Most tutorials tell you to scaffold routes first. I did the opposite — and it's the reason OptIVision didn't collapse under its own weight.

The foreign key problem

With 12+ interconnected tables, your schema is your architecture. I hit a foreign key ordering bug in init.js where tables were created before their dependencies.

-- Wrong: referencing a table before it exists
CREATE TABLE prescriptions (
  patient_id UUID REFERENCES patients(id)
);
-- patients table created AFTER this line

What I learned

Draw entity relationships before writing any application code. For a Kenya-specific system — SHA codes, KRA PINs, MCK registration numbers all linking correctly — the schema is the product.

Deploying to a VPS sounds simple until you're staring at a 502 Bad Gateway at 1am. Here's the unfiltered version.

The init.js ordering bug

Docker Compose doesn't guarantee database tables are created in dependency order. Silent failure that only surfaces on first insert.

Nginx reverse proxy

location / {
  proxy_pass http://app:8000;
  # NOT http://localhost:8000
}

Containers communicate by service name inside a Compose network — once you internalize that, everything clicks.

The goal: an RL agent that plays NFS: Most Wanted Black Edition using computer vision for state perception.

The state space problem

import cv2
frame = cv2.cvtColor(raw_frame, cv2.COLOR_BGR2GRAY)
frame = cv2.resize(frame, (84, 84))

Reward shaping

Defining a good reward function is harder than the model. I'm reading pixel color values from screen regions as a road/off-road proxy since I don't have game internals access.