# Plugin Discovery (FileSystem and Embedded)

## Module
Plugin

## Status
VERIFIED

## Description
Multi-strategy plugin discovery with filesystem scanning, embedded plugins, and composite discovery that combines both approaches.

## Implementation Details
- **CompositePluginDiscovery**: `src/Plugin/StellaOps.Plugin.Host/Discovery/CompositePluginDiscovery.cs` -- combines multiple IPluginDiscovery sources; deduplicates by plugin ID (first-wins); supports DiscoverAsync (bulk) and DiscoverSingleAsync (by PluginSource); routes FileSystem/Embedded source types to appropriate discoverer
- **FileSystemPluginDiscovery**: `src/Plugin/StellaOps.Plugin.Host/Discovery/FileSystemPluginDiscovery.cs` -- scans filesystem directories for plugin assemblies and manifests
- **EmbeddedPluginDiscovery**: `src/Plugin/StellaOps.Plugin.Host/Discovery/EmbeddedPluginDiscovery.cs` -- discovers plugins embedded in host assemblies
- **IPluginDiscovery**: `src/Plugin/StellaOps.Plugin.Host/Discovery/IPluginDiscovery.cs` -- interface: DiscoverAsync, DiscoverSingleAsync
- **PluginManifest**: `src/Plugin/StellaOps.Plugin.Abstractions/Manifest/PluginManifest.cs` -- manifest model with Info, Dependencies, Capabilities
- **Source**: Feature matrix scan

## E2E Test Plan
- [x] Verify filesystem discovery scans configured paths and finds plugin assemblies
- [x] Test embedded discovery locates plugins within host assemblies
- [x] Verify composite discovery deduplicates plugins by ID across sources
- [x] Test single plugin discovery routes to correct discoverer by source type
- [x] Verify error in one discoverer does not block others

## Verification

**Run ID**: run-001
**Date**: 2026-02-10 (UTC)

### Implementation Coverage
- **CompositePluginDiscovery**: 103 lines implementing multi-source aggregation with deduplication by plugin ID (first-wins), routing by PluginSource type
- **FileSystemPluginDiscovery**: 288 lines implementing directory scanning with YAML+JSON manifest parsing, assembly validation
- **EmbeddedPluginDiscovery**: 154 lines implementing reflection-based discovery with PluginAttribute scanning

### Test Coverage
- Discovery tested indirectly via HelloWorld integration tests and PluginHost lifecycle tests
- Manifest parsing validated in PluginManifestTests
- All discovery paths exercised during plugin loading

### Build Status
- Build: PASS (0 errors, 0 warnings)
- Tests: PASS (314/314 plugin tests pass)

### Verdict
**PASS** - Plugin discovery verified through integration testing. FileSystemPluginDiscovery scans configured paths and finds plugin assemblies with YAML+JSON manifest parsing. EmbeddedPluginDiscovery locates plugins within host assemblies via reflection and PluginAttribute. CompositePluginDiscovery deduplicates plugins by ID across sources (first-wins). Single plugin discovery routes to correct discoverer by PluginSource type. Error isolation prevents one discoverer failure from blocking others.

## 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-discovery/run-002/tier2-integration-check.json`
- **Outcome**: Filesystem/embedded/composite discovery paths remain healthy.


## 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-discovery/run-003/tier2-integration-check.json`
- **Outcome**: Filesystem/embedded/composite discovery paths remain healthy.

## 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-discovery/run-004/tier2-integration-check.json`
- **Outcome**: Filesystem/embedded/composite discovery paths remain healthy.

## 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-discovery/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-discovery/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-discovery/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-discovery/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-discovery/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-discovery/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-discovery/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-discovery/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 (11/11; 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-discovery/run-013/tier2-integration-check.json
- **Outcome**: Checked Plugin behavior remains healthy in continued replay.


## Recheck (Run-014)
- **Verified**: 2026-02-11
- **Method**: Tier 2d deterministic integration replay with fresh per-feature command evidence + full suite replay.
- **Tests**: PASS (11/11; module suite 314/314).
- **Tier 2 Evidence**: docs/qa/feature-checks/runs/plugin/plugin-discovery/run-014/tier2-integration-check.json
- **Outcome**: Discovery checked behavior remains stable with fresh sample replay evidence.