+}

MusifyBackend/Application/Events/UpdateTrackAudioEvent.cs

@@ -0,0 +1,9 @@
+namespace Musify.Application.Events
+{
+    public record UpdateTrackAudioEvent(
+        Guid TrackId,
+        string SourceBucket,
+        string SourceKey,
+        string DestinationBucket,
+        string DestinationFolderKey);
+}

MusifyBackend/Application/Events/UpdateTrackPictureEvent.cs

@@ -0,0 +1,12 @@
+using Musify.Application.Shared;
+
+namespace Musify.Application.Events
+{
+    public record UpdateTrackPictureEvent(
+        Guid TrackId,
+        string Bucket,
+        string SourceKey,
+        ImageSize Small,
+        ImageSize Medium,
+        ImageSize Large);
+}

MusifyBackend/Application/Extensions/ResultExtensions.cs

@@ -0,0 +1,25 @@
+using Ardalis.Result;
+
+namespace Musify.Application.Extensions;
+
+public static class ResultExtensions
+{
+    public static Result<TOut> As<TIn, TOut>(this Result<TIn> result)
+    {
+        return result.Status switch
+        {
+            ResultStatus.Ok or
+            ResultStatus.Created or
+            ResultStatus.NoContent   => throw new InvalidOperationException($"Cannot convert a successful result ( {result.Status} ) to another type. Use Map or Bind instead."),
+            ResultStatus.NotFound    => Result<TOut>.NotFound(result.Errors.ToArray()),
+            ResultStatus.Forbidden   => Result<TOut>.Forbidden(result.Errors.ToArray()),
+            ResultStatus.Unauthorized => Result<TOut>.Unauthorized(result.Errors.ToArray()),
+            ResultStatus.Invalid     => Result<TOut>.Invalid(result.ValidationErrors.ToArray()),
+            ResultStatus.Conflict    => Result<TOut>.Conflict(result.Errors.ToArray()),
+            ResultStatus.CriticalError => Result<TOut>.CriticalError(result.Errors.ToArray()),
+            ResultStatus.Unavailable => Result<TOut>.Unavailable(result.Errors.ToArray()),
+            ResultStatus.Error       => Result<TOut>.Error(string.Join(";", result.Errors)),
+            _                        => Result<TOut>.Error(string.Join(";", result.Errors))
+        };
+    }
+}

MusifyBackend/Application/MusifyApplication.cs

@@ -0,0 +1,4 @@
+using Mediator;
+using Microsoft.Extensions.DependencyInjection;
+
+[assembly: MediatorOptions(ServiceLifetime = ServiceLifetime.Scoped)]

MusifyBackend/Application/Pagination/PaginatedResponse.cs

@@ -0,0 +1,26 @@
+using X.PagedList;
+
+namespace Musify.Application.Pagination
+{
+    public record PaginatedResponse<T>(
+        IReadOnlyCollection<T> Items,
+        int PageNumber,
+        int PageSize,
+        int PageCount,
+        int TotalItemCount,
+        bool HasNextPage,
+        bool HasPreviousPage)
+    {
+        public static PaginatedResponse<T> FromPagedList(IPagedList<T> pagedList)
+        {
+            return new PaginatedResponse<T>(
+                pagedList.ToArray(),
+                pagedList.PageNumber,
+                pagedList.PageSize,
+                pagedList.PageCount,
+                pagedList.TotalItemCount,
+                pagedList.HasNextPage,
+                pagedList.HasPreviousPage);
+        }
+    }
+}

MusifyBackend/Application/PlayLists/Commands/AddTrackToPlayListCommand.cs

@@ -0,0 +1,8 @@
+using Ardalis.Result;
+using Mediator;
+
+namespace Musify.Application.PlayLists.Commands
+{
+    public record AddTrackToPlayListCommand(long UserId, Guid PlayListId, Guid TrackId)
+        : ICommand<Result>;
+}

MusifyBackend/Application/PlayLists/Commands/CreatePlayListCommand.cs

@@ -0,0 +1,13 @@
+using Ardalis.Result;
+using Mediator;
+using Musify.Application.PlayLists.Responses;
+
+namespace Musify.Application.PlayLists.Commands
+{
+    public record CreatePlayListCommand(
+        long UserId,
+        string Name,
+        string Description,
+        Guid? PictureIntentId)
+        : ICommand<Result<PlayListApplicationResponse>>;
+}

MusifyBackend/Application/PlayLists/Commands/DeletePlayListCommand.cs

@@ -0,0 +1,8 @@
+using Ardalis.Result;
+using Mediator;
+
+namespace Musify.Application.PlayLists.Commands
+{
+    public record DeletePlayListCommand(long UserId, Guid PlayListId)
+        : ICommand<Result>;
+}

MusifyBackend/Application/PlayLists/Commands/RemoveTrackFromPlayListCommand.cs

@@ -0,0 +1,8 @@
+using Ardalis.Result;
+using Mediator;
+
+namespace Musify.Application.PlayLists.Commands
+{
+    public record RemoveTrackFromPlayListCommand(long UserId, Guid PlayListId, Guid TrackId)
+        : ICommand<Result>;
+}

MusifyBackend/Application/PlayLists/Commands/RequestPlayListPictureUploadCommand.cs

@@ -0,0 +1,13 @@
+using Ardalis.Result;
+using Mediator;
+using Musify.Application.PlayLists.Responses;
+
+namespace Musify.Application.PlayLists.Commands
+{
+    public record RequestPlayListPictureUploadCommand(
+        long UserId,
+        string FileType,
+        string ContentType,
+        long? ExpectedSizeBytes = null)
+        : ICommand<Result<PlayListPictureUploadResponse>>;
+}

MusifyBackend/Application/PlayLists/Commands/UpdatePlayListCommand.cs

@@ -0,0 +1,14 @@
+using Ardalis.Result;
+using Mediator;
+using Musify.Application.PlayLists.Responses;
+
+namespace Musify.Application.PlayLists.Commands
+{
+    public record UpdatePlayListCommand(
+        long UserId,
+        Guid PlayListId,
+        string? NewName,
+        string? NewDescription,
+        Guid? NewPictureIntentId)
+        : ICommand<Result<PlayListApplicationResponse>>;
+}

MusifyBackend/Application/PlayLists/Handlers/AddTrackToPlayListCommandHandler.cs

@@ -0,0 +1,70 @@
+using Ardalis.Result;
+using Mediator;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.Logging;
+using Musify.Application.Contracts;
+using Musify.Application.PlayLists.Commands;
+using Musify.Domain.Entities;
+
+namespace Musify.Application.PlayLists.Handlers
+{
+    public class AddTrackToPlayListCommandHandler(
+        IDatabase database,
+        ILogger<AddTrackToPlayListCommandHandler> logger)
+        : ICommandHandler<AddTrackToPlayListCommand, Result>
+    {
+        public async ValueTask<Result> Handle(AddTrackToPlayListCommand request, CancellationToken cancellationToken)
+        {
+            var playList = await database.PlayLists
+                .SingleOrDefaultAsync(pl => pl.Id == request.PlayListId, cancellationToken);
+            if (playList is null)
+            {
+                logger.LogInformation("Playlist {PlayListId} not found", request.PlayListId);
+                return Result.NotFound();
+            }
+
+            if (playList.UserId != request.UserId)
+            {
+                logger.LogWarning("User {UserId} is not the owner of playlist {PlayListId}", request.UserId, request.PlayListId);
+                return Result.Unauthorized();
+            }
+
+            var trackExists = await database.Tracks
+                .AsNoTracking()
+                .AnyAsync(t => t.Id == request.TrackId, cancellationToken);
+            if (!trackExists)
+            {
+                logger.LogInformation("Track {TrackId} not found", request.TrackId);
+                return Result.NotFound($"Track {request.TrackId} not found");
+            }
+
+            var alreadyAdded = await database.PlayListHasTracks
+                .AsNoTracking()
+                .AnyAsync(plt => plt.PlayListId == request.PlayListId && plt.TrackId == request.TrackId, cancellationToken);
+            if (alreadyAdded)
+            {
+                logger.LogInformation("Track {TrackId} already in playlist {PlayListId}", request.TrackId, request.PlayListId);
+                return Result.Conflict("Track is already in the playlist.");
+            }
+
+            var nextPosition = await database.PlayListHasTracks
+                .Where(plt => plt.PlayListId == request.PlayListId)
+                .Select(plt => (int?)plt.Position)
+                .MaxAsync(cancellationToken) + 1 ?? 0;
+
+            await database.PlayListHasTracks.AddAsync(new PlayListHasTrack
+            {
+                PlayListId = request.PlayListId,
+                TrackId = request.TrackId,
+                Position = nextPosition
+            }, cancellationToken);
+
+            await database.SaveChangesAsync(cancellationToken);
+
+            logger.LogInformation("Added track {TrackId} to playlist {PlayListId} at position {Position}",
+                request.TrackId, request.PlayListId, nextPosition);
+
+            return Result.Success();
+        }
+    }
+}

MusifyBackend/Application/PlayLists/Handlers/CreatePlayListCommandHandler.cs

@@ -0,0 +1,131 @@
+using Ardalis.Result;
+using Mediator;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.Logging;
+using Musify.Application.Configuration;
+using Musify.Application.Shared;
+using Musify.Application.Events;
+using Musify.Application.PlayLists.Commands;
+using Musify.Application.PlayLists.Responses;
+using Musify.Application.Extensions;
+using Musify.Application.Services;
+using Musify.Domain.Entities;
+using Musify.Application.Contracts;
+
+namespace Musify.Application.PlayLists.Handlers
+{
+    public class CreatePlayListCommandHandler(
+        IEventBus eventBus,
+        IDatabase database,
+        UploadIntentValidator uploadIntentValidator,
+        ILogger<CreatePlayListCommandHandler> logger,
+        ApplicationStorageConfiguration storageConfiguration,
+        PlayListConfiguration playListConfiguration,
+        UploadIntentConfiguration uploadIntentConfiguration)
+        : ICommandHandler<CreatePlayListCommand, Result<PlayListApplicationResponse>>
+    {
+        public async ValueTask<Result<PlayListApplicationResponse>> Handle(CreatePlayListCommand request, CancellationToken cancellationToken)
+        {
+            var userExists = await database.Users
+                .AsNoTracking()
+                .AnyAsync(u => u.Id == request.UserId, cancellationToken);
+            if (!userExists)
+            {
+                logger.LogWarning("User {UserId} not found", request.UserId);
+                return Result.NotFound($"User {request.UserId} not found");
+            }
+
+            UploadIntent? pictureIntent = null;
+            string originalPictureName;
+
+            if (request.PictureIntentId.HasValue)
+            {
+                var validation = await uploadIntentValidator.ValidateAndLoadAsync(
+                    uploadIntentConfiguration,
+                    request.PictureIntentId.Value, request.UserId, cancellationToken);
+                if (!validation.IsSuccess)
+                    return validation.As<UploadIntent, PlayListApplicationResponse>();
+
+                pictureIntent = validation.Value;
+                originalPictureName = pictureIntent.ObjectName;
+            }
+            else
+            {
+                originalPictureName = playListConfiguration.Routes.PresetOriginalPicture;
+            }
+
+            var playList = new PlayList
+            {
+                UserId = request.UserId,
+                Name = request.Name,
+                NormalizedName = request.Name.Trim().ToUpperInvariant(),
+                Description = request.Description,
+                OriginalPictureName = originalPictureName,
+                SmallPictureName = playListConfiguration.Routes.PresetSmallPicture,
+                MediumPictureName = playListConfiguration.Routes.PresetMediumPicture,
+                LargePictureName = playListConfiguration.Routes.PresetLargePicture
+            };
+
+            await database.PlayLists.AddAsync(playList, cancellationToken);
+
+            if (pictureIntent is not null)
+            {
+                var finalPictureKey = playListConfiguration.Routes.BuildOriginalPicturePath(request.UserId, originalPictureName);
+                var publishResult = await PublishCreatePlayListEventAsync(
+                    playList.Id, pictureIntent, finalPictureKey, cancellationToken);
+                if (!publishResult.IsSuccess)
+                    return publishResult;
+            }
+
+            try
+            {
+                await database.SaveChangesAsync(cancellationToken);
+            }
+            catch (Exception exception)
+            {
+                logger.LogError(exception, "Failed to save playlist for user {UserId}", request.UserId);
+                return Result.Error($"Failed to create playlist for user {request.UserId}");
+            }
+
+            logger.LogInformation("Created playlist {PlayListId} for user {UserId}", playList.Id, request.UserId);
+            return Result.Created(PlayListApplicationResponse.FromEntity(playList));
+        }
+
+        async Task<Result<PlayListApplicationResponse>> PublishCreatePlayListEventAsync(
+            Guid playListId,
+            UploadIntent pictureIntent,
+            string finalPictureKey,
+            CancellationToken cancellationToken)
+        {
+            try
+            {
+                await eventBus.PublishAsync(
+                    new CreatePlayListResourcesEvent(
+                        playListId,
+                        pictureIntent.Id,
+                        storageConfiguration.Bucket,
+                        pictureIntent.Key,
+                        finalPictureKey,
+                        new ImageSize(
+                            playListConfiguration.Routes.SmallPicturesPath,
+                            playListConfiguration.PicturesSizes.SmallPictureWidth,
+                            playListConfiguration.PicturesSizes.SmallPictureHeight),
+                        new ImageSize(
+                            playListConfiguration.Routes.MediumPicturesPath,
+                            playListConfiguration.PicturesSizes.MediumPictureWidth,
+                            playListConfiguration.PicturesSizes.MediumPictureHeight),
+                        new ImageSize(
+                            playListConfiguration.Routes.LargePicturesPath,
+                            playListConfiguration.PicturesSizes.LargePictureWidth,
+                            playListConfiguration.PicturesSizes.LargePictureHeight)),
+                    cancellationToken);
+                return Result.Success();
+            }
+            catch (Exception exception)
+            {
+                logger.LogError(exception, "Failed to publish create playlist event for playlist {PlayListId}", playListId);
+                return Result.Error($"Failed to publish create playlist event for playlist {playListId}");
+            }
+        }
+    }
+}

MusifyBackend/Application/PlayLists/Handlers/DeletePlayListCommandHandler.cs

@@ -0,0 +1,60 @@
+using Ardalis.Result;
+using Mediator;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.Logging;
+using Musify.Application.Contracts;
+using Musify.Application.Events;
+using Musify.Application.PlayLists.Commands;
+using Musify.Domain.ValueObjects;
+
+namespace Musify.Application.PlayLists.Handlers
+{
+    public class DeletePlayListCommandHandler(
+        IDatabase database,
+        IEventBus eventBus,
+        ILogger<DeletePlayListCommandHandler> logger)
+        : ICommandHandler<DeletePlayListCommand, Result>
+    {
+        public async ValueTask<Result> Handle(DeletePlayListCommand request, CancellationToken cancellationToken)
+        {
+            var playList = await database.PlayLists.SingleOrDefaultAsync(p => p.Id == request.PlayListId, cancellationToken);
+            if (playList is null)
+            {
+                logger.LogDebug("Playlist {PlayListId} not found", request.PlayListId);
+                return Result.NotFound();
+            }
+
+            if (playList.UserId != request.UserId)
+            {
+                logger.LogWarning("Playlist {PlayListId} does not belong to user {UserId}", request.PlayListId, request.UserId);
+                return Result.Unauthorized();
+            }
+
+            playList.LifeCycleStatus = LifeCycleStatus.Removing;
+
+            try
+            {
+                await eventBus.PublishAsync(
+                    new DeletePlayListEvent(playList.Id, request.UserId),
+                    cancellationToken);
+            }
+            catch (Exception exception)
+            {
+                logger.LogError(exception, "Failed to publish delete playlist event for playlist {PlayListId}", request.PlayListId);
+                return Result.Error($"Failed to delete playlist {request.PlayListId}");
+            }
+
+            try
+            {
+                await database.SaveChangesAsync(cancellationToken);
+            }
+            catch (Exception exception)
+            {
+                logger.LogError(exception, "Failed to mark playlist {PlayListId} as removing", request.PlayListId);
+                return Result.Error($"Failed to delete playlist {request.PlayListId}");
+            }
+
+            return Result.NoContent();
+        }
+    }
+}

MusifyBackend/Application/PlayLists/Handlers/GetPlayListByIdQueryHandler.cs

@@ -0,0 +1,26 @@
+using Ardalis.Result;
+using Microsoft.EntityFrameworkCore;
+using Musify.Application.PlayLists.Responses;
+using Musify.Application.PlayLists.Queries;
+using Mediator;
+using Musify.Application.Contracts;
+
+namespace Musify.Application.PlayLists.Handlers
+{
+    public class GetPlayListByIdQueryHandler(IDatabase database)
+        : IQueryHandler<GetPlayListByIdQuery, Result<PlayListApplicationResponse>>
+    {
+        public async ValueTask<Result<PlayListApplicationResponse>> Handle(GetPlayListByIdQuery request, CancellationToken cancellationToken)
+        {
+            var playList = await database.PlayLists
+                .AsNoTracking()
+                .Where(p => p.Id == request.Id)
+                .Select(p => PlayListApplicationResponse.FromEntity(p))
+                .SingleOrDefaultAsync(cancellationToken);
+
+            return playList is null
+                ? Result<PlayListApplicationResponse>.NotFound()
+                : Result.Success(playList);
+        }
+    }
+}

MusifyBackend/Application/PlayLists/Handlers/GetPlayListTracksQueryHandler.cs

@@ -0,0 +1,38 @@
+using Ardalis.Result;
+using Mediator;
+using Microsoft.EntityFrameworkCore;
+using Musify.Application.Contracts;
+using Musify.Application.Pagination;
+using Musify.Application.PlayLists.Queries;
+using Musify.Application.Tracks.Responses;
+using X.PagedList.EF;
+
+namespace Musify.Application.PlayLists.Handlers
+{
+    public class GetPlayListTracksQueryHandler(IDatabase database)
+        : IQueryHandler<GetPlayListTracksQuery, Result<PaginatedResponse<TrackApplicationResponse>> >
+    {
+        public async ValueTask<Result<PaginatedResponse<TrackApplicationResponse> >> Handle(GetPlayListTracksQuery request, CancellationToken cancellationToken)
+        {
+            var playListExists = await database.PlayLists
+                .AsNoTracking()
+                .AnyAsync(p => p.Id == request.PlayListId, cancellationToken);
+            if (!playListExists)
+                return Result<PaginatedResponse<TrackApplicationResponse>>.NotFound();
+
+            var tracksQuery = database.PlayListHasTracks
+                .AsNoTracking()
+                .Include(plt => plt.Track)
+                .Where(plt => plt.PlayListId == request.PlayListId);
+
+            var totalCount = await tracksQuery.CountAsync(cancellationToken);
+
+            var pagedTracks = await tracksQuery
+                .OrderBy(plt => plt.Position)
+                .Select(plt => TrackApplicationResponse.FromEntity(plt.Track))
+                .ToPagedListAsync(request.PageNumber, request.PageSize, totalCount, cancellationToken);
+
+            return Result.Success(PaginatedResponse<TrackApplicationResponse>.FromPagedList(pagedTracks));
+        }
+    }
+}

MusifyBackend/Application/PlayLists/Handlers/GetPlayListsByUserIdQueryHandler.cs

@@ -0,0 +1,37 @@
+using Ardalis.Result;
+using Microsoft.EntityFrameworkCore;
+using Musify.Application.Pagination;
+using Musify.Application.PlayLists.Responses;
+using Musify.Application.PlayLists.Queries;
+using X.PagedList.EF;
+using Mediator;
+using Musify.Application.Contracts;
+
+namespace Musify.Application.PlayLists.Handlers
+{
+    public class GetPlayListsByUserIdQueryHandler(IDatabase database)
+        : IQueryHandler<GetPlayListsByUserIdQuery, Result<PaginatedResponse<PlayListApplicationResponse> > >
+    {
+        public async ValueTask<Result<PaginatedResponse<PlayListApplicationResponse> >> Handle(GetPlayListsByUserIdQuery request, CancellationToken cancellationToken)
+        {
+            var playListsQuery = database.PlayLists
+                .AsNoTracking()
+                .Where(p => p.UserId == request.UserId);
+
+            if (request.Name is not null)
+            {
+                var normalizedName = request.Name.Trim().ToUpperInvariant();
+                playListsQuery = playListsQuery.Where(p => p.NormalizedName.Contains(normalizedName));
+            }
+
+            var totalCount = await playListsQuery.CountAsync(cancellationToken);
+
+            var pagedPlayLists = await playListsQuery
+                .OrderBy(p => p.CreatedAt)
+                .Select(p => PlayListApplicationResponse.FromEntity(p))
+                .ToPagedListAsync(request.PageNumber, request.PageSize, totalCount, cancellationToken);
+
+            return Result.Success(PaginatedResponse<PlayListApplicationResponse>.FromPagedList(pagedPlayLists));
+        }
+    }
+}

MusifyBackend/Application/PlayLists/Handlers/GetPlayListsQueryHandler.cs

@@ -0,0 +1,28 @@
+using Ardalis.Result;
+using Microsoft.EntityFrameworkCore;
+using Musify.Application.Pagination;
+using Musify.Application.PlayLists.Responses;
+using Musify.Application.PlayLists.Queries;
+using X.PagedList.EF;
+using Mediator;
+using Musify.Application.Contracts;
+
+namespace Musify.Application.PlayLists.Handlers
+{
+    public class GetPlayListsQueryHandler(IDatabase database)
+        : IQueryHandler<GetPlayListsQuery, Result<PaginatedResponse<PlayListApplicationResponse> >>
+    {
+        public async ValueTask<Result<PaginatedResponse<PlayListApplicationResponse> >> Handle(GetPlayListsQuery request, CancellationToken cancellationToken)
+        {
+            var totalCount = await database.PlayLists.CountAsync(cancellationToken);
+
+            var pagedPlayLists = await database.PlayLists
+                .AsNoTracking()
+                .OrderBy(p => p.Id)
+                .Select(p => PlayListApplicationResponse.FromEntity(p))
+                .ToPagedListAsync(request.PageNumber, request.PageSize, totalCount, cancellationToken);
+
+            return Result.Success(PaginatedResponse<PlayListApplicationResponse>.FromPagedList(pagedPlayLists));
+        }
+    }
+}

MusifyBackend/Application/PlayLists/Handlers/RemoveTrackFromPlayListCommandHandler.cs

@@ -0,0 +1,47 @@
+using Ardalis.Result;
+using Mediator;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.Logging;
+using Musify.Application.Contracts;
+using Musify.Application.PlayLists.Commands;
+
+namespace Musify.Application.PlayLists.Handlers
+{
+    public class RemoveTrackFromPlayListCommandHandler(
+        IDatabase database,
+        ILogger<RemoveTrackFromPlayListCommandHandler> logger)
+        : ICommandHandler<RemoveTrackFromPlayListCommand, Result>
+    {
+        public async ValueTask<Result> Handle(RemoveTrackFromPlayListCommand request, CancellationToken cancellationToken)
+        {
+            var playList = await database.PlayLists
+                .SingleOrDefaultAsync(pl => pl.Id == request.PlayListId, cancellationToken);
+            if (playList is null)
+            {
+                logger.LogInformation("Playlist {PlayListId} not found", request.PlayListId);
+                return Result.NotFound();
+            }
+
+            if (playList.UserId != request.UserId)
+            {
+                logger.LogWarning("User {UserId} is not the owner of playlist {PlayListId}", request.UserId, request.PlayListId);
+                return Result.Unauthorized();
+            }
+
+            var link = await database.PlayListHasTracks
+                .SingleOrDefaultAsync(plt => plt.PlayListId == request.PlayListId && plt.TrackId == request.TrackId, cancellationToken);
+            if (link is null)
+            {
+                logger.LogInformation("Track {TrackId} not in playlist {PlayListId}", request.TrackId, request.PlayListId);
+                return Result.NotFound("Track is not in the playlist.");
+            }
+
+            database.PlayListHasTracks.Remove(link);
+            await database.SaveChangesAsync(cancellationToken);
+
+            logger.LogInformation("Removed track {TrackId} from playlist {PlayListId}", request.TrackId, request.PlayListId);
+
+            return Result.Success();
+        }
+    }
+}

MusifyBackend/Application/PlayLists/Handlers/RequestPlayListPictureUploadCommandHandler.cs

@@ -0,0 +1,99 @@
+using Ardalis.Result;
+using Mediator;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.Logging;
+using Musify.Application.Configuration;
+using Musify.Application.PlayLists.Commands;
+using Musify.Application.PlayLists.Responses;
+using Musify.Application.Services;
+using Musify.Domain.Entities;
+using Musify.Domain.ValueObjects;
+using Musify.Application.Contracts;
+
+namespace Musify.Application.PlayLists.Handlers
+{
+    public class RequestPlayListPictureUploadCommandHandler(
+        IDatabase database,
+        UploadIntentValidator uploadIntentValidator,
+        IStorageService storageService,
+        ILogger<RequestPlayListPictureUploadCommandHandler> logger,
+        ApplicationStorageConfiguration storageConfiguration,
+        PlayListConfiguration playListConfiguration,
+        UploadIntentConfiguration uploadIntentConfiguration)
+        : ICommandHandler<RequestPlayListPictureUploadCommand, Result<PlayListPictureUploadResponse>>
+    {
+        public async ValueTask<Result<PlayListPictureUploadResponse>> Handle(RequestPlayListPictureUploadCommand request, CancellationToken cancellationToken)
+        {
+            var userExists = await database.Users
+                .AsNoTracking()
+                .AnyAsync(u => u.Id == request.UserId, cancellationToken);
+            if (!userExists)
+            {
+                logger.LogWarning("User {UserId} not found", request.UserId);
+                return Result.NotFound($"User {request.UserId} not found");
+            }
+
+            var effectiveSizeBytes = request.ExpectedSizeBytes
+                ?? uploadIntentConfiguration.DefaultExpectedPictureSizeBytes;
+
+            var objectName = $"{Guid.NewGuid() }.{request.FileType.TrimStart('.').ToLowerInvariant() }";
+
+            var tempKey = playListConfiguration.Routes.BuildTempPicturePath(
+                uploadIntentConfiguration.TemporalRootPrefix, request.UserId, objectName);
+
+            try
+            {
+                var uploadUrl = await storageService.GetUploadUrlAsync(
+                    storageConfiguration.Bucket,
+                    tempKey,
+                    request.ContentType,
+                    TimeSpan.FromSeconds(uploadIntentConfiguration.UploadUrlExpiresInSeconds),
+                    cancellationToken);
+
+                await using var transaction = await database.BeginTransactionAsync(
+                    System.Data.IsolationLevel.Serializable, cancellationToken);
+
+                var quotaCheck = await uploadIntentValidator.CheckQuotaAsync(
+                    uploadIntentConfiguration,
+                    request.UserId, effectiveSizeBytes, 1, cancellationToken);
+                if (!quotaCheck.IsSuccess)
+                {
+                    logger.LogWarning("User {UserId} failed upload intent quota check", request.UserId);
+                    return quotaCheck;
+                }
+
+                var intent = new UploadIntent
+                {
+                    UserId = request.UserId,
+                    Bucket = storageConfiguration.Bucket,
+                    Key = tempKey,
+                    ObjectName = objectName,
+                    ContentType = request.ContentType,
+                    ExpectedSizeBytes = effectiveSizeBytes,
+                    Purpose = UploadIntentPurpose.PlayListPicture,
+                    ExpiresAt = DateTime.UtcNow.AddSeconds(uploadIntentConfiguration.UploadUrlExpiresInSeconds),
+                };
+
+                await database.UploadIntents.AddAsync(intent, cancellationToken);
+                await database.SaveChangesAsync(cancellationToken);
+                await transaction.CommitAsync(cancellationToken);
+
+                logger.LogInformation("Issued upload intent {IntentId} for user {UserId} (PlayListPicture, temp key: {Key})", intent.Id, request.UserId, tempKey);
+
+                return Result.Success(new PlayListPictureUploadResponse(
+                    intent.Id,
+                    storageConfiguration.Bucket,
+                    tempKey,
+                    objectName,
+                    request.ContentType,
+                    uploadIntentConfiguration.UploadUrlExpiresInSeconds,
+                    uploadUrl));
+            }
+            catch (Exception exception)
+            {
+                logger.LogError(exception, "Failed to generate playlist picture upload URL for user {UserId}", request.UserId);
+                return Result.Error("Failed to generate upload URL");
+            }
+        }
+    }
+}

MusifyBackend/Application/PlayLists/Handlers/UpdatePlayListCommandHandler.cs

@@ -0,0 +1,130 @@
+using Ardalis.Result;
+using Mediator;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.Logging;
+using Musify.Application.Configuration;
+using Musify.Application.Shared;
+using Musify.Application.Events;
+using Musify.Application.PlayLists.Commands;
+using Musify.Application.PlayLists.Responses;
+using Musify.Application.Extensions;
+using Musify.Application.Services;
+using Musify.Domain.Entities;
+using Musify.Application.Contracts;
+
+namespace Musify.Application.PlayLists.Handlers
+{
+    public class UpdatePlayListCommandHandler(
+        IEventBus eventBus,
+        IDatabase database,
+        UploadIntentValidator uploadIntentValidator,
+        ILogger<UpdatePlayListCommandHandler> logger,
+        ApplicationStorageConfiguration storageConfiguration,
+        PlayListConfiguration playListConfiguration,
+        UploadIntentConfiguration uploadIntentConfiguration)
+        : ICommandHandler<UpdatePlayListCommand, Result<PlayListApplicationResponse>>
+    {
+        public async ValueTask<Result<PlayListApplicationResponse>> Handle(UpdatePlayListCommand request, CancellationToken cancellationToken)
+        {
+            var playListEntity = await database.PlayLists.SingleOrDefaultAsync(pl => pl.Id == request.PlayListId, cancellationToken);
+            if (playListEntity is null)
+            {
+                logger.LogInformation("Playlist {PlayListId} not found", request.PlayListId);
+                return Result.NotFound();
+            }
+
+            if (playListEntity.UserId != request.UserId)
+            {
+                logger.LogWarning("User {UserId} is not the owner of playlist {PlayListId}", request.UserId, request.PlayListId);
+                return Result.Unauthorized();
+            }
+
+            if (request.NewName is not null)
+            {
+                playListEntity.Name = request.NewName;
+                playListEntity.NormalizedName = request.NewName.Trim().ToUpperInvariant();
+            }
+
+            if (request.NewDescription is not null)
+            {
+                playListEntity.Description = request.NewDescription;
+            }
+
+            UploadIntent? pictureIntent = null;
+            string? finalPictureKey = null;
+
+            if (request.NewPictureIntentId.HasValue)
+            {
+                var validation = await uploadIntentValidator.ValidateAndLoadAsync(
+                    uploadIntentConfiguration,
+                    request.NewPictureIntentId.Value, request.UserId, cancellationToken);
+                if (!validation.IsSuccess)
+                    return validation.As<UploadIntent, PlayListApplicationResponse>();
+
+                pictureIntent = validation.Value;
+                playListEntity.OriginalPictureName = pictureIntent.ObjectName;
+                finalPictureKey = playListConfiguration.Routes.BuildOriginalPicturePath(request.UserId, pictureIntent.ObjectName);
+            }
+
+            database.PlayLists.Update(playListEntity);
+
+            if (pictureIntent is not null && finalPictureKey is not null)
+            {
+                var publishResult = await PublishUpdatePlayListPictureSourceEventAsync(
+                    playListEntity.Id, pictureIntent, finalPictureKey, cancellationToken);
+                if (!publishResult.IsSuccess)
+                    return publishResult;
+            }
+
+            try
+            {
+                await database.SaveChangesAsync(cancellationToken);
+            }
+            catch (Exception exception)
+            {
+                logger.LogError(exception, "Failed to update playlist {PlayListId}", playListEntity.Id);
+                return Result.Error($"Failed to update playlist {playListEntity.Id}");
+            }
+
+            logger.LogInformation("Updated playlist {PlayListId}", playListEntity.Id);
+            return Result.Success(PlayListApplicationResponse.FromEntity(playListEntity));
+        }
+
+        async Task<Result<PlayListApplicationResponse>> PublishUpdatePlayListPictureSourceEventAsync(
+            Guid playListId,
+            UploadIntent pictureIntent,
+            string finalPictureKey,
+            CancellationToken cancellationToken)
+        {
+            try
+            {
+                await eventBus.PublishAsync(
+                    new UpdatePlayListPictureSourceEvent(
+                        playListId,
+                        pictureIntent.Id,
+                        storageConfiguration.Bucket,
+                        pictureIntent.Key,
+                        finalPictureKey,
+                        new ImageSize(
+                            playListConfiguration.Routes.SmallPicturesPath,
+                            playListConfiguration.PicturesSizes.SmallPictureWidth,
+                            playListConfiguration.PicturesSizes.SmallPictureHeight),
+                        new ImageSize(
+                            playListConfiguration.Routes.MediumPicturesPath,
+                            playListConfiguration.PicturesSizes.MediumPictureWidth,
+                            playListConfiguration.PicturesSizes.MediumPictureHeight),
+                        new ImageSize(
+                            playListConfiguration.Routes.LargePicturesPath,
+                            playListConfiguration.PicturesSizes.LargePictureWidth,
+                            playListConfiguration.PicturesSizes.LargePictureHeight)),
+                    cancellationToken);
+                return Result.Success();
+            }
+            catch (Exception exception)
+            {
+                logger.LogError(exception, "Failed to publish update playlist picture source event for playlist {PlayListId}", playListId);
+                return Result.Error($"Failed to publish update playlist picture source event for playlist {playListId}");
+            }
+        }
+    }
+}

MusifyBackend/Application/PlayLists/Queries/GetPlayListByIdQuery.cs

@@ -0,0 +1,9 @@
+using Ardalis.Result;
+using Mediator;
+using Musify.Application.PlayLists.Responses;
+
+namespace Musify.Application.PlayLists.Queries
+{
+    public record GetPlayListByIdQuery(Guid Id)
+        : IQuery<Result<PlayListApplicationResponse>>;
+}

MusifyBackend/Application/PlayLists/Queries/GetPlayListTracksQuery.cs

@@ -0,0 +1,13 @@
+using Ardalis.Result;
+using Mediator;
+using Musify.Application.Pagination;
+using Musify.Application.Tracks.Responses;
+
+namespace Musify.Application.PlayLists.Queries
+{
+    public record GetPlayListTracksQuery(
+        Guid PlayListId,
+        int PageNumber = 1,
+        int PageSize = 10)
+        : IQuery<Result<PaginatedResponse<TrackApplicationResponse>>>;
+}

MusifyBackend/Application/PlayLists/Queries/GetPlayListsByUserIdQuery.cs

@@ -0,0 +1,14 @@
+using Ardalis.Result;
+using Mediator;
+using Musify.Application.Pagination;
+using Musify.Application.PlayLists.Responses;
+
+namespace Musify.Application.PlayLists.Queries
+{
+    public record GetPlayListsByUserIdQuery(
+        long UserId,
+        string? Name,
+        int PageNumber = 1,
+        int PageSize = 10)
+        : IQuery<Result<PaginatedResponse<PlayListApplicationResponse>> >;
+}

MusifyBackend/Application/PlayLists/Queries/GetPlayListsQuery.cs

@@ -0,0 +1,10 @@
+using Ardalis.Result;
+using Mediator;
+using Musify.Application.Pagination;
+using Musify.Application.PlayLists.Responses;
+
+namespace Musify.Application.PlayLists.Queries
+{
+    public record GetPlayListsQuery(int PageNumber = 1, int PageSize = 10)
+        : IQuery<Result<PaginatedResponse<PlayListApplicationResponse>> >;
+}

MusifyBackend/Application/PlayLists/Responses/PlayListApplicationResponse.cs

@@ -0,0 +1,28 @@
+using Musify.Domain.Entities;
+
+namespace Musify.Application.PlayLists.Responses
+{
+    public record PlayListApplicationResponse(
+        Guid Id,
+        string Name,
+        string Description,
+        string SmallImageKeyName,
+        string MediumImageKeyName,
+        string LargeImageKeyName,
+        DateTime CreatedAt,
+        DateTime UpdatedAt)
+    {
+        public static PlayListApplicationResponse FromEntity(PlayList playList)
+        {
+            return new PlayListApplicationResponse(
+                playList.Id,
+                playList.Name,
+                playList.Description,
+                playList.SmallPictureName,
+                playList.MediumPictureName,
+                playList.LargePictureName,
+                playList.CreatedAt,
+                playList.UpdatedAt);
+        }
+    }
+}

MusifyBackend/Application/PlayLists/Responses/PlayListPictureUploadResponse.cs

@@ -0,0 +1,11 @@
+namespace Musify.Application.PlayLists.Responses
+{
+    public record PlayListPictureUploadResponse(
+        Guid IntentId,
+        string Bucket,
+        string Key,
+        string PictureName,
+        string ContentType,
+        int ExpiresInSeconds,
+        string UploadUrl);
+}

MusifyBackend/Application/Services/UploadIntentValidator.cs

@@ -0,0 +1,63 @@
+using Ardalis.Result;
+using Microsoft.EntityFrameworkCore;
+using Musify.Application.Configuration;
+using Musify.Domain.Entities;
+using Musify.Domain.ValueObjects;
+using Musify.Application.Contracts;
+
+namespace Musify.Application.Services;
+
+public sealed class UploadIntentValidator(
+    IDatabase database,
+    IStorageService storageService)
+{
+    public async Task<Result> CheckQuotaAsync(
+        UploadIntentConfiguration config,
+        long userId,
+        long requiredBytes,
+        int requiredIntentCount,
+        CancellationToken cancellationToken)
+    {
+        var activeIntents = await database.UploadIntents
+            .AsNoTracking()
+            .Where(i => i.UserId == userId && i.Status == UploadIntentStatus.Issued)
+            .ToListAsync(cancellationToken);
+
+        if (activeIntents.Count + requiredIntentCount > config.MaxActiveUploadIntentsPerUser)
+            return Result.Invalid(new ValidationError("Upload intent limit exceeded. Wait for existing uploads to complete or expire."));
+
+        var activeBytes = activeIntents.Sum(i => i.ExpectedSizeBytes ?? config.DefaultExpectedPictureSizeBytes);
+        if (activeBytes + requiredBytes > config.MaxActiveUploadBytesPerUser)
+            return Result.Invalid(new ValidationError("Upload byte quota exceeded. Wait for existing uploads to complete or expire."));
+
+        return Result.Success();
+    }
+
+    public async Task<Result<UploadIntent>> ValidateAndLoadAsync(
+        UploadIntentConfiguration config,
+        Guid intentId,
+        long userId,
+        CancellationToken cancellationToken)
+    {
+        var intent = await database.UploadIntents
+            .FirstOrDefaultAsync(i => i.Id == intentId, cancellationToken);
+
+        if (intent is null || intent.UserId != userId)
+            return Result.NotFound("Upload intent not found or not accessible.");
+
+        if (intent.Status == UploadIntentStatus.Consumed)
+            return Result.Conflict("Upload intent has already been consumed.");
+
+        if (intent.Status == UploadIntentStatus.Expired || intent.ExpiresAt < DateTime.UtcNow)
+            return Result.Invalid(new ValidationError("Upload intent has expired."));
+
+        var metadata = await storageService.HeadObjectAsync(intent.Bucket, intent.Key, cancellationToken);
+        if (metadata is null)
+            return Result.NotFound("Uploaded object not found in storage. Upload the file first.");
+
+        if (metadata.ContentLength > config.MaxUploadBytes)
+            return Result.Invalid(new ValidationError($"Uploaded file exceeds the maximum allowed size of {config.MaxUploadBytes} bytes."));
+
+        return Result.Success(intent);
+    }
+}

MusifyBackend/Application/Shared/ImageSize.cs

@@ -0,0 +1,7 @@
+namespace Musify.Application.Shared
+{
+    public record ImageSize(
+        string SavePath,
+        int Width,
+        int Height);
+}

MusifyBackend/Application/Shared/StorageKey.cs

@@ -0,0 +1,12 @@
+namespace Musify.Application.Shared
+{
+    public static class StorageKey
+    {
+        public static string Combine(params string[] segments)
+        {
+            return string.Join('/', segments
+                .Where(static s => !string.IsNullOrWhiteSpace(s))
+                .Select(static s => s.Trim().Trim('/', '\\')));
+        }
+    }
+}

MusifyBackend/Application/Tracks/Commands/CreateTrackCommand.cs

@@ -0,0 +1,13 @@
+using Ardalis.Result;
+using Mediator;
+using Musify.Application.Tracks.Responses;
+
+namespace Musify.Application.Tracks.Commands
+{
+    public record CreateTrackCommand(
+        long UserId,
+        string Title,
+        Guid PictureIntentId,
+        Guid AudioIntentId)
+        : ICommand<Result<TrackApplicationResponse>>;
+}

MusifyBackend/Application/Tracks/Commands/DeleteTrackCommand.cs

@@ -0,0 +1,10 @@
+using Ardalis.Result;
+using Mediator;
+
+namespace Musify.Application.Tracks.Commands
+{
+    public record DeleteTrackCommand(
+        long UserId,
+        Guid TrackId)
+        : ICommand<Result>;
+}

MusifyBackend/Application/Tracks/Commands/RequestTrackUploadUrlsCommand.cs

@@ -0,0 +1,16 @@
+using Ardalis.Result;
+using Mediator;
+using Musify.Application.Tracks.Responses;
+
+namespace Musify.Application.Tracks.Commands
+{
+    public record RequestTrackUploadUrlsCommand(
+        long UserId,
+        string PictureFileType,
+        string PictureContentType,
+        string AudioFileType,
+        string AudioContentType,
+        long? ExpectedPictureSizeBytes = null,
+        long? ExpectedAudioSizeBytes = null)
+        : ICommand<Result<TrackUploadUrlsResponse>>;
+}

MusifyBackend/Application/Tracks/Handlers/CreateTrackCommandHandler.cs

@@ -0,0 +1,124 @@
+using Ardalis.Result;
+using Mediator;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.Logging;
+using Musify.Application.Configuration;
+using Musify.Application.Shared;
+using Musify.Application.Events;
+using Musify.Application.Tracks.Commands;
+using Musify.Application.Tracks.Responses;
+using Musify.Application.Extensions;
+using Musify.Application.Services;
+using Musify.Domain.Entities;
+using Musify.Domain.ValueObjects;
+using Musify.Application.Contracts;
+
+namespace Musify.Application.Tracks.Handlers
+{
+    public class CreateTrackCommandHandler(
+        IDatabase database,
+        IEventBus eventBus,
+        UploadIntentValidator uploadIntentValidator,
+        ILogger<CreateTrackCommandHandler> logger,
+        ApplicationStorageConfiguration storageConfiguration,
+        TrackConfiguration trackConfiguration,
+        UploadIntentConfiguration uploadIntentConfiguration)
+        : ICommandHandler<CreateTrackCommand, Result<TrackApplicationResponse>>
+    {
+        public async ValueTask<Result<TrackApplicationResponse>> Handle(CreateTrackCommand request, CancellationToken cancellationToken)
+        {
+            var userExists = await database.Users.AsNoTracking()
+                .AnyAsync(u => u.Id == request.UserId, cancellationToken);
+            if (!userExists)
+            {
+                logger.LogWarning("User {UserId} not found", request.UserId);
+                return Result.NotFound($"User {request.UserId} not found");
+            }
+
+            var pictureValidation = await uploadIntentValidator.ValidateAndLoadAsync(
+                uploadIntentConfiguration,
+                request.PictureIntentId, request.UserId, cancellationToken);
+            if (!pictureValidation.IsSuccess)
+                return pictureValidation.As<UploadIntent, TrackApplicationResponse>();
+
+            var audioValidation = await uploadIntentValidator.ValidateAndLoadAsync(
+                uploadIntentConfiguration,
+                request.AudioIntentId, request.UserId, cancellationToken);
+            if (!audioValidation.IsSuccess)
+                return audioValidation.As<UploadIntent, TrackApplicationResponse>();
+
+            var pictureIntent = pictureValidation.Value;
+            var audioIntent = audioValidation.Value;
+
+            var finalPictureKey = trackConfiguration.Routes.BuildOriginalPicturePath(request.UserId, pictureIntent.ObjectName);
+            var finalAudioKey = trackConfiguration.Routes.BuildOriginalAudioPath(request.UserId, audioIntent.ObjectName);
+            var audioProcessedFolderKey = trackConfiguration.Routes.BuildProcessedAudioPath(Guid.NewGuid().ToString());
+
+            var trackEntity = new Track
+            {
+                Title = request.Title,
+                NormalizedTitle = request.Title.ToUpperInvariant(),
+                OriginalPictureName = pictureIntent.ObjectName,
+                OriginalAudioName = audioIntent.ObjectName,
+                SmallPictureName = trackConfiguration.Routes.PresetSmallPicture,
+                MediumPictureName = trackConfiguration.Routes.PresetMediumPicture,
+                LargePictureName = trackConfiguration.Routes.PresetLargePicture,
+                PicturesProcessingStatus = ProcessingStatus.Pending,
+                AudioTranscodeProcessingStatus = ProcessingStatus.Pending
+            };
+
+            await database.Tracks.AddAsync(trackEntity, cancellationToken);
+
+            await database.UserHasTracks.AddAsync(new UserHasTrack
+            {
+                UserId = request.UserId,
+                TrackId = trackEntity.Id
+            }, cancellationToken);
+
+            try
+            {
+                await eventBus.PublishAsync(
+                    new CreateTrackResourcesEvent(
+                        trackEntity.Id,
+                        pictureIntent.Id,
+                        audioIntent.Id,
+                        storageConfiguration.Bucket,
+                        pictureIntent.Key,
+                        finalPictureKey,
+                        audioIntent.Key,
+                        finalAudioKey,
+                        audioProcessedFolderKey,
+                        new ImageSize(
+                            trackConfiguration.Routes.SmallPicturesPath,
+                            trackConfiguration.PicturesSizes.SmallPictureWidth,
+                            trackConfiguration.PicturesSizes.SmallPictureHeight),
+                        new ImageSize(
+                            trackConfiguration.Routes.MediumPicturesPath,
+                            trackConfiguration.PicturesSizes.MediumPictureWidth,
+                            trackConfiguration.PicturesSizes.MediumPictureHeight),
+                        new ImageSize(
+                            trackConfiguration.Routes.LargePicturesPath,
+                            trackConfiguration.PicturesSizes.LargePictureWidth,
+                            trackConfiguration.PicturesSizes.LargePictureHeight)),
+                    cancellationToken);
+            }
+            catch (Exception exception)
+            {
+                logger.LogError(exception, "Failed to publish create track event for track {TrackId}", trackEntity.Id);
+                return Result.Error($"Failed to create track for {request.Title}");
+            }
+
+            try
+            {
+                await database.SaveChangesAsync(cancellationToken);
+            }
+            catch (Exception exception)
+            {
+                logger.LogError(exception, "Failed to save track {Title}", request.Title);
+                return Result.Error($"Failed to create track for {request.Title}");
+            }
+
+            return Result.Created(TrackApplicationResponse.FromEntity(trackEntity));
+        }
+    }
+}

MusifyBackend/Application/Tracks/Handlers/DeleteTrackCommandHandler.cs

@@ -0,0 +1,70 @@
+using Ardalis.Result;
+using Mediator;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.Logging;
+using Musify.Application.Tracks.Commands;
+using Musify.Domain.ValueObjects;
+using Musify.Application.Events;
+using Musify.Application.Contracts;
+
+namespace Musify.Application.Tracks.Handlers
+{
+    public class DeleteTrackCommandHandler(
+        IDatabase database,
+        IEventBus eventBus,
+        ILogger<DeleteTrackCommandHandler> logger)
+        : ICommandHandler<DeleteTrackCommand, Result>
+    {
+        public async ValueTask<Result> Handle(DeleteTrackCommand request, CancellationToken cancellationToken)
+        {
+            var track = await database.Tracks.SingleOrDefaultAsync(t => t.Id == request.TrackId, cancellationToken);
+            if (track is null)
+            {
+                logger.LogInformation("Track {TrackId} not found", request.TrackId);
+                return Result.NotFound();
+            }
+
+            var isOwner = await database.UserHasTracks
+                .AsNoTracking()
+                .AnyAsync(ut => ut.TrackId == request.TrackId && ut.UserId == request.UserId, cancellationToken);
+            if (!isOwner)
+            {
+                logger.LogWarning("User {UserId} unauthorized to delete track {TrackId}", request.UserId, request.TrackId);
+                return Result.Unauthorized();
+            }
+
+            if (track.AudioTranscodeProcessingStatus == ProcessingStatus.Processing
+                || track.AudioTranscodeProcessingStatus == ProcessingStatus.Pending)
+            {
+                logger.LogWarning("Track {TrackId} is currently being processed and cannot be deleted", request.TrackId);
+                return Result.Conflict("Track is currently being processed and cannot be deleted");
+            }
+
+            track.LifeCycleStatus = LifeCycleStatus.Removing;
+
+            try
+            {
+                await eventBus.PublishAsync(
+                    new DeleteTrackEvent(track.Id, request.UserId),
+                    cancellationToken);
+            }
+            catch (Exception exception)
+            {
+                logger.LogError(exception, "Failed to publish delete track event for track {TrackId}", request.TrackId);
+                return Result.Error($"Failed to delete track {request.TrackId}");
+            }
+
+            try
+            {
+                await database.SaveChangesAsync(cancellationToken);
+            }
+            catch (Exception exception)
+            {
+                logger.LogError(exception, "Failed to mark track {TrackId} as processing before deletion", request.TrackId);
+                return Result.Error($"Failed to delete track {request.TrackId}");
+            }
+
+            return Result.NoContent();
+        }
+    }
+}

MusifyBackend/Application/Tracks/Handlers/GetTrackByIdQueryHandler.cs

@@ -0,0 +1,25 @@
+using Ardalis.Result;
+using Mediator;
+using Microsoft.EntityFrameworkCore;
+using Musify.Application.Contracts;
+using Musify.Application.Tracks.Queries;
+using Musify.Application.Tracks.Responses;
+
+namespace Musify.Application.Tracks.Handlers
+{
+    public class GetTrackByIdQueryHandler(IDatabase database)
+        : IQueryHandler<GetTrackByIdQuery, Result<TrackApplicationResponse> >
+    {
+        public async ValueTask<Result<TrackApplicationResponse>> Handle(GetTrackByIdQuery request, CancellationToken cancellationToken)
+        {
+            var track = await database.Tracks.AsNoTracking()
+                .Where(t => t.Id == request.TrackId)
+                .Select(t => TrackApplicationResponse.FromEntity(t))
+                .SingleOrDefaultAsync(cancellationToken);
+
+            return track is null
+                ? Result<TrackApplicationResponse>.NotFound()
+                : Result.Success(track);
+        }
+    }
+}

MusifyBackend/Application/Tracks/Handlers/GetTrackStreamQueryHandler.cs

@@ -0,0 +1,54 @@
+using Ardalis.Result;
+using Mediator;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.Logging;
+using Musify.Application.Configuration;
+using Musify.Application.Contracts;
+using Musify.Application.Tracks.Queries;
+using Musify.Application.Tracks.Responses;
+using Musify.Domain.ValueObjects;
+
+namespace Musify.Application.Tracks.Handlers
+{
+    public class GetTrackStreamQueryHandler(
+        IDatabase database,
+        IStreamTicketService ticketService,
+        TrackConfiguration trackConfiguration,
+        StreamGatewayConfiguration streamGatewayConfiguration,
+        ILogger<GetTrackStreamQueryHandler> logger)
+        : IQueryHandler<GetTrackStreamQuery, Result<TrackStreamResponse>>
+    {
+        public async ValueTask<Result<TrackStreamResponse>> Handle(GetTrackStreamQuery request, CancellationToken cancellationToken)
+        {
+            var track = await database.Tracks.AsNoTracking()
+                .Where(t => t.Id == request.TrackId)
+                .Select(t => new { t.Id, t.AudioTranscodeProcessingStatus, t.AudioFolderName })
+                .SingleOrDefaultAsync(cancellationToken);
+
+            if (track is null)
+                return Result<TrackStreamResponse>.NotFound();
+
+            if (string.IsNullOrWhiteSpace(track.AudioFolderName)
+                || track.AudioTranscodeProcessingStatus != ProcessingStatus.Completed)
+            {
+                logger.LogInformation("Stream requested for track {TrackId} but audio is not ready", request.TrackId);
+                return Result<TrackStreamResponse>.Conflict("Track audio is not available for streaming yet.");
+            }
+
+            var folderPath = trackConfiguration.Routes.BuildProcessedAudioPath(track.AudioFolderName);
+            var keyPrefix = $"{folderPath}/";
+
+            var ticket = ticketService.IssueTicket(request.UserId, keyPrefix);
+
+            var manifestUrl = string.Join('/',
+                streamGatewayConfiguration.PublicBaseUrl.TrimEnd('/'),
+                "media",
+                folderPath,
+                streamGatewayConfiguration.AudioFileName);
+
+            logger.LogInformation("Issued stream ticket for track {TrackId} to user {UserId}", request.TrackId, request.UserId);
+
+            return Result.Success(new TrackStreamResponse(manifestUrl, ticket.Token, ticket.ExpiresInSeconds));
+        }
+    }
+}

MusifyBackend/Application/Tracks/Handlers/GetTracksByUserIdQueryHandler.cs

@@ -0,0 +1,41 @@
+using Ardalis.Result;
+using Mediator;
+using Microsoft.EntityFrameworkCore;
+using Musify.Application.Pagination;
+using Musify.Application.Tracks.Queries;
+using Musify.Application.Tracks.Responses;
+using X.PagedList.EF;
+using Musify.Application.Contracts;
+
+namespace Musify.Application.Tracks.Handlers
+{
+    public class GetTracksByUserIdQueryHandler(IDatabase database)
+        : IQueryHandler<GetTracksByUserIdQuery, Result<PaginatedResponse<TrackApplicationResponse>> >
+    {
+        public async ValueTask<Result<PaginatedResponse<TrackApplicationResponse> >> Handle(GetTracksByUserIdQuery request, CancellationToken cancellationToken)
+        {
+            var pageNumber = request.PageNumber < 1 ? 1 : request.PageNumber;
+            var pageSize = request.PageSize < 1 ? 10 : request.PageSize;
+
+            var tracksQuery = database.UserHasTracks
+                .AsNoTracking()
+                .Include(ut => ut.Track)
+                .Where(p => p.UserId == request.UserId);
+
+            if (request.Name is not null)
+            {
+                var normalizedName = request.Name.Trim().ToUpperInvariant();
+                tracksQuery = tracksQuery.Where(t => t.Track.NormalizedTitle.Contains(normalizedName));
+            }
+
+            var totalCount = await tracksQuery.CountAsync(cancellationToken);
+
+            var pagedTracks = await tracksQuery
+                .OrderBy(t => t.Track.CreatedAt)
+                .Select(t => TrackApplicationResponse.FromEntity(t.Track))
+                .ToPagedListAsync(pageNumber, pageSize, totalCount, cancellationToken);
+
+            return Result.Success(PaginatedResponse<TrackApplicationResponse>.FromPagedList(pagedTracks));
+        }
+    }
+}

MusifyBackend/Application/Tracks/Handlers/GetTracksQueryHandler.cs

@@ -0,0 +1,29 @@
+using Ardalis.Result;
+using Mediator;
+using Microsoft.EntityFrameworkCore;
+using Musify.Application.Pagination;
+using Musify.Application.Tracks.Queries;
+using Musify.Application.Tracks.Responses;
+using X.PagedList.EF;
+using Musify.Application.Contracts;
+
+namespace Musify.Application.Tracks.Handlers
+{
+    public class GetTracksQueryHandler(IDatabase database)
+        : IQueryHandler<GetTracksQuery, Result<PaginatedResponse<TrackApplicationResponse>> >
+    {
+        public async ValueTask<Result<PaginatedResponse<TrackApplicationResponse> >> Handle(GetTracksQuery request, CancellationToken cancellationToken)
+        {
+            var tracksQuery = database.UserHasTracks
+                .AsNoTracking()
+                .OrderBy(t => t.Id)
+                .Include(ut => ut.Track)
+                .Select(t => TrackApplicationResponse.FromEntity(t.Track));
+
+            var totalCount = await tracksQuery.CountAsync(cancellationToken);
+            var pagedTracks = await tracksQuery.ToPagedListAsync(request.PageNumber, request.PageSize, totalCount, cancellationToken);
+
+            return Result.Success(PaginatedResponse<TrackApplicationResponse>.FromPagedList(pagedTracks));
+        }
+    }
+}

MusifyBackend/Application/Tracks/Handlers/RequestTrackUploadUrlsCommandHandler.cs

@@ -0,0 +1,134 @@
+using Ardalis.Result;
+using Mediator;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.Logging;
+using Musify.Application.Configuration;
+using Musify.Application.Services;
+using Musify.Application.Tracks.Commands;
+using Musify.Application.Tracks.Responses;
+using Musify.Domain.Entities;
+using Musify.Domain.ValueObjects;
+using Musify.Application.Contracts;
+
+namespace Musify.Application.Tracks.Handlers
+{
+    public class RequestTrackUploadUrlsCommandHandler(
+        IDatabase database,
+        UploadIntentValidator uploadIntentValidator,
+        IStorageService storageService,
+        ILogger<RequestTrackUploadUrlsCommandHandler> logger,
+        ApplicationStorageConfiguration storageConfiguration,
+        TrackConfiguration trackConfiguration,
+        UploadIntentConfiguration uploadIntentConfiguration)
+        : ICommandHandler<RequestTrackUploadUrlsCommand, Result<TrackUploadUrlsResponse>>
+    {
+        public async ValueTask<Result<TrackUploadUrlsResponse>> Handle(RequestTrackUploadUrlsCommand request, CancellationToken cancellationToken)
+        {
+            var userExists = await database.Users
+                .AsNoTracking()
+                .AnyAsync(u => u.Id == request.UserId, cancellationToken);
+            if (!userExists)
+            {
+                logger.LogWarning("User {UserId} not found", request.UserId);
+                return Result.NotFound($"User {request.UserId} not found");
+            }
+
+            var effectivePictureSize = request.ExpectedPictureSizeBytes
+                ?? uploadIntentConfiguration.DefaultExpectedPictureSizeBytes;
+            var effectiveAudioSize = request.ExpectedAudioSizeBytes
+                ?? uploadIntentConfiguration.DefaultExpectedAudioSizeBytes;
+
+            var pictureObjectName = $"{Guid.NewGuid()}.{request.PictureFileType.TrimStart('.').ToLowerInvariant()}";
+            var audioObjectName = $"{Guid.NewGuid()}.{request.AudioFileType.TrimStart('.').ToLowerInvariant()}";
+
+            var tempPictureKey = trackConfiguration.Routes.BuildTempPicturePath(
+                uploadIntentConfiguration.TemporalRootPrefix, request.UserId, pictureObjectName);
+            var tempAudioKey = trackConfiguration.Routes.BuildTempAudioPath(
+                uploadIntentConfiguration.TemporalRootPrefix, request.UserId, audioObjectName);
+
+            try
+            {
+                var expiresIn = TimeSpan.FromSeconds(uploadIntentConfiguration.UploadUrlExpiresInSeconds);
+
+                var pictureUploadUrl = await storageService.GetUploadUrlAsync(
+                    storageConfiguration.Bucket,
+                    tempPictureKey,
+                    request.PictureContentType,
+                    expiresIn,
+                    cancellationToken);
+
+                var audioUploadUrl = await storageService.GetUploadUrlAsync(
+                    storageConfiguration.Bucket,
+                    tempAudioKey,
+                    request.AudioContentType,
+                    expiresIn,
+                    cancellationToken);
+
+                var expiresAt = DateTime.UtcNow.AddSeconds(uploadIntentConfiguration.UploadUrlExpiresInSeconds);
+
+                await using var transaction = await database.BeginTransactionAsync(
+                    System.Data.IsolationLevel.Serializable, cancellationToken);
+
+                var quotaCheck = await uploadIntentValidator.CheckQuotaAsync(
+                    uploadIntentConfiguration,
+                    request.UserId, effectivePictureSize + effectiveAudioSize, 2, cancellationToken);
+                if (!quotaCheck.IsSuccess)
+                {
+                    logger.LogWarning("User {UserId} failed upload intent quota check", request.UserId);
+                    return quotaCheck;
+                }
+
+                var pictureIntent = new UploadIntent
+                {
+                    UserId = request.UserId,
+                    Bucket = storageConfiguration.Bucket,
+                    Key = tempPictureKey,
+                    ObjectName = pictureObjectName,
+                    ContentType = request.PictureContentType,
+                    ExpectedSizeBytes = effectivePictureSize,
+                    Purpose = UploadIntentPurpose.TrackPicture,
+                    ExpiresAt = expiresAt,
+                };
+
+                var audioIntent = new UploadIntent
+                {
+                    UserId = request.UserId,
+                    Bucket = storageConfiguration.Bucket,
+                    Key = tempAudioKey,
+                    ObjectName = audioObjectName,
+                    ContentType = request.AudioContentType,
+                    ExpectedSizeBytes = effectiveAudioSize,
+                    Purpose = UploadIntentPurpose.TrackAudio,
+                    ExpiresAt = expiresAt,
+                };
+
+                await database.UploadIntents.AddAsync(pictureIntent, cancellationToken);
+                await database.UploadIntents.AddAsync(audioIntent, cancellationToken);
+                await database.SaveChangesAsync(cancellationToken);
+                await transaction.CommitAsync(cancellationToken);
+
+                logger.LogInformation("Issued upload intents {PictureIntentId}/{AudioIntentId} for user {UserId} (TrackPicture/TrackAudio)",
+                    pictureIntent.Id, audioIntent.Id, request.UserId);
+
+                return Result.Success(new TrackUploadUrlsResponse(
+                    pictureIntent.Id,
+                    audioIntent.Id,
+                    storageConfiguration.Bucket,
+                    tempPictureKey,
+                    pictureObjectName,
+                    request.PictureContentType,
+                    pictureUploadUrl,
+                    tempAudioKey,
+                    audioObjectName,
+                    request.AudioContentType,
+                    audioUploadUrl,
+                    uploadIntentConfiguration.UploadUrlExpiresInSeconds));
+            }
+            catch (Exception exception)
+            {
+                logger.LogError(exception, "Failed to generate track upload URLs for user {UserId}", request.UserId);
+                return Result.Error("Failed to generate upload URLs");
+            }
+        }
+    }
+}

MusifyBackend/Application/Tracks/Queries/GetTrackByIdQuery.cs

@@ -0,0 +1,9 @@
+using Ardalis.Result;
+using Mediator;
+using Musify.Application.Tracks.Responses;
+
+namespace Musify.Application.Tracks.Queries
+{
+    public record GetTrackByIdQuery(Guid TrackId)
+        : IQuery<Result<TrackApplicationResponse>>;
+}

MusifyBackend/Application/Tracks/Queries/GetTrackStreamQuery.cs

@@ -0,0 +1,9 @@
+using Ardalis.Result;
+using Mediator;
+using Musify.Application.Tracks.Responses;
+
+namespace Musify.Application.Tracks.Queries
+{
+    public record GetTrackStreamQuery(Guid TrackId, long UserId)
+        : IQuery<Result<TrackStreamResponse>>;
+}

MusifyBackend/Application/Tracks/Queries/GetTracksByUserIdQuery.cs

@@ -0,0 +1,14 @@
+using Ardalis.Result;
+using Mediator;
+using Musify.Application.Pagination;
+using Musify.Application.Tracks.Responses;
+
+namespace Musify.Application.Tracks.Queries
+{
+    public record GetTracksByUserIdQuery(
+        long UserId,
+    string? Name = null,
+        int PageNumber = 1,
+        int PageSize = 10)
+        : IQuery<Result<PaginatedResponse<TrackApplicationResponse> > >;
+}

MusifyBackend/Application/Tracks/Queries/GetTracksQuery.cs

@@ -0,0 +1,10 @@
+using Ardalis.Result;
+using Mediator;
+using Musify.Application.Pagination;
+using Musify.Application.Tracks.Responses;
+
+namespace Musify.Application.Tracks.Queries
+{
+    public record GetTracksQuery(int PageNumber = 1, int PageSize = 10)
+        : IQuery<Result<PaginatedResponse<TrackApplicationResponse> >>;
+}

MusifyBackend/Application/Tracks/Responses/TrackApplicationResponse.cs

@@ -0,0 +1,20 @@
+using Musify.Domain.Entities;
+
+namespace Musify.Application.Tracks.Responses
+{
+    public record TrackApplicationResponse(
+        Guid Id,
+        string Title,
+        DateTime CreatedAt,
+        DateTime UpdatedAt)
+    {
+        public static TrackApplicationResponse FromEntity(Track track)
+        {
+            return new TrackApplicationResponse(
+                track.Id,
+                track.Title,
+                track.CreatedAt,
+                track.UpdatedAt);
+        }
+    }
+}

MusifyBackend/Application/Tracks/Responses/TrackStreamResponse.cs

@@ -0,0 +1,7 @@
+namespace Musify.Application.Tracks.Responses
+{
+    public record TrackStreamResponse(
+        string ManifestUrl,
+        string Ticket,
+        int ExpiresInSeconds);
+}

MusifyBackend/Application/Tracks/Responses/TrackUploadUrlsResponse.cs

@@ -0,0 +1,16 @@
+namespace Musify.Application.Tracks.Responses
+{
+    public record TrackUploadUrlsResponse(
+        Guid PictureIntentId,
+        Guid AudioIntentId,
+        string Bucket,
+        string PictureKey,
+        string PictureName,
+        string PictureContentType,
+        string PictureUploadUrl,
+        string AudioKey,
+        string AudioName,
+        string AudioContentType,
+        string AudioUploadUrl,
+        int ExpiresInSeconds);
+}

MusifyBackend/Application/Users/Commands/CreateUserCommand.cs

@@ -0,0 +1,26 @@
+using Ardalis.Result;
+using Mediator;
+using Musify.Application.Users.Responses;
+using Musify.Domain.Entities;
+
+namespace Musify.Application.Users.Commands
+{
+    public record CreateUserCommand(long Id,
+        string Name,
+        string? FirstName,
+        string? SecondName)
+        : ICommand<Result<UserApplicationResponse>>
+    {
+        public static User ToEntity(CreateUserCommand command)
+        {
+            return new User
+            {
+                Id = command.Id,
+                Name = command.Name,
+                NormalizedName = command.Name.ToUpperInvariant(),
+                FirstName = command.FirstName,
+                SecondName = command.SecondName
+            };
+        }
+    }
+}

MusifyBackend/Application/Users/Commands/SyncUserCommand.cs

@@ -0,0 +1,13 @@
+using Ardalis.Result;
+using Mediator;
+
+namespace Musify.Application.Users.Commands
+{
+    public record SyncUserCommand(
+        long Id,
+        string Name,
+        string? FirstName,
+        string? SecondName,
+        string? ProfilePictureUrl)
+        : ICommand<Result>;
+}

MusifyBackend/Application/Users/Handlers/CreateUserCommandHandler.cs

@@ -0,0 +1,40 @@
+using Ardalis.Result;
+using Mediator;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.Logging;
+using Musify.Application.Contracts;
+using Musify.Application.Users.Commands;
+using Musify.Application.Users.Responses;
+
+namespace Musify.Application.Users.Handlers
+{
+    public class CreateUserCommandHandler(IDatabase database, ILogger<CreateUserCommandHandler> logger)
+        : ICommandHandler<CreateUserCommand, Result<UserApplicationResponse> >
+    {
+        public async ValueTask<Result<UserApplicationResponse>> Handle(CreateUserCommand request, CancellationToken cancellationToken)
+        {
+            var userExists = await database.Users.AnyAsync(u => u.Id == request.Id, cancellationToken);
+            if (userExists)
+            {
+                logger.LogInformation("User {UserId} already exists", request.Id);
+                return Result<UserApplicationResponse>.Conflict($"User {request.Id} already exists");
+            }
+
+            var newUser = CreateUserCommand.ToEntity(request);
+
+            try
+            {
+                await database.Users.AddAsync(newUser, cancellationToken);
+                await database.SaveChangesAsync(cancellationToken);
+            }
+            catch (Exception exception)
+            {
+                logger.LogError(exception, "Failed to create user {UserId}", request.Id);
+                return Result.Error($"Failed to create user {request.Id}");
+            }
+
+            logger.LogInformation("Created user {UserId}", newUser.Id);
+            return Result.Created(UserApplicationResponse.FromEntity(newUser));
+        }
+    }
+}

MusifyBackend/Application/Users/Handlers/GetUserByIdQueryHandler.cs

@@ -0,0 +1,26 @@
+using Ardalis.Result;
+using Mediator;
+using Microsoft.EntityFrameworkCore;
+using Musify.Application.Contracts;
+using Musify.Application.Users.Queries;
+using Musify.Application.Users.Responses;
+
+namespace Musify.Application.Users.Handlers
+{
+    public class GetUserByIdQueryHandler(IDatabase database)
+        : IQueryHandler<GetUserByIdQuery, Result<UserApplicationResponse> >
+    {
+        public async ValueTask<Result<UserApplicationResponse>> Handle(GetUserByIdQuery request, CancellationToken cancellationToken)
+        {
+            var user = await database.Users
+                .AsNoTracking()
+                .Where(u => u.Id == request.Id)
+                .Select(u => UserApplicationResponse.FromEntity(u))
+                .SingleOrDefaultAsync(cancellationToken);
+
+            return user is null
+                ? Result<UserApplicationResponse>.NotFound()
+                : Result.Success(user);
+        }
+    }
+}

MusifyBackend/Application/Users/Handlers/GetUsersQueryHandler.cs

@@ -0,0 +1,35 @@
+using Ardalis.Result;
+using Mediator;
+using Microsoft.EntityFrameworkCore;
+using Musify.Application.Pagination;
+using Musify.Application.Users.Queries;
+using Musify.Application.Users.Responses;
+using X.PagedList.EF;
+using Musify.Application.Contracts;
+
+namespace Musify.Application.Users.Handlers
+{
+    public class GetUsersQueryHandler(IDatabase database)
+        : IQueryHandler<GetUsersQuery, Result<PaginatedResponse<UserApplicationResponse> > >
+    {
+        public async ValueTask<Result<PaginatedResponse<UserApplicationResponse> >> Handle(GetUsersQuery request, CancellationToken cancellationToken)
+        {
+            var user = database.Users
+                .AsNoTracking()
+                .AsQueryable();
+
+            if (request.UsernameSearch is not null)
+            {
+                var normalizedUsername = request.UsernameSearch.Trim().ToUpperInvariant();
+                user = user.Where(u => u.NormalizedName.Contains(normalizedUsername));
+            }
+
+            var totalCount = await user.CountAsync(cancellationToken);
+            var pagedUser = await user
+                .Select(u => UserApplicationResponse.FromEntity(u))
+                .ToPagedListAsync(request.PageNumber, request.PageSize, totalCount, cancellationToken);
+
+            return Result.Success(PaginatedResponse<UserApplicationResponse>.FromPagedList(pagedUser));
+        }
+    }
+}

MusifyBackend/Application/Users/Handlers/SyncUserCommandHandler.cs

@@ -0,0 +1,50 @@
+using Ardalis.Result;
+using Mediator;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.Logging;
+using Musify.Application.Contracts;
+using Musify.Application.Users.Commands;
+using Musify.Domain.Entities;
+
+namespace Musify.Application.Users.Handlers
+{
+    public class SyncUserCommandHandler(IDatabase database, ILogger<SyncUserCommandHandler> logger)
+        : ICommandHandler<SyncUserCommand, Result>
+    {
+        public async ValueTask<Result> Handle(SyncUserCommand request, CancellationToken cancellationToken)
+        {
+            var user = await database.Users
+                .SingleOrDefaultAsync(u => u.Id == request.Id, cancellationToken);
+
+            if (user is null)
+            {
+                await database.Users.AddAsync(new User
+                {
+                    Id = request.Id,
+                    Name = request.Name,
+                    NormalizedName = request.Name.ToUpperInvariant(),
+                    FirstName = request.FirstName,
+                    SecondName = request.SecondName,
+                    ProfilePictureUrl = request.ProfilePictureUrl
+                }, cancellationToken);
+
+                await database.SaveChangesAsync(cancellationToken);
+                logger.LogInformation("Provisioned user {UserId}", request.Id);
+
+                return Result.Success();
+            }
+
+            user.Name = request.Name;
+            user.NormalizedName = request.Name.ToUpperInvariant();
+            user.FirstName = request.FirstName;
+            user.SecondName = request.SecondName;
+            user.ProfilePictureUrl = request.ProfilePictureUrl;
+
+            var written = await database.SaveChangesAsync(cancellationToken);
+            if (written > 0)
+                logger.LogInformation("Synced profile for user {UserId}", request.Id);
+
+            return Result.Success();
+        }
+    }
+}

MusifyBackend/Application/Users/Queries/GetUserByIdQuery.cs

@@ -0,0 +1,9 @@
+using Ardalis.Result;
+using Mediator;
+using Musify.Application.Users.Responses;
+
+namespace Musify.Application.Users.Queries
+{
+    public record GetUserByIdQuery(long Id)
+        : IQuery<Result<UserApplicationResponse> >;
+}

MusifyBackend/Application/Users/Queries/GetUsersQuery.cs

@@ -0,0 +1,10 @@
+using Ardalis.Result;
+using Mediator;
+using Musify.Application.Pagination;
+using Musify.Application.Users.Responses;
+
+namespace Musify.Application.Users.Queries
+{
+    public record GetUsersQuery(int PageNumber, int PageSize, string? UsernameSearch = null)
+        : IQuery<Result<PaginatedResponse<UserApplicationResponse> >>;
+}

MusifyBackend/Application/Users/Responses/UserApplicationResponse.cs

@@ -0,0 +1,26 @@
+using Musify.Domain.Entities;
+
+namespace Musify.Application.Users.Responses
+{
+    public record UserApplicationResponse(
+        long Id,
+        string Name,
+        string? FirstName,
+        string? SecondName,
+        string? ProfilePictureUrl,
+        DateTime CreatedAt,
+        DateTime UpdatedAt)
+    {
+        public static UserApplicationResponse FromEntity(User user)
+        {
+            return new UserApplicationResponse(
+                user.Id,
+                user.Name,
+                user.FirstName,
+                user.SecondName,
+                user.ProfilePictureUrl,
+                user.CreatedAt,
+                user.UpdatedAt);
+        }
+    }
+}

MusifyBackend/Domain/Abstractions/IAuditable.cs

@@ -0,0 +1,9 @@
+namespace Musify.Domain.Abstractions
+{
+    public interface IAuditable
+    {
+        DateTime CreatedAt { get; set; }
+
+        DateTime UpdatedAt { get; set; }
+    }
+}

MusifyBackend/Domain/Domain.csproj

@@ -0,0 +1,15 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net10.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+	<RootNamespace>Musify.Domain</RootNamespace>
+	<PackageId>Musify.Domain</PackageId>
+    <Version>0.1.2</Version>
+    <Authors>NotS1mp</Authors>
+	<RepositoryUrl>https://github.com/XShine555/MusifyBackend</RepositoryUrl>
+  </PropertyGroup>
+
+
+</Project>

MusifyBackend/Domain/Entities/PlayList.cs

@@ -0,0 +1,61 @@
+using System.ComponentModel.DataAnnotations;
+using System.ComponentModel.DataAnnotations.Schema;
+
+using Musify.Domain.Abstractions;
+using Musify.Domain.ValueObjects;
+
+namespace Musify.Domain.Entities
+{
+#pragma warning disable CS8618
+    [Table("PlayLists")]
+    public class PlayList : IAuditable
+    {
+        [Key]
+        public Guid Id { get; set; } = Guid.NewGuid();
+
+        [Required]
+        public required long UserId { get; set; }
+
+        [Required]
+        [MaxLength(50)]
+        public required string Name { get; set; }
+
+        [Required]
+        [MaxLength(50)]
+        public required string NormalizedName { get; set; }
+
+        [Required]
+        [MaxLength(256)]
+        public required string Description { get; set; } = "No description was provided.";
+
+        [Required]
+        [MaxLength(64)]
+        public required string OriginalPictureName { get; set; }
+
+        [Required]
+        [MaxLength(64)]
+        public required string SmallPictureName { get; set; }
+
+        [Required]
+        [MaxLength(64)]
+        public required string MediumPictureName { get; set; }
+
+        [Required]
+        [MaxLength(64)]
+        public required string LargePictureName { get; set; }
+
+        [Required]
+        public LifeCycleStatus LifeCycleStatus { get; set; } = LifeCycleStatus.Active;
+
+        [Required]
+        public DateTime CreatedAt { get; set; } = DateTime.UtcNow;
+
+        [Required]
+        public DateTime UpdatedAt { get; set; } = DateTime.UtcNow;
+
+        [ForeignKey(nameof(UserId)) ]
+        public User User { get; set; }
+
+        public ICollection<PlayListHasTrack> PlayListTracks { get; set; } = new List<PlayListHasTrack>();
+    }
+}

MusifyBackend/Domain/Entities/PlayListHasTrack.cs

@@ -0,0 +1,30 @@
+using System.ComponentModel.DataAnnotations;
+using System.ComponentModel.DataAnnotations.Schema;
+
+namespace Musify.Domain.Entities
+{
+#pragma warning disable CS8618
+    [Table("PlayListHasTrack")]
+    public class PlayListHasTrack
+    {
+        public Guid Id { get; set; } = Guid.NewGuid();
+
+        [Required]
+        public required Guid PlayListId { get; set; }
+
+        [Required]
+        public required Guid TrackId { get; set; }
+
+        [Required]
+        public int Position { get; set; } = 0;
+
+        [Required]
+        public DateTime AddedAt { get; set; } = DateTime.UtcNow;
+
+        [ForeignKey(nameof(PlayListId)) ]
+        public PlayList PlayList { get; set; }
+
+        [ForeignKey(nameof(TrackId)) ]
+        public Track Track { get; set; }
+    }
+}

MusifyBackend/Domain/Entities/Track.cs

@@ -0,0 +1,78 @@
+using System.ComponentModel.DataAnnotations;
+using System.ComponentModel.DataAnnotations.Schema;
+using System.Diagnostics.CodeAnalysis;
+
+using Musify.Domain.Abstractions;
+using Musify.Domain.ValueObjects;
+
+namespace Musify.Domain.Entities
+{
+#pragma warning disable CS8618
+    public class Track : IAuditable
+    {
+        [Key]
+        public Guid Id { get; set; } = Guid.NewGuid();
+
+        [Required]
+        [MaxLength(50)]
+        public required string Title { get; set; }
+
+        [Required]
+        [MaxLength(50)]
+        public required string NormalizedTitle { get; set; }
+
+        [Required]
+        [MaxLength(64)]
+        public required string OriginalPictureName { get; set; }
+
+        [MaxLength(64)]
+        public string? SmallPictureName { get; set; }
+
+        [MaxLength(64)]
+        public string? MediumPictureName { get; set; }
+
+        [MaxLength(64)]
+        public string? LargePictureName { get; set; }
+
+        [Required]
+        [MaxLength(64)]
+        public required string OriginalAudioName { get; set; }
+
+        [MaxLength(64)]
+        public string? AudioFolderName { get; set; }
+
+        [Required]
+        public ProcessingStatus PicturesProcessingStatus { get; set; } = ProcessingStatus.Pending;
+
+        [Required]
+        public ProcessingStatus AudioTranscodeProcessingStatus { get; set; } = ProcessingStatus.Pending;
+
+        [Required]
+        public LifeCycleStatus LifeCycleStatus { get; set; } = LifeCycleStatus.Active;
+
+        [Required]
+        public int RetryCount { get; set; } = 0;
+
+        public DateTime? LastRetryAt { get; set; }
+
+        [Required]
+        public DateTime CreatedAt { get; set; } = DateTime.UtcNow;
+
+        [Required]
+        public DateTime UpdatedAt { get; set; } = DateTime.UtcNow;
+
+        public ICollection<UserHasTrack> UserTracks { get; set; } = new List<UserHasTrack>();
+
+        public ICollection<PlayListHasTrack> PlayListTracks { get; set; } = new List<PlayListHasTrack>();
+
+        [NotMapped]
+        [MemberNotNullWhen(true, nameof(SmallPictureName)) ]
+        [MemberNotNullWhen(true, nameof(MediumPictureName)) ]
+        [MemberNotNullWhen(true, nameof(LargePictureName)) ]
+        public bool IsPicturesProcessed => PicturesProcessingStatus == ProcessingStatus.Completed;
+
+        [NotMapped]
+        [MemberNotNullWhen(true, nameof(AudioFolderName)) ]
+        public bool IsAudioProcessed => AudioTranscodeProcessingStatus == ProcessingStatus.Completed;
+    }
+}

MusifyBackend/Domain/Entities/Upload.cs

@@ -0,0 +1,29 @@
+using System.ComponentModel.DataAnnotations;
+using System.ComponentModel.DataAnnotations.Schema;
+
+using Musify.Domain.ValueObjects;
+
+namespace Musify.Domain.Entities
+{
+    [Table("Upload")]
+    public class Upload
+    {
+        [Key]
+        public Guid Id { get; set; } = Guid.NewGuid();
+
+        [Required]
+        public required string Bucket { get; set; }
+
+        [Required]
+        public required string Key { get; set; }
+
+        [Required]
+        public required string ContentType { get; set; }
+
+        [Required]
+        public DateTime CreatedTime { get; set; } = DateTime.UtcNow;
+
+        [Required]
+        public UploadState State { get; set; } = UploadState.Pending;
+    }
+}

MusifyBackend/Domain/Entities/UploadIntent.cs

@@ -0,0 +1,46 @@
+using System.ComponentModel.DataAnnotations;
+using System.ComponentModel.DataAnnotations.Schema;
+
+using Musify.Domain.ValueObjects;
+
+namespace Musify.Domain.Entities
+{
+    [Table("UploadIntents")]
+    public class UploadIntent
+    {
+        [Key]
+        public Guid Id { get; set; } = Guid.NewGuid();
+
+        [Required]
+        public required long UserId { get; set; }
+
+        [Required, MaxLength(128)]
+        public required string Bucket { get; set; }
+
+        [Required, MaxLength(512)]
+        public required string Key { get; set; }
+
+        [Required, MaxLength(128)]
+        public required string ObjectName { get; set; }
+
+        [Required, MaxLength(128)]
+        public required string ContentType { get; set; }
+
+        public long? ExpectedSizeBytes { get; set; }
+
+        [Required]
+        public UploadIntentPurpose Purpose { get; set; }
+
+        [Required]
+        public UploadIntentStatus Status { get; set; } = UploadIntentStatus.Issued;
+
+        [Required]
+        public DateTime ExpiresAt { get; set; }
+
+        [Required]
+        public DateTime CreatedAt { get; set; } = DateTime.UtcNow;
+
+        [ForeignKey(nameof(UserId)) ]
+        public User User { get; set; } = null!;
+    }
+}

MusifyBackend/Domain/Entities/User.cs

@@ -0,0 +1,41 @@
+using System.ComponentModel.DataAnnotations;
+using System.ComponentModel.DataAnnotations.Schema;
+using Musify.Domain.Abstractions;
+
+namespace Musify.Domain.Entities
+{
+    [Table("User")]
+    public class User : IAuditable
+    {
+        [Key]
+        [DatabaseGenerated(DatabaseGeneratedOption.None)]
+        public required long Id { get; set; }
+
+        [Required]
+        [MaxLength(48)]
+        public required string Name { get; set; }
+
+        [Required]
+        [MaxLength(48)]
+        public required string NormalizedName { get; set; }
+
+        [MaxLength(48)]
+        public string? FirstName { get; set; }
+
+        [MaxLength(48)]
+        public string? SecondName { get; set; }
+
+        [MaxLength(2048)]
+        public string? ProfilePictureUrl { get; set; }
+
+        [Required]
+        public DateTime CreatedAt { get; set; } = DateTime.UtcNow;
+
+        [Required]
+        public DateTime UpdatedAt { get; set; } = DateTime.UtcNow;
+
+        public ICollection<UserHasTrack> UserTracks { get; set; } = new List<UserHasTrack>();
+
+        public ICollection<PlayList> PlayLists { get; set; } = new List<PlayList>();
+    }
+}

MusifyBackend/Domain/Entities/UserHasTrack.cs

@@ -0,0 +1,24 @@
+using System.ComponentModel.DataAnnotations;
+using System.ComponentModel.DataAnnotations.Schema;
+
+namespace Musify.Domain.Entities
+{
+#pragma warning disable CS8618
+    [Table("UserHasTrack")]
+    public class UserHasTrack
+    {
+        public Guid Id { get; set; } = Guid.NewGuid();
+
+        [Required]
+        public required long UserId { get; set; }
+
+        [Required]
+        public required Guid TrackId { get; set; }
+
+        [ForeignKey(nameof(UserId)) ]
+        public User User { get; set; }
+
+        [ForeignKey(nameof(TrackId)) ]
+        public Track Track { get; set; }
+    }
+}

MusifyBackend/Domain/ValueObjects/LifeCycleStatus.cs

@@ -0,0 +1,8 @@
+namespace Musify.Domain.ValueObjects
+{
+    public enum LifeCycleStatus
+    {
+        Active = 0,
+        Removing = 1
+    }
+}

MusifyBackend/Domain/ValueObjects/ProcessingStatus.cs

@@ -0,0 +1,10 @@
+namespace Musify.Domain.ValueObjects
+{
+    public enum ProcessingStatus
+    {
+        Pending = 0,
+        Processing = 1,
+        Completed = 2,
+        Failed = 3
+    }
+}