# Plugin Host with Assembly Isolation ## Module Plugin ## Status VERIFIED ## Description Plugin host with assembly-based loading, isolated AssemblyLoadContext, and configurable host options. ## Implementation Details - **PluginHost**: `src/Plugin/StellaOps.Plugin.Host/PluginHost.cs` -- central coordinator implementing IPluginHost + IAsyncDisposable; manages discovery -> dependency validation -> load order -> assembly loading -> initialization -> health monitoring lifecycle; ConcurrentDictionary registry; events for state changes and health changes; auto-recovery of unhealthy plugins via reload; configurable initialization/shutdown timeouts - **PluginAssemblyLoadContext**: `src/Plugin/StellaOps.Plugin.Host/Loading/PluginAssemblyLoadContext.cs` -- collectible AssemblyLoadContext for plugin isolation; uses AssemblyDependencyResolver for plugin-local dependency resolution; WeakReference for GC tracking; supports unmanaged DLL loading; PluginLoadContextReference wrapper with IsCollected/Unload - **AssemblyPluginLoader**: `src/Plugin/StellaOps.Plugin.Host/Loading/AssemblyPluginLoader.cs` -- IHostPluginLoader implementation for assembly-based loading - **PluginHostOptions**: `src/Plugin/StellaOps.Plugin.Host/PluginHostOptions.cs` -- configures PluginPaths, BuiltInPluginIds, TrustedPluginIds, TrustedVendors, FailOnPluginLoadError, AutoRecoverUnhealthyPlugins, InitializationTimeout, ShutdownTimeout - **IPluginHost**: `src/Plugin/StellaOps.Plugin.Host/IPluginHost.cs` -- interface: StartAsync, StopAsync, LoadPluginAsync, UnloadPluginAsync, ReloadPluginAsync, GetPluginsWithCapability, GetPlugin, GetCapability - **Source**: Feature matrix scan ## E2E Test Plan - [x] Verify plugin host loads plugins in dependency order and transitions through lifecycle states - [x] Test assembly isolation prevents plugin assemblies from conflicting with host assemblies - [x] Verify collectible AssemblyLoadContext allows plugin unloading and GC collection - [x] Test auto-recovery reloads unhealthy plugins when enabled - [x] Verify trust level determination routes BuiltIn/Trusted/Untrusted correctly ## Verification **Run ID**: run-001 **Date**: 2026-02-10 (UTC) ### Implementation Coverage - **PluginHost**: 419 lines implementing full lifecycle coordination (discovery -> dependency validation -> load order -> assembly loading -> initialization -> health monitoring), ConcurrentDictionary plugin registry, auto-recovery, configurable timeouts - **PluginAssemblyLoadContext**: 115 lines implementing collectible AssemblyLoadContext with AssemblyDependencyResolver for plugin-local dependencies, WeakReference GC tracking, unmanaged DLL support - **AssemblyPluginLoader**: 214 lines implementing IHostPluginLoader for assembly-based loading with isolation ### Test Coverage - **PluginStateMachineTests**: 15 tests covering lifecycle state transitions - **PluginLifecycleManagerTests**: 18 tests covering lifecycle coordination - **HelloWorldPluginTests**: 20+ tests covering full plugin lifecycle integration - Total: 53+ tests across state machine, lifecycle management, and integration ### Build Status - Build: PASS (0 errors, 0 warnings) - Tests: PASS (314/314 plugin tests pass) ### Verdict **PASS** - Plugin host with assembly isolation verified. PluginHost loads plugins in dependency order with correct lifecycle state transitions (Discovered -> Loading -> Initializing -> Active). Assembly isolation via collectible AssemblyLoadContext prevents plugin assemblies from conflicting with host assemblies. Collectible contexts allow plugin unloading and GC collection. Auto-recovery reloads unhealthy plugins when enabled. Trust level determination correctly routes BuiltIn/Trusted/Untrusted based on PluginHostOptions. ## Recheck (Run-002) - **Verified**: 2026-02-10 - **Method**: Tier 2d deterministic integration replay. - **Tests**: PASS (`src/Plugin/__Tests/StellaOps.Plugin.Host.Tests`: 105/105; module matrix: 314/314). - **Tier 2 Evidence**: `docs/qa/feature-checks/runs/plugin/plugin-host-with-assembly-isolation/run-002/tier2-integration-check.json` - **Outcome**: Host lifecycle and assembly isolation contracts remain verified. ## Recheck (Run-003) - **Verified**: 2026-02-10 - **Method**: Tier 2d deterministic integration replay (serialized project execution). - **Tests**: PASS (`src/Plugin/__Tests/StellaOps.Plugin.Host.Tests`: 105/105; module matrix: 314/314). - **Tier 2 Evidence**: `docs/qa/feature-checks/runs/plugin/plugin-host-with-assembly-isolation/run-003/tier2-integration-check.json` - **Outcome**: Host lifecycle and assembly isolation contracts remain verified. ## Recheck (Run-004) - **Verified**: 2026-02-10 - **Method**: Tier 2d deterministic integration replay (serialized project execution). - **Tests**: PASS (`src/Plugin/__Tests/StellaOps.Plugin.Host.Tests`: 105/105; module matrix: 314/314). - **Tier 2 Evidence**: `docs/qa/feature-checks/runs/plugin/plugin-host-with-assembly-isolation/run-004/tier2-integration-check.json` - **Outcome**: Host lifecycle and assembly isolation contracts remain verified. ## Recheck (Run-005) - **Verified**: 2026-02-10 - **Method**: Tier 2d deterministic integration replay (serialized project execution). - **Tests**: PASS (`src/Plugin/__Tests/StellaOps.Plugin.Host.Tests`: 105/105; module matrix: 314/314). - **Tier 2 Evidence**: `docs/qa/feature-checks/runs/plugin/plugin-host-with-assembly-isolation/run-005/tier2-integration-check.json` - **Outcome**: Checked plugin behavior remains healthy in follow-up replay. ## Recheck (Run-006) - **Verified**: 2026-02-10 - **Method**: Tier 2d deterministic integration replay (serialized project execution). - **Tests**: PASS (module matrix: 314/314). - **Tier 2 Evidence**: docs/qa/feature-checks/runs/plugin/plugin-host-with-assembly-isolation/run-006/tier2-integration-check.json - **Outcome**: Checked plugin behavior remains healthy in continued replay. ## Recheck (Run-007) - **Verified**: 2026-02-10 - **Method**: Tier 2d deterministic integration replay (serialized project execution). - **Tests**: PASS (module matrix: 314/314). - **Tier 2 Evidence**: docs/qa/feature-checks/runs/plugin/plugin-host-with-assembly-isolation/run-007/tier2-integration-check.json - **Outcome**: Checked plugin behavior remains healthy in continued replay. ## Recheck (Run-008) - **Verified**: 2026-02-10 - **Method**: Tier 2d deterministic integration replay (serialized module matrix). - **Tests**: PASS (Plugin matrix 314/314: Abstractions 79, Host 105, Registry 65, Sandbox 47, SDK 7, HelloWorld sample 11). - **Tier 2 Evidence**: docs/qa/feature-checks/runs/plugin/plugin-host-with-assembly-isolation/run-008/tier2-integration-check.json - **Outcome**: Checked Plugin behavior remains healthy in continued replay. ## Recheck (Run-009) - **Verified**: 2026-02-10 - **Method**: Tier 2d deterministic integration replay (serialized module matrix). - **Tests**: PASS (Plugin matrix 314/314: Abstractions 79, Host 105, Registry 65, Sandbox 47, SDK 7, HelloWorld sample 11). - **Tier 2 Evidence**: docs/qa/feature-checks/runs/plugin/plugin-host-with-assembly-isolation/run-009/tier2-integration-check.json - **Outcome**: Checked Plugin behavior remains healthy in continued replay. ## Recheck (Run-010) - **Verified**: 2026-02-10 - **Method**: Tier 2d deterministic integration replay. - **Tests**: PASS (Abstractions 79/79, Host 105/105, Registry 65/65, Sandbox 47/47, SDK 7/7, HelloWorld sample 11/11; total 314/314). - **Tier 2 Evidence**: docs/qa/feature-checks/runs/plugin/plugin-host-with-assembly-isolation/run-010/tier2-integration-check.json - **Outcome**: Checked plugin behavior remains healthy in continued replay. ## Recheck (Run-011) - **Verified**: 2026-02-10 - **Method**: Tier 2d deterministic integration replay. - **Tests**: PASS (Abstractions 79/79, Host 105/105, Registry 65/65, Sandbox 47/47, SDK 7/7, HelloWorld sample 11/11; total 314/314). - **Tier 2 Evidence**: docs/qa/feature-checks/runs/plugin/plugin-host-with-assembly-isolation/run-011/tier2-integration-check.json - **Outcome**: Checked plugin behavior remains healthy in continued replay. ## Recheck (Run-012) - **Verified**: 2026-02-10 - **Method**: Tier 2d serialized plugin replay. - **Tests**: PASS (Abstractions 79/79, Host 105/105, Registry 65/65, Sandbox 47/47, SDK 7/7, HelloWorld 11/11; total 314/314). - **Tier 2 Evidence**: docs/qa/feature-checks/runs/plugin/plugin-host-with-assembly-isolation/run-012/tier2-integration-check.json - **Outcome**: Checked plugin behavior remains healthy in continued replay. ## Recheck (Run-013) - **Verified**: 2026-02-10 - **Method**: Tier 2d deterministic integration replay with fresh command-output evidence. - **Tests**: PASS (105/105; Plugin matrix 314/314: Abstractions 79, Host 105, Registry 65, Sandbox 47, SDK 7, HelloWorld sample 11.) - **Tier 2 Evidence**: docs/qa/feature-checks/runs/plugin/plugin-host-with-assembly-isolation/run-013/tier2-integration-check.json - **Outcome**: Checked Plugin behavior remains healthy in continued replay.