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Agent skill

Interval Difference Analyzer

by ArabelaTso in ArabelaTso/Skills-4-SE

Analyze differences in program intervals between two versions of a program (old and new) to identify added, removed, or modified intervals.

Apache-2.0Auto-check passedDevelopment

Install Interval Difference Analyzer

skills CLI
$ npx skills add ArabelaTso/Skills-4-SE --skill interval-difference-analyzer -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install ArabelaTso/Skills-4-SE interval-difference-analyzer --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/ArabelaTso/Skills-4-SE.git skills-src && mkdir -p .claude/skills && cp -r skills-src/skills/interval-difference-analyzer .claude/skills/interval-difference-analyzer && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Facts

Skill name
interval-difference-analyzer
GitHub stars
253
Token cost
~1.6k tokens
SKILL.md length
420 words
Files
5 (incl. scripts, references)
Skills in repo
151
Repo updated
First seen
Licence
Apache-2.0

At a glance

Analyze differences in program intervals between two versions of a program (old and new) to identify added, removed, or modified intervals.

  • Works in 4 steps: Setup Program Versions → Extract Intervals → Compare Intervals → …
  • Comparing program versions
  • SKILL.md covers Overview, Core Workflow, What Are Program Intervals? and Interval Extraction Methods, plus 7 more sections
  • Runs Python scripts from its folder; calls python

What it does

Interval Difference Analyzer is an agent skill from ArabelaTso/Skills-4-SE. Analyze differences in program intervals between two versions of a program (old and new) to identify added, removed, or modified intervals. Use when comparing program versions, analyzing variable ranges, detecting behavioral changes in numeric computations, validating refactorings, or assessing migration impacts. Supports optional test suite integration to validate interval changes. Generates comprehensive reports highlighting intervals requiring further testing or verification.

Its SKILL.md is about 1.6k tokens, which your agent loads only when the skill is triggered. The skill folder holds 6 other files, including scripts and reference files (for example `references/abstract_interpretation.md`, `references/interval_analysis.md` and `scripts/compare_intervals.py`).

It sits in Development, covering Test generation and Refactoring. The repository describes itself as: A curated list of 180+ useful Claude Skills for Software Engineering and resources for customizing AI for SE workflows. The licence is Apache-2.0.

When your agent uses it

  • Comparing program versions
  • Analyzing variable ranges
  • Detecting behavioral changes in numeric computations
  • Validating refactorings

Example prompts

  • “/interval-difference-analyzer”

Requirements

  • Python 3

Workflow steps

4 steps, taken from the step headings in SKILL.md.

  1. Setup Program Versions
  2. Extract Intervals
  3. Compare Intervals
  4. Review Report

What it can do on your machine

Read from SKILL.md and the folder at commit 4f38503. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    Ships 2 files in scripts/ (Python), which the agent can run.

    Shell commands in SKILL.md call:

    • python

    From the folder's file list and the shell code blocks in SKILL.md.

  • Network

    No URLs in SKILL.md.

    From URLs in SKILL.md, links to its own repository left out.

  • Credentials

    Names no API keys, tokens, secrets or passwords.

    From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Interval Difference Analyzer loads about 1.6k tokens when it runs, and up to ~5.8k if it reads all its reference files. Until then it costs about 128 tokens; SKILL.md has 420 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~128
When it runs · the whole SKILL.md, loaded when a task matches
~1.6k
With references · SKILL.md plus every file in references/, read only if the agent opens them
~5.8k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); the scripts in this folder are not scanned.

SKILL.md

The full file from ArabelaTso/Skills-4-SE at commit 4f38503, republished under its Apache-2.0 licence (© ArabelaTso). 420 words, ~1,635 tokens.

Download SKILL.mdSave it as .claude/skills/interval-difference-analyzer/SKILL.md (or your agent's skills folder). This skill also uses 4 other files; get the full folder from GitHub.
name
interval-difference-analyzer
description
Analyze differences in program intervals between two versions of a program (old and new) to identify added, removed, or modified intervals. Use when comparing program versions, analyzing variable ranges, detecting behavioral changes in numeric computations, validating refactorings, or assessing migration impacts. Supports optional test suite integration to validate interval changes. Generates comprehensive reports highlighting intervals requiring further testing or verification.

Interval Difference Analyzer

Overview

Analyze differences in program intervals (variable value ranges) between two versions of a program to detect behavioral changes, identify potential bugs, and guide testing efforts.

Core Workflow

1. Setup Program Versions

Prepare both program versions for analysis:

bash
OLD_VERSION=/path/to/old/program
NEW_VERSION=/path/to/new/program
TEST_SUITE=/path/to/tests  # Optional
2. Extract Intervals

Extract interval information from both versions:

bash
python scripts/interval_analyzer.py \
    --program $OLD_VERSION \
    --output old_intervals.json

python scripts/interval_analyzer.py \
    --program $NEW_VERSION \
    --output new_intervals.json
3. Compare Intervals

Compare intervals and identify differences:

bash
python scripts/compare_intervals.py \
    --old old_intervals.json \
    --new new_intervals.json \
    --output interval_diff_report.json
4. Review Report

Examine the generated report for:

  • Added intervals (new variables or wider ranges)
  • Removed intervals (deleted variables or narrower ranges)
  • Modified intervals (changed bounds)
  • Behavioral implications
  • Testing recommendations

What Are Program Intervals?

Program intervals represent the possible ranges of values that variables can take during program execution.

Example:

python
def calculate_discount(price, discount_rate):
    # Intervals:
    # price: [0, 10000]
    # discount_rate: [0.0, 1.0]
    # discount: [0, 10000]
    discount = price * discount_rate
    return discount

Why intervals matter:

  • Detect overflow/underflow risks
  • Identify boundary condition changes
  • Validate numeric computation correctness
  • Guide test case generation

Interval Extraction Methods

Method 1: Static Analysis

Analyze code to infer possible value ranges without execution.

Method 2: Dynamic Analysis

Execute program with test inputs and observe actual ranges.

Method 3: Abstract Interpretation

Use abstract domains to compute sound interval approximations.

Interval Comparison

Identifying Added Intervals

Pattern: New variables or wider ranges in new version

Implications:

  • New computation paths
  • Potential new bugs
  • Requires new tests
Identifying Removed Intervals

Pattern: Deleted variables or narrower ranges in new version

Implications:

  • Simplified computation
  • Reduced intermediate state
  • May affect debugging
Identifying Modified Intervals

Pattern: Changed bounds for existing variables

Example:

python
# Old version: age: [0, 120]
# New version: age: [0, 150]  # Widened!

Implications:

  • Relaxed constraints
  • May accept invalid inputs
  • Requires validation testing

Behavioral Change Detection

Overflow/Underflow Detection

Check if new intervals exceed type bounds.

Example:

python
# Old: result: [0, 1000000] ✓ Safe (int32)
# New: result: [0, 10000000000] ✗ Overflow risk!
Precision Loss Detection

Check if new intervals lose precision.

Example:

python
# Old: result: [0.0, 100.0] (float)
# New: result: [0, 100] (int) - precision loss!
Show full SKILL.md (165 more words)Show less
Boundary Condition Changes

Check if interval boundaries change critically.

Example:

python
# Old: index: [0, 99]
# New: index: [-1, 99]  # Negative index possible!

Testing Recommendations

Priority Levels

Critical: Test immediately

  • Overflow/underflow risks
  • Negative indices
  • Division by zero
  • Type mismatches

High: Test soon

  • Widened intervals
  • Boundary changes
  • Precision loss

Medium: Test when convenient

  • Narrowed intervals (safer)
  • Removed intermediate variables

Low: Optional testing

  • Cosmetic changes
  • Unchanged intervals
Test Case Generation

Generate test cases targeting interval boundaries:

python
# Interval: x: [0, 100]
test_cases = [0, 1, 50, 99, 100]

# For modified interval: [0, 100] → [0, 150]
additional_tests = [101, 125, 149, 150]

Report Format

The analyzer generates a comprehensive JSON report:

json
{
  "summary": {
    "total_intervals_old": 45,
    "total_intervals_new": 48,
    "added_intervals": 5,
    "removed_intervals": 2,
    "modified_intervals": 8
  },
  "differences": [
    {
      "type": "modified",
      "variable": "age",
      "old_interval": "[0, 120]",
      "new_interval": "[0, 150]",
      "severity": "high",
      "implications": ["Accepts wider range"],
      "testing_priority": "high",
      "suggested_tests": [121, 135, 149, 150]
    }
  ],
  "recommendations": [
    "Test modified intervals with boundary values",
    "Verify no overflow in calculations"
  ]
}

Integration with Test Suites

Validate Intervals with Tests

Run existing tests and verify intervals:

bash
python scripts/validate_intervals.py \
    --program $NEW_VERSION \
    --intervals new_intervals.json \
    --test-suite $TEST_SUITE
Generate Tests from Intervals

Automatically generate tests for interval boundaries:

bash
python scripts/generate_interval_tests.py \
    --intervals interval_diff_report.json \
    --output generated_tests.py

Best Practices

  1. Use both static and dynamic analysis: Combine for better coverage
  2. Focus on critical intervals: Prioritize safety-critical variables
  3. Test boundary values: Always test interval bounds
  4. Document intentional changes: Mark expected interval modifications
  5. Automate analysis: Integrate into CI/CD pipeline

Resources

  • references/interval_analysis.md: Detailed interval analysis techniques
  • references/abstract_interpretation.md: Abstract interpretation theory
  • scripts/interval_analyzer.py: Main interval extraction tool
  • scripts/compare_intervals.py: Interval comparison engine
  • scripts/validate_intervals.py: Test suite validation
  • scripts/generate_interval_tests.py: Test case generator

© ArabelaTso, Apache-2.0. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 4 other files (scripts, references) in skills/interval-difference-analyzer of ArabelaTso/Skills-4-SE.

  • SKILL.md
  • references/abstract_interpretation.md
  • references/interval_analysis.md
  • scripts/compare_intervals.py
  • scripts/interval_analyzer.py

Open the folder on GitHubat commit 4f38503

Compare with similar skills

Interval Difference Analyzer next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Interval Difference Analyzer compared with similar skills
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Devnpc-live/clawfirm156—~642Automated safety check: PassNone
Lsp Verifyblackwell-systems/agent-lsp157—~2kAutomated safety check: PassMIT
Improve Codebase ArchitectureTwiTech-LAB/devchain101—~3kAutomated safety check: PassMIT

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Categories

Questions about Interval Difference Analyzer

What does Interval Difference Analyzer do?

Analyze differences in program intervals between two versions of a program (old and new) to identify added, removed, or modified intervals. Interval Difference Analyzer is an agent skill from ArabelaTso/Skills-4-SE. Analyze differences in program intervals between two versions of a program (old and new) to identify added, removed, or modified intervals.

When should I use Interval Difference Analyzer?

Interval Difference Analyzer fits situations like: comparing program versions; analyzing variable ranges; detecting behavioral changes in numeric computations; validating refactorings.

How do I install Interval Difference Analyzer in Claude Code?

Run `npx skills add ArabelaTso/Skills-4-SE --skill interval-difference-analyzer -a claude-code`. Or copy the skill folder (skills/interval-difference-analyzer in ArabelaTso/Skills-4-SE) into .claude/skills/interval-difference-analyzer in your project. Claude Code loads it when a task matches its description.

How do I install Interval Difference Analyzer in Codex?

Run `npx skills add ArabelaTso/Skills-4-SE --skill interval-difference-analyzer -a codex`. Or copy the skill folder (skills/interval-difference-analyzer in ArabelaTso/Skills-4-SE) into .agents/skills/interval-difference-analyzer in your project. Codex loads it when a task matches its description.

Can I use Interval Difference Analyzer in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add ArabelaTso/Skills-4-SE --skill interval-difference-analyzer -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/interval-difference-analyzer, .gemini/skills/interval-difference-analyzer, .github/skills/interval-difference-analyzer and .opencode/skills/interval-difference-analyzer in your project.

What does Interval Difference Analyzer need to run?

Going by SKILL.md and its folder, Interval Difference Analyzer needs Python for the scripts in its folder and the command-line tools its instructions call (python). Our summary lists: Python 3.

Does Interval Difference Analyzer access the network?

SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.

Is Interval Difference Analyzer safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. The check reads SKILL.md only: the scripts in the folder are not scanned, so read them before running anything.

What licence does Interval Difference Analyzer use?

Interval Difference Analyzer is published under the Apache-2.0 licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Interval Difference Analyzer use?

About 1.6k tokens (SKILL.md is roughly 6.5k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full. Its references folder adds about 4.1k tokens, read only when the agent opens those files.

What are the alternatives to Interval Difference Analyzer?

Skills that share tags, products or a category with Interval Difference Analyzer: Exp Test Maintainability (dotnet/skills, 5.6k stars), Feature Contract (FastLED/FastLED, 7.5k stars), Dev (npc-live/clawfirm, 156 stars) and Lsp Verify (blackwell-systems/agent-lsp, 157 stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Interval Difference Analyzer?

ArabelaTso (a GitHub user) maintains it in ArabelaTso/Skills-4-SE, which has 253 GitHub stars. The repository holds 151 skills in this directory. The repository was last updated on August 21, 2026.

Source: ArabelaTso/Skills-4-SE on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.