Track project · 01

Debug a Local Web App

Use the runtime mental models from this track to diagnose a deliberately broken local web application without guessing.

Definition of done

What you are building

Deliverables

A tiny local web serverA documented port and URLA failure logA short boundary diagram

Build plan

Work through it one observable step at a time

01
Start a tiny server and confirm the exact process and port it uses.
02
Open the URL in the browser and write down the request/response you expect.
03
Change the configured port without updating the browser URL and capture the failure.
04
Use `netstat`, `Get-NetTCPConnection`, or an equivalent tool to identify the listening process.
05
Break PATH for one terminal session or invoke a missing command; explain why the shell cannot find it.
06
Add one environment variable, read it at runtime, then compare runtime configuration with build-time configuration.
07
Write a one-page boundary map: shell → process → port → HTTP → browser.
08
Reset everything and reproduce the healthy path from memory.

Evidence

Do not rely on “it seems to work”

Evidence to collect

A clean Git diff or file-tree changeCommands used and their exit/resultBrowser, HTTP, database, test, container, or CI evidence that proves the behaviorOne deliberate failure, the evidence you used, and the root-cause fixA short explanation of why the final responsibility lives in the chosen layer

Project exit ticket

Close the project only when these are true

Completion

I can demonstrate every deliverable.I can reproduce one key part without the walkthrough.I can explain one trade-off I deliberately chose.I can show one failure that my tests, constraints, or runbook now protects against.