# Abstract State Analyzer

> Performs abstract interpretation over source code to infer possible program states, variable ranges, and data properties without executing the program. Reports potential runtime errors including out-of-bounds accesses, null dereferences, type inconsistencies, division by zero, and integer overflows. Use when analyzing code for potential runtime errors, performing static analysis, checking safety…

- **Type:** Skill
- **Install:** `agentstack add skill-arabelatso-skills-4-se-abstract-state-analyzer`
- **Verified:** Yes — security-reviewed for prompt injection and unsafe behavior
- **Seller:** [ArabelaTso](https://agentstack.voostack.com/s/arabelatso)
- **Installs:** 0
- **Category:** [Agent Skills](https://agentstack.voostack.com/c/agent-skills)
- **Latest version:** 0.1.0
- **License:** Apache-2.0
- **Upstream author:** [ArabelaTso](https://github.com/ArabelaTso)
- **Source:** https://github.com/ArabelaTso/Skills-4-SE/tree/main/skills/abstract-state-analyzer
- **Website:** https://ArabelaTso.github.io/Skills-4-SE/

## Install

```sh
agentstack add skill-arabelatso-skills-4-se-abstract-state-analyzer
```

Requires the [AgentStack CLI](https://agentstack.voostack.com/docs/cli). Works with Claude Code, Cursor, and any MCP-compatible agent.

## About

# Abstract State Analyzer

## Overview

This skill performs abstract interpretation to statically analyze source code and infer possible program states, variable ranges, and data properties. It identifies potential runtime errors without executing the program.

## Analysis Workflow

### Step 1: Parse and Understand Code Structure

Analyze the code to identify:
- Functions and their control flow
- Variable declarations and types
- Loops and conditionals
- Array/buffer operations
- Pointer/reference operations
- Function calls and parameter passing

### Step 2: Select Abstract Domains

Choose appropriate abstract domains based on the analysis goals:

**Interval Domain**: Track numeric variable ranges
- Example: `x ∈ [0, 100]` means x is between 0 and 100
- Good for: Array bounds checking, overflow detection

**Sign Domain**: Track whether values are positive, negative, or zero
- Values: {+, -, 0, ⊤}
- Good for: Division by zero, sign-dependent operations

**Null Domain**: Track whether pointers/references can be null
- Values: {null, not-null, maybe-null, ⊤}
- Good for: Null dereference detection

**Type Domain**: Track possible types of variables
- Good for: Type consistency checking, dynamic language analysis

**Combination**: Use multiple domains together for more precise analysis

### Step 3: Initialize Abstract States

Set initial abstract values for:
- Function parameters (based on preconditions or ⊤ for unknown)
- Global variables
- Constants and literals

Example:
```python
def process(arr, index):
    # Initial state:
    # arr: not-null (assumed)
    # index: ⊤ (unknown integer)
```

### Step 4: Perform Forward Analysis

Propagate abstract states through the program:

**Assignment**: Update abstract value
```python
x = 5
# x: [5, 5]

y = x + 3
# y: [8, 8]
```

**Conditionals**: Split into branches
```python
if x > 10:
    # Branch 1: x ∈ [11, ∞]
else:
    # Branch 2: x ∈ [-∞, 10]
```

**Loops**: Iterate until fixpoint
```python
i = 0
while i  max_val:
            max_val = arr[i]
        i += 1
    return max_val
```

**Analysis:**

**Initial State:**
- arr: not-null (assumed)
- n: ⊤ (unknown integer)

**Line 2: `if n  0): n ∈ [1, ∞]

**Line 3: `return None`** (Branch 1)
- Safe return

**Line 5: `max_val = arr[0]`** (Branch 2)
- Access: arr[0]
- Check: 0  max_val`**
- Access: arr[i] where i ∈ [1, n-1]
- Check: i  len(arr), out-of-bounds access
- State: max_val updated if arr[i] > max_val

**Line 10: `i += 1`**
- State: i ∈ [2, n]

**Report:**

```
POTENTIAL ERRORS FOUND:

1. Out-of-Bounds Access
   Location: line 5, arr[0]
   State: n ∈ [1, ∞], arr length unknown
   Severity: Potential
   Explanation: Array 'arr' might be empty when n > 0
   Suggestion: Add check: if len(arr) == 0 or add precondition

2. Out-of-Bounds Access
   Location: line 8, arr[i]
   State: i ∈ [1, n-1], arr length unknown
   Severity: Potential
   Explanation: If n > len(arr), accessing beyond array bounds
   Suggestion: Add precondition: n  0 and x < 10:
    # x ∈ [1, 9] (path-sensitive)
    # vs x ∈ [-∞, ∞] (path-insensitive)
```

## References

For detailed information on abstract interpretation techniques and domains:
- **references/abstract_domains.md**: Detailed abstract domain definitions and operations
- **references/analysis_patterns.md**: Common analysis patterns for different error types
- **references/language_specifics.md**: Language-specific analysis considerations

## Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

- **Author:** [ArabelaTso](https://github.com/ArabelaTso)
- **Source:** [ArabelaTso/Skills-4-SE](https://github.com/ArabelaTso/Skills-4-SE)
- **License:** Apache-2.0
- **Homepage:** https://ArabelaTso.github.io/Skills-4-SE/

Install and usage instructions live in the source repository linked above.

## Pricing

- **Free** — Free

## Security capabilities

Automated source analysis of v0.1.0 — what this tool can access:

- **Network access:** no
- **Filesystem access:** no
- **Shell / process execution:** no
- **Environment & secrets:** no
- **Dynamic code execution:** no

*"Yes" means the capability is present in the source — more access means more to trust, not that it is unsafe.*


## Versions

- **0.1.0** — security scan: passed — Imported from the upstream source.

## Links

- Listing page: https://agentstack.voostack.com/l/skill-arabelatso-skills-4-se-abstract-state-analyzer
- Seller: https://agentstack.voostack.com/s/arabelatso
- Browse the marketplace: https://agentstack.voostack.com/browse

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