Koan Framework Debugging

Core Principle

Framework-specific debugging focuses on boot reports, provider elections, and auto-registration patterns rather than generic .NET troubleshooting.

Quick Diagnostics

# Check boot logs for framework initialization
docker logs koan-app --tail 20 --follow | grep "Koan:"

# Expected success patterns:
[INFO] Koan:discover postgresql: server=localhost... OK
[INFO] Koan:modules data→postgresql
[INFO] Koan:modules web→controllers
[INFO] Koan:modules ai→openai
[INFO] Koan:modules MyApp v1.0.0

Debugging Categories

1. Bootstrap and Initialization Issues

Symptom: Service not found in DI container

System.InvalidOperationException: Unable to resolve service for type 'ITodoService'

Diagnosis:

1. Check if KoanAutoRegistrar exists at /Initialization/KoanAutoRegistrar.cs
2. Verify class implements IKoanAutoRegistrar
3. Verify class is public (not internal)
4. Check boot logs for module registration

Solution:

// Verify KoanAutoRegistrar is discoverable
public sealed class KoanAutoRegistrar : IKoanAutoRegistrar
{
    public string ModuleName => "MyApp";

    public void Initialize(IServiceCollection services)
    {
        services.AddScoped<ITodoService, TodoService>();
    }

    public void Describe(BootReport report, IConfiguration cfg, IHostEnvironment env)
    {
        report.AddModule(ModuleName, "1.0.0");
    }
}

---

Symptom: Module not discovered

[WARNING] Koan:modules MyModule not found

Diagnosis:

1. Verify <ProjectReference> or <PackageReference> exists
2. Check assembly is copied to output directory
3. Verify namespace and class visibility

Solution:

<!-- Ensure project reference exists -->
<ProjectReference Include="..\MyModule\MyModule.csproj" />

2. Entity and Data Layer Issues

Symptom: ID not generated

System.InvalidOperationException: Entity ID is required but not set

Diagnosis:

• Using Entity<T, TKey> with custom key type requires manual ID assignment
• Verify entity inherits Entity<T> (not Entity<T, TKey>)

Solution:

// ✅ CORRECT: Auto GUID v7 generation
public class Todo : Entity<Todo>
{
    public string Title { get; set; } = "";
}

// OR: Manual key management
public class NumericTodo : Entity<NumericTodo, int>
{
    public override int Id { get; set; } // Must set manually
}

---

Symptom: Query not working

System.NotSupportedException: Provider does not support LINQ queries

Diagnosis:

• Provider lacks LINQ support (JSON, InMemory, Redis)
• Need client-side filtering

Solution:

// Check capabilities first
var caps = Data<Todo, string>.QueryCaps;

if (caps.Capabilities.HasFlag(QueryCapabilities.LinqQueries))
{
    return await Todo.Query(t => t.Completed);
}
else
{
    var all = await Todo.All();
    return all.Where(t => t.Completed).ToList();
}

3. Multi-Provider Issues

Symptom: Provider not available

[ERROR] Koan:discover mongodb: connection failed
[INFO] Koan:modules data→json (fallback)

Diagnosis:

1. Verify service is running (Docker, local install)
2. Check connection string in appsettings.json
3. Verify network connectivity
4. Check provider package is referenced

Solution:

// Verify configuration
{
  "Koan": {
    "Data": {
      "Sources": {
        "Default": {
          "Adapter": "mongodb",
          "ConnectionString": "mongodb://localhost:27017/myapp"
        }
      }
    }
  }
}

# Test MongoDB connectivity
docker ps | grep mongo
docker logs mongo-container

---

Symptom: Wrong provider elected

[INFO] Koan:modules data→json (expected: mongodb)

Diagnosis:

• Configuration missing or incorrect
• Provider package not referenced
• Connection failed, fallback activated

Solution:

// Force specific provider with attribute
[DataAdapter("mongodb")]
public class Todo : Entity<Todo>
{
    public string Title { get; set; } = "";
}

// Or verify boot report
if (KoanEnv.IsDevelopment)
{
    KoanEnv.DumpSnapshot(logger);
}

4. Performance and Optimization Issues

Symptom: N+1 query problem

// App making hundreds of queries
[DEBUG] Executing query: SELECT * FROM Todo WHERE Id = 'id1'
[DEBUG] Executing query: SELECT * FROM Todo WHERE Id = 'id2'
[DEBUG] Executing query: SELECT * FROM Todo WHERE Id = 'id3'
... (repeated hundreds of times)

Diagnosis:

• Loading entities in loop instead of batch
• Not using batch retrieval

Solution:

// ❌ WRONG: N queries
foreach (var id in ids)
{
    var todo = await Todo.Get(id);
}

// ✅ CORRECT: 1 query
var todos = await Todo.Get(ids);

---

Symptom: Out of memory

System.OutOfMemoryException: Array dimensions exceeded supported range

Diagnosis:

• Loading large dataset with .All() instead of streaming
• Materializing everything into memory

Solution:

// ❌ WRONG: Loads everything into memory
var allTodos = await Todo.All(); // 1 million records!

// ✅ CORRECT: Stream in batches
await foreach (var todo in Todo.AllStream(batchSize: 1000))
{
    await ProcessTodo(todo);
}

5. Container and Environment Issues

Symptom: Container fails to start

[ERROR] Application startup exception
[ERROR] Unable to connect to database

Diagnosis:

1. Check container networking (wrong host references)
2. Verify Docker Compose service dependencies
3. Check health check endpoints

Solution:

# docker-compose.yml
services:
  app:
    depends_on:
      postgres:
        condition: service_healthy

  postgres:
    healthcheck:
      test: ["CMD-SHELL", "pg_isready -U koan"]
      interval: 5s
      timeout: 5s
      retries: 5

// Use container hostname, not localhost
{
  "Koan": {
    "Data": {
      "Sources": {
        "Default": {
          "ConnectionString": "Host=postgres;Database=myapp"
        }
      }
    }
  }
}

6. Framework-Specific Error Patterns

Auto-Registration Errors

• Symptom: Service not found in DI
• Cause: Missing KoanAutoRegistrar or assembly not loaded
• Solution: Verify file exists, implements interface, is public

Provider Capability Mismatches

• Symptom: Query features not working as expected
• Cause: Provider doesn't support specific capabilities
• Solution: Check QueryCaps and implement graceful fallbacks

Entity Pattern Violations

• Symptom: ID generation issues or manual repository injection
• Cause: Not using Entity<T> patterns properly
• Solution: Migrate to entity-first patterns with proper inheritance

Context Routing Conflicts

• Symptom: Data going to wrong partition/source
• Cause: Nested contexts or Source+Adapter conflict
• Solution: Follow Source XOR Adapter rule, check context nesting

Boot Report Analysis

Enabling Detailed Boot Reporting

// In Development environment
if (KoanEnv.IsDevelopment)
{
    var logger = app.Services.GetRequiredService<ILogger<Program>>();
    KoanEnv.DumpSnapshot(logger);
}

Reading Boot Report

[INFO] Koan:discover postgresql: server=localhost;database=myapp;username=koan;password=*** OK
[INFO] Koan:discover mongodb: connection timeout FAILED
[INFO] Koan:modules data→postgresql (elected: connection successful)
[INFO] Koan:modules web→controllers (discovered: 5 controllers)
[INFO] Koan:modules ai→openai (api_key present, model: gpt-4)
[INFO] Koan:modules MyApp v1.0.0 (services: TodoService, EmailService)
[WARNING] Email SMTP configuration missing - using console fallback

What to look for:

• ✅ OK status for expected providers
• ✅ Correct provider elections (data→postgresql)
• ✅ Your modules listed with version
• ⚠️ Warnings about missing configuration
• ❌ FAILED status for critical services

Debug Provider Capabilities

// Log capabilities for current provider
var caps = Data<Todo, string>.QueryCaps;
logger.LogInformation("Provider: {Provider}", caps.ProviderName);
logger.LogInformation("Capabilities: {Capabilities}", caps.Capabilities);

// Check specific capabilities
if (caps.Capabilities.HasFlag(QueryCapabilities.LinqQueries))
{
    logger.LogInformation("Provider supports server-side LINQ");
}

if (caps.Capabilities.HasFlag(QueryCapabilities.Transactions))
{
    logger.LogInformation("Provider supports transactions");
}

if (Todo.SupportsFastRemove)
{
    logger.LogInformation("Provider supports TRUNCATE/DROP");
}

Environment Detection Debug

logger.LogInformation("Environment: {Env}", KoanEnv.CurrentEnvironment);
logger.LogInformation("IsDevelopment: {Dev}", KoanEnv.IsDevelopment);
logger.LogInformation("IsProduction: {Prod}", KoanEnv.IsProduction);
logger.LogInformation("InContainer: {Container}", KoanEnv.InContainer);
logger.LogInformation("AllowMagicInProduction: {Magic}", KoanEnv.AllowMagicInProduction);

Common Debug Commands

# Container development workflow
./start.bat  # Always use project start scripts

# View structured logs
docker logs koan-app --tail 20 --follow | grep "Koan:"

# Check assembly discovery
docker exec koan-app ls /app/*.dll

# Test database connectivity
docker exec postgres-container psql -U koan -d myapp -c "SELECT 1"

# Check Redis connectivity
docker exec redis-container redis-cli PING

When This Skill Applies

Invoke this skill when:

• ✅ Troubleshooting errors
• ✅ Analyzing boot failures
• ✅ Debugging provider issues
• ✅ Investigating performance problems
• ✅ Validating initialization
• ✅ Reviewing boot reports

Reference Documentation

• Troubleshooting Guides: docs/guides/troubleshooting/
• Bootstrap Failures: docs/guides/troubleshooting/bootstrap-failures.md
• Adapter Issues: docs/guides/troubleshooting/adapter-connection-issues.md
• Deep Dive: docs/guides/deep-dive/bootstrap-lifecycle.md