ProteinLens: Vibe Coding on Azure… and the Christmas Lunch That Triggered ‘Quota exceeded’

On Dec 25th I messaged a few friends: “I’m working on this project… if you want to put the site under pressure with some tests. It’s all on Azure. Merry Christmas!”

The project is ProteinLens: you take a photo of your meal and the app tries to figure out what it is and how much protein it contains. Simple idea, “weekend MVP” vibes — but with a real goal: build something production-shaped, with proper cloud infrastructure and automated deploys.

Then reality showed up, fast:

• “Failed to Load History”
• “Unexpected end of JSON input”
• “Something went wrong”
• “Quota exceeded”
• And the best one: “I uploaded the Apulian lunch… told you it would blow up 😁”

That Christmas stress test turned into a mini post-mortem. And honestly, it was perfect.

What ProteinLens does (and what’s under the hood)

The MVP does one thing clearly: snap a photo → get a structured result (recognition + estimated proteins). The AI part runs via AI Foundry.

Current stack:

• Frontend: Azure Static Web Apps
• Backend: Azure Functions
• Database: Azure Database for PostgreSQL
• Deploy: full CI/CD pipeline (infra, permissions, frontend + backend)
• Security hygiene: secret scanning (e.g., gitleaks), proper secret handling

In the chat I joked “it’s super scalable.” The services are, on paper. But “scalable services” don’t automatically make a scalable system — especially when an entire group starts hammering it with food photos at the same time.

The uncomfortable part: “AI writes your code” isn’t real yet (not end-to-end)

I built a lot of this using Spec Driven Vibe Coding with tools like SpecKit/Copilot. They absolutely speed things up — but the “AI will build the whole app for you” story is still oversold.

Here’s what happened when I iterated fast with LLM-generated infra + pipelines:

• Each pipeline run started creating duplicate resources (Key Vaults, etc.)
• Result: frontend and backend stopped talking because they had different secrets
• Environment variables were wrong or invented
• CI/CD builds ballooned and started hitting resource limits (compilation, upload, deploy)
• Zero retry logic, so transient issues cascaded into total failure
• The classic: “works on my machine,” then fails in cloud for reasons you can’t fully reproduce locally

The most dangerous pattern: Many tools “help” by adding something on every interaction — another resource, another config file, another pipeline step. But real progress often comes from the opposite: removing, simplifying, testing, refining.

“Quota exceeded” isn’t just a bug — it’s product and architecture feedback

When multiple people hit an MVP simultaneously, the real bottlenecks show up immediately:

• service quota / rate limits
• large payloads (images)
• endpoints with no caching or backoff
• missing queues for burst handling
• no resilience patterns (retries, circuit breakers)

At that moment I realized it wasn’t just “I need more horsepower.” It was: I need engineering discipline — observability, retry/backoff, sane limits, guardrails.

Authentication: custom in Postgres or managed identity (Entra / SWA Auth)?

After the first stress test, it became obvious I need auth to unlock:

• user profiles
• scan history
• preferences
• email confirmation / reset flows

Because the frontend is on Static Web Apps, the platform already offers built-in auth options — which is appealing for moving fast without reinventing identity from scratch. The alternative is rolling your own user table in Postgres, but then you own passwords, email flows, security, compliance… and the debt grows quickly.

For an MVP that wants to become a real product: managed identity tends to save months.

Another reality check: model availability and quota are part of the design

One more thing that surprised me: you can’t always “just use the best model” when you want.

Concrete examples I ran into:

• gpt-5.1-codex-max: deployable for me only via swedencentral, not eastus
• claude-opus-4.5: showed no quota available worldwide at the time
• Partner models can have separate billing constraints depending on your subscription setup

This affects real decisions: fallback models, region strategy, budgeting, and even UX (clear messages when you’re rate-limited).

What I learned (the honest version)

1. AI accelerates — it doesn’t replace: if you don’t understand what it generated, you’ll ship a Frankenstein that “sort of works.”
2. The difference between a demo and a product is made of boring things: retries, logging, caching, tests, limits.
3. Good iteration includes deleting: fewer resources, fewer variables, less magic.
4. Quotas aren’t an afterthought — they’re part of system design.
5. Cloud ≠ local, and fighting that truth wastes time. Build with observability and resilience early.

What’s next for ProteinLens

Very practical next steps:

• authentication + user profiles
• history and preferences
• retry/backoff + queues where needed
• telemetry to see where it actually breaks
• quota-aware UX + model fallback strategy

If you want to try it (and yes, feel free to “stress test” it with a heavy meal photo 😄): https://www.proteinlens.com/