LLearnCode
Capstones/Complete the debugging gauntlet

Cross-academy build · 6 substantial stages

Complete the debugging gauntlet

Build a disposable broken application from the supplied small fixtures, then diagnose independent input, async, database, layout and verification failures. Keep hypotheses, counterexamples and regression evidence for each repair.

This is a project brief and local evidence notebook. Implement the project in your own development repository using synthetic data. Checklists and the review question record self-review; LearnLab does not execute these project files, inspect a live database, grade the implementation or certify security. Starter snippets are deliberately partial. Link actual commands, outputs, revisions and screenshots to your notes. Publishing requires a separate deliberate release decision.

Skills this project brings together

Implementation stage · self-review

1. Reproduce and separate the failures

Create an isolated educational repository and copy only these tiny intentionally broken fixtures. Start a case file for each defect with expected behavior, actual behavior, smallest input and environment. Investigate one failure at a time.

Acceptance criteria

Mark an item only after you have reviewed the corresponding implementation and evidence. These are your declarations, not automated test results.

Concrete tests to run

  1. Calling increment('5') produces the string '51' in the broken fixture.
  2. A numeric input 5 produces 6, providing a nearby successful comparison.
  3. A fresh checkout follows your written steps and reproduces the same symptom.
  4. Removing unrelated UI does not eliminate the minimal coercion failure.
Failure to watch for

If the problem disappears only after removing several interacting systems, narrow which removed behavior mattered before declaring a root cause.

Open the partial starter
function increment(value) { return value + 1; }
console.log(increment('5'));
// Contract: a submitted count must be explicitly validated as an integer.
// First record the result; do not reveal a fix before predicting it.

This fragment frames the next design decision. It is not a finished implementation.

Your evidence notebook

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