ln-770-crosscutting-setup

name	ln-770-crosscutting-setup
description	Sets up logging, error handling, CORS, health checks, and API docs. Use when adding cross-cutting concerns to backend projects.
license	MIT

Paths: File paths (references/, ../ln-*) are relative to this skill directory.

ln-770-crosscutting-setup

Type: L2 Domain Coordinator Category: 7XX Project Bootstrap Parent: ln-700-project-bootstrap

Coordinates cross-cutting concerns configuration for .NET and Python projects.

---

Overview

Aspect	Details
Input	Project root directory
Output	Configured logging, error handling, CORS, health checks, API docs
Workers	ln-771 to ln-775
Stacks	.NET (ASP.NET Core), Python (FastAPI)

---

Phase 1: Detect Project Stack

Determine the technology stack by scanning project files.

Detection Rules:

File Pattern	Stack	Framework
*.csproj	.NET	ASP.NET Core
pyproject.toml or requirements.txt + FastAPI	Python	FastAPI

Actions:

1. Glob for *.csproj files
2. If not found, Glob for pyproject.toml or requirements.txt
3. If Python, check for FastAPI in dependencies
4. Store detected stack in Context Store

Context Store Initial:

{
  "STACK": ".NET" | "Python",
  "FRAMEWORK": "ASP.NET Core" | "FastAPI",
  "PROJECT_ROOT": "/path/to/project",
  "FRAMEWORK_VERSION": "8.0" | "0.109.0"
}

---

Phase 2: Check Existing Configuration

Scan for already configured cross-cutting concerns.

Detection Patterns:

Concern	.NET Pattern	Python Pattern
Logging	Serilog in *.csproj, UseSerilog in Program.cs	structlog in requirements, logging config
Error Handling	GlobalExceptionMiddleware, UseExceptionHandler	@app.exception_handler, exception_handlers.py
CORS	AddCors, UseCors	CORSMiddleware
Health Checks	AddHealthChecks, MapHealthChecks	/health routes
API Docs	AddSwaggerGen, UseSwagger	FastAPI auto-generates

Actions:

1. Grep for each pattern
2. Mark configured concerns as skip: true
3. Update Context Store with findings

Context Store Updated:

{
  "concerns": {
    "logging": { "configured": false },
    "errorHandling": { "configured": false },
    "cors": { "configured": true, "skip": true },
    "healthChecks": { "configured": false },
    "apiDocs": { "configured": false }
  }
}

---

Phase 3: Invoke Workers (Conditional)

Delegate to workers only for unconfigured concerns.

Worker Invocation Order:

Order	Worker	Condition	Skill Call
1	ln-771-logging-configurator	logging.configured == false	/skill ln-771-logging-configurator
2	ln-772-error-handler-setup	errorHandling.configured == false	/skill ln-772-error-handler-setup
3	ln-773-cors-configurator	cors.configured == false	/skill ln-773-cors-configurator
4	ln-774-healthcheck-setup	healthChecks.configured == false	/skill ln-774-healthcheck-setup
5	ln-775-api-docs-generator	apiDocs.configured == false	/skill ln-775-api-docs-generator

Invocations (conditional — skip if concern already configured):

Skill(skill: "ln-771-logging-configurator", args: "{STACK} {FRAMEWORK}")
Skill(skill: "ln-772-error-handler-setup", args: "{STACK} {FRAMEWORK}")
Skill(skill: "ln-773-cors-configurator", args: "{STACK} {FRAMEWORK}")
Skill(skill: "ln-774-healthcheck-setup", args: "{STACK} {FRAMEWORK}")
Skill(skill: "ln-775-api-docs-generator", args: "{STACK} {FRAMEWORK}")

Pass Context Store to each worker.

Worker Response Format:

{
  "status": "success" | "skipped" | "error",
  "files_created": ["path/to/file.cs"],
  "packages_added": ["Serilog.AspNetCore"],
  "message": "Configured structured logging with Serilog"
}

---

Phase 4: Generate Aggregation File

Create a single entry point for all cross-cutting services.

.NET: Extensions/ServiceExtensions.cs

Generate based on configured workers:

// Structure only - actual code generated via MCP ref
public static class ServiceExtensions
{
    public static IServiceCollection AddCrosscuttingServices(
        this IServiceCollection services,
        IConfiguration configuration)
    {
        // Calls added based on configured workers:
        // services.AddLogging(configuration);      // if ln-771 ran
        // services.AddCorsPolicy(configuration);   // if ln-773 ran
        // services.AddHealthChecks();              // if ln-774 ran
        // services.AddSwaggerServices();           // if ln-775 ran
        return services;
    }
}

Python: middleware/init.py

Generate based on configured workers:

# Structure only - actual code generated via MCP ref
def configure_middleware(app):
    # Middleware added based on configured workers:
    # configure_logging(app)        # if ln-771 ran
    # configure_error_handlers(app) # if ln-772 ran
    # configure_cors(app)           # if ln-773 ran
    # configure_health_routes(app)  # if ln-774 ran
    pass

---

Phase 5: Summary Report

Display summary of all configured concerns.

Output Format:

Cross-cutting Setup Complete
============================
Stack: .NET (ASP.NET Core 8.0)

Configured:
  ✓ Logging (Serilog) - Extensions/LoggingExtensions.cs
  ✓ Error Handling - Middleware/GlobalExceptionMiddleware.cs
  ✓ CORS - Extensions/CorsExtensions.cs
  ✓ Health Checks - Extensions/HealthCheckExtensions.cs
  ✓ API Docs (Swagger) - Extensions/SwaggerExtensions.cs

Skipped (already configured):
  - None

Entry Point: Extensions/ServiceExtensions.cs
  Add to Program.cs: builder.Services.AddCrosscuttingServices(builder.Configuration);

Packages to Install:
  dotnet add package Serilog.AspNetCore
  dotnet add package Swashbuckle.AspNetCore

---

Workers

Worker	Purpose	Stacks
ln-771-logging-configurator	Structured logging	.NET (Serilog), Python (structlog)
ln-772-error-handler-setup	Global exception middleware	.NET, Python
ln-773-cors-configurator	CORS policy configuration	.NET, Python
ln-774-healthcheck-setup	/health endpoints	.NET, Python
ln-775-api-docs-generator	Swagger/OpenAPI	.NET (Swashbuckle), Python (FastAPI built-in)

---

Context Store Interface

Workers receive and return via Context Store:

Input to Workers:

{
  "STACK": ".NET",
  "FRAMEWORK": "ASP.NET Core",
  "FRAMEWORK_VERSION": "8.0",
  "PROJECT_ROOT": "/path/to/project",
  "ENVIRONMENT": "Development"
}

Output from Workers:

{
  "status": "success",
  "files_created": [],
  "packages_added": [],
  "registration_code": "services.AddLogging(configuration);"
}

---

Idempotency

This skill is idempotent:

• Phase 2 detects existing configuration
• Workers skip if already configured
• Aggregation file preserves existing entries

---

Critical Rules

• Skip already configured concerns — Phase 2 detection must gate worker invocation (set skip: true)
• Pass Context Store to every worker — workers depend on STACK, FRAMEWORK, PROJECT_ROOT
• Generate aggregation file only for workers that ran — do not add registration calls for skipped concerns
• Support only .NET and Python — detect via *.csproj or pyproject.toml/requirements.txt + FastAPI
• Idempotent execution — re-running must not duplicate configs or break existing setup

TodoWrite format (mandatory):

- Detect project stack (in_progress)
- Check existing configuration (pending)
- Invoke ln-771-logging-configurator (pending)
- Invoke ln-772-error-handler-setup (pending)
- Invoke ln-773-cors-configurator (pending)
- Invoke ln-774-healthcheck-setup (pending)
- Invoke ln-775-api-docs-generator (pending)
- Generate aggregation file (pending)
- Summary report (pending)

Worker Invocation (MANDATORY)

Host Skill Invocation: Skill(skill: "...", args: "...") is mandatory delegation.

• Claude: call the Skill tool exactly as shown.
• Codex: if no Skill tool exists, locate the named skill in available skills, read its SKILL.md, treat args as $ARGUMENTS, execute that skill workflow, then return here with its result/artifact.
• Do not inline worker logic or mark the worker complete without executing the target skill.

Phase	Worker	Context
3	ln-771-logging-configurator	Shared (Skill tool) — structured logging setup
3	ln-772-error-handler-setup	Shared (Skill tool) — global exception middleware
3	ln-773-cors-configurator	Shared (Skill tool) — CORS policy configuration
3	ln-774-healthcheck-setup	Shared (Skill tool) — /health endpoints
3	ln-775-api-docs-generator	Shared (Skill tool) — Swagger/OpenAPI docs

All workers: Invoke via Skill tool — workers see coordinator context.

Definition of Done

• Project stack detected and stored in Context Store
• Existing configurations detected (Phase 2 complete)
• All unconfigured concerns delegated to workers (ln-771 through ln-775)
• Aggregation entry point generated (ServiceExtensions.cs or middleware/__init__.py)
• Summary report displayed with configured/skipped concerns and package install commands

Reference Files

• Worker skills: ln-771-logging-configurator/SKILL.md through ln-775-api-docs-generator/SKILL.md
• references/logging_patterns.md — structured logging patterns per stack (passed to ln-771)
• references/error_handling_patterns.md — global exception handling patterns (passed to ln-772)
• references/cors_configuration.md — CORS dev/prod policies per stack (passed to ln-773)

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Phase 6: Meta-Analysis

Optional reference: load references/meta_analysis_protocol.md only when the user asks for post-run meta-analysis or protocol-formatted run reflection.

Skill type: execution-orchestrator. When requested, run after all phases complete. Output to chat using the execution-orchestrator format.

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Version: 2.0.0 Last Updated: 2026-01-10