# Pack Run Execution Engine

## Module
TaskRunner

## Status
IMPLEMENTED

## Description
Full execution engine with graph-based execution planning, step state machine, and processor for running task packs.

## Implementation Details
- **Processor**: `src/TaskRunner/StellaOps.TaskRunner/StellaOps.TaskRunner.Core/Execution/PackRunProcessor.cs` -- main execution engine processor
- **Processor result**: `src/TaskRunner/StellaOps.TaskRunner/StellaOps.TaskRunner.Core/Execution/PackRunProcessorResult.cs` -- execution result model
- **Execution graph**: `src/TaskRunner/StellaOps.TaskRunner/StellaOps.TaskRunner.Core/Execution/PackRunExecutionGraph.cs` -- DAG-based execution planning
- **Graph builder**: `src/TaskRunner/StellaOps.TaskRunner/StellaOps.TaskRunner.Core/Execution/PackRunExecutionGraphBuilder.cs` -- builds execution graphs from manifests
- **Step state machine**: `src/TaskRunner/StellaOps.TaskRunner/StellaOps.TaskRunner.Core/Execution/PackRunStepStateMachine.cs` -- state transitions for individual steps
- **Step executor interface**: `src/TaskRunner/StellaOps.TaskRunner/StellaOps.TaskRunner.Core/Execution/IPackRunStepExecutor.cs` -- step execution contract
- **Execution context**: `src/TaskRunner/StellaOps.TaskRunner/StellaOps.TaskRunner.Core/Execution/PackRunExecutionContext.cs` -- runtime context for execution
- **State management**: `src/TaskRunner/StellaOps.TaskRunner/StellaOps.TaskRunner.Core/Execution/PackRunState.cs`, `PackRunStateFactory.cs` -- execution state tracking
- **Job dispatcher**: `src/TaskRunner/StellaOps.TaskRunner/StellaOps.TaskRunner.Core/Execution/IPackRunJobDispatcher.cs`, `IPackRunJobScheduler.cs` -- job scheduling and dispatch
- **Simulation engine**: `src/TaskRunner/StellaOps.TaskRunner/StellaOps.TaskRunner.Core/Execution/Simulation/PackRunSimulationEngine.cs`, `PackRunSimulationModels.cs` -- dry-run simulation
- **Telemetry**: `src/TaskRunner/StellaOps.TaskRunner/StellaOps.TaskRunner.Core/Execution/TaskRunnerTelemetry.cs` -- execution metrics
- **Worker service**: `src/TaskRunner/StellaOps.TaskRunner/StellaOps.TaskRunner.Worker/Services/PackRunWorkerService.cs` -- background worker
- **Infrastructure**: file-based and no-op step executors, dispatchers, artifact uploaders under `StellaOps.TaskRunner.Infrastructure/Execution/`
- **Postgres state store**: `src/TaskRunner/__Libraries/StellaOps.TaskRunner.Persistence/Postgres/Repositories/PostgresPackRunStateStore.cs`, `PostgresPackRunLogStore.cs`
- **Tests**: `src/TaskRunner/StellaOps.TaskRunner/StellaOps.TaskRunner.Tests/PackRunProcessorTests.cs`, `PackRunExecutionGraphBuilderTests.cs`, `PackRunStepStateMachineTests.cs`, `PackRunStateFactoryTests.cs`, `PackRunSimulationEngineTests.cs`
- **Source**: Feature matrix scan

## E2E Test Plan
- [ ] Verify execution graph correctly orders steps based on dependencies
- [ ] Test step state machine transitions (pending -> running -> completed/failed)
- [ ] Verify processor handles step failures with configured retry/abort behavior
- [ ] Test simulation engine produces accurate dry-run results
- [ ] Verify execution state persists across service restarts