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motiram shinde
motiram shinde

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cognitive-debt: Measure Code Readability Before It Becomes a Problem

#webdev #opensource #codequality #devtool

We've all been there. You find a file that "works perfectly" but nobody dares touch it. The tests pass. There are no bugs. Yet the moment you try to refactor it, you realize why everyone avoids it—it's impossible to understand.

That's cognitive debt.

Unlike technical debt (which measures bugs and violations), cognitive debt measures the mental effort required to read, understand, and safely modify code.

Today, we're announcing three powerful new features that make cognitive-debt even more useful for teams.

What is Cognitive Debt?

"Cognitive Debt is the accumulated mental effort required to understand, predict, and safely modify a system, independent of its functional correctness."

A file can be:

  • ✅ Syntactically correct
  • ✅ Fully tested
  • ✅ Following all linting rules

And still be mentally exhausting to work with.

Most code quality tools (ESLint, Prettier, SonarQube) focus on correctness or style. cognitive-debt focuses on comprehension.

The Problem Most Tools Miss

Traditional tools measure:

  • Syntax errors ❌
  • Code style violations ❌
  • Test coverage ❌

But they DON'T measure:

  • Can a human actually understand this?
  • How long will it take to comprehend?
  • Will changing this file break other files?
  • Is this code getting more or less complex over time?

That's the gap cognitive-debt fills.

What We're Announcing: 3 New Features

1. 🎯 Change Impact Forecaster

Before you refactor a file, predict the risk.

cognitive-debt impact src/utils/auth.js
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Output:

Risk Level: HIGH
Ripple Effects: 12 files depend on this
Cognitive Load: 42/100 (Poor)

Actionable Advice:
→ This file is complex AND has high coupling
→ Write regression tests BEFORE making changes
→ Consider breaking it into 3 smaller modules
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Why this matters:

  • You can see upfront if a refactoring will be risky
  • Understand which files are "fragile" despite passing tests
  • Make data-driven decisions about refactoring strategy

2. 📉 Cognitive Debt Diff

Track whether your code is improving or degrading over time.

Compare Git branches:

cognitive-debt diff main..feature-branch
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Output:

⚠️ DEBT INCREASED
- Total Lines: +150
- Dependencies: +3
- Avg Function Length: +12 lines

Files Improved:
✅ src/handlers/auth.js (50→65, score improved)
✅ src/utils/validation.js (60→55, cleaner)

Files Degraded:
🚨 src/api/request.js (nesting depth 3→5)
🚨 src/middleware/logger.js (param count 4→7)
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Why this matters:

  • Prevents cognitive debt from sneaking in
  • Developers can see their impact on code quality
  • Perfect for code review metrics
  • Track progress over sprints and quarters

3. 📊 HTML Reports & JSON Export

Beautiful dashboards for teams + machine-readable data for automation.

Generate an HTML dashboard:

cognitive-debt src/ --output report.html
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Sample output format example :-

Opens in your browser with:

  • Score distribution across all files
  • Interactive charts and visualizations
  • Time-to-understand estimates
  • Detailed breakdowns per file
  • Recommended refactoring priorities

Generate JSON for automation:

cognitive-debt src/ --output report.json
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Use in:

  • CI/CD pipelines (fail builds if cognitive debt > threshold)
  • Custom dashboards (track trends over time)
  • Slack bots (notify team of high-debt files)
  • Executive reports (quantify technical burden)

How It Works: The Math Behind It

cognitive-debt measures 5 dimensions:

1. Naming Clarity (30% impact)

Variables like data, tmp, obj, a, b force your brain to hold mental mappings. Bad names are the #1 cause of confusion.

2. Nesting Depth (10% per level)

Miller's Law: Your brain holds 7±2 items. Deep nesting (5+ levels) exceeds that limit.

Example:

// Hard to understand (5 levels)
if (user) {
  if (user.active) {
    if (user.permissions) {
      if (user.permissions.includes('admin')) {
        if (request.isValid()) {
          // Finally, we do something
        }
      }
    }
  }
}

// Easy to understand (flat)
if (!isAuthorizedAdmin(user, request)) return;
// Do something
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3. Parameter Count (5% per param)

More parameters = exponentially harder to use correctly.

// Easy
function validateEmail(email) { ... }

// Hard
function processUser(id, name, email, phone, role, permissions, status, timestamp, metadata) { ... }
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4. Function Length (0.5% per line)

Long functions require constant context switching. You scroll to understand one part, lose track of another.

5. Dependencies (2% per import)

A file importing 15 other modules requires understanding 15 files simultaneously.

The Transparency Principle

Unlike other tools (especially AI-powered ones), cognitive-debt uses simple, auditable math.

You can verify the score yourself:

  • No black boxes
  • No ML magic
  • No mysterious algorithms
  • Just transparent formulas

You can even customize thresholds in .cognitivedebtrc.json for your team's standards.

Real-World Use Cases

For Code Reviews 

Reviewer: "Why is this file hard to review?"
cognitive-debt: "50/100 (Fair). Main issues:
- 5 functions over 50 lines
- 7 levels of nesting in auth.js
- 40% of variable names unclear (data, tmp, val)"
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For Onboarding

New developers can see which files are hardest to understand before diving in.

For CI/CD Pipelines 

# Fail the build if any file drops below 40/100
cognitive-debt src/ || exit 1
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For Refactoring Decisions

Track whether your refactoring actually improved readability:

cognitive-debt diff v1 v2
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For Team Metrics

Monthly dashboard showing code quality trends:

  • Is average cognitive debt improving?
  • Which files are becoming harder to maintain?
  • What's our onboarding burden?

Why We Built This

The Reality:

  • Developers spend 70% of their time reading code, not writing it
  • Cognitive load is the #1 barrier to onboarding new developers
  • "Technical debt" is often really "cognitive debt"
  • Most tools ignore this completely

Our Philosophy:

  1. Transparency: You should understand the math
  2. Privacy: Your code never leaves your machine
  3. Education: Explain WHY, not just what
  4. Empathy: Code is communication between humans

Getting Started

Install globally:

npm install -g cognitive-debt
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Analyze your code:

cognitive-debt src/
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Generate reports:

cognitive-debt src/ --output report.html
cognitive-debt src/ --output report.json
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Predict refactoring risk:

cognitive-debt impact src/utils/auth.js
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Track improvements:

cognitive-debt diff main..feature-branch
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What Makes This Different

Feature ESLint/Prettier Cyclomatic Complexity SonarQube cognitive-debt
Measures Syntax & Style Logic paths Everything Readability
Goal Consistency Testability Compliance Comprehension
Output Errors Single number Dashboard Actionable insights
Philosophy "Is it wrong?" "Hard to test?" "Compliant?" "Hard to read?"

Open Source & Community

cognitive-debt is open source on GitHub. We welcome:

  • Feature requests
  • Bug reports
  • Contributions
  • Custom analyzers

Links:

A Word of Caution

This tool is powerful, but use it wisely:

❌ Don't use this to punish developers. Cognitive debt is often systemic, not personal.

❌ Don't use as a hard gate without discussion. Sometimes complex problems require complex solutions.

❌ Don't optimize for score alone. A score of 100 with wrong logic is useless.

✅ DO use this to foster empathy for future maintainers.

✅ DO use this to identify risk before refactoring.

✅ DO use this to improve onboarding and developer experience.

The Quote

"The best code is code that doesn't need to be read. The second-best code is code that's easy to read."

Let's make our codebases easier to understand. Try cognitive-debt today.

Have questions? Want to contribute? Join us on GitHub!

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