feat: Decompose Inventory module into standalone microservice

[devin-ai-integration]

Summary

Standalone inventory microservice decomposed from the OrderManager monolith. Includes:

• .NET 8 Web API — InventoryItemService with CRUD + stock operations (restock, deduct, check-stock, low-stock), backed by EF Core + SQLite, seeded with 5 demo items
• Angular 17 frontend — standalone components with lazy-loaded routes for inventory list (with inline restock) and low-stock view
• Dockerfile — multi-stage build (node:20-alpine → dotnet/sdk:8.0 → dotnet/aspnet:8.0-alpine), serves Angular from wwwroot
• Helm chart — deployment, service, ingress, NetworkPolicy, ServiceMonitor, HPA with per-environment overrides (dev: 1 replica, staging: 2 replicas + HPA)
• ArgoCD manifests — targeting decomposition-dev and decomposition-staging namespaces
• GitHub Actions CI/CD — test → build → push to ECR on main
• 9 unit tests covering all service methods

Review & Testing Checklist for Human

• DeductStockAsync returns null on insufficient stock — verify the controller translates this into an appropriate HTTP error (e.g. 409), not a silent 200 null. The service layer swallows the failure; if the controller just passes through null, callers (especially the monolith's InventoryHttpClient) will misinterpret it.
• SQLite is incompatible with multi-replica deployments — the staging Helm values set replicaCount: 2 with HPA, but SQLite doesn't support concurrent writes from multiple pods sharing a volume. Confirm this is acceptable for the workshop or swap to an external DB for staging.
• No authentication on destructive endpoints — POST .../restock and POST .../deduct are unauthenticated and callable by anyone. Fine for a workshop demo, but flag if this will be exposed beyond local/dev.
• CORS is AllowAnyOrigin — wide open; acceptable for dev but should be tightened before staging/prod.
• Angular components have no HTTP error handling — loadInventory() and restock() silently swallow failures. Verify this is acceptable UX for the demo.

Recommended test plan:

1. dotnet build && dotnet test — confirm 9 tests pass
2. dotnet run --urls http://localhost:5100 — hit GET /api/inventory, POST .../product/1/restock, GET /api/inventory/low-stock, GET /health
3. Verify the monolith's InventoryHttpClient can call the deduct endpoint and correctly handles the null/error case for insufficient stock
4. docker build -f docker/Dockerfile . — confirm multi-stage image builds
5. helm template helm/inventory-service -f helm/inventory-service/values-dev.yaml — verify rendered manifests include NetworkPolicy and ServiceMonitor

Notes

• The InventoryItem model denormalizes ProductName from the product service. This will drift if product names are updated upstream — no sync mechanism exists.
• Seed data hardcodes ProductId 1–5, which must match the monolith's product IDs for the integration to work.
• The GitHub Actions workflow references ECR registry 599083837640.dkr.ecr.us-east-1.amazonaws.com and an IAM role — verify these exist and have correct permissions before merging to main.

Link to Devin session: https://partner-workshops.devinenterprise.com/sessions/3f9970732a094e99a2c7a45ddfc98e8e

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[devin-ai-integration]

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[devin-ai-integration]

Devin Review found 2 potential issues.

View 5 additional findings in Devin Review.

[devin-ai-integration]

🔴 Restock endpoint returns 500 instead of proper error when product not found

The Restock controller action at src/InventoryService.Api/Controllers/InventoryController.cs:30 calls _service.RestockAsync(), which throws an unhandled ArgumentException when the product doesn't exist (src/InventoryService.Api/Services/InventoryItemService.cs:29). Since the controller has no try-catch, this propagates as a 500 Internal Server Error. This is inconsistent with other endpoints — GetByProduct returns 404 and DeductStock returns BadRequest for missing/invalid products. The Restock endpoint should handle the missing-product case gracefully.

Suggested change

	public async Task<IActionResult> Restock(int productId, [FromBody] RestockRequest request)
	{
	var item = await _service.RestockAsync(productId, request.Quantity);
	return Ok(item);
	}
	[HttpPost("product/{productId}/restock")]
	public async Task<IActionResult> Restock(int productId, [FromBody] RestockRequest request)
	{
	var item = await _service.GetInventoryByProductIdAsync(productId);
	if (item is null) return NotFound();
	var result = await _service.RestockAsync(productId, request.Quantity);
	return Ok(result);
	}

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[devin-ai-integration]

🔴 Malformed IAM role ARN will cause AWS credential configuration to fail

The IAM ARN arn:aws:iam::599083837640:role/github-actions-ecr-push on line 51 has an extra colon — the correct format for an IAM ARN should have no region but still needs exactly one empty segment, i.e., arn:aws:iam::599083837640:role/.... However, looking more closely, the ARN actually appears correct (IAM ARNs have an empty region field resulting in :: between iam and the account ID). Let me re-examine... Actually, the ARN format IS correct for IAM. Withdrawing this.

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