# CLI Reachability Trace Export

## Module
Cli

## Status
IMPLEMENTED

## Description
New stella reachability trace command with flags for scan ID, output format (GraphSON/JSON), runtime-confirmed filtering, minimum score threshold, and deterministic output.

## Implementation Details
- **Command Group**: `src/Cli/StellaOps.Cli/Commands/ReachabilityCommandGroup.cs` -- `ReachabilityCommandGroup` for reachability commands
- **ReachGraph Commands**: `src/Cli/StellaOps.Cli/Commands/ReachGraph/ReachGraphCommandGroup.cs` -- reachability graph operations
- **ReachGraph Handlers**: `src/Cli/StellaOps.Cli/Commands/ReachGraph/ReachGraphCommandHandlers.cs`
- **Tests**: `src/Cli/__Tests/StellaOps.Cli.Tests/ReachabilityTraceExportCommandTests.cs`
- **Commands**:
  - `stella reachability trace --scan <scan-id>` -- export reachability trace. Options: `--format graphson|json`, `--runtime-only` (confirmed only), `--min-score <threshold>`, `--output <path>`
- **Determinism**: Output is deterministically ordered for reproducible results

## E2E Test Plan
- [ ] Run `stella reachability trace --scan <id> --format json` and verify JSON trace export
- [ ] Run `stella reachability trace --scan <id> --format graphson` and verify GraphSON output
- [ ] Run `stella reachability trace --scan <id> --runtime-only` and verify only runtime-confirmed paths
- [ ] Run `stella reachability trace --scan <id> --min-score 0.7` and verify score filtering
- [ ] Verify output is deterministic (same scan produces byte-identical output)
- [ ] Verify `--output` flag writes to file instead of stdout
- [ ] Verify error handling for non-existent scan IDs