13 · DEBUG & FIX
Don’t just spot the flaw — fix it.
Where Debug Lab asks you to annotate, Debug & Fix asks you to restructure. Apply the pattern, extract the class, validate against the expected clean design.
+ createUser()
+ updateProfile()
+ sendEmail()
+ validatePassword()
+ hashPassword()
+ sendSMS()
+ generateReport()
+ cacheUser()
+ queryDB()
+ createUser()
+ updateProfile()
+ validatePassword()
+ hashPassword()
+ sendEmail()
+ sendSMS()
+ generateReport()
How it works
From diagnosis to clean design.
01
Detect
Identify violations in the broken diagram
02
Plan
Decide your restructuring approach
03
Fix
Restructure classes on the canvas
04
Validate
Compare to the expected clean design
01
Detect
Identify violations in the broken diagram
02
Plan
Decide your restructuring approach
03
Fix
Restructure classes on the canvas
04
Validate
Compare to the expected clean design
Validation
Your fix, scored.
The validator compares your restructured design against the expected clean design structurally — a structural diff, not pixel-perfect comparison.
Your restructured design
Expected clean design
UserService extracted
UserService extracted
AuthService extracted
AuthService extracted
PasswordHasher not extracted
PasswordHasher separate class
EmailService separated
EmailService separated
Features
Built for active remediation.
Fix mode, not annotate mode
You restructure the design on the canvas rather than just marking what is wrong. This is hands-on practice, not passive critique.
Real authored scenarios
Each scenario is based on real system archetypes — notification pipelines, auth modules, booking engines — deliberately designed with specific violations.
Validation against the clean design
Your fix is compared structurally against the expected clean design. You see exactly what you got right and what you missed.
Explanation per diff
Every structural difference is explained — why it matters, what the correct reasoning is, and what the clean alternative looks like.
Multiple valid fixes accepted
Where more than one correct restructuring exists, the validator accepts all known-good approaches and explains the trade-offs between them.
Pattern application focus
Scenarios are designed around applying specific patterns — SRP extraction, Facade, Repository — so practice builds real pattern vocabulary.
Who it’s for
Built for engineers who want to fix, not just find.
The hands-on learner
Engineers who understand design principles in theory but need deliberate practice actually applying them to broken designs.
The refactoring candidate
Interview candidates preparing for rounds where they are handed an existing design and asked to improve it on the spot.
The Debug Lab graduate
Anyone who has practised spotting violations in Debug Lab and is now ready to practise fixing them — the natural next step.
The pattern applier
Engineers who know design pattern names but struggle to recognise when and how to apply them to resolve a real structural problem.
FAQ
Questions people ask
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