# Speculative Execution Engine (Shell Script Symbolic Execution)

## Module
Scanner

## Status
VERIFIED

## Description
Symbolic execution engine for shell scripts that enumerates all possible execution paths through entrypoint scripts (Dockerfile CMD/ENTRYPOINT), tracking symbolic variable states and branch conditions to determine all reachable terminal states with confidence scoring.

## Implementation Details
- **Symbolic Executor**:
  - `src/Scanner/__Libraries/StellaOps.Scanner.EntryTrace/Speculative/ShellSymbolicExecutor.cs` - `ShellSymbolicExecutor` performing symbolic execution of shell scripts, tracking variable states and branch conditions
  - `src/Scanner/__Libraries/StellaOps.Scanner.EntryTrace/Speculative/ISymbolicExecutor.cs` - Interface for symbolic execution
- **Execution Tree**:
  - `src/Scanner/__Libraries/StellaOps.Scanner.EntryTrace/Speculative/ExecutionTree.cs` - `ExecutionTree` representing all possible execution paths through the script with terminal states
- **Path Analysis**:
  - `src/Scanner/__Libraries/StellaOps.Scanner.EntryTrace/Speculative/PathEnumerator.cs` - `PathEnumerator` enumerating all possible execution paths through branch conditions
  - `src/Scanner/__Libraries/StellaOps.Scanner.EntryTrace/Speculative/PathConfidenceScorer.cs` - `PathConfidenceScorer` scoring each path's likelihood based on branch conditions and variable constraints

## E2E Test Plan
- [ ] Execute symbolic analysis on a Dockerfile ENTRYPOINT shell script with conditional branches and verify all possible execution paths are enumerated
- [ ] Verify the execution tree correctly tracks symbolic variable states through assignment and substitution
- [ ] Verify branch conditions (if/else, case/esac) create appropriate path forks in the execution tree
- [ ] Verify `PathConfidenceScorer` assigns higher confidence to paths with fewer conditional dependencies
- [ ] Verify the engine handles common shell constructs (loops, subshells, command substitution, environment variable expansion)
- [ ] Verify terminal states include the final command that would be executed in each path

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## Verification

| Check | Result |
|-------|--------|
| Tier 0 - Source files exist | PASS |
| Tier 1 - Build + code review | PASS |
| Tier 2 - Integration tests | PASS |
| Verified | 2026-02-13T18:10:00Z |